Vortex diffusion mass flux boundary layer parameterization method suitable for typhoon forecast

Abstract

The invention relates to the technical field of numerical weather forecasting, in particular to a vortex diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting. The method comprises the following steps: obtaining a model planet boundary layer considering the influence of in-cloud mixing on turbulence and considering the influence of a strong wind speed and a lower boundary layer height under a typhoon condition; obtaining the momentum vertical vortex diffusivity above the height of the boundary layer and the characteristic velocity of a mixed layer in the boundary layer by using the Richardson number; and obtaining the vertical vortex diffusivity of the momentum of the boundary layer by using the Richardson number and the characteristic velocity of the mixed layer in the boundary layer. According to the method, the problems that the boundary layer height is too high, the turbulence diffusivity is too large, the unreasonable assumption that the influence of in-cloud mixing on turbulence is not considered and the typhoon simulation intensity is relatively weak under the typhoon simulation condition of a traditional boundary layer parameterization scheme EDMF are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of numerical weather forecasting, and in particular to a eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting. Background Art

[0002] Typhoon is one of the important disastrous weather systems, which can often bring disasters such as strong winds, heavy rains and storm surges, affecting the development of social economy and posing a huge threat to people's lives and safety. Therefore, the typhoon path and intensity forecast is of vital importance. At present, the development of high-resolution numerical forecasting technology is an important way to improve the typhoon intensity forecast and wind and rain precision capabilities. For sub-grid scales that the model cannot resolve, the model relies on parameterization schemes. For example, when the model resolution is increased to the kilometer scale, the model can resolve some turbulent processes in the boundary layer, but in the "gray area" between the large eddy scale and the kilometer scale, numerical simulations mainly rely on boundary layer parameterization schemes.

[0003] In the prior art, boundary layer parameterization schemes are usually determined based on the assumption of the profile distribution form, such as the EDMF (Eddy-Diffusive Mass Flux) scheme. This scheme takes into account the effects of along-gradient turbulent diffusion and against-gradient mass transport, but its disadvantages are that the boundary layer turbulent diffusion rate under simulated typhoon conditions is relatively strong and the typhoon boundary layer height is too high, which is inconsistent with the boundary layer conditions under hurricane conditions observed by aircraft, and is not conducive to the simulation of inflow intensity. Correspondingly, the typhoon intensity simulated by the EDMF scheme is relatively weak. In addition, the EDMF scheme's assumptions about intra-cloud turbulent mixing are not completely reasonable. For example, under cloudy conditions, the impact of intra-cloud diffusion on turbulent mixing is not considered. The main reason for these problems is that the EDMF scheme is not specifically designed for typhoon conditions, and lacks observation-based correction of its original assumptions.

[0004] At present, there is not much research on the parameterization scheme of the eddy diffusion mass flux boundary layer suitable for typhoon forecasting, and there is no specific parameterization method of the eddy diffusion mass flux boundary layer suitable for typhoon forecasting. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting.

[0006] The present invention provides a parameterization method for an eddy diffusion mass flux boundary layer suitable for typhoon forecasting, comprising the following steps: obtaining a Richardson number of a model planetary boundary layer that takes into account the influence of intra-cloud mixing on turbulence and the influence of strong wind speed and lower boundary layer height under typhoon conditions; using the Richardson number, obtaining a momentum vertical eddy diffusion rate above the boundary layer height and a characteristic velocity of a mixing layer in the boundary layer; and using the Richardson number and the characteristic velocity of the mixing layer in the boundary layer, obtaining a boundary layer momentum vertical eddy diffusion rate. The present invention accurately calculates the Richardson number of the planetary boundary layer and derives the vertical eddy diffusion rate of the boundary layer momentum based on it, which is conducive to more accurately simulating the dynamic characteristics of the typhoon generation and development process, thereby improving the forecast accuracy of key information such as the typhoon path and intensity; using advanced parameterization technology, a large amount of meteorological data can be quickly processed and analyzed, thereby shortening the forecast period and improving the timeliness of the forecast, which is of great significance for timely issuing typhoon warning information and formulating effective disaster prevention and mitigation measures; it not only provides a practical tool for typhoon forecasting, but also deepens the scientific understanding of the typhoon generation and development mechanism by revealing the role of the physical characteristics of the boundary layer in typhoon dynamics, and plays a positive role in promoting research progress in meteorology and related fields.

