A fine simulation method for water and heat processes of glaciers and snow in alpine regions

Abstract

The application relates to a high-cold-region glacier and snow water and heat process fine simulation method, which comprises the following steps: firstly, dividing the high-cold-region into a seasonal ice and snow zone and a perennial ice and snow zone, and the upper layer of the snow area is a snow layer and the lower layer is a soil layer; the upper layer of the glacier area is a snow layer and the lower layer is an ice layer. Since the ice layer is thick, the heat conduction process of the soil layer or the bedrock layer under the ice layer is not considered in the model. The water and heat process calculation steps of the snow layer are as follows: respectively performing dynamic rain and snow separation calculation, snow layer compaction process calculation, snow layer energy balance calculation and snow layer internal water flux calculation; the water and heat process calculation steps of the ice layer are as follows: ice layer energy balance calculation and material balance calculation, so that the fine simulation of the snow-glacier hydrological process is realized. According to the characteristics of the ice sheet and the large snow cover of the frozen earth, the water and heat coupling model is used to simulate the glacier / snow melt water process, so that the scientific description of the glacier / snow melt water runoff process is realized.

Description

Technical Field

[0001] This invention relates to the field of hydrogeography, and in particular to a refined simulation method for hydrothermal processes of glaciers and snow cover in high-altitude and cold regions. Background Technology

[0002] The "Third Pole" region, centered on the Qinghai-Tibet Plateau, is the world's largest ice and snow storage area after the Antarctic and Arctic, giving rise to major rivers such as the Yangtze, Yellow, and Lancang Rivers, and is known as the "Water Tower of Asia." The primary function of the Asian Water Tower is to store precipitation as snow or ice, which then melts in spring and summer to form runoff. With global climate change, the cryosphere is undergoing accelerated changes, and the response of cryosphere hydrological processes to climate change and their impacts have become a hot topic in global change research.

[0003] Currently, there is no consensus in the academic community regarding the simulation, attribution, and prediction of changes in cryospheric runoff and its components. The reason for this is that there are many challenges in simulating the special geo-hydrological processes of the cryospheric system. The main problem is the insufficient quantitative and detailed characterization of hydrothermal processes of glaciers / snow cover in the region. Therefore, how to solve this problem is something that needs to be considered at present. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a refined simulation method for the hydrothermal processes of glaciers and snow cover in high-altitude and cold regions, thus solving the deficiencies of the prior art.

[0005] The objective of this invention is achieved through the following technical solution: a method for refined simulation of hydrothermal processes in glaciers and snow cover in high-altitude cold regions, the method comprising:

[0006] Zoning: Based on altitude and the state of solid accumulation, the high-altitude cold region is first divided into seasonal snow and ice zones (referred to as "snow cover zones" in this text) and perennial snow and ice zones (referred to as "glacier zones" in this text), based on whether there is snow cover for two or more years. If a region has snow cover for two or more years, it is classified as a glacier zone; otherwise, it is a snow cover zone. Within the glacier zone, the glacier profile is further divided into snow and ice layers based on density: snow layer density is less than 0.85 g / cm³, and ice layer density is greater than or equal to 0.85 g / cm³. In the snow cover zone, the surface layer is snow, and the underlying layer is soil; the snow cover state changes dynamically with the seasons. In the glacier zone, the surface layer is snow, and the underlying layer is ice, or it may be in a state of bare ice; the snow layer in the glacier zone undergoes a dynamic process of change. During the ablation period, as temperatures rise, the surface snow melts, and the glacier also melts and thins. When the snow layer disappears, it manifests as bare ice. During the accumulation period, when snowfall increases, the new snow gradually accumulates in the glacier area through compaction and ferruginous melting, transforming into glacial ice. The surface is restored to snow cover, presenting a two-layer structure of snow layer and ice layer. This dynamic change is mainly controlled by energy balance and mass balance, reflecting the seasonal transformation characteristics of the snow-glacier system in the glacier area.

