A method and device for predicting non-uniform temperature fields in urban three-dimensional street canyons

Abstract

The present invention discloses a method and device for predicting a non-uniform temperature field within a three-dimensional urban street canyon. The method comprises: constructing a three-dimensional urban street canyon model and dividing it into several surface zones; calculating sky view parameters for each surface zone; generating a shadow distribution field for each surface zone; obtaining the solar shortwave radiation flux and ground longwave radiation flux for each surface zone based on the sky view parameters and shadow distribution field for each surface zone; calculating the sensible heat flux and latent heat flux for each surface zone; generating a non-uniform temperature field based on the sensible heat flux, latent heat flux, solar shortwave radiation flux, and ground longwave radiation flux for each surface zone; dividing the illuminated zone into a shadowed zone based on the shadow distribution field for each surface zone; and calculating the average temperature of the illuminated and shadowed zones based on the non-uniform temperature field. The present invention achieves real-time and accurate prediction of the non-uniform temperature field within a three-dimensional urban street canyon while reducing computing resource consumption.

Description

Technical Field

[0001] The present invention belongs to the technical field of temperature field prediction within a three-dimensional urban street canyon, and in particular relates to a method and device for predicting a non-uniform temperature field within a three-dimensional urban street canyon. Background Art

[0002] With the acceleration of urbanization, temperature variations within urban microenvironments and their impacts on residents' lives, energy consumption, and environmental quality are receiving increasing attention from society. The increase in urban building density alters the surface energy budget, forming a complex urban street canyon canopy structure. This results in high spatial and temporal heterogeneity in temperature, humidity, wind speed, and other characteristics within the urban microenvironment. The complex spatial and temporal distribution of temperature fields at the street canyon scale not only affects the urban thermal environment and human comfort but is also closely related to energy management, building heat loads, and the occurrence of extreme weather events (such as heat waves and icy roads). Currently, common methods for simulating heterogeneous temperature fields within urban street canyons include mesoscale meteorological numerical models and computational fluid dynamics (CFD).

[0003] Mesoscale meteorological numerical models, such as the Weather Research and Forecasting Model (WRF), typically have spatial resolutions ranging from hundreds to thousands of meters, making it difficult to accurately resolve temperature variations within street canyon scales (10-100 meters). This results in limited simulation accuracy and makes it difficult to meet the needs of refined simulations. Computational fluid dynamics (CFD) methods, such as large eddy simulation (LES), can accurately simulate air flow, turbulent transport, and temperature distribution between buildings. However, they are computationally intensive and require high computing resources, making it difficult to achieve large-scale, multi-time, real-time simulations, limiting their practicality. Consequently, existing technical methods are no longer able to meet the growing demand for simulating heterogeneous temperature fields within complex urban street canyons. Summary of the Invention

[0004] To address the deficiencies in the prior art, the present invention provides a method and device for predicting non-uniform temperature fields in three-dimensional urban street canyons, which achieves real-time and accurate prediction of non-uniform temperature fields in three-dimensional urban street canyons and reduces the consumption of computing resources.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, a method for predicting a non-uniform temperature field in a three-dimensional urban street canyon is provided, comprising: constructing a three-dimensional urban street canyon model and dividing it into a plurality of surface zones; calculating sky view parameters for each surface zone; generating a shadow distribution field for each surface zone; obtaining the solar shortwave radiation flux and the ground longwave radiation flux for each surface zone based on the sky view parameters and the shadow distribution field for each surface zone; calculating the sensible heat flux and latent heat flux for each surface zone; generating a non-uniform temperature field based on the sensible heat flux, latent heat flux, solar shortwave radiation flux, and ground longwave radiation flux for each surface zone; dividing the illuminated zone into a shadowed zone based on the shadow distribution field for each surface zone; and calculating the average temperature of the illuminated zone and the shadowed zone based on the non-uniform temperature field.

[0007] Furthermore, a 3D urban street valley model was constructed and divided into several surface areas, including:

[0008] S11. Obtain street parameters of the target area in the city;

[0009] S12. Based on the model assumptions and street parameters, a three-dimensional urban street valley model is constructed, and the analytical equations of each surface area of ​​the model are obtained. The model assumptions include: (1) All buildings are independent, fixed-position rectangular blocks with a certain length, width, and height; (2) The ground in the model is an infinitely extended plane; (3) The length, width, and height extension lines of the building model are parallel to the coordinate axes. The analytical equations of each surface area of ​​the model are:

[0010] ,

[0011] in, X 、 Y 、 Z Respectively represent the coordinate positions in the three-dimensional coordinate system; x neg 、 y neg 、 z neg They represent the coordinates of the endpoints in the building model with the smallest value and closest to the negative directions of the three coordinate axes; L 、 W 、 H Respectively represent the length, width, and height of the building model along the positive directions of the three coordinate axes;

[0012] S13. Divide the surface area of ​​the constructed urban 3D street valley model into the following: the ground area at the center of the intersection is GR1; the ground area extending outward from the intersection by one road width is GR2; the remaining ground area within the street valley is GR3; the wall area extending outward from the intersection by one building height is WA1; the remaining wall area within the street valley is WA2; and the building roof is RF.

[0013] Furthermore, the sky view parameters of each surface area are calculated, including:

[0014] S21. Using the Monte Carlo method and the Marsaglia uniform sampling algorithm, a hemisphere is set at the geometric center point of each surface area, and a discretization method is adopted to obtain a set number of sampling points and rays, and the analytical equation of the ray is obtained:

[0015] ,

[0016] in, 、 The quantities are respectively N The two sets of independent variables are both in the interval Independent and uniform distribution; ensure that every two corresponding variables 、 All satisfied ;

[0017] S22, simultaneously calculating the analytical equation of the ray and the analytical equation of each surface area of ​​the model, and determining whether there is an intersection between the two sets of equations. If there is an intersection, it is determined that the ray is blocked by the building; if there is no intersection, it is determined that the ray is not blocked by the building;

[0018] S23. Count the number of rays not blocked by buildings, calculate the SVF value of each surface area, and combine it with the street aspect ratio to obtain the parameterized formula of the sky view parameter through fitting:

[0019] ,

[0020] Among them, SVF represents the sky view parameter; HWR represents the height-to-width ratio in the street canyon; a, b, c, and d are fitting parameters, and each surface area can obtain a set of parameter values.

[0021] Furthermore, a shadow distribution field of each surface area is generated, including:

[0022] S31. Name each surface area based on the geographic location, and substitute the actual solar altitude angle, solar azimuth angle, and street deflection angle into the equivalent solar azimuth angle calculation expression and the solar altitude angle projection angle calculation expression for each surface area to obtain the equivalent azimuth angle and solar altitude angle projection angle for each surface area;

[0023] S32, performing grid processing on each surface area, and judging whether each grid is in shadow according to the equivalent azimuth angle of each surface area and the projection angle of the solar altitude angle;

[0024] S33. Traverse all grids in each surface area to obtain shadow distribution fields of different surface areas in the three-dimensional urban street canyon.

