Estimates of solar irradiance at the earth’s surface from satellite observations are useful for planning both the deployment of distributed photovoltaic systems and their integration into electricity grids. In order to use surface solar irradiance from satellites for these purposes, validation of its accuracy against ground observations is needed. In this study, satellite estimates of surface s...

IN THE NEWS FOCUS STORY “WEATHER forecasts slowly clearing up” (9 November, p. 734), R. Kerr nicely summarizes how the growing improvement in prediction is coming from a focus on “more computer power, the assimilation of radar observations, and more physically realistic models.” He emphasizes that better assimilation of satellite data is a key element of improved forecasting. Unfortunately, the...

I describe some of the outstanding “big picture” questions in quasar research and how the development of the plasma simulation code Cloudy is being guided to answer them. QSO spectra are complex and challenge even the most sophisticated spectral codes. Particular emphasis is given to a central question – how do the properties of the central black hole and the accretion disk are manifested in th...

This paper discusses recent advances in the full spectral simulation of scenes with partial cloud cover. We examine the effect of broken cloud fields on the solar illumination reaching the ground. Application of aerosol retrieval techniques in the vicinity of broken clouds leads to significant over-prediction of aerosol optical depth because of the enhancement of visible illumination due to sca...