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start:hype_model_description:hype_land [2018/08/10 15:47]
cpers [Glaciers]
start:hype_model_description:hype_land [2018/10/16 08:36] (current)
cpers [Soil temperature and snow depth]
Line 64: Line 64:
  
 There are two parameters in order to be able to choose if you want the frost depth to be land use dependent or soil dependent. The not used parameter is set to one. There are two parameters in order to be able to choose if you want the frost depth to be land use dependent or soil dependent. The not used parameter is set to one.
 +
 +==== Links to file reference ====
 +
 +^Section ^Symbol ^Parameter/​Data ^File ^
 +|Basic assumptions| |//​soillayerdepth,​ tiledepth, streamdepth//​|[[start:​hype_file_reference:​geoclass.txt|GeoClass.txt]]|
 +|:::​|//​soillayerthick//​|calculated from //​soillayerdepth//​|:::​|
 +|:::|//wp, fc, ep//​|calculated from //​wcwp,​wcfc,​wcep,​wcwp1-3,​wcfc1-3,​wcep1-3//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|Diagnostic variables| |//​frost,​sfrost//​|:::​|
 +|:::​|//​soiltemp//​|see needed data in [[start:​hype_model_description:​hype_land#​links_to_file_reference2|Links for soil temperature]]||
 +
 ==== Links to relevant procedures in the code ==== ==== Links to relevant procedures in the code ====
  
Line 77: Line 87:
 ==== Groundwater runoff ==== ==== Groundwater runoff ====
    
-Runoff depends on the water table in relation to the drainage ​depth. Runoff occurs when soil water reaches above field capacity ​of the soil layers ​situated above the stream level. Runoff depends on water in the effective porosity (also used to calculate the groundwater table) and a recession coefficient (//rc//). If the soil is not saturated, runoff from the soil layer depends only on the water of that soil layer. Runoff occurs from all three soil layers (//runoff1-3//) down to the drainage ​depth, which is the level of the ditch or creek.+Runoff depends on the water table in relation to the drainage ​level. Runoff occurs when soil water reaches above field capacity ​in the soil layers. Runoff depends on soil water in the effective porosity (also used to calculate the groundwater table) and a recession coefficient (//rc//). If the soil is not saturated, runoff from the soil layer depends only on the water of that soil layer. Runoff occurs from all three soil layers (//runoff(k), k=1-3//) down to the drainage ​level, which is the depth of the stream (streamdepth).
  
-  IF(soil(1) > fc(1) + wp(1)) 
-    runoff1 = rc(1) * (soil(1)-wp(1)-fc(1)) 
-  IF(soil(2) > fc(2) + wp(2)) 
-    runoff2 = rc(2) * (soil(2)-wp(2)-fc(2)) 
-  IF(soil(3) > fc(3) + wp(3)) 
-    runoff3 = rc(3) * (soil(3)-wp(3)-fc(3)) 
  
-If for example the stream drainage level (//​streamdepth//​is in the third layer (figure 6and the soil layer is not saturated, the runoff depends on the water level above the stream drainage depth and the following equation replaces the one above. ​+<m> runoff(k)=delim{lbrace}{ 
 + ​matrix{2}{2}{ 
 +   {rc(k)*(soil(k)-wp(k)-fc(k))} {wp(k)+fc(k)<​soil(k)<​wp(k)+fc(k)+ep(k)} 
 +   0 {soil(k)<​wp(k)+fc(k)}} 
 +   }{} </m>
  
-  deltah = (soil(3)-wp(3)-fc(3))/​ep(3) * soillayerthick(3) –  +For the soillayer at drainage level, e.g. in the third layer of figure 6, and if the soil layer is not saturated, the runoff depends on the water level above the stream depth and the following equation replaces the one above. ​ 
-           (soillayerdepth(3) - streamdepth) +       ​ 
-  IF(deltah>​0.)THEN +<m> runoff(k)=delim{lbrace}{ 
-    ​runoff3 = rc(3) * deltah / soillayerthick(3) * ep(3+ matrix{2}{2}{ 
-  ​ELSE +   {rc(k)*{{deltah*ep(k)}/{soillayerthick(k)}}} {deltah>​0} 
-    runoff3 = 0. +   0 {deltah<0}} 
-  ENDIF+   }{} </m>
  
