Validation of Outgoing Longwave Radiation in the GLAS (Goddard Laboratory for Atmospheric Sciences) General Circulation Model
Abstract
Outgoing longwave radiation (OLR) simulated by the GLAS general circulation model is validated with that derived from measurements made by polar orbiting satellites. The mean observed and simulated OLR fields are compared for spatial and seasonal variations by expanding them into spherical surface harmonics. The student's 't' test is to determine the significance of differences between the simulated and observed fields. The global mean and standard deviation of the simulated geographical fields are respectively about 20 per sq. Wm-2 smaller and 10 per sq. Wm-2 larger than the corresponding values of the observed field. The major fraction of the variability in the simulated field is due to a sharp meridional gradient in the field. The seasonal variation of the global mean and standard derivation of the simulated fields are in good agreement with observations. Correlation coefficients between the observed and simulated fields as a function of spatial scales show that the phase relationship for large spatial scales is very good for January and July months but fair for April and October. In the tropics, the differences between simulated and observed OLR means are not significantly different from zero, except over deep convective regions (Asiatic monsoon, Amazon, Central Africa) where the model convective clouds do not interact with radiation. The differences in the middle and high latitudes are highly significant, more so in the southern hemisphere than in the northern hemisphere.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1985
- Accession Number
- ADA158006
Entities
People
- G. R. Borger
Organizations
- Air Force Institute of Technology