THE ESTIMATION OF EMITTED AND REFLECTED ENERGY OVER THE CENTRAL PACIFIC USING METEOROLOGICAL PARAMETERS

The authors conducted a quantitative investigation of the relationship between meteorological parameters (chiefly cloud cover) and the princ ipal components of the earth's radiation budget. The area of study is the tropical central Pacific, where considerable variation in cloudine ss and flux was observed from 1985 to 1989. The observed variations we re in response to the El Nino-Southern Oscillation event of 1987. Inte rnational Satellite Cloud Climatology Project (ISCCP) C2 parameters we re used as independent variables in the development of multiple linear models to predict Earth Radiation Budget Experiment (ERBE) outgoing l ongwave radiation (OLR) and shortwave (SW) fluxes. Net radiation estim ates were obtained from OLR and SW predicted fluxes. The technique of all-subsets regression was used to determine which combination of ISCC P C2 parameters could best predict OLR and SW fluxes. The models were developed for the years 1985 and 1989 (non-ENSO years) and tested by b oth month and year on the years 1986 through 1988. Predicted fluxes we re obtained for three 15 degrees latitude zones, north (7.5 degrees to 22.5 degrees N), central (7.5 degrees N to 7.5 degrees N), and south (7.5 degrees S to 22.5 degrees S). Over the 60 months of data, explain ed variances (R(2)) of over 90% for the development and test periods w ere typical. An increase in the accuracy of the OLR models was observe d when noncloud variables were included. This accuracy improvement was most apparent when cloud amounts were either very low or very high an d homogeneous. Biases (predicted-observed) were all less than 4 Wm(-2) and rms estimates were within the range of uncertainty for ERBE month ly mean flux estimates. Flux estimates based on linear models could se rve as a means of extending long-term radiation balance datasets durin g intervals of time with limited satellite coverage.