Surface measurements of solar irradiance: a study of the spatial correlation between simultaneous measurements at separated sites

Abstract

Pyranometers have been used for many years to measure broadband surface incoming solar irradiance, data that is necessary for surface energy budegt, cloud forcing, and satellite validation research. because such measurements are made at a specific location, it is unclear how representative they may be of a larger area. This study attemps to determine a reasonable spacing between measurement sites for such research by computing the correlation, and standard deviation from perfect correlation, between simultaneous measurements of incoming solar irradiance for a network of surface measurement sites covering a 75 km × 75 km area. For individual days, the correlation between sites varied widely, depending primarily on the type of cloud cover the region experienced that day. A spacing of 150 km between measurement sites seems reasonable for studies of midlatitude frontal weather regimes using daily averages over periods of weeks or more. -from Authors