Climate

Air humidity deficit map. February .

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Authors:

A.N. Afonin, K.L. Lipiyaynen

Compilation date:

15.03.2007

Scale:

10 km/pix

Map's precision:

The map contains averaged mean annual mean monthly values of air humidity deficit for fragments of the Earth's surface with the area of 10 x 10 km.

Projection:

Albers equal-area projection for the USSR
ref. system : Alber's Equal Area Conic for Russia
projection : Alber's Equal Area Conic
datum : Pulkovo 1942 (S42)
delta WGS84 : 28 -130 -95
ellipsoid : Krasovsky
major s-ax : 6378245.000
minor s-ax : 6356863.019
origin long : 100
origin lat : 0
origin X : 0
origin Y : 0
scale fac : na
units : m
parameters : 2
stand ln 1 : 44
stand ln 2 : 68

Main content:

A bitmapped map. The map contains mean annual mean monthly values of air humidity deficit.

Classifier's precision:

Air humidity deficit values are expressed with precision to 0.1.

Map's compilation procedure:

The mean annual air humidity deficit values have been found in the database of mean monthly air humidity deficit values observed at weather-stations of the former USSR (Climate Handbooks of the USSR, 1965-1974). The data from over 3,550 weather-stations have been used for the map. The bitmapped air humidity deficit layer was created by the climate simulation technique with some elements of the remainder interpolation (Kriging) (Hart, T., Greene, S., Afonin, A., 1996). The mapping allowed for the influence on air humidity deficit values exerted by the seas and other large bodies of water. Thus, it treated separately the coastal and mainland weather-stations. All weather-stations located less that 30 km away from the coast were considered coastal. The main features taken into consideration for the mapping were the station's altitude above sea level, its latitude and longitude, precipitation amount, and the average air temperature at the station's site. Air humidity deficit's dependence on the station's altitude above sea level, its latitude and longitude, precipitation amount, and the average air temperature at its site was determined with the multiple linear regression equation. Air humidity deficit's values for coastal and mainland weather-stations were subject to separate calculations. The difference between actual and calculated values was the remainder which was interpolated over the whole area of the matrix (ordinary Kriging). Air humidity deficit's matrix was calculated with the Idrisi program (Image Calculator module) in accordance with the obtained regression formula where the corresponding matrices were substituted for latitude, longitude, altitude above sea level, precipitation amount and temperature values.The interpolated remainder's layer was added to the calculated layer. The resolution cells' height was determined with the help of the digital Earth surface topography model (SRTM). The resultant field of air humidity deficit was obtained by combining corresponding coastal and mainland resultant fields of air humidity deficit values.

Data sources:

Climate Handbooks of the USSR. Air Humidity, Atmospheric Precipitation, Snow Cover. Issues 1-34. - Leningrad, Gidrometeoizdat Publishers, 1964-1974.
SRTM (Shuttle Radar Topography Mission) 3 arc second (90 meter) SRTM DTED(r) Level 1 "Finished" data derived from SRTM IFSAR data/ http://edc.usgs.gov/products/elevation.html
Hart T., Greene S., Afonin A. Mapping for Germplasm Collections: Site Selection and Attribution/ ASPRS Annual meeting in Baltimore, Maryland. Web-paper. April, 1996

Rights and copyrights:

All rights to the map and descriptions are reserved for their authors.