[0025] Furthermore, the solar shortwave radiation flux and the ground longwave radiation flux of each surface area are obtained, including:

[0026] S41. Based on the shadow distribution field of different surface areas in the three-dimensional urban street canyon, calculate the ratio of the number of shadowed grid points in the selected area of ​​each surface area to the total number of grid points in the area, and obtain the proportion of direct solar shortwave radiation received in the total area of ​​the area. The expression is:

[0027] ,

[0028] in, is the proportion of direct solar shortwave radiation received by the selected surface area; is the number of shaded grid points in the selected area; is the total number of grid points;

[0029] S42. Calculate the long-wave radiation emitted by each surface area:

[0030] ,

[0031] Where L represents the long-wave radiation emission; em is the emissivity of each surface area; δ is the Stefan-Boltzmann constant; T is the surface temperature of each surface area of ​​the building;

[0032] S43. Based on the proportion of direct solar shortwave radiation received in the selected surface area, the amount of longwave radiation emitted by each surface area, the material albedo and emissivity of the urban three-dimensional street valley surface area, and the sky view parameters of each surface area, the absorption and reflection processes of solar shortwave radiation and ground longwave radiation in the urban three-dimensional street canyon are calculated to obtain the solar shortwave radiation flux and ground longwave radiation flux in different areas of each surface area.

[0033] Furthermore, the sensible heat flux and latent heat flux of each surface area are calculated, including:

[0034] S51. Construct a multi-layer turbulent heat exchange model based on model assumptions, wherein the model assumptions include: assuming that the top of the entire urban canopy atmosphere is higher than the height of buildings, and dividing the canopy atmosphere into an inner canopy atmosphere with a height lower than the height of buildings and an outer canopy atmosphere with a height higher than the height of buildings;

[0035] S52. Based on the constructed multi-layer turbulent heat exchange model, the calculation formulas for the sensible heat flux and latent heat flux of each surface area are obtained:

[0036] ,

[0037] ,

[0038] in, Surface area The sensible heat flux; Surface area latent heat flux; is the atmospheric density of the first layer of the atmospheric numerical model; is the heat capacity per unit mass of dry air; is the latent heat of phase change per unit mass of water vapor at room temperature; Surface area The aerodynamic impedance coefficient between the canopy atmosphere and the atmosphere; Surface area The weight coefficient of the area of ​​​​the total surface area; is the ratio of the area of ​​the wetted surface of surface zone i to the total area of ​​surface zone i; Surface area temperature; Surface area Specific humidity; is the temperature of the inner canopy atmosphere or the outer canopy atmosphere, is the specific humidity of the inner canopy atmosphere or the outer canopy atmosphere; when When representing the RF area, is the outer canopy atmosphere; otherwise, is the inner canopy atmosphere;

[0039] S53. Based on the assumption that the heat storage of the air in the inner and outer canopy atmosphere is zero and the wall surface does not participate in the latent heat transfer process, the energy balance relationship between different surface areas and the urban canopy atmosphere is obtained, and the unknown variables are solved. 、 、 and , the sensible heat flux and latent heat flux of each surface are obtained, and the energy balance relationship between different surface areas and the inner and outer canopy atmosphere is as follows:

[0040] ,

[0041] ,

[0042] ,

[0043] ,

[0044] in, is the sensible heat flux in GR1 region, is the sensible heat flux on the surface of the sth block in the GR2 region, is the sensible heat flux on the surface of the sth block in the GR3 region, is the sensible heat flux of the outer canopy atmosphere, is the sensible heat flux of the inner canopy atmosphere, is the latent heat flux in GR1 region, is the latent heat flux on the surface of the sth block in the GR2 region, is the latent heat flux on the surface of the sth block in the GR3 region, is the latent heat flux of the outer canopy atmosphere, is the latent heat flux of the inner canopy atmosphere; 、 、 、 Obtained by the following calculation expression:

[0045] ,

[0046] ,

[0047] ,

[0048] ,

[0049] in, 、 are the temperature and specific humidity of the upper atmosphere, respectively; 、 are the aerodynamic impedance coefficients between the outer canopy atmosphere and the upper atmosphere, and between the inner canopy atmosphere and the outer canopy atmosphere, respectively; 、 are the temperatures of the outer canopy atmosphere and the inner canopy atmosphere, respectively. 、 are the specific humidity of the outer canopy atmosphere and the specific humidity of the inner canopy atmosphere, respectively.

[0050] Furthermore, a non-uniform temperature field is generated based on the sensible heat flux, latent heat flux, solar shortwave radiation flux and ground longwave radiation flux of each surface area, including:

[0051] S61. Based on the sensible heat flux, latent heat flux, solar shortwave radiation flux, and ground longwave radiation flux of each surface zone, establish an energy budget model for each surface zone, including:

[0052] ,

[0053] in, Surface area The net heat flux; Surface area The sensible heat flux; Surface area latent heat flux; Surface area The shortwave radiation flux; Surface area The long-wave radiation flux; Surface area Other calories

[0054] S62. Based on the forced-balance method and the energy budget model of each surface area, the temperature change value of each surface area is calculated to obtain the non-uniform temperature field in the three-dimensional urban street canyon. The specific calculation expression is:

[0055] ,

[0056] in, is the surface temperature of any surface area; is the rate of change of temperature with time; is the net heat flux obtained from the energy budget model for each surface zone as a forcing term; is the surface temperature inside the building, as a recovery term; is the oscillation period of the forcing term; is the thermal diffusivity of the building material; C is the specific heat capacity of the building material.

[0057] Furthermore, based on the shadow distribution field of each surface area, the illuminated area and the shadow area are divided, including:

[0058] S71. Based on the obtained non-uniform temperature field of different surface areas within the three-dimensional urban street canyon, calculate the ratio of the number of shadow grid points in any area of ​​the ground to the total number of grid points in the area, obtain the shadow area ratio coefficient in the selected area of ​​the ground, and divide the ground into illuminated areas and shadow areas based on the shadow division rule of the ground;

[0059] The shadow area ratio coefficient expression is:

[0060] ,

[0061] in, is the number of shaded grid points in the selected area; is the total number of grid points in the selected area; is the shadow area ratio coefficient in the selected area;

[0062] Shadow division rules include: ≤0.3, the selected area on the ground is the shadow area. When ≤0.5, the selected area on the ground is the half-shadow area. When 0.5< ≤0.7, the selected area on the ground is a semi-illuminated area. When ≤1, the selected area on the ground is the illumination area;

[0063] S72, based on the equivalent solar azimuth angle of each wall surface area , the wall surface is divided into shadow area and light area, among which the shadow area ≤180 degrees, illumination area >180 degrees.

[0064] Furthermore, the average temperature of the illuminated area and the shadowed area is calculated based on the non-uniform temperature field, including:

[0065] S73. Distinguish between daytime and nighttime based on the actual solar altitude angle. If the actual solar altitude angle is greater than 0.05 rad, it is daytime; otherwise, it is nighttime.

