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Pre & Post Processing V2 |
New Terrain Program
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.
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.
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.
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
Please read the README file and notes near the top of terrain.deck before running the program.
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