- +where  
 +<m> deltah = {{(soil(k)-wp(k)-fc(k))/​{ep(k)}} * {soillayerthick(k)}}-  
 +           ​({soillayerdepth(k)} - streamdepth) </​m>​ 
 +  
 |{{:​start:​hype_model_description:​runofffromthird_layer.png?​400|}}| |{{:​start:​hype_model_description:​runofffromthird_layer.png?​400|}}|
 |Figure 6: Runoff from the third soil layer with a stream.| |Figure 6: Runoff from the third soil layer with a stream.|
  
-Similarly the equations change for the other layers if the drainage is in them. Soil layers that lye entirely below the creek level have no groundwater runoff.+Soil layers that lye entirely below the stream depth have no groundwater runoff.
  
-If a soil layer is saturated, i.e. //​soil>​=fc+wp+ep//,​ the runoff of the soil layer depends also on the water in the soil layer(s) above. For example if the drainage is in soil layer 3 and both soil layer 2 and 3 are saturated, the groundwater table in soil layer 1 determines the runoff of soil layer 3. The runoff is limited to the water in the layer above field capacity.+If a soil layer is saturated, i.e. //​soil>​=fc+wp+ep//,​ the runoff of the soil layer depends also on the water in the soil layer(s) above. For example if the drainage is in soil layer 3 and both soil layer 2 and 3 are saturated, the groundwater table in soil layer 1 determines the runoff of soil layer 3. The runoff is limited to the water above field capacity ​in the third layer though.
  
-  deltah = (soil(3)-wp(3)-fc(3)) / ep(3) * soillayerthick(3) –  +<m> runoff(3) = MIN(soil(3)-wp(3)-fc(3),​{rc(3)}*{{deltah/ ​{soillayerthick(3)}}*{ep(3)}}</m>
-           ​(soildepth(3) - streamdep) +
-  IF(soil(3)-wp(3)-fc(3)-ep(3)>​=0.)THEN ​     !saturated +
-    deltah2 = soil(2)-wp(2)-fc(2) +
-    IF(deltah2>​0.) deltah = deltah + deltah2 / ep(2) * soillayerthick(2) +
-    IF(soil(2)-wp(2)-fc(2)-ep(2)>​=0.)THEN +
-      deltah2 = soil(1)-wp(1)-fc(1) +
-      IF(deltah2>​0.) deltah = deltah + deltah2 / ep(1) * soillayerthick(1) +
-    ENDIF +
-  ENDIF +
-  IF(deltah>​0.)THEN +
-    runoff3 ​= MIN(soil(3)-wp(3)-fc(3),​rc(3)*deltah/​ soillayerthick(3)*ep(3)) +
-  ELSE +
-    runoff3 = 0. +
-  ENDIF+
  
 +<​m> ​ deltah = {{(soil(3)-wp(3)-fc(3)) * {soillayerthick(3)}} / {ep(3)}- ​
 +           ​(soildepth(3) - streamdepth)} + {{(soil(2)-wp(2)-fc(2)) * {soillayerthick(2)}}/​ {ep(2)}} + {{(soil(1)-wp(1)-fc(1)) * {soillayerthick(1)}}/​ {ep(1)}} </m>
 +           
 If the stream depth is below the bottom of the lowest soil layer. The extra distance will act as a level to  increase //deltah// and the runoff from the lowest soillayer. If the stream depth is below the bottom of the lowest soil layer. The extra distance will act as a level to  increase //deltah// and the runoff from the lowest soillayer.
 +
 +=== Recession coefficient of groundwater runoff ===
  