[0007] The calculation steps for the hydrothermal process of snow cover are as follows: perform dynamic rain-snow separation calculation, snow compaction process calculation, snow energy balance calculation, and snow internal water flux calculation respectively;

[0008] The calculation steps for the hydrothermal process of the ice layer are as follows: the energy balance process of the glacier is calculated by using incident shortwave radiation, incident longwave radiation, outgoing longwave radiation, sensible heat flux, latent heat flux and geothermal flux, and the glacier mass balance equation is constructed.

[0009] The dynamic rain and snow separation calculation includes: using a piecewise function to determine the precipitation phase based on three-dimensional criteria of air temperature, humidity and altitude, thereby improving the accuracy of snow and rain identification.

[0010] The snow compaction process calculation includes: after identifying the precipitation phase, determining the actual snow density by atmospheric temperature, establishing a layered compaction model, distinguishing between the destructive compaction and densification stages of new snow, introducing an exponential compaction rate formula, coupling the effects of liquid water content, air density and additional pressure, calculating the snow compaction rate, and finally determining the stage of snow condition by the density of solid water.

[0011] The calculation of the water flux inside the snow layer includes:

[0012] First, the transient changes in liquid water content in the snow layer and its water balance relationship with the conversion of solid water to water vapor, solid water to liquid water, and liquid water to gaseous water are calculated. Then, the vertical water flux term is introduced to calculate the water transfer process between snow layers. A piecewise linear empirical function of snow layer water holding capacity as a function of snow dry bulk density is given. When the dry bulk density is not lower than the critical value, the water holding capacity takes a constant minimum value. Otherwise, it is linearly interpolated between the minimum and maximum values.

[0013] The infiltration rate is determined by taking the minimum value of the current layer's liquid water volume, the upper layer's available water volume, and its potential infiltration capacity due to the decrease in particle size and dryness index. The runoff is calculated by subtracting the final liquid water flux retained and the infiltration rate.

[0014] The snow energy balance calculation includes:

[0015] The snow cover energy balance is calculated using the energy conservation equation. The upper boundary of the snow cover is the flux boundary, which is obtained by the algebraic sum of net shortwave radiation, net longwave radiation, energy carried by precipitation, sensible heat flux, latent heat flux, and geothermal flux.

[0016] Net shortwave radiation flux and net longwave radiation flux constitute the dominant heat input terms, used to characterize the radiation exchange process between the atmosphere and snow layer; the heat flux brought in by precipitation is used to describe the heat transferred by liquid or solid precipitation when it comes into contact with the snow layer.

[0017] Sensible heat flux and latent heat flux are used to characterize sensible heat and latent heat transport in turbulent exchange processes, respectively.

[0018] Geothermal flux is used to characterize the heat exchange between the snow layer and the soil, or the heat exchange with the underlying ice layer.

[0019] The net shortwave radiation is calculated by correcting the extra-atmospheric radiation for sunshine duration and combining it with the surface albedo; the heat flux input from precipitation is calculated based on the difference in specific heat capacity between liquid precipitation and solid precipitation, respectively, to determine the heat contribution from temperature; the sensible heat flux and latent heat flux are based on the aerodynamic impedance method, driven by the gradient between air temperature and snow surface temperature and the water vapor gradient, reflecting the influence of turbulent exchange processes on the energy balance of snow cover.

[0020] The present invention has the following advantages: a refined simulation method for hydrothermal processes of glaciers and snow cover in high-altitude cold regions. Taking into account the large coverage of glaciers and snow cover in the cryosphere, the method uses a hydrothermal coupling model to simulate the glacier / snow cover meltwater process, thereby achieving a scientific description of the glacier / snow cover meltwater runoff process. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the present invention.

[0022] Figure 2This is a schematic diagram of the cryosphere partitioning of the present invention.

