File Format and Naming Convention

Files are in ESRI shapefile format. A shapefile consists of several actual files that are usually considered as one file by most GIS applications. The following file types are included:

*.dbf = attribute data
*.prj = projection information
*.shp = feature geometry
*.shp.xml = ESRI/FGDC formatted metadata (This file is optional and does not include all the information in this document)
*.shx = the shape index, which stores an index to the feature geometry
*.sbx, *.sbn = spatial index of the features

The data set consists of the following shapefiles:

cryo_landslide.shp = point locations of cryogenic landslides
cryo_planation.shp = point locations of cryogenic planation
dig_country_bnd.shp = digitized country boundary polygon from the 1:4,500,000 map
dig_lakes.shp = digitized lake polygons from the 1:4,500,000 map
dig_streams.shp = digitized stream vectors from the 1:4,500,000 map
geocryo_regions.shp = digitized geocryological region polygons from the 1:12,000,000 map. See the attribute description below.
geocryology.shp = digitized polygons of areas with detailed geocryological information from the 1:4,500,000 map. See the attribute description below.
icings.shp = point locations of icings
per_frost_mound.shp = point locations of perennial frost mounds
solifluction.shp = point locations of solifluction
thermokarst.shp = point locations of thermokarst

File Size

11 ESRI shapefiles consisting of 79 actual files total 1.6 MB. Individual files sizes range from from 2 KB to 1 MB.

Spatial Coverage

Mongolia

Southernmost Latitude: 40.608° N
Northernmost Latitude: 52.230° N
Westernmost Longitude: 87.002° E
Easternmost Longitude: 121.355° E

Projection

Albus Equal Area-Conic
Central Meridian: 103.833 degrees
Origin Latitude: 46.867 degrees
Standard Parallel 1: 43.342 degrees
Standard Parallel 2: 50.383 degrees

Parameters and Attributes

Parameters include the locations of thermokarst, icings, perennial frost mounds cryogenic landslides, solifluction, and cryogenic planation. The geocryo_regions.shp file shows the location of four geocryological regions: continuous and discontinuous permafrost, insular and sparsely insular permafrost, sporadic permafrost, and seasonal frozen ground. These regions are labeled in the shapefile attribute table. This classification scheme is not defined. It is unclear how it relates to the International Permafrost Association definitions for permafrost regions. The geocryology.shp file includes a more detailed 14-level classification scheme shown in the table below. The values in the table are included in the attribute table of the shapefile.

Sample Images

These figures show examples of geocryology.shp and geocryo_regions.shp using a color scheme that approximates that used in the original paper maps. Click on the image for a larger version.

geocryology.shp

geocryo_regions.shp

Errors and Uncertainty

The original published atlas (Sodnom and Yanshin 1990) included the following table with the maps.

An analysis of the digital versions of the maps produces different percentages that can vary as much as two percentage points depending on whether lake area is included in the analysis. Furthermore, Sodnom and Yanshin's table gives the total area of Mongolia as 1,565,000 km² while the calculated area of geocryo_regions.shp is 1,611,023 km². The World Factbook (CIA 2005) lists the area of Mongolia as 1,564,116 km² and the Digital Chart of the World (ESRI 1992) indicates 1,565,866 km². Some error was inevitably introduced as part of the digitization process. The lack of information of how the original maps were produced and how the regions are defined adds additional uncertainty. This data set is best used for broad scale analysis and comparisons and is unsuitable for very fine scale spatial analysis.