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In addition to the paper and the list of variables and constants, there are a couple which were not explained, so I compiled them together with their units, actual names (from Müller Schmied where possible) and descriptions to create a glossary that could accompany the paper theory. Just an idea. Some of the variables can probably removed (like „landareafrac_ratio“ as there is already a „land_area_frac“ but for completion purposes decided to include them here).
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Code Name
Actual name (Müller Schmied et al. 2021)
Name
Description
Unit
adiabatic_lapse_rate
Adiabatic lapse rate
Adiabatic lapse rate
An adiabatic lapse rate of 0,6°C (6 K) is applied to daily temperature calculations based on (Schulze and Döll, 2004).
Km-1
arid_gw_cell
-
Humid-arid classification array based on [sources].
-
aridity
Land cover classification
Aridity
Compute groundwater for “Humid” or “Arid” region.
builtup_area
-
Buildup area
The fraction of the total land area which is considered Urban based on the MODIS data set, section C [source]. In such areas 50% of all precipitation is directly converted into runoff.
-
cell_area
Cell Area
Cell Area
Total area per grid cell.
km2
cum_precipitation
Cumulative precipitation
Cumulative precipitation
The cumulative precipitation is the sum of all precipitations from day 0 to the current day.
mm/d
current_landarea_frac
-
Current Land-Area-Fraction
Land-Area-Fraction of the current time step.
-
Daily_leaf_area_index
-
Daily leaf area index
Daily leaf area index
-
daily_storage_transfer
-
Daily storage transfer
Daily Storage Transfer describes the water storage from the previous timestep that gets added to the runoff after the current Landarea Fraction reaches 0.
mm
daily_storage_transfer
-
Daily storage transfer
Daily Storage Transfer describes the water storage from the previous timestep that gets added to the runoff after the current Landarea Fraction reaches 0.
mm
days
Days
Days
Number of days.
d
degreeday
Degree-day factor
Degree-day Factor
Snow melt is calculated with a land-cover-specific degree-day factor DF which can be found in Table C2.
mmday-1C-1
diffuse_gw_recharge
Diffuse groundwater recharge
Daily groundwater recharge from diffuse sources
Daily groundwater recharge from diffuse sources.
km^3/day
drainage_direction
Drainage direction
Drainage Direction
The drainage direction for any given grid cell is based on the drainage direction map DDM30 [source].
-
effective_precipitation
Effective precipitation
Effective precipitation
The effective precipitation is the fraction of the total precipitation P that is available to plants and is computed as a simple empirical function of precipitation.
mmd-1
Elevation
Elevation
Elevation
Elevation for each grid cell is taken from the surface elevation map based on GTOPO30 (U.S. Geological Survey, 1996) [1].
m
groundwater_discharge
Groundwater discharge
Daily groundwater discharge
Daily groundwater discharge.
km^3/day
groundwater_storage
Groundwater storage
Daily groundwater storage.
Daily groundwater storage.
km3
growth_status
-
Growth status
Growth status per grid cell shows whether a specific land cover is not growing (value = 0), growing (value = 0), or fully grown (value = 1).
-
humid_arid
Land cover classification
Humid-arid classification array
Humid-arid classification array based on [Müller Schmied et all. 2021, Figure C1].
-
immediate_runoff
-
Immediate runoff
The fraction of effective precipitation that immediately becomes runoff.
mmd-1
initial_days
Initial days
Initial Days
The initial days array saves the specific number of days for each land cover type, for which the daily temperature must stay above 8°C to initialize the start of the growing season.
d
land_area_frac
Land area fraction
Land area fraction
Land area fraction.
%
land_cover
Land cover class
Land Cover
WaterGAP uses a static land cover input map as described in [Müller Schmied et all 2021, Table C1].
Land_storage_change_sum
-
Change of Land Storage sum
The change of Land Storage is the sum of all vertical water balances.
mm
landareafrac_ratio
-
Landarea fraction ratio
The Ratio of the Land-Area-Fraction between the current and the previous time step.
-
max_groundwater_recharge
-
Maximum groundwater recharge
Maximum groundwater recharge data taken from [source].
mmd-1
max_storage_coefficient
-
Maximum storage coefficient
Coefficient for computing maximum canopy storage
-
max_temp_elev
-
Maximum temperature at lowest elevation
Maximum temperature is recorded from the sub grid cell with the lowest elevation.
K
netabs_gw
Net abstraction from groundwater
Net abstraction from groundwater
Net abstraction from groundwater.
km3d-1
pet_to_soil
-
Potential Evapotranspiration to soil
The part of the Potential Evapotranspiration PET which goes to the soil.
mm
point_source_recharge
Point groundwater recharge
Point groundwater recharge
Sum of all point groundwater recharge from surface water bodies in arid regions.
km^3/day
remainingUse
-
Total unsatisfied water use
Daily total unsatisfied water use.
km^3/day
snow_melt_temp
-
Snow melt temperature
Snow melt temperatures are everything above the snow freeze Temperature of 0°C.
C
snow_water_storage
Snow water balance
Snow Water Storage
Snow_water_storage describes the sum of all snow water storage values for each subgrid in a 0.5° x 0.5° grid cell.
mm
snow_water_storage_subgrid
-
Snow Water Storage per sub grid
Each 0.5° x 0.5° grid cell is divided into 100 subgrids based on the U.S. Geological Survey land elevation map (GTOPO30) from 1996 and the snow water storage is calculated for each individually. The snow_water_storage is divided into the 100 subgrids for the current time step.
— In addition to the paper and the list of variables and constants, there are a couple which were not explained, so I compiled them together with their units, actual names (from Müller Schmied where possible) and descriptions to create a glossary that could accompany the paper theory. Just an idea. Some of the variables can probably removed (like „landareafrac_ratio“ as there is already a „land_area_frac“ but for completion purposes decided to include them here). —