Interannual Variability in Radiative Cloud Effects and Cloud Macrophysical Properties from Surface Measurements

Recently significant progress has been made in inferring cloud effects and cloud macrophysical properties using surface measurements of broadband irradiance and basic meteorological variables. These "Flux Analysis" methodologies build on the original work by Long and Ackerman (2000), who show that these techniques include a high degree of repeatability since both the clear-sky and all-sky values include the same measuring instrument characteristics. Thus the resultant all-sky/clear-sky ratios and differences, while not reflecting improvement in the absolute accuracy inherent in the measurements, do lend themselves well to trend analyses.

We will present results of the Flux Analysis methodology applied to measurements from various ARM and BSRN sites spanning the years of available data. These results include analyses of shortwave (SW) and longwave (LW) all-sky and clear-sky climatology; SW, LW, and net cloud effects; total (daylight) and LW effective (24 hour) fractional sky cover; cloud visible optical thickness; and estimates of cloud field effective radiating temperature and radiating surface height. Preliminary results of the upwelling components of clear-sky and cloud effect will also be presented, and used to infer the total net surface radiative cloud forcing.