force-lut-modis

The water vapor database may be generated/updated with force-lut-modis, which automatically downloads MODIS water vapor products (MOD05 and MYD05, collection 6.1) from the Level1 and Atmosphere Archive and Distribution System (LAADS) at NASA’s Goddard Space Flight Center.

Note

Any permanent or temporary change/shutdown/decommissioning on LAADS’ or MODIS’ end may result in the nonfunctioning of force-lut-modis (as it happened between the release of FORCE v. 1.1 and v. 2.0).

Note

The tables can also be generated with other data and/or software. If you want to create the tables on your own, refer to the WVDB format.

See also

An application-ready global water vapor database (daily values for 2000–2020 + monthly climatology) can be downloaded from Zenodo.

See also

Check out this tutorial, which explains how to prepare the Water Vapor Database (WVDB).

Usage

force-lut-modis

Usage: force-lut-modis [-h] [-v] [-i] [-d] [-t] [-c] coords-file wvp-dir geometa-dir download-dir

optional arguments

  • -h show help page

  • -v show version of FORCE

  • -i show program’s purpose

  • -d date range as YYYYMMDD,YYYYMMDD. The default is 20000224,today

  • -t build daily tables? The default is true

  • -c build climatology? The default is true

mandatory arguments

  • coords-file

    A text file with coordinates, i.e. central coordinates of the WRS-2 frames.
    Water vapor averages are estimated for each given coordinate.
    The file should contain two columns separated by white space, and no header.
    The first column should give the longitude, the second column the latitude with coordinates in decimal degree (negative values for West/South).

  • wvp-dir

    The final water vapor tables are saved in wvp-dir (this directory must exist).
    Tables that are already in wvp-dir are not processed again (i.e. no download of geometa tables and hdf files; the user may delete the MODIS *.hdf files after the water vapor tables are successfully generated).
    This directory is the directory, which should be given in DIR_WVPLUT in the Level 2 Parameter file.

  • geometa-dir

    MOD05/MYD05 data are swath products, and MOD03/MYD03 geometa tables are necessary to relate coordinates to MODIS granules.
    The geometa tables are downloaded to geometa-dir (this directory must exist).
    Tables that are already in geometa-dir are not downloaded again.
    If the tool crashes because a table is invalid, it is necessary to manually delete this file and run the tool again.
    Unfortunately, this happens from time to time due to incomplete downloads or if LAADS is unresponsive.
    The program attempts to re-download a corrupt file up to 10 times, but this error can occur nonetheless.
    Note that the geometa tables are a global product, and as such, the same geometa-dir can be used for different study areas.

  • download-dir

    The MODIS data are downloaded to download-dir (this directory must exist).
    MODIS data that are already in download-dir are not downloaded again.
    If the tool crashes because a dataset is corrupt, it is necessary to manually delete this file and run the tool again.
    Unfortunately, this happens from time to time due to incomplete downloads or if LAADS is unresponsive.
    The program attempts to re-download a corrupt file up to 10 times, but this error can occur nonetheless.