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New Terrain Program


Motivation

A global 30 sec terrain elevation dataset and a global 30 sec vegetation dataset have recently become available from USGS. The workstation version of terrain program is therefore being updated to take advantage of these datasets.

Program Function

The program functions similarly to the old program if one does not choose to use the global 30 sec dataset and new landuse option (switches set up at the top of the deck).

Two preprocessors are added in the deck to acquire and reformat the new 30 sec data so that much of the old terrain program can be used.

The terrain job script can be set up to automatically acquire data from either NCAR's MSS or USGS's anonymous ftp. The data can also be downloaded prior to running the program. In this case, the directory where data resides needs to be specified.

The program can be run on both Cray and workstations, but only limited tests have been performed. The program should be considered as experimental.

To use the 30 sec global terrain data, set script variable GLOBAL30S to TRUE in the deck. The terrain program defines this dataset as type 5 data, and this data may be used in place of the old 30 sec data over the continental US.

To use the vegetation dataset to create landuse, set script variable NewLandUse to TRUE. The new landuse datasets have data at 1 degree, 30 min, 10 min, 5 min, and 30 sec resolution.

The vegetation dataset is also used to create land-water mask and used in the program in place of EZFUDGE option (which makes use of NCAR Graphics' coastline information) if one chooses the NewLandUse option.

There are two types of vegetation datasets one can choose to generate landuse. The USGS data is nearly a global one (except Antarctica (south of 60 S), eastern Greenland (east of 40 W), and the east tip of Siberia (east of 180 E)), and has 24 landuse categories including urban. The category for water is 16. The SiB dataset is North American (60W - 180W, and 0N - 90N), and has 16 landuse categories but without urban. The water category is 15. The SiB dataset is the same one used in NCEP's Eta model.


Source Datasets

Global 30 Second Elevation Data

USGS provides the 30 sec terrain data from their anonymous ftp site: ftp://edcftp.cr.usgs.gov/pub/data/gtopo30/global. The dataset is archived in a total of 33 files. A tile map can be found from the same site: tiles.gif.

Global 30 Second Vegetation Data

We have acquired the USGS global 30 sec vegetation data, and reformatted them to latitude/longitude grid. Coarser resolution datasets at 1 degree, 30', 10', 5' were also generated from the 30 sec dataset. We provide these datasets on anonymous ftp site:

ftp://ftp.ucar.edu/mesouser/Data/TERRAIN

The data were derived from satellite observations over a period 1992-3, and when using these categories care should be taken to ensure that the land-uses are realistic and relevant to the area of interest. For instance, the meaning of the "desert" classification in the USGS data is now more limited, applying mostly to sandy deserts such as the Sahara, while areas like Arizona, that were desert under the 13-category definition are now "shrubland". Distinction is also made between irrigated and unirrigated croplands. The 16-category SiB classification also lacks an "urban" category, which would be a drawback for fine-scale models over large urban areas.

Program Tar File

On NCAR's anonymous ftp:

ftp://ftp.ucar.edu/mesouser/MM5V2/Terrain/terrain.tar.gz

On NCAR's MSS:

/MESOUSER/MM5V2/TERRAIN/NEW-TERRAIN.TAR.gz

How to Run It?

  1. Obtain the source code tar file from NCAR's anonymous ftp;

  2. Read the README file inside the tar file;

  3. Edit the configure.make file to set RUNTIME_SYSTEM variable and select appropriate compiler options;

  4. Type make terrain.deck to obtain the deck for your system;

  5. Edit terrain.deck to set appropriate script and namelist options;

  6. Type terrain.deck to run the job.

Program Documentation

Please read the README file and notes near the top of terrain.deck before running the program.

Miscellaneous

Updates Since April 7, 99

  • Updated April 28, 1999

    All workstation decks are updated to prevent multiple conversions of 30 sec global elevation data. Error possible if one chooses Data_Dir = your-data-directory option. (Thanks to Kuang-Yuan Huang of CAA Taiwan for locating the problem.)

  • Updated May 9, 1999
  • Two subroutines (data30s.F and cr30sdata.F) are updated to correct a problem for finding the right datasets when the domain area of interest crosses the dateline. (Thanks to Norm Henry of Meteorological Service of New Zealand for reporting and providing a fix for the problem.)

  • Updated June 11, 1999

    Packed data for old dataset (terln_ieee.tar.Z on ftp) have been replaced by new format data that are read in the code using character string. This change allows both workstation and Cray to access the same dataset (terln.tar.gz on ftp site, and /MESOUSER/MM5V2/TERRAIN/terln.tar on MSS). All terrain decks are modified to account for this change.

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