[0023] Figure 3 This is a schematic diagram of snow / glacier melting according to the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is not intended to limit the scope of protection of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The present invention will be further described below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, this invention specifically relates to a refined simulation method for hydrothermal processes of glaciers and snow cover in high-altitude and cold regions, particularly suitable for the dynamic analysis of glacier and snowmelt runoff processes under the background of climate change. This method achieves high-precision simulation of glacier and snowmelt runoff processes in high-altitude and cold regions by constructing a multi-physics coupled model. Specifically, it includes the following:

[0026] like Figure 2 and Figure 3 As shown, based on altitude and the density of solid water, the cryosphere is divided into snow cover and glacier zones, determined by whether there has been snow cover for two or more years. If a region has been covered by snow for two or more years, it is classified as a glacier zone; otherwise, it is a snow cover zone. Within the glacier zone, the glacier profile is further divided into a snow layer and an ice layer based on density: snow layer density is less than 0.85 g / cm³, and ice layer density is greater than or equal to 0.85 g / cm³. In the snow cover zone, the surface layer is snow, and the underlying layer is soil; the snow cover condition changes dynamically with the seasons. In the glacier zone, the surface layer is snow, and the underlying layer is ice, or it may be bare ice; the snow layer within the glacier zone undergoes a dynamic process of change. During the ablation period, as temperatures rise, the surface snow melts, and the glacier also melts and thins. When the snow layer disappears, it appears as bare ice. During the accumulation period, when snowfall increases, the new snow gradually accumulates in the glacier area through compaction and ferruginous melting, transforming into glacial ice. The surface is then covered with snow again, presenting a two-layer structure of snow layer and ice layer. This dynamic change is mainly controlled by energy balance and mass balance, reflecting the seasonal transformation characteristics of the snow-glacier system in the glacier area.

[0027] Step 1: Snow Layer Hydrothermal Process Calculation: This involves calculating dynamic rain-snow separation, snow compaction, snow energy balance, and internal snow moisture flux. Dynamic rain-snow separation determines the density and mass of new snow and the energy from precipitation, providing initial conditions for other processes. Energy balance is the core driving force: it calculates snow temperature changes and snowmelt water production through radiation, turbulence, precipitation heat, and soil heat. After meltwater enters the moisture flux module, it may refreeze during infiltration, releasing latent heat that in turn affects the energy balance. Simultaneously, the presence of liquid water alters the snow's thermal conductivity and compaction rate. The compaction process is controlled by snow temperature and moisture content: higher temperatures and more liquid water result in more significant compaction. The reduced layer thickness and increased density caused by compaction not only change the grid scale of heat conduction but also affect moisture flux by adjusting porosity and water conductivity.

[0028] 1. Dynamic rain and snow separation calculation: Based on the three-dimensional criteria of temperature, humidity and altitude, a piecewise function is used to determine the precipitation phase (distinguishing between rain and snow) to improve the accuracy of snow and rain identification;

[0029] Furthermore, by coupling temperature, humidity, and altitude, this invention constructs a dynamic temperature threshold, which can more accurately simulate the determination of precipitation type (rain / snow / sleet) in high-altitude and cold regions.

[0030] ,

[0031] ,

[0032] ,

[0033] in, Indicates the temperature threshold range. This is a temperature offset correction parameter used to adjust the upper and lower limits of the temperature threshold. The baseline critical temperature is the theoretical precipitation type boundary temperature calculated based on altitude and humidity. H represents relative humidity, and H represents altitude.

[0034] ,

[0035] ,

[0036] ,

[0037] in, This is the upper limit temperature for snowfall; below this temperature, precipitation will be classified as snow. This is the lower limit temperature for rainfall; precipitation above this temperature is considered rain. This refers to near-surface air temperature, i.e., the measured air temperature.

[0038] 2. Snow compaction process calculation: After identifying the precipitation phase, the actual snow density is determined by atmospheric temperature. A layered compaction model is established to distinguish between the destructive compaction and densification stages of new snow. An exponential compaction rate formula is introduced, coupled with the effects of liquid water content, air density and additional pressure, to calculate the snow compaction rate.