[0007] Optionally, the obtaining of the Richardson number of the model planetary boundary layer taking into account the influence of intra-cloud mixing on turbulence and the influence of strong wind speed and lower boundary layer height under typhoon conditions includes: obtaining the Richardson number above the model planetary boundary layer height, taking into account the influence of intra-cloud mixing on turbulence; obtaining the Richardson number within the model planetary boundary layer, taking into account the influence of strong wind speed and lower boundary layer height under typhoon conditions. The present invention obtains the Richardson number considering the influence of intra-cloud mixing on turbulence above the model planet boundary layer height and the Richardson number under typhoon conditions in the boundary layer respectively, comprehensively considers the influence of different environmental conditions on the Richardson number, helps to more accurately reflect the stability characteristics of the atmospheric boundary layer, and provides a reliable basis for the subsequent calculation of the momentum vertical eddy diffusion rate; by considering that under typhoon conditions, strong wind speed and lower boundary layer height will have a significant impact on the Richardson number, more accurately simulates the influence of typhoon on the stability of the boundary layer, thereby improving the adaptability of the parameterization scheme to extreme weather events such as typhoons; by finely obtaining the Richardson number at different heights and conditions, more accurately describes the physical process in the boundary layer, thereby enhancing the refinement of the forecast, helping to better understand the dynamic characteristics of the typhoon, improve the accuracy and reliability of the forecast, and provide a more scientific basis for disaster prevention and mitigation.

[0008] Optionally, the Richardson number considering the effect of intra-cloud mixing on turbulence satisfies the following expression: in, is the Richardson number above the boundary layer height, considering the effect of intra-cloud mixing on turbulence; is the Richardson number under cloud-free conditions above the boundary layer height; is the coagulation mixing ratio, is the latent heat of evaporation, is the gas constant for dry air, is the gas constant of water vapor, is the specific heat capacity of dry air at standard atmospheric pressure, is the temperature, is the acceleration due to gravity, is vertical wind shear. The Richardson number expression constructed by the present invention, which takes into account the influence of intra-cloud mixing on turbulence, has achieved the following effects: first, the Richardson number is calculated and analyzed more accurately, thereby improving the accuracy and reliability of the forecast; second, it reveals how clouds interact with boundary layer stability, which is of great significance for understanding atmospheric science issues such as atmospheric circulation and climate change; third, it can be applied to numerical weather forecast models to improve the simulation and forecast of boundary layer stability, which helps to more accurately predict the development path and intensity of extreme weather events such as typhoons, and provide strong support for disaster prevention and mitigation; fourth, it provides new ideas and methods for the development of forecasting technology and promotes progress in the field of atmospheric science.

[0009] Optionally, the Richardson number considering the influence of strong wind speed and lower boundary layer height under typhoon conditions satisfies the following expression: in, The Richardson number is the one that takes into account the strong wind speed and low boundary layer height under typhoon conditions. is the height of the bottom layer of the model, is the boundary layer height, is the acceleration due to gravity, for The zonal wind at altitude, for Radial wind at altitude, For virtual temperature, for Virtual temperature at altitude, for The zonal wind at altitude, for Radial wind at altitude, is the surface friction velocity; Under stable and neutral boundary layer conditions, High virtual temperature, under unstable conditions, is The sum of the virtual temperature at altitude and the virtual temperature near the ground. The present invention constructs an expression for the Richardson number by considering the influence of strong wind speed and lower boundary layer height under typhoon conditions, and calculates the Richardson number, achieving the following effects: First, it accurately quantifies the influence of strong wind speed and lower boundary layer height on the Richardson number under typhoon conditions, providing a mathematical basis for a deep understanding of typhoon dynamics; second, it significantly improves the accuracy of typhoon forecasts, providing a more reliable scientific basis for disaster prevention and mitigation; third, it promotes the further optimization of numerical weather forecast models, enabling them to more accurately simulate extreme weather events such as typhoons, and improves the timeliness and accuracy of forecasts.