[0066] S74. Based on the obtained non-uniform temperature field in the three-dimensional urban street canyon, perform arithmetic average calculation on the surface temperatures of the illuminated area and the shadowed area of ​​the wall or ground during the day to obtain the average temperature of the illuminated area and the shadowed area of ​​the wall or ground. The specific calculation formula is:

[0067] ,

[0068] ,

[0069] in, 、 are the average temperatures of the illuminated and shadowed areas of the wall or floor, respectively; 、 are the temperatures of the kth surface in the illuminated area and shadowed area of ​​the wall or ground respectively; n1 and n2 are the total number of surfaces in the illuminated area and shadowed area of ​​the wall or ground respectively.

[0070] In a second aspect, a device for predicting a non-uniform temperature field in a three-dimensional urban street canyon is provided, comprising a storage medium and a processor; the storage medium is used to store instructions; and the processor is used to operate according to the instructions to execute the method for predicting a non-uniform temperature field in a three-dimensional urban street canyon described in the first aspect.

[0071] Compared with the prior art, the present invention achieves the following beneficial effects: the present invention constructs a three-dimensional urban street canyon model and divides it into several surface areas; calculates the sky view parameters of each surface area; generates a shadow distribution field for each surface area; obtains the solar shortwave radiation flux and the ground longwave radiation flux for each surface area based on the sky view parameters and the shadow distribution field of each surface area; calculates the sensible heat flux and latent heat flux of each surface area; generates a non-uniform temperature field based on the sensible heat flux, latent heat flux, solar shortwave radiation flux, and ground longwave radiation flux of each surface area; divides the illuminated area into the shadowed area based on the shadow distribution field of each surface area; and calculates the average temperature of the illuminated area and the shadowed area based on the non-uniform temperature field. Thus, the present invention achieves real-time and accurate prediction of the non-uniform temperature field in the three-dimensional urban street canyon and reduces the consumption of computing resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is an overall flow chart of a method for predicting a non-uniform temperature field in a three-dimensional urban street canyon provided by an embodiment of the present invention;

[0073] Figure 2 2. 3D cross street valley model schematic diagram according to an embodiment of the present invention;

[0074] Figure 3 is a structural diagram of a multi-layer turbulent heat exchange model in an embodiment of the present invention (in the figure, H can represent both latent heat flux and sensible heat flux; T represents temperature; and Q represents specific humidity);

[0075] Figure 4 is the surface albedo change curve under different HWRs solved by the method of the present invention, wherein, (1) is the surface albedo change curve when HWR=0.25, (2) is the surface albedo change curve when HWR=0.5, (3) is the surface albedo change curve when HWR=1, (4) is the surface albedo change curve when HWR=2, and (5) is the surface albedo change curve when HWR=4;

[0076] Figure 5 is the surface temperature variation curve of different surfaces under a fixed HWR solved by the method of the present invention;

[0077] Figure 6 It is a comparison diagram of the surface temperature of the ground illuminated area and the ground shadow area under a fixed HWR solved by the method of the present invention;

[0078] Figure 7 This is a comparison diagram of the surface temperatures of the illuminated area and the shadowed area of ​​the wall under a fixed HWR solved using the method of the present invention. DETAILED DESCRIPTION

[0079] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0080] Example 1

[0081] A method for predicting a non-uniform temperature field in a three-dimensional urban street canyon comprises: constructing a three-dimensional urban street canyon model and dividing it into a plurality of surface zones; calculating sky view parameters for each surface zone; generating a shadow distribution field for each surface zone; obtaining the solar shortwave radiation flux and the ground longwave radiation flux for each surface zone based on the sky view parameters and the shadow distribution field for each surface zone; calculating the sensible heat flux and latent heat flux for each surface zone; generating a non-uniform temperature field based on the sensible heat flux, latent heat flux, solar shortwave radiation flux, and ground longwave radiation flux for each surface zone; dividing the illuminated zone and the shadowed zone based on the shadow distribution field for each surface zone; and calculating the average temperature of the illuminated zone and the shadowed zone based on the non-uniform temperature field.

[0082] like Figures 1 to 7 As shown, the present invention can model the structure of urban cross-canyons and perform parameterized calculations of sky view parameters for each surface area within the canyon based on the Monte Carlo method and geometric optics principles. Based on geometric principles, it simulates the dynamic changes in shadow areas within each surface area within the canyon, generating a dynamic shadow distribution field within the canyon. It also achieves refined simulation of the absorption and reflection processes of solar shortwave radiation and surface longwave radiation within the canyon, constructs a multi-layer turbulent heat exchange model, and dynamically calculates the radiation flux, sensible heat flux, and latent heat flux within the canyon, thereby determining the total energy budget for each surface within the canyon. Based on the forced-balance method, it achieves refined predictions of the temperature field for each surface within the canyon and, combined with shadow demarcation rules, outputs the temperatures of shadow and illuminated areas. This invention can precisely characterize the heterogeneous temperature field within urban cross-canyons, improving the accuracy of temperature field predictions within urban microenvironments and enhancing urban services.

[0083] like Figure 1 As shown, the specific steps of the method for predicting the non-uniform temperature field in a three-dimensional urban street canyon described in the present invention are as follows.

[0084] S1. Construct a three-dimensional urban cross street valley model and divide it into several surface areas.

[0085] S11. Obtain street parameters of the cross street valleys within the target area through actual surveying or statistical analysis. Street parameters include height-to-width ratio (HWR), length-to-height ratio (LHR), and characteristic length of the street.

[0086] ,

[0087] ,

[0088] Among them, L, W, and H represent the length, width, and height of the building model along the positive directions of the three coordinate axes, respectively.

[0089] S12. Based on the model assumptions and the obtained street parameters, the analytical equations for each surface area in the model are obtained. The model assumptions include: (1) All buildings are independent, fixed-position rectangular blocks with a certain length, width, and height; (2) The ground in the model is an infinitely extended plane; (3) The length, width, and height extension lines of the building model are parallel to the coordinate axes.

[0090] The analytical equations for each surface area of ​​the model are:

[0091] ,

[0092] in, X 、 Y 、 ZRespectively represent the coordinate positions in the three-dimensional coordinate system; x neg 、 y neg 、 z neg They represent the coordinates of the endpoints in the building model with the smallest value and closest to the negative directions of the three coordinate axes; L 、 W 、 H They represent the length, width, and height of the building model along the positive directions of the three coordinate axes respectively.

[0093] S13, such as Figure 2 As shown in the figure, the surface area of ​​the constructed urban three-dimensional cross street canyon model is divided. The specific division rules are: the ground area at the center of the intersection is the GR1 area; the ground area extending outward from the intersection by the width of a road is the GR2 area; the remaining ground area in the street canyon is the GR3 area; the wall area extending outward from the intersection by the height of a building is the WA1 area; the remaining wall area in the street canyon is the WA2 area; and the roof of the building is the RF area.

[0094] S2. Calculate the sky view parameters of each surface area based on the Monte Carlo method and the principles of geometric optics.

[0095] S21. Using the Monte Carlo method and the Marsaglia uniform sampling algorithm, a hemisphere is set at the geometric center point of each surface area, and a discretization method is adopted to obtain 100,000 sampling points, generate 100,000 rays, and obtain the analytical equation of the ray.