 The recession coefficient is calculated from two parameters, //rrcs1// and //rrcs2// which depend on soil type and a parameter that is general //rrcs3//. The recession coefficient is assumed to decrease with depth and the parameters indicate the coefficient value in the topmost layer (//rrcs1//) and in the bottom layer (//​rrcs2//​). If //rrcs2// is not specified it is assumed to be similar to the recession in the topmost layer. The third parameter adjusts the upper layer recession due to the subbasin gradient (//​slope//​). The recession coefficient is calculated from two parameters, //rrcs1// and //rrcs2// which depend on soil type and a parameter that is general //rrcs3//. The recession coefficient is assumed to decrease with depth and the parameters indicate the coefficient value in the topmost layer (//rrcs1//) and in the bottom layer (//​rrcs2//​). If //rrcs2// is not specified it is assumed to be similar to the recession in the topmost layer. The third parameter adjusts the upper layer recession due to the subbasin gradient (//​slope//​).
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 <m> rrcs2 = rrcs2*(1+rrcscorr) </m> <m> rrcs2 = rrcs2*(1+rrcscorr) </m>
  
-The correction factor corrects //​rrcscorr//​ parameters //rrcs1// and //rrcs2// for different parameter regions (//​parreg//​). It is defined as an increase. Note that the recession is limited to one. The recession is assumed to diminish exponentially and values of //rrcs1// and //rrcs2// applies to the midpoint of each layer. ​+The correction factor corrects //​rrcscorr//​ parameters //rrcs1// and //rrcs2// for different parameter regions (//​parreg//​). It is defined as an increase. Note that the recession is limited to one. The recession is assumed to diminish exponentially and values of //rrcs1// and //rrcs2// applies to the midpoint of each layer (//​d<​sub>​k</​sub>//​)
  
  
-<m> rc(d)=rrcs*e^{-b*d} </m>+<m> rc(k)=rrcs*e^{-b*d_k} </m>
  
 The variable //b// is an auxiliary variable. ​ The variable //b// is an auxiliary variable. ​
                                                
-<m> b = {log(rrcs1/​rrcs2)}/​{(soillayerdepth(3) - {soillayerthick(3)}/​2. +<m> b = {log(rrcs1/​rrcs2)}/​{(soillayerdepth(3) - {soillayerthick(3)}/​2)- 
-                       ​{soillayerthick(1)}/​2.} </m>+                       ​{soillayerthick(1)}/​2} </m>
  
 The result is: The result is:
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 <m> rc(1) = rrcs1 </m> <m> rc(1) = rrcs1 </m>
  
-<m> rc(2) = rrcs1*exp(-b*({soillayerthick(1)}/​2.+{soillayerthick(2)}/​2.)) </m>+<m> rc(2) = rrcs1*exp( - b*({soillayerthick(1)}/​2+{soillayerthick(2)}/​2)) </m>
  
 <m> rc(3) = rrcs2 </m> <m> rc(3) = rrcs2 </m>
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 ==== Infiltration ==== ==== Infiltration ====
-Infiltration is calculated from the sum of rain and snowmelt (//​infilt0//​) .+Infiltration is calculated from the sum of rain and snowmelt (//​infilt0//​, mm/time step) .
  
 <m> infilt0 = rainfall + melt </​m> ​ <m> infilt0 = rainfall + melt </​m> ​
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 The actual infiltration is calculated by subtracting the macropore flow and surface runoff from the sum of snow melt and rain. The actual infiltration is calculated by subtracting the macropore flow and surface runoff from the sum of snow melt and rain.
  