[0010] Optionally, the use of the Richardson number to obtain the momentum vertical eddy diffusivity above the boundary layer height and the characteristic velocity of the mixing layer in the boundary layer includes: using the Richardson number that takes into account the influence of intra-cloud mixing on turbulence to obtain the momentum vertical eddy diffusivity above the planetary boundary layer height; using the Richardson number that takes into account the influence of strong wind speed and lower boundary layer height under typhoon conditions to obtain the characteristic velocity of the mixing layer in the planetary boundary layer. The present invention uses the Richardson number that takes into account the influence of intra-cloud mixing on turbulence to accurately calculate the momentum vertical eddy diffusivity above the planetary boundary layer height; by considering the influence of strong wind speed and lower boundary layer height under typhoon conditions, the corresponding Richardson number is used to accurately evaluate the characteristic velocity of the mixing layer in the planetary boundary layer; the forecast performance of the numerical weather forecast model under extreme weather conditions such as typhoons is significantly improved, providing more powerful support for disaster prevention and mitigation.

[0011] Optionally, the use of the Richardson number that takes into account the effect of intra-cloud mixing on turbulence to obtain the momentum vertical eddy diffusivity above the planetary boundary layer height includes: using the Richardson number that takes into account the effect of intra-cloud mixing on turbulence to obtain a stability function; and obtaining the momentum vertical eddy diffusivity above the planetary boundary layer height according to the stability function. The present invention uses the Richardson number that takes into account the effect of intra-cloud mixing on turbulence to accurately calculate the stability function of the atmospheric boundary layer; accurately derive the momentum vertical eddy diffusivity above the planetary boundary layer height according to the obtained stability function; and improve the accuracy of the numerical weather forecast model under complex weather conditions, especially to more accurately simulate the momentum exchange process under cloudy conditions.

[0012] Optionally, the stability function includes the stability function of a stable stratified free atmosphere and the stability functions of a neutral and unstable stratified atmosphere. The stability function of a stable stratified free atmosphere provided by the present invention describes the dynamic characteristics of the atmosphere under stable stratification conditions; the stability functions of a neutral and unstable stratified atmosphere provided can be applied to a wider range of atmospheric stratification states; by comprehensively considering the stability functions under different stratification states, the adaptability of the numerical weather forecast model to different weather conditions is significantly improved, thereby improving the accuracy of the forecast.

[0013] Optionally, the use of the Richardson number and the characteristic velocity of the mixing layer in the boundary layer to obtain the vertical eddy diffusion rate of the momentum of the boundary layer includes: using the Richardson number in the model planetary boundary layer, considering the influence of strong wind speed and lower boundary layer height under typhoon conditions, to define the typhoon boundary layer height; according to the typhoon boundary layer height and the characteristic velocity of the mixing layer in the boundary layer, obtain the vertical eddy diffusion rate of the momentum of the boundary layer. The present invention uses the Richardson number in the model planetary boundary layer, considering the influence of strong wind speed and lower boundary layer height under typhoon conditions, to accurately define the boundary layer height under typhoon conditions, and provides key parameters for the subsequent calculation of the vertical eddy diffusion rate of momentum; combined with the defined typhoon boundary layer height and the characteristic velocity of the mixing layer in the boundary layer, the influence of the wind speed distribution and turbulence characteristics in the mixing layer on the vertical eddy diffusion rate of momentum is comprehensively considered, so that the calculation result is more in line with the actual situation; the precision of the numerical weather forecast model in typhoon forecasting is significantly improved, especially in the simulation of the momentum exchange process in the boundary layer, providing a more accurate and reliable scientific basis for disaster prevention and mitigation.

[0014] Optionally, the typhoon boundary layer height includes: when the wind speed of the model grid at a height of ten meters is greater than or equal to 17.2 meters per second, the critical Richardson number is set to 0.05, and the typhoon boundary layer height is obtained; when the wind speed of the model grid at a height of ten meters is less than 17.2 meters per second, the critical Richardson number is set to 0.25, and the typhoon boundary layer height is obtained. Among them, the reason why whether the wind field at a height of ten meters is greater than 17.2 meters per second is used as a judgment condition is to judge whether the tropical storm intensity is reached, and the critical Richardson number is taken as 0.05 to reduce the typhoon boundary layer height. The present invention reasonably sets the Richardson number according to the wind speed of the model grid at a height of ten meters, so as to more carefully calculate the typhoon boundary layer height under different wind speed conditions, thereby improving the accuracy of the calculation; by considering the setting of the Richardson number under different wind speed conditions, it adapts to typhoon conditions of different intensities, and improves the forecast performance and accuracy under complex weather conditions.