[0096] Based on the Marsaglia method, the coordinate set of each point on the hemisphere is obtained. The expression of the Marsaglia method is:

[0097]

[0098] in, 、 The quantities are respectively N The two sets of independent variables are both in the interval Independent and uniform distribution; ensure that every two corresponding variables 、 All satisfied ; The coordinates of the point on the spherical surface that satisfies the first three conditions of the expression of the Marsaglia method in the three-dimensional rectangular coordinate system; are the coordinates of all points obtained after uniform sampling on the surface of the unit sphere;

[0099] The analytical equation of the ray is:

[0100] ,

[0101] in, X 、 Y 、 Z They represent the coordinate positions in the three-dimensional coordinate system respectively.

[0102] S22. Combine the analytical equations of the rays and the analytical equations of each surface area of ​​the model, and use a computer to calculate and determine whether there is an intersection between the two sets of equations. If there is an intersection, it is determined that the ray is blocked by the building; if there is no intersection, it is determined that the ray is not blocked by the building.

[0103] S23. Count the number of rays not blocked by buildings, calculate the SVF value of each surface area based on the simplified formula for calculating the sky view parameter, and combine it with the street aspect ratio to obtain the parameterized formula of the sky view parameter through fitting.

[0104] A brief formula for the sky view parameter is:

[0105] ,

[0106] Where SVF represents the sky field of view parameter; m represents the number of rays that enter the sky without being blocked; and N represents the total number of rays.

[0107] The parameterization formula of the sky view parameter is:

[0108] ,

[0109] Among them, SVF represents the sky view parameter; HWR represents the height-to-width ratio in the street canyon; a, b, c, and d are fitting parameters, and each surface area can obtain a set of parameter values. Generally, a is a negative value, and b, c, and d are positive values ​​between 0 and 2.

[0110] S3. Establish an urban light and shadow model based on geometric principles to generate a dynamic shadow distribution field for each surface area.

[0111] S31. Name each surface area based on the geographical orientation. Based on the actual solar altitude angle, solar azimuth angle, and street deflection angle, substitute them into the equivalent solar azimuth angle calculation expression and the solar altitude angle projection angle calculation expression for different surface areas to obtain the equivalent azimuth angle and solar altitude angle projection angle of each surface area.

[0112] The naming rules for each surface are as follows: starting from the west wall of the building at the southeast corner, the wall is named W1, and in a clockwise direction, the eight walls are named W1 to W8 respectively; starting from the road on the south side, the combined area of ​​the road and the center area of ​​the intersection is named G1, and in a clockwise direction, the combined road surface areas on the south, west, north, and east sides can be named G1 to G4 respectively.

[0113] The equivalent solar azimuth angle calculation expressions for different surfaces include:

[0114] The calculation expression of the equivalent solar azimuth angle of each wall surface is:

[0115] ,

[0116] in, ~ The equivalent solar azimuth angle of wall W1-W8 is in degrees. is the actual solar azimuth, For modular calculation, we take Divide by The remainder of .

[0117] The calculation expression of the equivalent solar azimuth angle of each ground surface is:

[0118] ,

[0119] in, ~ is the equivalent solar azimuth of the ground region G1-G4, in degrees; is the actual solar azimuth.

[0120] The calculation expression of the projection angle of the sun altitude angle on each surface of the wall is:

[0121] ,

[0122] ,

[0123] in, is the projection angle of the sun's altitude in the north-south direction; is the projection angle of the sun’s altitude in the east-west direction; is the solar altitude angle; is the equivalent solar azimuth of the current wall.

[0124] The calculation expression of the projection angle of the sun altitude angle on each surface of the wall is:

[0125] ,

[0126] in, It is the projection angle of the solar altitude in the north-south direction when the solar azimuth angle is greater than 270°; It is the projection angle of the solar altitude angle in the east-west direction when the solar azimuth angle is greater than 270°; It is the projection angle of the solar altitude in the north-south direction when the solar azimuth angle is less than 90°; It is the projection angle of the solar altitude angle in the east-west direction when the solar azimuth angle is less than 90°; It is the projection angle of the solar altitude in the north-south direction when the solar azimuth angle is greater than 180° and less than 270°; It is the projection angle of the solar altitude angle in the east-west direction when the solar azimuth angle is greater than 180° and less than 270°; It is the projection angle of the solar altitude in the north-south direction when the solar azimuth angle is greater than 90° and less than 180°; It is the projection angle of the solar altitude angle in the east-west direction when the solar azimuth angle is greater than 90° and less than 180°; is the solar altitude angle; is the equivalent solar azimuth of the current ground area.

[0127] S32. Grid each surface area. The grid size depends on the characteristic length of the street and the refinement requirements. Based on the geometric relationship of the model, the equivalent azimuth angle of each surface area and the projection angle of the solar altitude angle are used to determine whether each grid is in shadow. The specific shadow judgment expression is:

[0128] Assume that the selected wall has a total grid point The shadow judgment expression of the wall is the following two sets of equations. A grid point (i1, j1) is considered to be in the shadow if it satisfies one of the following two equations, where i1=1,2,…,n1; j1=1,2,…,m1:

[0129] ,

[0130] ,

[0131] in, is the angle at the grid point (i1, j1) formed by the grid point, the perpendicular point A1 of the grid point on the roof plane (hereinafter referred to as the "roof plane"), and the perpendicular point A2 of the perpendicular point A1 on the opposite wall, with the perpendicular point A2 as the vertex; The angle at the grid point (i1, j1) is formed by the grid point, the vertical point A2, and the vertical point A3 on the wall of the other side of the building where the vertical point A2 is located, with the vertical point A3 as the vertex; The angle at the grid point (i1, j1) is formed by the grid point, the vertical point A1, and the vertical point A4 on the wall opposite to the wall of the building where the vertical point A1 is located, with the vertical point A4 as the vertex.

[0132] Assuming that the selected ground has a total of n2*m2 grid points, the ground shadow determination expression is the following six sets of equations. A grid point (i2, j2) is considered to be in shadow if it satisfies one of the following six equations, where i2=1,2,…,n2; j2=1,2,…,m2:

[0133] ,

[0134] ,

[0135] ,

[0136] ,

[0137] ,

[0138] ,

[0139] in, The angle at the grid point (i2, j2) is formed by the grid point, the perpendicular point B1 of the grid point on the wall to its left, and the perpendicular point B2 of the perpendicular point B1 on the roof surface, with the grid point as the vertex. is the angle at the grid point (i2, j2) consisting of the grid point, the perpendicular point B1a of the grid point on the wall to its right, and the perpendicular point B2a of the perpendicular point B1a on the roof surface, with the grid point as its vertex; The angle at the grid point (i2, j2) is formed by the grid point, the perpendicular point B1, and the perpendicular point B3 on the wall of the other side of the building where the perpendicular point B1 is located, with the perpendicular point B3 as the vertex; The angle at the grid point (i2, j2) is formed by the grid point, the perpendicular point B1a, and the perpendicular point B3a on the wall of the other side of the building where the perpendicular point B1a is located, with the perpendicular point B3a as the vertex; The angle at grid point (i2, j2) is formed by the grid point, the grid point's perpendicular point B4 on the roof, and the perpendicular point B5 on the plane of the wall on the other side of the building near the intersection where the perpendicular point B1 is located. This angle is positive only when the grid point is in the GR1 zone and is negative in all other zones. The angle at the grid point (i2, j2) is formed by the grid point, the perpendicular point B4, and the perpendicular point B5a on the plane of the wall opposite to the wall of the building where the perpendicular point B1 is located, with the perpendicular point B5a as its vertex. and Represents logical AND and logical OR respectively.