-<m> infilt = infilt0 - macroflow ​– infoverflow </m>+<m> infilt = infilt0 - macroflow ​infoverflow </m>
  
 === Additional infiltration limitation by frozen soil === === Additional infiltration limitation by frozen soil ===
Line 266: Line 268:
 ==== Saturated surface runoff ==== ==== Saturated surface runoff ====
    
-Surface runoff due to a high ground water table (//satoverflow//) occurs when the water table in the upper soil layer reaches above the surface. It depends on a parameter //srrcs// which is dependent on land use. The recession parameter is corrected with the correction factor //​rrcscorr//​ for different parameter regions (parreg). It is defined as an increase.+Surface runoff due to a high ground water table (//q//, mm/time step) occurs when the water table in the upper soil layer reaches above the surface. It depends on a parameter //srrcs// which is dependent on land use. The recession parameter is corrected with the correction factor //​rrcscorr//​ for different parameter regions (parreg). It is defined as an increase.
  
 <m> srrcs = srrcs*(1+rrcscorr) </m> <m> srrcs = srrcs*(1+rrcscorr) </m>
  
-<​m> ​satoverflow ​= MAX(srrcs * (soil(1)-wp(1)-fc(1)-ep(1)),​0.) </m>+<​m> ​= MAX(srrcs * (soil(1)-wp(1)-fc(1)-ep(1)),​0.) </m>
  
 Runoff is removed from the uppermost soil layer. The total surface runoff (due to high ground water table and low infiltration capacity) is calculated and printed. Runoff is removed from the uppermost soil layer. The total surface runoff (due to high ground water table and low infiltration capacity) is calculated and printed.
Line 284: Line 286:
  
 Zhao, L., and D.M. Gray 1999. Estimating snowmelt infiltration into frozen soils, Hydrological Processes, 13:​1827-1842. Zhao, L., and D.M. Gray 1999. Estimating snowmelt infiltration into frozen soils, Hydrological Processes, 13:​1827-1842.
 +
 +==== Links to file reference ====
 +
 +^Section ^Symbol ^Parameter/​Data ^File ^
 +|Groundwater runoff|//​wp,​ fc, ep//​|calculated from //​wcwp,​wcfc,​wcep,​wcwp1-3,​wcfc1-3,​wcep1-3//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|:::| |//rrcs1, rrcs2, rrcs3, rrcscorr//​|:::​|
 +|:::| |//​soillayerdepth,​ streamdepth,​ tiledepth//​|[[start:​hype_file_reference:​geoclass.txt|GeoClass.txt]]|
 +|:::​|//​soillayerthick//​|calculated from //​soillayerdepth//​|:::​|
 +|:::​|//​slope//​|//​slope_mean//​|[[start:​hype_file_reference:​geodata.txt|GeoData.txt]]|
 +|:::| |//​parreg//​|:::​|
 +|Runoff through drainage pipes| |//​trrcs//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|Infiltration| |//​mactrinf,​ mactrsm, macrate, srrate, bfroznsoil//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|:::​|//​pw//​|calculated from //​wc+fc+wp//​|:::​|
 +|Percolation| |//mperc1, mperc2//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|Saturated surface runoff| |//​srrcs//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +
  
 ==== Links to relevant procedures in the code ==== ==== Links to relevant procedures in the code ====
Line 303: Line 321:
 <m> melt = MIN(cmlt*(temp-ttmp),​snow) </m> <m> melt = MIN(cmlt*(temp-ttmp),​snow) </m>
  
-The parameters //cmlt// and //ttmp// are related to land use. The parameter //ttpi// is a general parameter, but was in earlier versions always equal to one. The parameter //ttpd// is general. ​+The parameters //cmlt// and //ttmp// are related to land use.  
  
 === Snow melt models === === Snow melt models ===
Line 329: Line 347:
 Alternatively if parameters are given, snow cover fraction (//fsc//) within a class is calculated based on snow water equivalent (//snow//). The formulation is based on Samuelsson et al. (2006). During snow build up the snow cover increase as a function of snow water equivalent until a maximum value (general parameter //fscmax//) is reached. Alternatively if parameters are given, snow cover fraction (//fsc//) within a class is calculated based on snow water equivalent (//snow//). The formulation is based on Samuelsson et al. (2006). During snow build up the snow cover increase as a function of snow water equivalent until a maximum value (general parameter //fscmax//) is reached.
  