[0039] (1) The snowfall density is calculated as shown in Table 1 below:

[0040] Table 1. Snowfall Density Calculation Table

[0041] Ta<-5 0.075 -5<Ta<-3 0.1 -3≤Ta<-1.5 0.15 -1.5≤Ta<-0.5 0.175 -0.5≤Ta<0 0.2

[0042] (2) Snow compaction process;

[0043] Snow compaction is divided into two stages: the destructive compaction stage of new snow and the later densification stage. Initially, the density of new snow is low (typically 50–150 kg / m³). It then undergoes two stages of compaction: Destructive compaction of new snow: This occurs in the early stages of snowfall, when snow crystals are brittle and easily break. The compaction rate is significantly influenced by temperature (low temperature promotes compaction) and initial density. Later densification: This continues under gravity and external pressure, primarily involving plastic deformation, and is jointly controlled by temperature (high temperature promotes compaction), the rate of destructive compaction of new snow, and the current snow layer density.

[0044] ,

[0045] in, This is the snow compaction rate (the absolute value of the relative rate of change per unit height). For the rate of destructive compaction of fresh snow, This represents the rate of the later-stage compaction process under gravity. This is the snow density correction factor, a dimensionless parameter. η is the total density of the snow layer, and η0 is the reference viscosity coefficient.

[0046] When the snow density is compacted to 0.85 g / cm³ 3 At that time, it was believed that the snow layer had been compacted into an ice layer.

[0047] Based on the aforementioned physical processes and rate models, under the continuous load of its own weight and the addition of new snow, the density of snow undergoes a sustained evolution from low to high, eventually forming glacial ice. This evolutionary process can be divided into the following stages according to density thresholds:

[0048] Table 2. Solid water density range

[0049] 0.05~0.10 g / cm³ New snow phase Loose grains and unstable structure 0.10~0.40 g / cm³ Destructive compaction stage Brittle grain rearrangement and rapid densification 0.40~0.55 g / cm³ Grain stage Grain rounding and interconnection development, pore connectivity 0.55~0.83 g / cm³ Later densification stage Grain translational deformation reduces porosity ≥0.85 g / cm³ Ice formation stage Pores close and connectivity is lost, transforming into glacial ice.

[0050] 3. Snow cover energy balance calculation: The snow cover energy balance is calculated using the energy conservation equation. The upper boundary of the snow cover is the flux boundary, which is obtained by the algebraic sum of net shortwave radiation, net longwave radiation, energy carried by precipitation, sensible heat flux, latent heat flux, and geothermal flux.

[0051] Net shortwave radiation flux and net longwave radiation flux constitute the dominant heat input terms, used to characterize the radiation exchange process between the atmosphere and snow layer; the heat flux brought in by precipitation is used to describe the heat transferred by liquid or solid precipitation when it comes into contact with the snow layer.

[0052] Sensible heat flux and latent heat flux are used to characterize sensible heat and latent heat transport in turbulent exchange processes, respectively.

[0053] Geothermal flux is used to characterize the heat transfer from inside the snow layer.

[0054] The net shortwave radiation is calculated by correcting the extra-atmospheric radiation for sunshine duration and combining it with the surface albedo; the heat flux input from precipitation is calculated based on the difference in specific heat capacity between liquid precipitation and solid precipitation, respectively, to determine the heat contribution from temperature; the sensible heat flux and latent heat flux are based on the aerodynamic impedance method, driven by the gradient between air temperature and snow surface temperature and the water vapor gradient, reflecting the influence of turbulent exchange processes on the energy balance of snow cover.

[0055] Furthermore, the heat conduction of the snow layer is governed by the energy conservation equation. Calculate, where, , , θ represents the volume ratio, ρ represents density, c represents the specific heat capacity of snow, subscripts i, w, and a represent solid water, liquid water, and air, respectively, T represents snow temperature, t represents time, z represents the coordinate axis, and K represents the volume ratio. s The thermal conductivity of snow. Q represents the amount of shortwave radiation penetrating the snow layer. f For source and sink items.

[0056] The thermal conductivity of snow is calculated as follows: , where K t K represents the thermal conductivity of the snow layer due to the temperature gradient. v The thermal conductivity is due to the phase change of the snow layer and the diffusion of water vapor.

[0057] Upper boundary condition: The upper boundary is the flux boundary.