[0140] S33. Use a computer to traverse all grids in each surface area to obtain the shadow distribution field of different surface areas in the three-dimensional urban cross street valley.

[0141] S4. Based on the sky view parameters and shadow distribution field of each surface area, the multiple reflection and absorption processes of solar shortwave radiation and ground longwave radiation are calculated to obtain the solar shortwave radiation flux and ground longwave radiation flux of each surface area.

[0142] S41. Based on the shadow distribution field of different surface areas in the three-dimensional urban cross street valley, calculate the ratio of the number of grid points with or without shadows in the selected area of ​​different surface areas to the total number of grid points in the area, and obtain the proportion of direct solar shortwave radiation received in the total area of ​​the area. The expression is:

[0143] ,

[0144] in, is the proportion of direct solar shortwave radiation received by the selected surface area; is the number of shaded grid points in the selected area; is the total number of grid points.

[0145] S42. Based on the ground long-wave radiation radiation calculation formula, obtain the long-wave radiation radiation emitted by each surface. The ground long-wave radiation radiation calculation formula is:

[0146] ,

[0147] Where L represents the long-wave radiation emission; em is the emissivity of each surface, which is set to 0.97; δ is the Stefan-Boltzmann constant, which is ; T is the surface temperature of each surface of the building.

[0148] S43. Assuming that there is no specular reflection in the reflection process, only diffuse reflection, and ignoring the absorption and reflection effects of the atmosphere on radiation, the absorption and reflection processes of solar shortwave radiation and ground longwave radiation within the street canyon are calculated by combining the material albedo and emissivity of the street canyon surface and the sky view parameters of each surface. This process is repeated four times to obtain the solar shortwave radiation flux and ground longwave radiation flux of surface area i within the street canyon. The specific expression is:

[0149] The initial absorption and reflection process of solar shortwave radiation is expressed as follows:

[0150] ,

[0151] ,

[0152] in, is the incident solar shortwave radiation; is the solar shortwave radiation absorbed by surface area i during the first absorption and reflection process; is the solar shortwave radiation reflected by surface area i during the first absorption and reflection process; is the proportion of direct solar shortwave radiation received in surface zone i; is the albedo of the street valley surface material; Can represent any surface (such as 、 、 、 wait).

[0153] The expressions for the subsequent absorption and reflection processes of solar shortwave radiation are:

[0154] ,

[0155] ,

[0156] ,

[0157] ,

[0158] in, is the solar shortwave radiation emitted into the sky by surface area i during the pth absorption and reflection process; is the solar shortwave radiation reflected by surface area i to other building surfaces or the ground during the pth absorption and reflection process; is the solar shortwave radiation reflected by other building surfaces or the ground to surface area i during the pth absorption and reflection process; 、 is the solar shortwave radiation absorbed by surface area i during the pth and p+1th absorption and reflection processes; 、 is the solar shortwave radiation reflected by surface area i during the p-th and p+1-th absorption and reflection processes; is the sky view parameter of surface area i; order p=1,2,3,4.

[0159] The initial absorption and reflection process of ground long-wave radiation is expressed as follows:

[0160] ,

[0161] ,

[0162] in, It is the downward longwave radiation of the atmosphere; is the long-wave radiation emitted by surface area i itself; is the long-wave radiation absorbed by surface area i during the first absorption and reflection process; is the long-wave radiation reflected by surface area i during the first absorption and reflection process; em is the emissivity of each surface, which is set to 0.97; is the sky view parameter of surface area i; subscript Can represent any surface (such as 、 、 、 wait).

[0163] The subsequent absorption and reflection processes of the ground long-wave radiation are expressed as follows:

[0164] ,

[0165] ,

[0166] ,

[0167] ,

[0168] in, is the long-wave radiation emitted into the sky by surface area i during the p-th absorption and reflection process; is the long-wave radiation reflected by surface area i to other building surfaces or the ground during the p-th absorption and reflection process; is the long-wave radiation reflected by other building surfaces or the ground to surface area i during the p-th absorption and reflection process; 、 is the long-wave radiation absorbed by surface area i during the p-th and p+1-th absorption and reflection processes; 、 is the long-wave radiation reflected by surface area i during the p-th and p+1-th absorption and reflection processes; the number p=1, 2, 3, 4.

[0169] After repeating the calculation four times, the magnitude of the remaining radiation participating in the reflection process is extremely small and can be ignored. The long-wave radiation absorption of each surface and the radiation incident on the sky are obtained.

[0170] Of the reflected radiation, part of it will be reflected into the sky, and the remaining part will be reflected onto a building surface or the ground. This part of the radiation reflected onto a building surface or the ground will be partially absorbed by the surface, and the remaining part will continue to be diffusely reflected. The ratio of this absorption and reflection depends on the albedo of the corresponding surface material.

[0171] S44. Calculate the surface albedo of urban areas based on the solar shortwave radiation flux at different locations on each surface area. The specific calculation expression is:

[0172] ,

[0173] in, is the incident solar shortwave radiation; 、 、 、 It is the sum of the solar shortwave radiation reflected back to the sky by each surface partition from the 1st to the 4th time.

[0174] S5. Construct a multi-layer turbulent heat exchange model and calculate the sensible heat flux and latent heat flux of each surface area.

[0175] S51, such as Figure 3 As shown, the model assumptions of the multi-layer turbulent heat exchange model are proposed. The model assumptions include: assuming that the top of the entire urban canopy atmosphere is higher than the height of buildings, and dividing the canopy atmosphere into the inner canopy atmosphere (lower than the height of buildings) and the outer canopy atmosphere (higher than the height of buildings), which together with the upper atmosphere constitute a multi-layer model.

[0176] S52. Calculate the sensible heat flux and latent heat flux of each surface based on the calculation formula of sensible heat flux and latent heat flux. The calculation formula of sensible heat flux and latent heat flux is expressed as follows:

[0177] ,

[0178] ,

[0179] in, Surface area The sensible heat flux; Surface area latent heat flux; is the atmospheric density of the first layer of the atmospheric numerical model; is the heat capacity per unit mass of dry air; is the latent heat of phase change per unit mass of water vapor at room temperature; Surface area The aerodynamic impedance coefficient between the canopy atmosphere and the atmosphere; Surface area The weight coefficient of the area of ​​​​the total surface area; is the ratio of the area of ​​the wetted surface of surface zone i to the total area of ​​surface zone i; Surface area temperature; Surface area Specific humidity; is the temperature of the inner canopy atmosphere or the outer canopy atmosphere, is the specific humidity of the inner canopy atmosphere or the outer canopy atmosphere; when When representing the RF area, is the outer canopy atmosphere; otherwise, It is the inner canopy atmosphere.

