Legates & Willmott Surface Air Temperature Climatology

Legates and Willmott surface air temperature climatology

This WWW page contains the original Legates and Willmott climatology. This group has continued to work on this and other data sets, and newer versions of the data can be found at the University of Delaware. I am keeping this version of the data because it has grid points at the poles and on the equator, and is consequently easier to compare with the NCEP reanalysis grids.

Analyses

Animations for North America and the Northern Hemisphere (mpeg)

Annual Mean (C)

The range of annual mean temperatures is from < -50C in the Antartic to > 30C in the western equatorial Pacific warm pool and over parts of the Sahara. The major mountain ranges and ocean boundaries are regions in which the general trend for temperatures to decrease with latitude is modified. A "tongue" of cooler temperatures extends westward from the Ecuador coast to near 140 degrees W in the equatorial Pacific.

Individual Calendar Months (C): J F M A M J J A S O N D

The high latitudes are dominated by single warm and cold seasons. The Antarctic is colder than the Arctic in almost all calendar months with temperatures below -40C. Temperatures near or below -40C are observed in small regions of Siberia and Greenland during the months December through February. The "cold tongues" in the eastern equatorial portions of the Pacific and Atlantic Oceans are strongest in October and August, respectively.

All figures are produced with the Freud visualization software.

Data
2.5-degree latitude-longitude resolution that has been shifted in space to be the same as the NCEP NCAR reanalysis grids
netCDF format (0.25 Mb)
All errors in the netCDF file are due to Todd Mitchell.

Reference and details of the calculation
Legates, D. R., and C. J. Willmott, 1990: Mean seasonal and spatial variability in global surface air temperature. Theor. Appl. Climatol., 41, 11-21.

The abstract from Legates and Willmott (1990):
Using terrestrial observations of shelter-height air temperature and shipboard measurements, a global climatology of mean monthly surface air temperature has been compiled. Data were obtained from ten sources, screened for coding errors, and redundant stations were removed. The combined data base consists of 17986 independent terrestrial station records and 6955 oceanic grid-point records. These data were then interpolated to a 0.5-degree latitude-longitude lattice using a spherically-based interpolation algorithm. Spatial distributions of the annual mean and intra-annual variance are presented along with a harmonic deomposition of the intra-annual variance.

Most of the land station records are for the years between 1920 and 1980. Median air temperatures over the oceans are taken from the Comprehensive Ocean-Atmosphere Data Set (COADS) for the years 1950-79. COADS data are 2-degree latitude-longitude resolution.

May 2000

Todd Mitchell (mitchell@atmos.washington.edu)

JISAO data