-<m> fsc=fscmax×tanh(0.1×snow) </m>+<m> fsc=fscmax*tanh(0.1*snow) </m>
  
 It is also possible to specify a minimum snow cover (general parameter //​fscmin//​). ​ It is also possible to specify a minimum snow cover (general parameter //​fscmin//​). ​
 As soon as the fractional snow cover area reaches above a certain threshold (//​fscmax-fsclim//​),​ the snow cover area is determined by another relation that represents the redistribution of snow during winter. In this case snow cover is dependent on maximum snow pack during the winter (//​snowmax//​) and a snow cover redistribution factor that is dependent on variation in elevation (//​stdelev//,​ the standard deviation of elevation within the subbasin) and land use. As soon as the fractional snow cover area reaches above a certain threshold (//​fscmax-fsclim//​),​ the snow cover area is determined by another relation that represents the redistribution of snow during winter. In this case snow cover is dependent on maximum snow pack during the winter (//​snowmax//​) and a snow cover redistribution factor that is dependent on variation in elevation (//​stdelev//,​ the standard deviation of elevation within the subbasin) and land use.
  
-<m> fsc= snow / {snowmax×fscdist} </m>+<m> fsc= snow / {snowmax*fscdist} </m>
  
-<m> fscdist=fscdist0+fscdist1×stdelev ​</m>+<m> fscdist=fscdist0+fscdist1*stdelev ​</m>
  
 The snow distribution factor (//​fscdist//​) is determined by three land use dependent parameters; //​fscdist0//​ and //​fscdist1//​ in the linear equation and a maximum value (//​fscdistmax//​). Also in this case the snowcover is limited by the maximum and minimum value parameters. When the end of the snow season approaches (defined by general parameter //fsck1//) the //snowmax// variable is gradually decreased in order to be reset before next winter season: The snow distribution factor (//​fscdist//​) is determined by three land use dependent parameters; //​fscdist0//​ and //​fscdist1//​ in the linear equation and a maximum value (//​fscdistmax//​). Also in this case the snowcover is limited by the maximum and minimum value parameters. When the end of the snow season approaches (defined by general parameter //fsck1//) the //snowmax// variable is gradually decreased in order to be reset before next winter season:
  
-<m> snowmax=snowmax-(fsck1×snowmax-snow)×{1-e^{-fsckexp×ts}}/{fsck1} </m>+<m> snowmax=snowmax-(fsck1*snowmax-snow)*{1-e^{-fsckexp*ts}}/{fsck1} </m>
  
 <m> {snow}/​{snowmax}<​fsck1 </m> <m> {snow}/​{snowmax}<​fsck1 </m>
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 ==== Soil temperature and snow depth ==== ==== Soil temperature and snow depth ====
  
-Soil layer temperature (//​soiltemp//​) is calculated as a weight ​of three temperatures;​ previous time step soil layer temperature,​ soil temperature at deep depth (//​deeptemp//​) and air temperature (//temp//). The weight of the deep soil is constant (0.001), while the weight of the air temperature (//​weightair//​) depends on snow depth (//​snowdepth//​) and parameters. The soil memory (//​soilmem//​) depends on depth and land use, with parameters //surfmem// and //​depthrel//​. The memory of deep soil temperature is a general parameter (//​deepmem//​).+Soil layer temperature (//​soiltemp//​) is calculated as a balance ​of three temperatures;​ previous time step soil layer temperature,​ soil temperature at deep depth (//​deeptemp//​) and air temperature (//T//). The weight of the deep soil is constant (0.001), while the weight of the air temperature (//​weightair//​) depends on snow depth (//​snowdepth//​) and parameters. The soil memory (//​soilmem//​) depends on depth and land use, with parameters //surfmem// and //​depthrel//​. The memory of deep soil temperature is a general parameter (//​deepmem//​).
  