[0015] Optionally, when the wind speed of the model grid at a height of ten meters is greater than or equal to 17.2 meters per second, the vertical eddy diffusion rate of the momentum of the boundary layer is reduced to half of the original value, the purpose of which is to make the magnitude of the calculated vertical eddy diffusion rate of the momentum of the boundary layer and the vertical distribution of the profile closer to the intensity and vertical distribution of the vertical eddy diffusion rate of the momentum of the boundary layer estimated by observation. The present invention reflects the physical phenomenon that the momentum exchange process in the boundary layer is strongly suppressed under strong wind conditions, and the reduction of the vertical eddy diffusion rate of the momentum reflects the weakening trend of turbulent activity under strong wind speeds; by considering the influence of strong wind speeds on the vertical eddy diffusion rate of the momentum, the accuracy and reliability of the numerical weather forecast model in simulating typhoon weather events are enhanced, providing a more scientific prediction basis for responding to typhoon weather.

[0016] Compared with the traditional EDMF scheme, the beneficial effects of the present invention include: fully considering the influence of intra-cloud mixing on turbulence and the influence of strong wind speed and lower boundary layer height under typhoon conditions, developing a boundary layer parameterization scheme suitable for typhoon conditions, improving the typhoon boundary layer and turbulence simulation, thereby improving the simulation of typhoon intensity, and achieving a more realistic simulation of eddy diffusion, typhoon path and intensity under typhoon conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of a eddy diffusion mass flux boundary layer parameterization method applicable to typhoon forecasting according to an embodiment of the present invention; Figure 2 A schematic diagram of the vertical distribution of the axis-averaged turbulent diffusion coefficient within a radius of 200 kilometers of Typhoon Lekima (1909) simulated by the new scheme of the embodiment of the present invention and the old EDMF scheme; Figure 3 Schematic diagram of the paths of five typical typhoons simulated by the new scheme of the embodiment of the present invention and the old EDMF scheme, the lowest sea level pressure near the typhoon center, and the maximum value of the wind field at a height of ten meters; Figure 4 Schematic diagram of path error distribution and intensity error distribution of five typical typhoon cases simulated by the new scheme of the embodiment of the present invention and the old EDMF scheme. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not need to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, software or methods are not specifically described.

[0019] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or subcombination. In addition, it should be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale.

[0020] See also Figure 1The embodiment of the present invention provides a eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting, the method comprising the following steps: S1. Obtain the Richardson number of the model planetary boundary layer.

[0021] Among them, S1 includes the following steps: S11. Obtain the Richardson number under cloud-free conditions above the model planetary boundary layer height.

[0022] In one embodiment, first, the definition and physical meaning of the Richardson number are clarified. The Richardson number is a dimensionless number that represents the ratio of the buoyancy term to the flow shear term and is used to measure the degree of balance between momentum and density in a fluid. In atmospheric science, it is particularly used to describe the ratio of atmospheric static stability to vertical wind shear.

[0023] Furthermore, relevant meteorological data are obtained and collected, including temperature, wind speed, and air pressure data.

[0024] Furthermore, the collected relevant meteorological data are processed and analyzed to obtain the virtual temperature and wind shear data.

[0025] Furthermore, the virtual temperature and wind shear data are substituted into the local gradient Richardson number expression to obtain the Richardson number under cloud-free conditions above the model planetary boundary layer height. The local gradient Richardson number expression is as follows: = in, is the Richardson number under cloud-free conditions above the boundary layer height, is the acceleration due to gravity, For virtual temperature, It is vertical wind shear.

[0026] S12. Obtain the Richardson number above the model planetary boundary layer height, taking into account the effect of intra-cloud mixing on turbulence.