[0058] Where, ρ s Where is the density of snow, c is the specific heat capacity of snow, and T is the specific heat capacity of snow. s Q represents the surface temperature of the snow. sn For net shortwave radiation, Q ln For net longwave radiation, Q pQ represents the energy carried by precipitation. sh For sensible heat flux, Q lh For latent heat flux, Q g This is the geothermal flux. The formula states that the rate of change of internal energy per unit volume of snow cover is equal to the algebraic sum of all energy fluxes, where long-range and short-range radiation fluxes (Q) are... sn Q ln ) dominates.

[0059] Among them, the net longwave radiation is calculated as follows: the process of snow absorbing longwave radiation is essentially the superposition of the snow layer's absorption of the downward thermal radiation from the atmosphere and its own thermal radiation.

[0060] Q ln =RLD-RLU,

[0061] ,

[0062] ,

[0063] Among them, Q ln Net longwave radiation flux (positive downwards), RLD is the downward longwave radiation from the atmosphere, RLU is the upward longwave radiation from the snow surface, and T a For atmospheric temperature, T s Let be the surface temperature of the snow cover, and σ be the Stefan-Boltzmann constant (4.903 × 10⁻⁶). -9 MJ / m 2 ·K 4 ·day), ε s This is the snow emissivity (default value is 0.95).

[0064] Net shortwave radiation is calculated as follows: In snowmelt simulations, shortwave radiation is usually the primary energy source for daytime snow ablation. The calculation process is as follows:

[0065] ,

[0066] ,

[0067] Q sn =(1-α)RS,

[0068] Where RS0 is the shortwave radiation from outside the atmosphere, a s is the shortwave radiation diffusion constant (default value is 0.25), b s ω is the shortwave radiation direct arrival constant (default value 0.5), n is the actual sunshine duration (hours) of the day, N is the possible sunshine duration (hours) of the day, ϕ is the latitude of the observation point (positive value in the Northern Hemisphere, negative value in the Southern Hemisphere), and ω is the shortwave radiation direct arrival constant. s Sunset is the solar hour angle (in radians), δ is the solar tilt angle, and d rThe relative distance between the Earth and the Sun is represented by J, where J is the Julian day (counting from January 1st); Q sn α represents net shortwave radiation, and α represents reflectivity.

[0069] For clear skies and a horizontal surface, the basic albedo, taking into account the distinction between new and old snow, is calculated using the following formula:

[0070] ,

[0071] ,

[0072] ,

[0073] ,

[0074] Wherein, α is the basic albedo, α s It is the snow albedo, α b Reflectance of snow accumulation on a sunny day; Δα c For cloud reflectance; Δα β Solar altitude affects emissivity; α b The reflectance of fresh snow on a sunny day; α b，0 The reflectance on a sunny day when the snow cover is not fresh; α fs The reflectance of deep, fresh snow on a clear day; K is a parameter; f sn M represents the percentage of snow cover. n This refers to the cumulative amount of snowfall or sleet, expressed in kg / m³. 2 ;p r p represents the total precipitation intensity. s This refers to the intensity of solid precipitation.

[0075] The process of penetration and absorption distribution of net shortwave radiation within snow cover. Snow is a semi-transparent medium; net shortwave radiation (especially in the near-infrared band) is not entirely absorbed at the surface, but rather decreases exponentially with depth. Surface calculations directly drive surface melting or heating, and with increasing depth, can cause internal melting.

[0076] Clouds alter the solar spectrum reaching the ground—clouds absorb / scatter near-infrared wavelengths, increasing the proportion of visible light in the radiation reaching the snow surface. Since snow has a higher albedo in the visible light band than in the near-infrared band, the albedo of the snow surface is slightly higher on cloudy days than on sunny days.

[0077] The energy carried by precipitation is expressed by the formula The calculation yields, where P s =PP w C w C is the specific heat capacity of water. s For the specific heat capacity of snow, P w For rainfall, P sThe snow water equivalent of snowfall, T a P represents the air temperature and P represents the total precipitation.