 <m> soilmem = {lbrace}{ <m> soilmem = {lbrace}{
  ​\matrix{2}{2}  ​\matrix{2}{2}
     {deepmem {for\ deeptemp}     {deepmem {for\ deeptemp}
-    ​surfmem×e^{-depthrel×depth(k)} {for\ soil\ layer\ k} }} </m>+    ​surfmem*e^{-depthrel*depth(k)} {for\ soil\ layer\ k} }} </m>
  
-<m> weigth_{air}={1}/​{soilmem+10×snowdepth} </m>+<m> weigth_{air}={1}/​{soilmem+10*snowdepth} </m>
  
-<m> deeptemp=weight_{air}*temp+(1-weight_{air})×deeptemp ​</m>+<m> deeptemp=weight_{air}*T+(1-weight_{air})*deeptemp ​</m>
  
-<m> soiltemp=weight_{air}*temp+(1-weight_{air}-weight_{deep} )×soiltemp+weight_{deep}×deeptemp ​</m>+<m> soiltemp=weight_{air}*T+(1-weight_{air}-weight_{deep} )*soiltemp+weight_{deep}*deeptemp ​</m>
  
 In the default snow depth model, snow density (//​snowdens//​) depends on the snow's age in days (//​snowage//​). Snow density for fresh snow (//​sdnsnew//​) and the increase of density with snow age (//​snowdensdt//​) are general parameters (~ 0.1 and ~0.002). The snow's age increases by one every time step, but are weighted with age (0) for any new snow. In the default snow depth model, snow density (//​snowdens//​) depends on the snow's age in days (//​snowage//​). Snow density for fresh snow (//​sdnsnew//​) and the increase of density with snow age (//​snowdensdt//​) are general parameters (~ 0.1 and ~0.002). The snow's age increases by one every time step, but are weighted with age (0) for any new snow.
Line 371: Line 389:
 <​m> ​ snowdepth = 0.1 * snow/​snowdens </m> <​m> ​ snowdepth = 0.1 * snow/​snowdens </m>
  
-In the alternative snow depth model, snow density ​(//​snowdens//​) ​is calculated by a compacting factor. Snow density for fresh snow (//​sdnsnew//​),​ maximum snow density (//​sdnsmax//​),​ compactation rate for low temperatures (//​sdnsrate//​) and additional compactation for high temperature (//​sdnsradd//​) are all general parameters. The change in snowdensity (//​densdt//​) due to compactation each time step is calculated as:+In the alternative snow depth model, snow density is calculated by a compacting factor. Snow density for fresh snow (//​sdnsnew//​),​ maximum snow density (//​sdnsmax//​),​ compactation rate for low temperatures (//​sdnsrate//​) and additional compactation for high temperature (//​sdnsradd//​) are all general parameters. The change in snowdensity (//​densdt//​) due to compactation each time step is calculated as:
  
 <​m> ​ densdt = sdnsrate*(sdnsmax-snowdens) </m> <​m> ​ densdt = sdnsrate*(sdnsmax-snowdens) </m>
Line 381: Line 399:
 for warm days. for warm days.
  
 +==== Links to file reference ====
 +
 +^Section ^Symbol ^Parameter/​Data ^File ^
 +|Snow melt|//​cmlt,​ ttmp//​|//​cmlt,​ ttmp//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|:::​|//​T//​|calculated from|[[start:​hype_file_reference:​tobs.txt|Tobs.txt]]|
 +|Snow cover|//​stdelev//​|//​elev_std//​|[[start:​hype_file_reference:​geodata.txt|GeoData.txt]]|
 +|:::​|//​fscmax,​ fscdist0, fscdist1, fsck1, fsckexp//​|//​fscmax,​ fscdist0, fscdist1, fsck1, fsckexp//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|:::| |//​fscmin,​fsclim,​fscdistmax//​|:::​|
 +|Soil temperature and snow depth|//​deeptemp//​|//​init2//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|:::| |//deepmem, surfmem, depthrel, sdnsnew, snowdensdt, sdnsmax, sdnsrate, sdnsradd, ttmp//|:::|
  