[0180] S53. Based on the assumption that the heat storage of the air in the inner and outer canopy atmosphere is zero and the wall surface does not participate in the latent heat transfer process, the energy balance relationship between different surface areas and the urban canopy atmosphere is obtained, and the unknown variables are solved. 、 、 and , the sensible heat flux and latent heat flux of each surface are obtained, and the energy balance relationship between different surface areas and the inner and outer canopy atmosphere is as follows:

[0181] ,

[0182] ,

[0183] ,

[0184] ,

[0185] in, is the sensible heat flux in GR1 region, is the sensible heat flux on the surface of the sth block in the GR2 region, is the sensible heat flux on the surface of the sth block in the GR3 region, is the sensible heat flux of the outer canopy atmosphere, is the sensible heat flux of the inner canopy atmosphere, is the latent heat flux in GR1 region, is the latent heat flux on the surface of the sth block in the GR2 region, is the latent heat flux on the surface of the sth block in the GR3 region, is the latent heat flux of the outer canopy atmosphere, is the latent heat flux of the inner canopy atmosphere. 、 、 、 Obtained by the following calculation expression:

[0186] ,

[0187] ,

[0188] ,

[0189] ,

[0190] in, 、 are the temperature and specific humidity of the upper atmosphere, respectively; 、 are the aerodynamic impedance coefficients between the outer canopy atmosphere and the upper atmosphere, and between the inner canopy atmosphere and the outer canopy atmosphere, respectively; 、 are the temperatures of the outer canopy atmosphere and the inner canopy atmosphere, respectively. 、 are the specific humidity of the outer canopy atmosphere and the specific humidity of the inner canopy atmosphere, respectively.

[0191] S6. Based on the sensible heat flux, latent heat flux, solar shortwave radiation flux and ground longwave radiation flux of each surface area, the forced-balance method is combined with the energy budget to generate a non-uniform temperature field, including:

[0192] S61. Based on the sensible heat flux, latent heat flux, solar shortwave radiation flux, and ground longwave radiation flux of each surface zone, establish an energy budget model for each surface zone, including:

[0193] ,

[0194] in, Surface area The net heat flux; Surface area The sensible heat flux; Surface area latent heat flux; Surface area The shortwave radiation flux; Surface area The long-wave radiation flux; Surface area Other heat (such as anthropogenic heat, etc.); Can represent any surface (such as 、 、 、 wait).

[0195] S62. Based on the forced-balance method and the energy budget model of each surface area, the temperature change value of each surface area is calculated to obtain the non-uniform temperature field in the three-dimensional urban street canyon. The specific calculation expression is:

[0196] ,

[0197] in, is the surface temperature of any surface area; is the rate of change of temperature with time; is the net heat flux obtained from the energy budget model for each surface zone as a forcing term; is the surface temperature inside the building, as a recovery term; is the oscillation period of the forcing term (τ = 24 h); is the thermal diffusivity of the building material; C is the specific heat capacity of the building material.

[0198] S7. Distinguish the illuminated area and the shadow area according to the shadow division rule, and output the dynamic shadow area / illuminated area temperature result.

[0199] S71. Based on the obtained non-uniform temperature field of different surface areas within the three-dimensional urban street canyon, calculate the ratio of the number of shadow grid points in any area of ​​the ground to the total number of grid points in the area, obtain the shadow area ratio coefficient in the selected area of ​​the ground, and divide the ground into illuminated areas and shadow areas based on the shadow division rule of the ground;

[0200] The shadow area ratio coefficient expression is:

[0201] ,

[0202] in, is the number of shaded grid points in the selected area; is the total number of grid points in the selected area; is the shadow area ratio coefficient in the selected area;

[0203] Shadow division rules include: ≤0.3, the selected area on the ground is the shadow area. When ≤0.5, the selected area on the ground is the half-shadow area. When 0.5< ≤0.7, the selected area on the ground is a semi-illuminated area. When ≤1, the selected area on the ground is the illumination area.

[0204] S72, based on the equivalent solar azimuth angle of each wall surface area , the wall surface is divided into shadow area and light area, among which the shadow area ≤180 degrees, illumination area >180 degrees.

[0205] S73. Distinguish between daytime and nighttime based on the actual solar altitude angle. If the actual solar altitude angle is greater than 0.05 rad, it is daytime; otherwise, it is nighttime.

[0206] S74. Based on the obtained non-uniform temperature field within the urban three-dimensional cross street canyon, perform arithmetic average calculation on the surface temperatures of the illuminated area and the shadowed area of ​​the wall or ground during the day to obtain the average temperature of the illuminated area and the shadowed area of ​​the wall or ground. The specific calculation formula is:

[0207] ,

[0208] ,

[0209] in, 、 are the average temperatures of the illuminated and shadowed areas of the wall or floor, respectively; 、 are the temperatures of the kth surface in the illuminated area and shadowed area of ​​the wall or ground respectively; n1 and n2 are the total number of surfaces in the illuminated area and shadowed area of ​​the wall or ground respectively.

[0210] In the specific implementation, the present invention is coupled with the mesoscale meteorological numerical model WRF4.0, Nanjing and its surrounding areas are selected as the target area, the time range is set from 08:00 on October 29 to 08:00 on November 2, 2024, the time resolution is 1 hour, and the spatial resolution is 9 km. 9 km, and urban street parameters within the area were obtained using geographic data. The initial meteorological field data used in this paper uses the Global Reanalysis (FNL) data provided by the National Centers for Environmental Prediction (NECP) and the National Center for Atmospheric Research (NCAR). During the simulation period, the actual weather conditions were: sunny from October 29th to 30th; cloudy with light rain from October 31st to November 1st, with a significant decrease in solar shortwave radiation; and clearing on November 2nd.

[0211] Based on the acquired street parameters, a three-dimensional urban cross street valley model is constructed, and analytical equations of different surfaces are obtained.

[0212] Based on the obtained street parameters, the sky view parameters of each surface in the street canyon are obtained through the Monte Carlo method. These parameters are substituted into the fitting formula of the sky view parameters to obtain the sky view parameter calculation formula applicable to this scenario.

[0213] The solar azimuth and solar altitude data obtained at each moment are substituted into the equivalent solar azimuth and solar altitude projection formulas for each surface to obtain the equivalent solar azimuth and solar altitude projection angles for each surface at each moment. Each surface is gridded, and shadow analysis is performed at each grid point to obtain a refined shadow distribution field for different surfaces within the cross street canyon at each moment.

[0214] At the initial moment, the initial surface temperature of the mesoscale model was used as the initial temperature of each surface in the cross street valley model. The initial value of the ground longwave radiation was obtained according to the ground longwave radiation emission calculation formula. The solar shortwave radiation and ground longwave radiation at each moment were substituted into their respective radiation absorption and reflection formulas, and the reflection process was calculated four times continuously to obtain the longwave and shortwave radiation fluxes of each surface at each moment.

