External dataset

A Global Lake Database (GLDB), version 2 (GLDBv2), developed by Ekaterina Kourzeneva and Margarita Choulga, provides data required to generate external-parameter fields of lake fraction and lake depth for numerical models of the atmosphere (e.g. NWP and climate models). See Kourzeneva (2009), Kourzeneva (2010), Kourzeneva et al. (2012) and Choulga et al. (2014) for details. Please cite these papers when using data from GLDB.

Download a gldbv2.tar.gz file.
GLDBv2 contains the following information given in a number of separate files (all included in gldbv2.tar).

A binary file GlobalLakeDepth.dat is a global gridded lake-depth data file with the spatial resolution (pixel size) of 30 arcsec (ca. 1 km at the equator). A raster map of ECOCLIMAP2 data set is used to locate lakes on the globe, i.e. to discriminate between the lake pixels and the non-lake pixels. The lake depth is given in decimetres. The lake pixels associated with lakes whose mean depth is known from in situ measurements contain those direct mean-depth estimates. Local depth to the bottom (as different from mean depth used for all pixels associated with the lake in question) is used for a number of large lakes whose bathymetry is known in some detail. If no direct lake-depth estimate is available for a lake pixel, an indirect estimate based on the lake geological origin is used. This method is applied to the boreal zone only. If neither direct nor indirect estimate of lake depth is available, a default value of 10 m is used. The internal-water-type pixels identified as river pixels contain a default river-depth value of 3 m. For other pixels (land and ocean/sea), the lake depth is zero.
A brief description of GlobalLakeDepth.dat is given in GlobalLakeDepth.txt (ASCII).

A binary file GlobalLakeStatus.dat contains the status information for the lake-depth estimates given in GlobalLakeDepth.dat (the number of pixels and the pixels size of the two files are identical). The status flag takes the following values: 0 if a pixel is neither lake nor river, the lake depth is set to zero; 1 if a pixel is identified as the lake pixel but the respective lake is not present in the lake-depth data set (files FreshWaterLakeDepthDataSet_v2.txt, SalineLakeDepthDataSet_v2.txt and LargeLakesWithBathymetry_v2.txt, see below), a default lake depth of 10 m is used; 2 if a lake pixel is associated with a known lake but the lake depth is missing in the lake-depth data set, a default lake depth of 10 m is used; 3 if a lake pixel is associated with the lake whose mean or local depth is known from in situ measurements, the ("true") lake-depth value from the lake-depth data set is used; 4 if a pixel is identified as the river pixel, a default river depth of 3 m is used; 5 if a pixel is the lake pixel and the lake depth is estimated indirectly by the expert evaluation method; 6 if a pixel is the lake pixel and the lake depth is estimated indirectly by the geographic method; and 7 if a pixel is the lake pixel and the lake depth is estimated indirectly by the geomorphologic method.
A brief description of GlobalLakeStatus.dat is given in GlobalLakeStatus.txt (ASCII).
The data used to develop the above binary files, indirect methods to estimate the lake depth and the mapping procedures are described in detail in Kourzeneva (2009), Kourzeneva (2010), Kourzeneva et al. (2012) and Choulga et al. (2014).

FreshWaterLakeDepthDataSet_v2.txt and SalineLakeDepthDataSet_v2.txt (ASCII) contain the lists of fresh-water lakes and saline lakes, respectively, included into GLDBv2. Each lake is identified with its location (geographical co-ordinates) and its international name. Whenever available, the local name used in the country where the lake is located, the lake mean depth, its maximum depth, and its surface area are given. The lakes in the lists are ordered with respect to the continent and the country of their location. The continents and the countries are ordered alphabetically. Major sources of data are given.
LargeLakesWithBathymetry_v2.txt (ASCII) contains the list of lakes for which a detailed bathymetric information is available.

ProjectLake2.tar contains FORTRAN 90 software (files ProjectLake.f90, Bitmap.f90, Coor2Num.f90 and inpoly.f90) that help to project (aggregate) the lake-depth data onto a target grid of an atmospheric model. A SUBROUTINE ProjectLake computes the lake fraction, the lake depth and the value of status flag in a polygon specified through geographical lat-lon co-ordinates of its vertices. The most probable lake depth and the most probable status flag are computed by default (this choice is recommended by E. Kourzeneva). Optionally, the average depth and the average status flag can be computed. Notice that the result depends on how the lake-depth range considered is divided into the lake-depth segments (see ProjectLake.f90 for details). Please contact Ekaterina Kourzeneva for the software details.

Answers to some questions commonly asked by GLDB users are given in LakeDataset_FAQ_2014.pdf.

Dear Users,
should you have questions concerning GLDBv2,
please contact Margarita Choulga,
Russian State Hydrometeorological University, Malookhtinsky pr. 98, RU-195196, Saint-Petersburg, Russia,
mailto: botan4ik_at_hotmail.com.
Margarita will answer your questions via e-mail within a week.
Margarita is also accessible on Skype (margarita.choulga) on Mondays from 10 to 12 a.m. Moscow time (UTC+3h).

Diverse information about lakes: Wikipedia list of lakes, World lakes database