 ==== Links to relevant procedures in the code ==== ==== Links to relevant procedures in the code ====
Line 403: Line 431:
 <m> glac_{vol} = coef*{glac_{area}}^{exp} </m> <m> glac_{vol} = coef*{glac_{area}}^{exp} </m>
  
-<m> coef = glacvcoef*{e}^{c} </m>+<m> coef = coef0*{e}^{c} </m>
  
 The initial glacier volume if calculated from class area: The initial glacier volume if calculated from class area:
Line 413: Line 441:
 <m> glac_{area} = ({glac_{vol}*{1/​{coef}}})^{1/​exp} </m> <m> glac_{area} = ({glac_{vol}*{1/​{coef}}})^{1/​exp} </m>
  
-The equation coefficients //coef// and //exp// can have different values for specific glaciers. The first coefficient coef is calculated as the product of //EXP( c)//, where //c// is a glacier volume correction and a general parameter (//​glacvcoef/​glacvcoef1//​) depending on glacier type. The second coefficient,​ //exp// is a general parameter (//​glacvexp/​glacvexp1//​) depending on glacier type. Glacier density (//​glacdens//​) is a general model parameter (m3 water / m3 ice).+The equation coefficients //coef// and //exp// can have different values for specific glaciers. The first coefficient coef is calculated as the product of //EXP( c)//, where //c// is a glacier volume correctionand a general parameter (//​glacvcoef/​glacvcoef1//​) depending on glacier type. The second coefficient,​ //exp// is a general parameter (//​glacvexp/​glacvexp1//​) depending on glacier type. Glacier density (//​glacdens//​) is a general model parameter (m<​sup>​3</​sup> ​water / m<​sup>​3</​sup> ​ice).
  
 Glaciers are divided into four types. The default type is mountain glacier, the alternatives are ice cap, ice sheet and infinite glacier. Glacier type is given as input, or determined by the glacier area (a threshold (//​glac2arlim//,​ a general parameter). The glacier area is used to determine the glacier type if it is not given as input and the threshold parameter is set. The glaciers will then be divided into mountain glaciers and ice caps.  Glaciers are divided into four types. The default type is mountain glacier, the alternatives are ice cap, ice sheet and infinite glacier. Glacier type is given as input, or determined by the glacier area (a threshold (//​glac2arlim//,​ a general parameter). The glacier area is used to determine the glacier type if it is not given as input and the threshold parameter is set. The glaciers will then be divided into mountain glaciers and ice caps. 
Line 425: Line 453:
 For snowfields, all soil processes are calculated as for the common land classes. Snow pack is only calculated for the snowfield, i.e. snow depth is assumed zero on glaciers. For glaciers, all precipitation is added to the glacier ice. Glacier melting is calculated as: For snowfields, all soil processes are calculated as for the common land classes. Snow pack is only calculated for the snowfield, i.e. snow depth is assumed zero on glaciers. For glaciers, all precipitation is added to the glacier ice. Glacier melting is calculated as:
  
-<m> melt = cmlt*(temp-ttmp) </m>+<m> melt = cmlt*(T-ttmp) </m>
  
 where //cmlt// is the general parameter //​glaccmlt//​ and //ttmp// the general parameter //​glacttmp//​. ​ where //cmlt// is the general parameter //​glaccmlt//​ and //ttmp// the general parameter //​glacttmp//​. ​
  
-An alternative glacier melting model exist, which depend on temperature (//temp//) and radiation (//swrad//) and has a refreezing component (goverened by general parameter //crefr//). The radiation component depend on the albedo of the glacier, which in turn depends on if the glacier is snow covered (//​snowcov//​) or not, and general parameters for rate (//cmrad//) and glacier ice albedo (//​glacalb//​). The refreezing component is limited to the glacier melt.+An alternative glacier melting model exist, which depend on class' ​temperature (//T//) and radiation (//swrad//) and has a refreezing component (goverened by general parameter //crefr//). The radiation component depend on the albedo of the glacier, which in turn depends on if the glacier is snow covered (//​snowcov//​) or not, and general parameters for rate (//cmrad//) and glacier ice albedo (//​glacalb//​). The refreezing component is limited to the glacier melt.
  
