clm(5)

NAME
clm - Input data files for LPJmL runs

DESCRIPTION
LPJmL is driven by monthly fields of temperature, precipitation, cloudiness and number of days with rain. Additionally static information on soil properties, geographic coordinates of climate and soil data, and mean annual atmospheric CO2 concentration are required. Except for CO2 all files are binary data including a header (except for the soil and lake fraction data).

  Structure of the header

header name
    (7 byte char array, LPJCLIM for temp, precip, wet days and cloudiness, LPJGRID for coordinate data, LPJLUSE for land use data, LPJ_COW for country codes, LPJDAMS for reservoir data)

header version
    (4 byte integer, currently set to 3, also used to determine if input data needs byte swapping)

order
    (4 byte integer, values are either 1 (cellyear) or 2 (yearcell))

firstyear
    (4 byte integer, first year of data record)

nyear
    (4 byte integer, total number of years)

firstcell
    (4 byte integer)

ncell
    (4 byte integer, number of grid cells represented)

nbands
    (4 byte integer)

cellsize_lon
    (4 byte float, longitude cellsize in deg)

scalar
    (4 byte float conversion factor)

cellsize_lat
    (4 byte float, latitude cellsize in deg)

datatype
    (4 byte int, 0 for byte, 1 for short, 2 for int, 3 for float, 4 for double)

  Sorting of the climate data
The sorting of the monthly climate data and of the land use data does not correspond to a standard file format but is a mixture of BSQ (band sequential) and BIP (band interleaved by pixel). You start with 12 monthly values (or with 24 land use-fractions) of the first year and first grid cell. After that, the first twelve monthly values of the second cell follow and so on. Once you are done with all grid cells, you continue with the first grid cell's monthly data of the second year. This format is called "cellyear" in the LPJmL vocabulary and is the only format that is supported from LPJmL-version 3.2 and above ("YEARCELL" = BIP has been used in previous LPJ-versions). Once you have a data set that you want to apply, you use any programming language, to write the header to a file. In C, you can use the function fwriteheader(..) in src/tools/header.c to write headers (or freadheader(...) to read it) Datasets can be converted to LPJ-format (including headers) from plain binary input files (BIP) with the executable cru2clm that has been provided with the LPJmL distribution. Data needs to be stored in the same order as the input grid.

  Input data files

soil data
    (1 file) data type char (1 byte), the grid needs to be the same as your input grid / climate data
    values are currently ranging from 0 to 9
    corresponding soil parameters can be found in par/soil.par
    no header

climate data
    (all monthly values, 4 files + 1 file with atmospheric CO2 concentrations) - temperature [scaled: degree Celsius*10]
      size of header: 38 bytes - precipitation [mm/month]
      size of header: 38 bytes - cloudiness [%]
      for internal computation of radiation
      size of header: 38 bytes - wet days
      number of wet days per month (needed only, if your are using the
      "weather generator", that distributes rain within month randomly)
      size of header: 38 bytes - atmospheric carbon dioxide [ppmv]
      global annual mean CO2 concentration as ASCII file
      format: year concentration
      Example
        1990 354.19
        1991 355.59
        1992 356.37
        1993 357.04
        1994 358.88

Land use data
    - land use:
      in C data type short (2 bytes), grid needs to be the same as your input grid / climate data
      values range between 0 and 1000 (fraction *1000)
      each grid cell and year has 24 entries: 12 for rain-fed crops, 12 for irrigated crops
      crop order is as follows:
      1: temperate cereals, 2: rice, 3: maize, 4: tropical cereals, 5: pulses,
      6: temperate roots, 7: tropical roots, 8: oil crops sunflower, 9: oil crops soybean,
      10: oil crops groundnut, 11: oil crops rapeseed, 12: pasture (C3/C4 mix left to LPJmL to determine) - country codes:
      in C data type short (2 bytes)
      for each cell two values: countrycodes (n=197) and regioncodes (n=433) - river routing:
      in C data type int (4 bytes), the grid needs to be the same as your input grid / climate data
      for each cell two values: one in which cell to rout the water
                            one with the distance [km] between the midpoints of the two cells
      -9: inland sink or outflow to the ocean

AUTHORS
Werner von Bloh (Werner.von.Bloh@pik-potsdam.de), Sibyll Schaphoff (Sibyll.Schaphoff@pik-potsdam.de), Stefanie Rost (Jachner) (Stefanie.Rost@pik-potsdam.de), Marlies Gumpenberger (Marlies.Gumpenberger@pik-potsdam.de), Tim Beringer (Erbrecht) (Tim.Beringer@pik-potsdam.de), Christoph Mueller (Christoph.Mueller@pik-potsdam.de)

SEE ALSO
lpjml(1), cru2clm(1), txt2clm(1), catclm(1), grid2clm(1), cft2clm(1), printclm(1), printheader(1)