Climate

Relative air humidity 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 relative air humidity 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 relative air humidity.

Classifier's precision:

Relative air humidity values are expressed with precision to 1%.

Map's compilation procedure:

The mean annual relative air humidity values have been found in the database of mean monthly relative air humidity values observed at weather-stations of the former USSR (Climate Handbooks of the USSR, 1965-1974). The data from over 3,560 weather-stations have been used for the map. The bitmapped relative air humidity layer was created by the climate simulation technique with elements of the remainder interpolation (Kriging) (Hart, T., Greene, S., Afonin, A., 1996). The mapping allowed for the influence on relative air humidity 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. Relative air humidity'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. Relative air humidity'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). Relative air humidity'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 relative air humidity was obtained by combining corresponding coastal and mainland resultant fields of relative air humidity 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.