Data Format

Here you will find some general information on the chosen data and file formats, in addition to information on the ALMA convention. For specific information, see modelling protocol.

Content 

  • NetCDF
  • Data convention (ALMA)

    NetCDF
    NetCDF is the chosen data format both for the input data and the output data. A good source of documentation on the netCDF format can be found at http://www.unidata.ucar.edu/software/netcdf. The online user manual is filled with example code blocks. Also, Jan Polcher has written and assembled some general software for reading and writing netCDF format (see http://www.lmd.jussieu.fr/~polcher/ALMA/alma_bazar.html). The files are to be submitted in compressed formats. Please use the Linux/UNIX compress or gzip (GNU zip) to compress the output files. For those using Windows, WinZip is also acceptable.

    Data convention
    The ALMA data exchange convention (http://www.lmd.jussieu.fr/~polcher/ALMA/), which has been used in e.g. PILPS and GSWP projects, will be used. The additional variables requested for the simulations with human impacts are listed and described in Table 2 below. 

    Table 1: Convention for model output data. ALMA convention. Be aware that this list may include more variables than should be submitted. See "Modelling Protocol" for the list of variables that should be submitted for your modelling purpose. 

    Variable Description  Definition 

    Units 

    		 Positive dir.
    Precip Precipitation rate

    Average of the total precipitation (rainfall and snowfall) over a time step and grid cell, i.e. the standard ALMA Snowf and Rainf are added. 

    		 kg/m2s

    Downward

    Snowf Snowfall

    Average of the total snowfall over a time step and grid cell

    kg/m2s

    Downward

    Evap

    Total evapotranspiration

    Sum of all evaporation sources, averaged over a grid cell  

    kg/m2s

    Upward

    Qs

    Surface runoff

    Runoff from the landsurface and/or subsurface stormflow. This variable should include the fast component of runoff response. This includes any surface runoff generated as infiltration excess runoff or saturation excess runoff (or the parameterized equivalent). In addition it should include any subsurface lateral quick-flow, which based on modelers experience is best routed as a fast storm-flow component, rather than a drainage or base-flow component.

    kg/m2s

    Out of gridcell

    Qsb

    Subsurface runoff

    This variable should include the slow drainage component of runoff response. This includes gravity drainage and slow response lateral flow. Ground water recharge will have the opposite sign.

    kg/m2s

    Out of gridcell

    Qrec Recharge to the flood plain Recharge from river to the flood plain. This variable represents streamflow which leaves the channel network and returns to the grid cell interface. The sign will always be opposite to that of surface runoff and the recharge quantity should not be subtracted from the surface runoff variable when recharge is specified.  kg/m2s Into gridcell

    SoilMoist

    Soil moisture

    Soil water content in total soil layer (not one for each soil layer). Includes the liquid, vapor and solid phases of water in the soil.

    kg/m2

    - 

    RootMoist

    Root zone soil moisture

    Total simulated soil moisture available for evapotranspiration. "Available water" means that frozen water should not be included, and water below wilting point should also be excluded.

    kg/m2

    - 

    RootSoilStress

    Root zone soil stress

    RootMoist / (Critical soil moisture – Wilting point). Remember that RootMoist does not include frozen water or water below wilting point. Upper/lower limits should be set at 1/0.

    -

    - 

    SWE

    Snow water equivalent

    Total water mass of the snowpack (liquid or frozen), averaged over a grid cell.

    kg/m2

    - 

    SnowFrac

    Snow covered fraction

    Grid cell snow covered fraction  

    - 

    - 

    Dis

    Simulated river discharge

    Simulated river discharge

    m3/s

    - 

    ECanop

    Interception evaporation

    Evaporation from canopy interception, averaged over all vegetation types within a grid cell. 

    kg/m2s 

    Upward

    TVeg

    Vegetation transpiration

    Transpiration from canopy, averaged over all vegetation types within a grid cell

    kg/m2s 

    Upward

    ESoil

    Bare soil evaporation

    Evaporation from bare soil

    kg/m2s 

    Upward 

    EWater

    Open water evaporation

    Evaporation from surface water storage

    kg/m2s 

    Upward 

    ESSNow

    Snow evaporation and sublimation

    Total sublimation and evaporation from the snow pack, i.e. we ask for the sum of the standard ALMA EvapSnow and SubSnow, (ESSNow = EvapSnow + SubSnow). 

    kg/m2s 

    Upward 

    SurfStor

    Surface water storage

    Total liquid water storage, other than soil, snow or interception storage (i.e. lakes, river channel or depression storage).  

    kg/m2 

    - 

    GroundMoist

    Groundwater

    Total ground water content. This variable is not included in the ALMA convention. 

    kg/m2 

    - 

    PotEvap

    Potential evapotranspiration

    The flux as computed for evapotranspiration but with all resistances set to zero, except the aerodynamic resistance. 