[0027] In one embodiment, the effect of intra-cloud mixing on turbulence is taken into consideration, and the calculation expression of the Richardson number in step S11 is improved. The improved expression is for the calculation of the Richardson number under cloudy conditions.

[0028] Specifically, the Richardson number considering the effect of intra-cloud mixing on turbulence satisfies the following expression: in, is the Richardson number above the boundary layer height, considering the effect of intra-cloud mixing on turbulence; is the Richardson number under cloud-free conditions above the boundary layer height; is the coagulation mixing ratio, is the latent heat of evaporation, is the gas constant for dry air, is the gas constant of water vapor, is the specific heat capacity of dry air at standard atmospheric pressure, is the temperature, is the acceleration due to gravity, It is vertical wind shear.

[0029] Furthermore, by collecting parameter data in the expression of the Richardson number that takes into account the effect of intra-cloud mixing on turbulence and substituting them into the expression, the Richardson number that takes into account the effect of intra-cloud mixing on turbulence above the model planetary boundary layer height can be obtained.

[0030] S13. Obtain the Richardson number within the model planetary boundary layer without considering the effects of strong wind speed and lower boundary layer height under typhoon conditions.

[0031] In one embodiment, the calculation expression for the Richardson number is obtained by using the calculation expression for the model boundary layer height.

[0032] Specifically, the model boundary layer height satisfies the following expression: in, is the model boundary layer height, is the virtual potential temperature of the lowest layer of the model, is the temperature scale near the surface, For height The virtual temperature, is the acceleration due to gravity, is the horizontal wind speed at the boundary layer height, is the Richardson number.

[0033] Furthermore, the Richardson number satisfies the following expression: Furthermore, by collecting parameter data in the expression of the Richardson number and substituting them into the expression, the Richardson number in the model planetary boundary layer without considering the influence of strong wind speed and lower boundary layer height under typhoon conditions can be obtained.

[0034] It should be noted that in the traditional EDMF scheme, the critical Richardson number is generally taken as .

[0035] S14. Obtain the Richardson number within the model planetary boundary layer, taking into account the effects of strong wind speed and lower boundary layer height under typhoon conditions.

[0036] In one embodiment, considering the influence of strong wind speed and low boundary layer height under typhoon conditions, the Richardson number calculation expression in step S13 is improved, and the improved Richardson number satisfies the following expression: in, is the Richardson number considering the strong wind speed and low boundary layer height under typhoon conditions. is the height of the bottom layer of the model, is the boundary layer height, is the acceleration due to gravity, for The zonal wind at altitude, for Radial wind at altitude, For virtual temperature, for Virtual temperature at altitude, for The zonal wind at altitude, for Radial wind at altitude, is the surface friction velocity; Under stable and neutral boundary layer conditions, High virtual temperature, under unstable conditions, is The sum of the virtual temperature at height and the virtual temperature near the ground.

[0037] Furthermore, by collecting parameter data in the expression and substituting them into the expression, the Richardson number in the model planetary boundary layer can be obtained, which takes into account the influence of strong wind speed and lower boundary layer height under typhoon conditions.

[0038] S2. Using the Richardson number, the momentum vertical eddy diffusivity above the boundary layer height and the characteristic velocity of the mixing layer in the boundary layer are obtained.

[0039] Among them, S2 includes the following steps: S21. Using the Richardson number that takes into account the effect of intra-cloud mixing on turbulence, the momentum vertical eddy diffusivity above the planetary boundary layer height is obtained.

[0040] Specifically, step S21 includes the following steps: S211. Calculate the stability function using the Richardson number that takes into account the effect of intra-cloud mixing on turbulence.

[0041] In one embodiment, the Richardson number is used to consider the effect of intra-cloud mixing on turbulence. and neutral and unstable stratified atmospheres Calculation of stability functions.

[0042] Specifically, for a stably stratified free atmosphere, the stability function as follows: For an unstable stratified atmosphere, the stability function and as follows: Furthermore, by substituting the Richardson number calculated under cloudy conditions into the expression of the stability function, the calculation result of the stability function can be obtained.

[0043] It should be noted that the stability function is an important indicator for evaluating the vertical exchange capacity of the atmospheric boundary layer for physical quantities such as momentum, heat and water vapor.