[0078] Inductive heat flux is expressed by the formula The calculation yields, where ρ a c is the atmospheric density. p For atmospheric specific heat, T a For air temperature, T s r represents the snow layer temperature. a The aerodynamic impedance is given by the reference height, x is the reference height (2m), γ is the wind speed at 2m above the snow layer, and z is the aerodynamic impedance. h and z m These are the thermal and water vapor resistance coefficients and the dynamic resistance coefficient, respectively, with values ​​of 0.0002 and 0.001, and k is a constant with a value of 0.4.

[0079] Latent heat flux is expressed by the formula The calculation yielded that, hτ is the latent heat of sublimation; r d E(T) is the dry air constant. a E(T) represents the air vapor pressure, which can be calculated by multiplying the relative humidity by the saturated vapor pressure of the air temperature; s E represents the water vapor pressure at the snow surface, which is assumed to be saturated and can be considered as the saturated water vapor pressure of the snow cover surface temperature. svp (T s E represents the saturated vapor pressure at the surface temperature of the snow cover. svp (T a E represents the saturated vapor pressure of the air at that temperature. svp It is the saturated vapor pressure.

[0080] Lower boundary condition: The lower boundary is the flux boundary, which is calculated in two cases.

[0081] When the snow layer is covered by soil, the lower boundary geothermal flux (lower boundary) is expressed by the formula... The calculation yields Z, where Z s Z represents the thickness of the snow layer. c This refers to the thickness of the topsoil layer; The thermal conductivity of the snow layer; Rc is the thermal conductivity of the soil; Tc is the contact thermal resistance between the soil layer and the snow layer; Tc is the surface soil temperature; and Ts is the snow layer temperature.

[0082] When the snow layer is covered by an ice layer, the formula for calculating the geothermal flux at the lower boundary is:

[0083]

[0084] Where: K siis the thermal conductivity between the ice and snow layers, and is the average thermal conductivity of the lower snow layer and the ice layer.

[0085] 4. The water flux within the snow layer is calculated using a mass equation:

[0086] ,

[0087] ,

[0088] Among them, M iv M represents the amount of solid water converted into water vapor. il M represents the amount of water that is converted from solid to liquid; lv The amount of liquid water converted into gaseous water; U1 is the snow layer water flux.

[0089] Snow layer water holding capacity calculation:

[0090] ,

[0091] Among them, R H,min R H,max and γ e These are parameters, with values ​​of 0.03, 0.10, and 200 kg / m³. 3 ;γ i The dry bulk density of snow.

[0092] Snow infiltration and runoff calculation: The snow infiltration rate depends on the outflow of upper snowmelt, the volume of liquid water that the snow layer can hold, and the potential infiltration capacity. The specific calculation formula is as follows:

[0093] ,

[0094] ,

[0095] ,

[0096] Among them, R H V represents the water-holding capacity of the snow layer in liquid water. lp Potential infiltration capacity; m i,j For solid water mass; m l ρ is the mass of liquid water. l V is the density of liquid water. l,j V is the infiltration rate; R,j This refers to runoff.

[0097] Step 2: Calculation of heat flux in the ice layer;

[0098] (1) Calculation of upper boundary conditions:

[0099] When the ice layer is covered by a snow layer, the upper boundary of the ice layer is the flux boundary, and the calculation is the same as the lower boundary of the snow layer (old snow), i.e.: ,in Heat flux through the interface between snow and ice (unit: W / m²) 2 This indicates that heat is transferred from the snow layer to the ice layer (vertically downward is the positive direction). It is the thermal conductivity of the snow-ice interface (unit: W / (m·K)). In actual calculations, the average value of the thermal conductivity of the ice layer and the snow layer can be taken.