[0215] like Figure 3 Based on the temperature of different surfaces at each moment, according to the calculation formulas of sensible heat flux and latent heat flux and the energy balance relationship between different surfaces and the inner and outer canopy atmosphere, the actual sensible heat flux and latent heat flux of different surfaces are calculated, and combined with the long-wave and short-wave radiation fluxes of each surface, the energy balance of each surface at each moment is obtained.

[0216] Based on the forced-balance method, the energy balance of each surface at each moment is combined to obtain the temperature change of each surface at each moment, so as to obtain the temperature of each surface at the next moment, and use it as the initial temperature value of each surface at the next moment for calculation. The results are as follows: Figure 5 As shown in the figure, GR1 is the ground area at the center of the intersection; GR2 is the ground area extending outward from the intersection by one road width; GR3 is the remaining ground area in the street canyon; WA1 is the wall area extending outward from the intersection by one building height; WA2 is the remaining wall area in the street canyon; and RF is the roof of the building.

[0217] Finally, based on the shadow division rules of each surface, the temperatures of the shadow area and the illuminated area of ​​the wall and the ground in the street canyon are obtained. The specific results are as follows: Figure 6 and Figure 7 As shown in the figure, the surface temperatures of the street canyons, including those in the illuminated and shadowed areas, simulated by this method have all changed significantly since October 31, when Nanjing turned cloudy with light rain. Specifically, the temperature differences between the surfaces have decreased significantly, and the surface temperatures in the illuminated and shadowed areas have become more consistent. This change pattern conforms to the principles of thermodynamics.

[0218] In addition, the present invention simulates and calculates the surface albedo under different street parameters by adjusting the street height-width ratio (HWR). The specific calculation results are as follows: Figure 4 As shown in the figure, the analysis results show that as the street aspect ratio increases, the building shielding effect increases, resulting in a significant decrease in surface albedo. This change is consistent with physical rules, fully demonstrating the reliability and scientific nature of this calculation method.

[0219] Example 2

[0220] Based on the method for predicting a non-uniform temperature field in a three-dimensional urban street canyon described in Example 1, this embodiment provides a device for predicting a non-uniform temperature field in a three-dimensional urban street canyon, comprising a storage medium and a processor; the storage medium is used to store instructions; and the processor is used to operate according to the instructions to execute the method for predicting a non-uniform temperature field in a three-dimensional urban street canyon described in Example 1.

[0221] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for predicting non-uniform temperature fields in urban three-dimensional street canyons, characterized in that: include: Construct a 3D urban street canyon model and divide it into several surface areas; Calculate the sky view parameters for each surface area; Generate shadow distribution fields for each surface area; According to the sky view parameters and shadow distribution field of each surface area, the solar shortwave radiation flux and ground longwave radiation flux of each surface area are obtained; Calculate the sensible heat flux and latent heat flux for each surface area; Generate a non-uniform temperature field based on the sensible heat flux, latent heat flux, solar shortwave radiation flux and ground longwave radiation flux of each surface area; Based on the shadow distribution field of each surface area, the illuminated area and the shadowed area are divided; based on the non-uniform temperature field, the average temperature of the illuminated area and the shadowed area is calculated; Among them, a three-dimensional urban street valley model is constructed and divided into several surface areas, including: S11. Obtain street parameters of the target area in the city; S12. Based on the model assumptions and street parameters, a three-dimensional urban street valley model is constructed, and the analytical equations of each surface area of ​​the model are obtained. The model assumptions include: (1) All buildings are independent, fixed-position rectangular blocks with a certain length, width, and height; (2) The ground in the model is an infinitely extended plane; (3) The length, width, and height extension lines of the building model are parallel to the coordinate axes. The analytical equations of each surface area of ​​the model are: ， in, X 、 Y 、 Z Respectively represent the coordinate positions in the three-dimensional coordinate system; x neg 、 y neg 、 z neg They represent the coordinates of the endpoints in the building model with the smallest value and closest to the negative directions of the three coordinate axes; L 、 W 、 H Respectively represent the length, width, and height of the building model along the positive directions of the three coordinate axes; S13. Divide the surface area of ​​the constructed urban 3D street canyon model into: the ground area at the center of the intersection is GR1; the ground area extending outward from the intersection by the width of a road is GR2; the remaining ground area in the street canyon is GR3; the wall area extending outward from the intersection by the height of a building is WA1; the remaining wall area in the street canyon is WA2; and the roof of the building is RF. Calculates sensible and latent heat fluxes for each surface area, including: S51. Construct a multi-layer turbulent heat exchange model based on model assumptions, wherein the model assumptions include: assuming that the top of the entire urban canopy atmosphere is higher than the height of buildings, and dividing the canopy atmosphere into an inner canopy atmosphere with a height lower than the height of buildings and an outer canopy atmosphere with a height higher than the height of buildings; S52. Based on the constructed multi-layer turbulent heat exchange model, the calculation formulas for the sensible heat flux and latent heat flux of each surface area are obtained: ， ， in, Surface area The sensible heat flux; Surface area latent heat flux; is the atmospheric density of the first layer of the atmospheric numerical model; is the heat capacity per unit mass of dry air; is the latent heat of phase change per unit mass of water vapor at room temperature; Surface area The aerodynamic impedance coefficient between the canopy atmosphere and the atmosphere; Surface area The weight coefficient of the area of ​​​​the total surface area; is the ratio of the area of ​​the wetted surface of surface zone i to the total area of ​​surface zone i; Surface area temperature; Surface area Specific humidity; is the temperature of the inner canopy atmosphere or the outer canopy atmosphere, is the specific humidity of the inner canopy atmosphere or the outer canopy atmosphere; when When representing the RF area, is the outer canopy atmosphere; otherwise, is the inner canopy atmosphere; S53. Based on the assumption that the heat storage of the air in the inner and outer canopy atmosphere is zero and the wall surface does not participate in the latent heat transfer process, the energy balance relationship between different surface areas and the urban canopy atmosphere is obtained, and the unknown variables are solved. 、 、 and , the sensible heat flux and latent heat flux of each surface are obtained, and the energy balance relationship between different surface areas and the inner and outer canopy atmosphere is as follows: ， ， ， ， in, is the sensible heat flux in GR1 region, is the sensible heat flux on the surface of the sth block in the GR2 region, is the sensible heat flux on the surface of the sth block in the GR3 region, is the sensible heat flux of the outer canopy atmosphere, is the sensible heat flux of the inner canopy atmosphere, is the latent heat flux in GR1 region, is the latent heat flux on the surface of the sth block in the GR2 region, is the latent heat flux on the surface of the sth block in the GR3 region, is the latent heat flux of the outer canopy atmosphere, is the latent heat flux of the inner canopy atmosphere; 、 、 、 Obtained by the following calculation expression: ， ， ， ， in, 、 are the temperature and specific humidity of the upper atmosphere, respectively; 、 are the aerodynamic impedance coefficients between the outer canopy atmosphere and the upper atmosphere, and between the inner canopy atmosphere and the outer canopy atmosphere, respectively; 、 are the temperatures of the outer canopy atmosphere and the inner canopy atmosphere, respectively. 、 are the specific humidity of the outer canopy atmosphere and the specific humidity of the inner canopy atmosphere, respectively.