[0044] S212. According to the calculation result, the momentum vertical eddy diffusion rate above the planetary boundary layer height is obtained.

[0045] In one embodiment, the calculation result of the stability function is substituted into the expression of the momentum vertical eddy diffusivity to obtain the momentum vertical eddy diffusivity.

[0046] Specifically, the momentum vertical eddy diffusivity expression is as follows: in, is the mixing length, is the vertical wind shear, is the stability function.

[0047] Furthermore, the momentum vertical eddy diffusivity expression is used to obtain the momentum vertical eddy diffusivity above the planetary boundary layer height.

[0048] S22. Using the Richardson number that takes into account the effects of strong wind speed and lower boundary layer height under typhoon conditions, the characteristic velocity of the mixing layer in the planetary boundary layer is obtained.

[0049] In one embodiment, first, the model boundary layer height is obtained by using the Richardson number that takes into account the influence of strong wind speed and lower boundary layer height under typhoon conditions, combined with the model boundary layer height expression in step S13.

[0050] Furthermore, the model boundary layer height is substituted into the expression of the characteristic velocity of the mixing layer to obtain the characteristic velocity of the mixing layer in the planetary boundary layer, and the characteristic velocity of the mixing layer satisfies the following expression: in, is the characteristic velocity of the mixing layer, is the surface friction velocity scale, is the wind profile function, is the von Karman constant, which is 0.4. is the height within the model boundary layer, is the height of the model boundary layer. In addition, the characteristic velocity of the boundary layer It can be calculated by the expression in the traditional EDMF scheme, which is as follows: S3. Using the Richardson number and the characteristic velocity of the mixing layer in the boundary layer, the vertical eddy diffusion rate of the boundary layer momentum is obtained.

[0051] Wherein, step S3 further comprises the following steps: S31. Define the typhoon boundary layer height using the Richardson number in the model planetary boundary layer, taking into account the effects of strong wind speed and lower boundary layer height under typhoon conditions.

[0052] In one embodiment, by calculating the critical Richardson number under typhoon conditions , to define the typhoon boundary layer height.

[0053] Specifically, when the wind speed at the model grid at a height of ten meters is greater than or equal to 17.2 m / s, Set to 0.05, which can be , to calculate the typhoon boundary layer height; when the wind speed at the model grid at a height of ten meters is less than 17.2 m / s, Set it to 0.25 to calculate the boundary layer height under non-typhoon conditions. In this step, the reason why the wind field at a height of 10 meters is greater than 17.2 meters per second is used as the judgment condition to determine whether it has reached the intensity of a tropical storm. The critical Richardson number is taken The value of 0.05 is to reduce the height of the typhoon boundary layer.

[0054] S32. Obtain the vertical eddy diffusion rate of the boundary layer momentum according to the typhoon boundary layer height and the characteristic velocity of the mixing layer in the boundary layer.

[0055] In one embodiment, according to the typhoon boundary layer height and the characteristic velocity of the mixing layer in the boundary layer, combined with the expression of the momentum vertical eddy diffusivity, the boundary layer momentum vertical eddy diffusivity under typhoon conditions is calculated. The momentum vertical eddy diffusivity satisfies the following expression: in, is the vertical eddy diffusion rate of momentum, is the characteristic velocity of the mixing layer, is the von Karman constant, which is 0.4. is the height within the model boundary layer, is the height of the model boundary layer, is the shape parameter. Different from the EDMF scheme, it is modified according to the wind speed at a height of ten meters. Size: When the wind speed at 10 meters is greater than or equal to 17.2 meters per second, reduce The value is half of the original value, the purpose is to make The magnitude and vertical distribution of the profile are closer to the observed estimates. intensity and vertical distribution.

[0056] In one embodiment, a typhoon (1909) was simulated, such as Figure 2 As shown. In the first 72 hours of the simulation, the simulated and observed typhoon paths and intensities are relatively consistent. For example, around the 60th hour of the simulation, the model can reproduce the maximum value of the strongest ten-meter wind speed of the observed typhoon. In addition, from 60 to 61 hours, the turbulent mixing coefficient calculated by this scheme is consistent with the observation in terms of vertical distribution form and magnitude. The above results show that this scheme has achieved a true simulation of eddy diffusion under typhoon conditions, and also has the ability to simulate typhoon paths and intensities more realistically.

