Surface Solar Irradiance from ISCCP 1983-1991

James. K. B. Bishop, William B. Rossow, Ellsworth G. Dutton

J. Geophys. Res. (Atmospheres), 102, 6883-6910.

Abstract. An eight year (July 1983 through June 1991) time series of daily and monthly mean surface solar irradiance has been produced for the globe using data from the International Satellite Cloud Climatology Project (ISCCP) using a revised Bishop and Rossow [1991] algorithm. This uniquely long data set has been publicly available since 1994 at the National Center for Atmospheric Research. A new validation analysis includes a comparison of calculated daily all-sky and clear sky surface solar irradiance to daily averages derived from contemporaneous high frequency (<20 minutes) data sets obtained from sensors deployed on ocean buoys during the 1987 BioWATT and the 1989 and 1991 MLML experiments, and from hourly resolved time series from island locations Samoa, Kwajalein, Cape Grim and Bermuda. Additionally, we compute the global distribution of an atmospheric optical extinction anomaly based on the difference between our calculated irradiance and contemporaneous monthly irradiance observations from the Global Energy Balance Archives (GEBA, Ohmura et al. [1991]). Differences were attributed to (1) comparison of single point observations vs. the 280 km scale of the satellite retrieved values of surface solar irradiance; (2) micro and mesoscale meteorology of surface observing sites vs. surrounding ocean waters; (3) data errors in surface observation data; (4) incomplete knowledge of the global and seasonal variability of aerosols; and (5) errors in calibrations of satellite radiance values from satellites used to standardize the ISCCP data set. Our analysis points to the value of carefully chosen monitoring locations and suggests additional quality control criteria for surface observations of solar irradiance. Particularly, we suggest that deep sea buoys should be investigated for validation of oceanic surface fluxes.

The revised Bishop and Rossow data set is accurate to within 10 W m-2 in the monthly mean for most oceanic regions where aerosols levels are generally low. The data set shows that there are significant differences in fluxes received by the major oceans on seasonal to interannual timescales.

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