[0100] When there is no snow accumulation on the ice layer, the upper boundary is the flux boundary, which includes incident shortwave radiation, incident longwave radiation, outgoing longwave radiation, sensible heat flux, latent heat flux, and geothermal flux. The energy balance is calculated as follows:

[0101] ,

[0102] Where Ki is the thermal conductivity of the glacier, taken as 2.2 W / (m·K); T s SW represents the surface temperature of the ice. in For incident shortwave radiation; Q is the corrected albedo of the glacier surface; ln Net longwave radiation, calculated in the same way as snow cover; Q sh For sensible heat flux, the calculation process is the same as for snow cover; Q lh For latent heat flux, the calculation process is the same as for snow cover; Q p The calculation process for the energy carried by precipitation is the same as that for snow cover; Q g This refers to geothermal flux.

[0103] (2) Albedo dynamic update

[0104] When there is fresh snow on the ice layer, the ice layer albedo is dynamically calculated based on snow age and snow depth. The calculation process is the same as for the snow layer, but the albedo of the snow surface is taken. When there is no snow cover, albedo Albedo of pure ice It is usually taken as (0.30-0.40).

[0105] (3) Calculation of net shortwave radiation penetration;

[0106] Surface energy calculation: The calculation below the surface layer (m from 1 to the bottom layer - 1) is as follows: Where dz is the height of each subsurface layer, dt is the time step (3600 s), and α is the basic albedo.

[0107] (4) Calculation of heat flux in ice layer: Heat conduction in ice layer is calculated using the energy balance equation:

[0108] ,

[0109] Where: T is the ice layer temperature; t is time; K i The coefficient of thermal conductivity of the ice layer is denoted by z; z represents the coordinate axis. It is the portion of shortwave radiation that penetrates the surface of ice and is converted into heat below the surface, measured in W / m².

[0110] The heat flux of penetrating shortwave radiation is determined by the net shortwave radiation. and surface absorption share Decide:

[0111] ,

[0112] in, , It is incident shortwave radiation. It is the albedo of the glacier surface; It represents the surface absorption fraction, which is 0.8 for ice layers.

[0113] Penetrating shortwave radiation is distributed in the deep layers according to an exponential decay law. As the volume heat source term in the heat conduction equation, its variation with depth is as follows:

[0114] ,

[0115] in, It is the remaining shortwave radiation flux at depth z, W m⁻²; is the extinction coefficient, which is 2.5 m⁻¹ for ice layers; z is the depth, positive downwards, in meters.

[0116] Lower boundary condition of ice layer: Since the ice layer is relatively thick, the thickness is taken as 10m, and the lower boundary is set to a constant temperature of -1℃.

[0117] (5) Glacier material balance calculation: calculate the amount of melting on the glacier surface, the latent heat flux (sublimation / condensation or evaporation / condensation) under different temperature conditions, and the amount of subsurface melting caused by excessively high temperatures inside the glacier.

[0118] Surface melting calculation: Where M is the amount melted. Heat of fusion;

[0119] When the surface temperature is less than 273.15K, only sublimation (maximum) and deposition (minimum) occur. The calculations are as follows:

[0120] ,

[0121] At K greater than 273.15, only evaporation and condensation occur; the calculations are the same as above. Become .

[0122] Infiltration and refreezing: When the glacier surface temperature is greater than 273.15°C, additional heat is used to melt the ice. .

[0123] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and improvements, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A refined simulation method for hydrothermal processes in glaciers and snow cover in high-altitude cold regions, characterized in that: The method includes: Zoning: Based on altitude and the state of solid water accumulation, the high-altitude cold region is first divided into seasonal snow and ice zones and perennial snow and ice zones. If a region has snow cover for two or more years, it is classified as a glacier zone; otherwise, it is a snow cover zone. Within the glacier zone, the glacier profile is further divided into snow cover and ice cover based on density. The criteria for this division include: snow cover density less than 0.85 g / cm³, and ice cover density greater than or equal to 0.85 g / cm³. g / cm³; In the snow-covered area, the surface layer is snow and the underlying layer is soil. The snow cover state changes dynamically with the seasons. In the glacier area, the surface layer is snow and the underlying layer is ice, or it may be bare ice. The snow layer in the glacier area undergoes a dynamic change process. During the ablation period, when the temperature rises, the surface snow melts, and the glacier also melts and thins. After the snow layer melts, the glacier is in a bare ice state. During the accumulation period, new snow accumulates in the glacier area. Through the processes of compaction and ferruginous deposition, it gradually accumulates and transforms into glacial ice. The surface is restored to snow cover, presenting a two-layer structure of snow-ice layer. This dynamic change is mainly controlled by energy balance and mass balance, reflecting the seasonal transformation characteristics of the snow-glacier system in the glacier area. The calculation steps for the hydrothermal process of snow cover are as follows: perform dynamic rain-snow separation calculation, snow compaction process calculation, snow energy balance calculation, and snow internal water flux calculation respectively; Calculation steps for hydrothermal processes in ice layers: calculation of ice layer energy balance and water balance.