  
 <m> melt= {lbrace}{ <m> melt= {lbrace}{
  ​\matrix{2}{2}  ​\matrix{2}{2}
-    {cmrad*swrad*(1-albedo_glacier)+cmlt*(temp-ttmp) {for\ temp>​=ttmp} +    {cmrad*swrad*(1-albedo_glacier)+cmlt*(T-ttmp) {for\ T>​=ttmp} 
-    cmrad*swrad*(1-albedo_glacier)-crefr*cmlt*(ttmp-temp) {for\ temp<ttmp} }} </m>+    cmrad*swrad*(1-albedo_glacier)-crefr*cmlt*(ttmp-T) {for\ T<ttmp} }} </m>
  
 <m> albedo_{glacier}=albedo_snow*snowcov+glacalb*(1-snowcov) </m> <m> albedo_{glacier}=albedo_snow*snowcov+glacalb*(1-snowcov) </m>
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 Glacier melting, snow melting on snowfield and/or rain are added to the soil. Thus the soil represents the whole glacier class area. The concentrations in the glacial melt water are zero. This means that any atmospheric deposition of nutrients is lost on the glacier. Glacier melting, snow melting on snowfield and/or rain are added to the soil. Thus the soil represents the whole glacier class area. The concentrations in the glacial melt water are zero. This means that any atmospheric deposition of nutrients is lost on the glacier.
 +
 +==== Links to file reference ====
 +
 +^Symbol ^Parameter/​Data ^File ^
 +|//​class<​sub>​area</​sub>//​|//​slc_nn,​ area//​|[[start:​hype_file_reference:​geodata.txt|GeoData.txt]]|
 +|//​annmb//​|//​annualmb//​|[[start:​hype_file_reference:​glacierdata.txt|GlacierData.txt]]|
 +|:::|or //​glacannmb//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|//​yeardiff//​|calculated from //​slcdate//​|[[start:​hype_file_reference:​glacierdata.txt|GlacierData.txt]] or [[start:​hype_file_reference:​par.txt|par.txt]]|
 +|:::|and //bdate// |[[start:​hype_file_reference:​info.txt|info.txt]]|
 +|//​c//​|//​logvolcorr//​|[[start:​hype_file_reference:​glacierdata.txt|GlacierData.txt]]|
 +| |//​glactype//​|:::​|
 +|//T//|see needed data in [[start:​hype_model_description:​processes_above_ground#​links_to_file_reference|Links for temperature]]| |
 +|//​swrad//​|calculated or from|[[start:​hype_file_reference:​swobs.txt|SWobs.txt]]|
 +|//​coef0//​|//​glacvcoef//​ or //​glacvcoef1//​|[[start:​hype_file_reference:​par.txt|par.txt]]|
 +|//​exp//​|//​glacvexp//​ or //​glacvexp1//​|:::​|
 +|//cmlt, ttmp//​|//​glaccmlt,​ glacttmp//​|:::​|
 +|//​albedo<​sub>​snow</​sub>//​|calculated from //snalbmin, snalbmax, snalbkexp//​|:::​|
 +| |//glacalb, glacdens, glac2arlim, crefr, cmrad, fepotglac//​|:::​|
  
 ==== Links to relevant procedures in the code ==== ==== Links to relevant procedures in the code ====
start/hype_model_description/hype_land.1533908855.txt.gz · Last modified: 2018/08/10 15:47 by cpers