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Pan-Arctic Drainage System Masks
MaskData FileFieldsGif Image
Land/Ocean land59.ease.asc Land59.txt Land59.gif
Ice ice59.ease.asc Ice59.txt Ice59.gif
Pan-Arctic arctic59.ease.asc Arctic59.txt Arctic59.gif
Sea Basins sea59.ease.asc Sea59.txt Sea59.gif
Drainage Basins basin59.ease.asc Basin59.txt Basin59.gif
NSIDC Land/Ocean nlmask.ease.asc NLMASK.txt NLmask.gif
ID id.ease.asc

Col.Row cr.ease.asc

Longitude longf.ease.asc

Latitude latf.ease.asc

Alaska-Yukon Alaska-Yukon.asc Alaska-Yukon Alaska-Yukon.gif
Domain gif
Domain close-up gif
All data all_data.tar.gz





The above table contains a set of gridded masks covering the pan-Arctic drainage region. These masks were derived from our gridded global river network STN-30 v5.9 (in geographic coordinates at 30 minutes grid cell resolution) and projected to the EASE grid. The EASE grid appears to be the same as the Lambert's Azimuthal Equal Area Polar projection. More information on the EASE grid can be obtained from: http://nsidc.org/NASA/GUIDE/EASE/ease_grid.html. The projection covers the Northern Hemisphere from the equator to the North Pole.

Mask Descriptions:

Land/Ocean - contains land and ocean values only

Ice - shows grid cells which are dominantly ice covered. This was derived primarily from the IPA Permafrost map.

Pan-Arctic - shows those regions contained within the Pan-Arctic drainage system.

Sea Basins - Shows the Pan-Arctic drainage system divided into those regions flowing into the individual Seas. Our definition of the pan-Arctic includes some drainage basins that drain into the North Atlantic and the North Pacific Oceans. The Ocean name is included in the look-up table.

Drainage Basins - A mask showing all of the drainage basins delineated in the STN-30 v5.9. The look-up table sorts the drainage basins in descending order by drainage area.

NSIDC Land/Ocean - This is the land mask supplied by NSIDC and is provided if you need to make a comparison with the UNH mask. There are two primary differences between the UNH mask and the NSIDC mask. The masks do not match exactly along complex coastlines or over small islands and the UNH mask includes lakes as part of the land mask. Including lakes in the land mask is particularly important since precipitation and evaporation over these regions is an integral part of the drainage basin hydrological budget.

ID - a unique ID value for each grid cell. Counting starts with the upper left hand corner and sweeps from left to right then down the columns. The value in the lower right hand corner is 519,841 which is 7212. This allows us to identify any given grid cell by using only a single number (Lat/Long or Row/Column require pairs).

Col.Row - Column and row values expressed as a floating point number, COL.ROW, with the column expressed to the left of the decimal and the row to the right of the decimal. Numbering for the rows and columns starts at 0, therefore the lower right corner has the value 720.720.

Longitude - Longitude values at every grid cell. Greenwich, England is Longitude 0.0 with positive values to the east and negative values to the west. NOTE: This data was taken from an NSIDC CD-ROM product and only has 2 decimal place accuracy, therefore use with caution.

Latitude - Latitude values at every grid cell. The equator is 0 Latitude and the North Pole is 90.0. NOTE: This data was taken from an NSIDC CD-ROM product and only has 2 decimal place accuracy, therefore use with caution.

Alaska-Yukon - Land mask for Alaska and the entire Yukon River Basin only. The "Domain" gif shows the Alaska domain relative to the entire NH EASE grid and the "Domain close-up" gif shows a 180 degree rotated close-up.

Each mask is given by an ASCII data file with a 6 line header in the Arc/Info Grid ASCII format. There is a tab delimited look-up table for each mask in the Fields column which defines the grid cell values in each mask. Gif images are given in the last column to show you how the mask should look.

The final entry in the table contains a gzipped tar file with many of the data sets, text files and gif images.

Return to Pan-Arctic, ArcticRIMS, R-ArcticNet, Global Hydrology Group, or the Complex Systems Home Page.