    kg/m2s  

    Upward 

    Qst

    Snow throughfall

    Liquid water flowing out of the snow pack, meaning water (melted snow and/or rain) percolating through the snowpack.

    kg/m2s  

    - 

    Albedo

    Surface albedo

    Grid cell average albedo for all wavelengths 

    - 

    - 

    SAlbedo

    Snow albedo

    Albedo of the snow-covered surface, averaged over the grid cell 

    -

    - 

    WaterTableD

    Water table depth

    Depth of the water table  

    m 

    - 

    SWnet

    Net shortwave radiation

    Incoming solar radiation less the simulated outgoing shortwave radiation, averaged over a grid cell  

    		 W/m2

     

    Downward

    LWnet

    Net longwave radiation

    Incident longwave radiation less the simulated outgoing longwave radiation, averaged over a grid cell  

    		 W/m2

    Downward 

    Qle

    Latent heat

    Energy of evaporation, averaged over a grid cell  

    		 W/m2

    Upward 

    Qh

    Sensible heat

    Sensible energy, averaged over a grid cell  

    		 W/m2

    Upward  

    Qg

    Ground heat

    Heat flux into the ground, averaged over a grid cell  

    		 W/m2

    Downward 

    Table 2: Convention for model output data, water use terms. Be aware that this list may include more variables than should be submitted. See "Modelling Protocol" for the list of variables that should be submitted for your modelling purpose.

    Variable Description 

    Definition

    		     Units    
    PIrrUse Potential irrigation water use 

    Potential irrigation water use (water consumed), averaged over a gridcell 

    kg/m2s

    PIrrWW

    Potential irrigation water withdrawals

    Potential irrigation water withdrawn, averaged over a grid cell

    kg/m2s

    PEConv Potential irrigation conveyance losses Potential irrigation conveyance losses, averaged over a grid cell

    kg/m2s

    PReturnFlow Potential irrigation return flow Potential irrigation return flow, averaged over a gridcell

    kg/m2s

    AIrrUse

    Actual irrigation water use

    Actual irrigation water use (water consumed), averaged over a grid cell

    kg/m2s

    AIrrWW

    Actual irrigation water withdrawals

    		 Actual irrigation water withdrawn, averaged over a grid cell

    kg/m2s

    AEConv Actual irrigation conveyance losses Actual irrigation conveyance losees, averaged over a grid cell   kg/m2s
    AReturnFlow Actual irrigation return flow Actual irrigation return flow, averaged over a grid cell

    kg/m2s

    ADomWW

    Actual domestic water withdrawals

    Actual domestic water withdrawn, averaged over a grid cell

    kg/m2s

    ADomUse Actual domestic water use

    Actual domestic water consumed, averaged over a grid cell 

    kg/m2s

    AManWW

    Actual manufacturing water withdrawals

    Actual water withdrawn for manufacturing, averaged over a grid cell 

    kg/m2s

    AManUse

    Actual manufacturing water use

    Actual water consumed, manufacturing, averaged over a grid cell

    kg/m2s

    AElecWW

    Actual electricity water withdrawals

    Actual water withdrawn for electricity production, averaged over a grid cell 

    kg/m2s

    AElecUse Actual electricity water use

    Actual water consumed, electricity production, averaged over a grid cell 

    kg/m2s

    ALiveWW

    Actual livestock water withdrawals

    Actual water withdrawn for livestock farming, averaged over a grid cell 

    kg/m2s

    ALiveUse

    Actual livestock water use

    Actual water consumed, livestock farming, averaged over a grid cell

    kg/m2s

    ResStor Reservoir storage

     

    m3

    ResRel Reservoir release

    m3/s

    Table 3: Convention for model output data, blue/green water terms. This list is for those submitting results for the blue/green water initiative. If you do not know what the blue/green water initiative is, you can ignore this Table,  or, if you are interested, contact Jens Heinke and/or Holger Hoff (see Contacts information).

    Variable Description 

    Definition

    		     Units    
    IrrigCropUseGreen

    Green water use (water consumed) on irrigated cropland

    Sum of evaporative fluxes (TVeg + ECanop + ESoil) from rain water over irrigated cropland, averaged over a grid cell. Fallow period should also be included.

    kg/m2s

    RainfCropUseGreen

    Green water use (water consumed) on rainfed cropland

    Sum of evaporative fluxes (TVeg + ECanop + ESoil) from rain water over rainfed (non-irrigated) cropland , averaged over a grid cell. Fallow period should also be included.

    kg/m2s

    PastureUseGreen

    Green water use (water consumed) on pasture

    Sum of evaporative fluxes (TVeg + ECanop + ESoil) from rain water over pasture, averaged over a grid cell.

    kg/m2s