Sea ice concentrations derived from
gridded brightness temperatures.
The rapid growth in atmospheric radiation studies in recent years is a result both of the increasing use of satellites to monitor atmospheric phenomena and of the increased emphasis on climate modeling. Because satellites measure only radiation, the interpretation of their data requires the study of radiative transfer in the atmosphere. Because the transfer of solar and terrestrial radiation represents the prime physical process that drives the circulation of the atmosphere and the ocean, an understanding of climate and the mechanisms of climatic changes also requires detailed understanding of radiative processes and the radiative energy balance in the earth-atmosphere system.
Current and recent research projects include the use of satellite data for microwave remote sensing of sea-surface temperatures, winds, humidity and liquid and ice water content of clouds, infrared remote sensing of upper atmosphere composition and dynamics, evaluation of the influence of clouds on the regional and interannual variations of the earth's radiation budget, and investigation of cloud-radiation interactions and their feedback to the climate system. Surface and aircraft fieldwork includes studies of solar and infrared radiation over the sea surface, microwave properties of sea ice, and light-absorption properties of atmospheric aerosols as well as the evaluations of GCM cloud and radiation parameterizations using ground-based remote sensing and in-situ aircraft observations. Theoretical work is underway to understand the light scattering by nonspherical ice particles and aerosols, to explain the radiative properties of snow and sea ice surfaces, to examine radiative processes in the upper atmosphere, and to study the influence of radiation on the maintenance of stratus clouds.