2. The method for refined simulation of hydrothermal processes in glaciers and snow cover in high-altitude cold regions according to claim 1, characterized in that: The dynamic rain and snow separation calculation includes: using a piecewise function to determine the precipitation phase based on three-dimensional criteria of air temperature, humidity and altitude, thereby improving the accuracy of snow and rain identification.

3. The method for refined simulation of hydrothermal processes in glaciers and snow cover in high-altitude cold regions according to claim 1, characterized in that: The snow compaction process calculation includes: after identifying the precipitation phase, determining the actual snow density by atmospheric temperature, establishing a layered compaction model, distinguishing between the destructive compaction and densification stages of new snow, introducing an exponential compaction rate formula, coupling the effects of liquid water content, air density and additional pressure, calculating the snow compaction rate, and finally determining the stage of snow condition by the density of solid water.

4. The method for refined simulation of hydrothermal processes in glaciers and snow cover in high-altitude cold regions according to claim 1, characterized in that: The calculation of the water flux inside the snow layer includes: First, the transient changes in liquid water content in the snow layer and its water balance relationship with the conversion of solid water to water vapor, solid water to liquid water, and liquid water to gaseous water are calculated. Then, the vertical water flux term is introduced to calculate the water transfer process between snow layers. A piecewise linear empirical function of snow layer water holding capacity as a function of snow dry bulk density is given. When the dry bulk density is not lower than the critical value, the water holding capacity takes a constant minimum value. Otherwise, it is linearly interpolated between the minimum and maximum values. The infiltration rate is determined by taking the minimum value of the current layer's liquid water volume, the upper layer's available water volume, and its potential infiltration capacity due to the decrease in particle size and dryness index. The runoff is calculated by subtracting the final liquid water flux retained and the infiltration rate.

5. The method for refined simulation of hydrothermal processes in glaciers and snow cover in high-altitude cold regions according to claim 1, characterized in that: The snow energy balance calculation includes: The snow cover energy balance is calculated using the energy conservation equation. The upper boundary of the snow cover is the flux boundary, which is obtained by the algebraic sum of net shortwave radiation, net longwave radiation, energy carried by precipitation, sensible heat flux, latent heat flux, and geothermal flux. Net shortwave radiation flux and net longwave radiation flux constitute the dominant heat input terms, used to characterize the radiation exchange process between the atmosphere and snow layer; the heat flux brought in by precipitation is used to describe the heat transferred by liquid or solid precipitation when it comes into contact with the snow layer. Sensible heat flux and latent heat flux are used to characterize sensible heat and latent heat transport in turbulent exchange processes, respectively. Geothermal flux is used to characterize the heat conducted upward from the soil beneath the snow layer or the lower soil layer.

6. The method for refined simulation of hydrothermal processes in glaciers and snow cover in high-altitude cold regions according to claim 5, characterized in that: The net shortwave radiation is calculated by correcting the extra-atmospheric radiation for sunshine duration and combining it with the surface albedo; the heat flux input from precipitation is calculated based on the difference in specific heat capacity between liquid precipitation and solid precipitation, respectively, to determine the heat contribution from temperature; the sensible heat flux and latent heat flux are based on the aerodynamic impedance method, driven by the gradient between air temperature and snow surface temperature and the water vapor gradient, reflecting the influence of turbulent exchange processes on the energy balance of snow cover.

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