[0057] In another embodiment, the typhoon low-level turbulent diffusion rate of Typhoon Lekima (1909) simulated by the old EDMF scheme and the new scheme at the time of its strongest intensity is compared, such as Figure 2 As shown in the figure. The typhoon low-level turbulence diffusion rate simulated by the EDMF scheme is significantly greater than the observation, and its boundary layer height simulation is too high, resulting in a profile distribution that is significantly different from the observation; in contrast, the typhoon low-level turbulence diffusion rate simulated by the new scheme is not only consistent with the observed intensity, but also has a relatively consistent profile vertical distribution.

[0058] In another embodiment, based on the above two sets of boundary layer parameterization schemes, five typical typhoons are simulated for 120 hours. The typhoon paths and intensities are as follows: Figure 3 As shown, the error distribution is Figure 4 As shown. In general, the typhoon paths of the five cases simulated by the EDMF scheme and the new scheme are similar, with an error of no more than 50 kilometers. However, the typhoon intensity simulated by the EDMF scheme is significantly weaker than the observation, while the new scheme reduces the error of the maximum wind speed at a height of 10 meters for the typhoon by 50%, especially the maximum wind speed at 10 meters simulated by the new scheme for Typhoon Soudelor (1513) and Lekima (1909) is more consistent with the observation. The reason is that the new scheme is more consistent with the observation in simulating the intensity and vertical distribution of turbulent diffusion rate in the boundary layer under typhoon conditions.

[0059] In summary, the present invention is based on the global variable resolution grid atmospheric model GRIST, optimizes and upgrades its old scheme EDMF, and develops a new boundary layer parameterization scheme suitable for typhoon conditions.

[0060] (1) The main calculation steps of the EDMF scheme are as follows: Calculate the momentum vertical eddy diffusivity above the model planetary boundary layer height; Calculate the mixing layer characteristic velocity and Richardson number within the model boundary layer; Calculate the vertical eddy diffusivity of boundary layer momentum.

[0061] (2) The main calculation steps of the new boundary layer parameterization scheme proposed in this invention are as follows: Calculate the momentum vertical eddy diffusivity above the model planetary boundary layer height, taking into account the effect of intra-cloud mixing on turbulence; Calculate the mixing characteristic velocity and Richardson number within the model boundary layer, taking into account the effects of strong wind speeds and lower boundary layer heights under typhoon conditions; Calculate the vertical eddy diffusivity of boundary layer momentum under typhoon conditions.

[0062] The new boundary layer parameterization scheme proposed in the present invention effectively solves the problems of the traditional EDMF scheme simulating the boundary layer height under typhoon conditions being too high, the turbulent diffusion rate being too large, the unreasonable assumption of not considering the effect of intra-cloud mixing on turbulence, and the simulation of weak typhoon intensity. The present invention accurately calculates the Richardson number of the planetary boundary layer and derives the vertical eddy diffusion rate of the boundary layer momentum based on it, so as to more accurately simulate the dynamic characteristics of the typhoon generation and development process, which helps to improve the forecast accuracy of key information such as typhoon path and intensity; using advanced parameterization technology, a large amount of meteorological data can be quickly processed and analyzed, thereby shortening the forecast period and improving the timeliness of the forecast, which is of great significance for the timely release of typhoon warning information and the formulation of effective disaster prevention and mitigation measures; it not only provides a practical tool for typhoon forecasting, but also deepens the scientific understanding of the typhoon generation and development mechanism by revealing the role of boundary layer physical characteristics in typhoon dynamics, and has a positive effect on promoting research progress in meteorology and related fields.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A vortex diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting, characterized in that: The method comprises the following steps: Obtain the Richardson number of the model planetary boundary layer considering the effect of intra-cloud mixing on turbulence and the effect of strong wind speed and lower boundary layer height under typhoon conditions; Using the Richardson number, the momentum vertical eddy diffusivity above the boundary layer height and the mixing layer characteristic velocity within the boundary layer are obtained; The boundary layer momentum vertical eddy diffusivity is obtained by using the Richardson number and the characteristic velocity of the mixing layer in the boundary layer.

2. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 1 is characterized in that: The Richardson number of the planetary boundary layer in the acquisition model considering the influence of intra-cloud mixing on turbulence and the influence of strong wind speed and lower boundary layer height under typhoon conditions includes: Obtain the Richardson number above the model planetary boundary layer height, considering the effect of intra-cloud mixing on turbulence; Obtain the Richardson number within the model planetary boundary layer, considering the strong wind speed under typhoon conditions and the influence of the lower boundary layer height.

3. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 2 is characterized in that: The Richardson number considering the effect of intra-cloud mixing on turbulence satisfies the following expression: in, is the Richardson number above the boundary layer height, considering the effect of intra-cloud mixing on turbulence; is the Richardson number under cloud-free conditions above the boundary layer height; is the coagulation mixing ratio, is the latent heat of evaporation, is the gas constant of dry air, is the gas constant of water vapor, is the specific heat capacity of dry air at standard atmospheric pressure, is the temperature, is the acceleration due to gravity, It is vertical wind shear.

4. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 2 is characterized in that: The Richardson number considering the strong wind speed and the low boundary layer height under typhoon conditions satisfies the following expression: in, The Richardson number is a factor that takes into account the effects of strong wind speed and low boundary layer height under typhoon conditions. is the height of the bottom layer of the model, is the boundary layer height, is the acceleration due to gravity, for The zonal wind at altitude, for Radial wind at altitude, For virtual temperature, for Virtual temperature at altitude, for The zonal wind at altitude, for Radial wind at altitude, is the surface friction velocity; Under stable and neutral boundary layer conditions, High virtual temperature, under unstable conditions, is The sum of the virtual temperature at height and the virtual temperature near the ground.

5. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 1, characterized in that: The method of using the Richardson number to obtain the momentum vertical eddy diffusivity above the boundary layer height and the characteristic velocity of the mixing layer in the boundary layer comprises: The momentum vertical eddy diffusivity above the planetary boundary layer height is obtained by using the Richardson number which takes into account the effect of intra-cloud mixing on turbulence. The characteristic velocity of the mixing layer in the planetary boundary layer is obtained by using the Richardson number which takes into account the effects of strong wind speed and lower boundary layer height under typhoon conditions.

6. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 5, characterized in that: The method of using the Richardson number taking into account the effect of intra-cloud mixing on turbulence to obtain the momentum vertical eddy diffusion rate above the planetary boundary layer height includes: The stability function is obtained by using the Richardson number which takes into account the effect of intra-cloud mixing on turbulence. According to the stability function, the momentum vertical eddy diffusivity above the planetary boundary layer height is obtained.

7. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 6, characterized in that: The stability function includes the stability function of a stably stratified free atmosphere and the stability functions of a neutral and unstable stratified atmosphere.

8. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 1, characterized in that: The obtaining of the vertical eddy diffusion rate of the boundary layer momentum by using the Richardson number and the characteristic velocity of the mixing layer in the boundary layer comprises: The typhoon boundary layer height is defined by using the critical Richardson number in the model planetary boundary layer, considering the effects of strong wind speed and lower boundary layer height under typhoon conditions; The vertical eddy diffusion rate of the boundary layer momentum is obtained according to the typhoon boundary layer height and the characteristic velocity of the mixing layer in the boundary layer.

9. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 8, characterized in that: The typhoon boundary layer height includes: When the wind speed at the model grid at a height of ten meters is greater than or equal to 17.2 m / s, the critical Richardson number is set to 0.05, and the typhoon boundary layer height is obtained; When the wind speed at the model grid at a height of ten meters is less than 17.2 m / s, the critical Richardson number is set to 0.25, and the typhoon boundary layer height is obtained.

10. The eddy diffusion mass flux boundary layer parameterization method suitable for typhoon forecasting according to claim 9, characterized in that: When the wind speed at the model grid at a height of ten meters is greater than or equal to 17.2 m / s, the vertical eddy diffusion rate of boundary layer momentum is reduced to half of its original value.

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