2. The method for predicting non-uniform temperature fields in urban three-dimensional street canyons according to claim 1, characterized in that: Calculate sky view parameters for each surface area, including: S21. Using the Monte Carlo method and the Marsaglia uniform sampling algorithm, a hemisphere is set at the geometric center point of each surface area, and a discretization method is adopted to obtain a set number of sampling points and rays, and the analytical equation of the ray is obtained: ， in, 、 The quantities are respectively N The two sets of independent variables are both in the interval Independent and uniform distribution; ensure that every two corresponding variables 、 All satisfied ; S22, simultaneously calculating the analytical equation of the ray and the analytical equation of each surface area of ​​the model, and determining whether there is an intersection between the two sets of equations. If there is an intersection, it is determined that the ray is blocked by the building; if there is no intersection, it is determined that the ray is not blocked by the building; S23. Count the number of rays not blocked by buildings, calculate the SVF value of each surface area, and combine it with the street aspect ratio to obtain the parameterized formula of the sky view parameter through fitting: ， Among them, SVF represents the sky view parameter; HWR represents the height-to-width ratio in the street canyon; a, b, c, and d are fitting parameters, and each surface area can obtain a set of parameter values.

3. The method for predicting non-uniform temperature fields in urban three-dimensional street canyons according to claim 2, characterized in that: Generates a shadow distribution field for each surface area, including: S31. Name each surface area based on the geographic location, and substitute the actual solar altitude angle, solar azimuth angle, and street deflection angle into the equivalent solar azimuth angle calculation expression and the solar altitude angle projection angle calculation expression for each surface area to obtain the equivalent azimuth angle and solar altitude angle projection angle for each surface area; S32, performing grid processing on each surface area, and judging whether each grid is in shadow according to the equivalent azimuth angle of each surface area and the projection angle of the solar altitude angle; S33. Traverse all grids in each surface area to obtain shadow distribution fields of different surface areas in the three-dimensional urban street canyon.

4. The method for predicting non-uniform temperature fields in urban three-dimensional street canyons according to claim 3, characterized in that: Obtain the solar shortwave radiation flux and ground longwave radiation flux of each surface area, including: S41. Based on the shadow distribution field of different surface areas in the three-dimensional urban street canyon, calculate the ratio of the number of shadowed grid points in the selected area of ​​each surface area to the total number of grid points in the area, and obtain the proportion of direct solar shortwave radiation received in the total area of ​​the area. The expression is: ， in, is the proportion of direct solar shortwave radiation received by the selected surface area; is the number of shaded grid points in the selected area; is the total number of grid points; S42. Calculate the long-wave radiation emitted by each surface area: ， Where L represents the long-wave radiation emission; em is the emissivity of each surface area; δ is the Stefan-Boltzmann constant; T is the surface temperature of each surface area of ​​the building; S43. Based on the proportion of direct solar shortwave radiation received in the selected surface area, the amount of longwave radiation emitted by each surface area, the material albedo and emissivity of the urban three-dimensional street valley surface area, and the sky view parameters of each surface area, the absorption and reflection processes of solar shortwave radiation and ground longwave radiation in the urban three-dimensional street canyon are calculated to obtain the solar shortwave radiation flux and ground longwave radiation flux in different areas of each surface area.

5. The method for predicting non-uniform temperature fields in urban three-dimensional street canyons according to claim 4, characterized in that: Generate a non-uniform temperature field based on the sensible heat flux, latent heat flux, solar shortwave radiation flux, and ground longwave radiation flux of each surface area, including: S61. Based on the sensible heat flux, latent heat flux, solar shortwave radiation flux, and ground longwave radiation flux of each surface zone, establish an energy budget model for each surface zone, including: ， in, Surface area The net heat flux; Surface area The sensible heat flux; Surface area latent heat flux; Surface area The shortwave radiation flux; Surface area The long-wave radiation flux; Surface area Other calories S62. Based on the forced-balance method and the energy budget model of each surface area, the temperature change value of each surface area is calculated to obtain the non-uniform temperature field in the three-dimensional urban street canyon. The specific calculation expression is: ， in, is the surface temperature of any surface area; is the rate of change of temperature with time; is the net heat flux obtained from the energy budget model for each surface zone as a forcing term; is the surface temperature inside the building, as a recovery term; is the oscillation period of the forcing term; is the thermal diffusion coefficient of the building material; C is the specific heat capacity of the building material.

6. The method for predicting non-uniform temperature fields in urban three-dimensional street canyons according to claim 5, characterized in that: Based on the shadow distribution field of each surface area, the illuminated area and shadow area are divided, including: S71. Based on the obtained non-uniform temperature field of different surface areas within the three-dimensional urban street canyon, calculate the ratio of the number of shadow grid points in any area of ​​the ground to the total number of grid points in the area, obtain the shadow area ratio coefficient in the selected area of ​​the ground, and divide the ground into illuminated areas and shadow areas based on the shadow division rule of the ground; The shadow area ratio coefficient expression is: ， in, is the number of shaded grid points in the selected area; is the total number of grid points in the selected area; is the shadow area ratio coefficient in the selected area; Shadow division rules include: ≤0.3, the selected area on the ground is the shadow area. When ≤0.5, the selected area on the ground is the half-shadow area. When 0.5< ≤0.7, the selected area on the ground is a semi-illuminated area. When ≤1, the selected area on the ground is the illumination area; S72, based on the equivalent solar azimuth angle of each wall surface area , the wall surface is divided into shadow area and light area, among which the shadow area ≤180 degrees, illumination area >180 degrees.

7. The method for predicting non-uniform temperature fields in urban three-dimensional street canyons according to claim 6, characterized in that: Calculate the average temperature of the illuminated and shadowed areas based on the non-uniform temperature field, including: S73. Distinguish between daytime and nighttime based on the actual solar altitude angle. If the actual solar altitude angle is greater than 0.05 rad, it is daytime; otherwise, it is nighttime. S74. Based on the obtained non-uniform temperature field in the three-dimensional urban street canyon, perform arithmetic average calculation on the surface temperatures of the illuminated area and the shadowed area of ​​the wall or ground during the day to obtain the average temperature of the illuminated area and the shadowed area of ​​the wall or ground. The specific calculation formula is: ， ， in, 、 are the average temperatures of the illuminated and shadowed areas of the wall or floor, respectively; 、 are the temperatures of the kth surface in the illuminated area and shadowed area of ​​the wall or ground respectively; n1 and n2 are the total number of surfaces in the illuminated area and shadowed area of ​​the wall or ground respectively.

8. A device for predicting non-uniform temperature fields in urban three-dimensional street canyons, characterized in that: including storage media and processors; The storage medium is used to store instructions; The processor is configured to operate according to the instruction to execute the method for predicting a non-uniform temperature field in a three-dimensional urban street canyon according to any one of claims 1 to 7.

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