Effects of Spatial Sampling of Satellite Data on Derived Surface Solar Irradiance

Abstract

The usefulness of satellites in climate research is primarily due to the ability to produce global, uniformly distributed, long term records of observations. To achieve efficiency in storing, there is a need to compromise on the spatial and temporal resolution of the data. Questions arise about the impact of the reduced resolution on the parameters to be derived. In this study the effect of different spatial sampling of satellite observations on retrieved surface solar irradiance (SW1) was studied. Our results indicate that sampled (8-km resolution) andareally averaged (50-km resolution) visible brightness is highly correlated; the correlation has a regional, seasonal,and diurnal dependence. Using the two different resolutions of satellite observations, SW1 was computed for awhole annual cycle. On the average, the results differed by about 8%-9%. Therefore, to validate satellite methodsagainst ground truth to an accuracy which exceeds 8%-9% of the mean, attention should be given to the typeof satellite data and ground truth used in the validation process. The scales selected for investigation are ofinterest to the International Satellite Goud Climatology Project (ISCCP) B3 sampling.