Role of Clouds and Radiation in Climate , rth and Bruce

The role of clouds in modifying the earth’s radiation balance is well recognized as a key uncertainty in predicting any potential future climate change. This statement is true whether the climate change of interest is caused by changing emissions of greenhouse gases and sulfates, deforestation, ozone depletion, volcanic eruptions, or changes in the solar constant. This paper presents an overview of the role of the National Aeronautics and Space Administration’s Earth Observing System (EOS) satellite data in understanding the role of clouds in the global climate system. The paper gives a brief summary of the cloud/radiation problem, and discusses the critical observations needed to support further investigations. The planned EOS data products are summarized, including the critical advances over current satellite cloud and radiation budget data. Key advances include simultaneous observation of radiation budget and cloud properties, additional information on cloud particle size and phase, improved detection of thin clouds and multilayer cloud systems, greatly reduced ambiguity in partially cloud-filled satellite fields of view, improved calibration and stability of satellite-observed radiances, and improved estimates of radiative fluxes at the top of the atmosphere, at the surface, and at levels within the atmosphere. Outstanding sampling and remote sensing issues that affect data quality are also discussed. Finally, the EOS data are placed in the context of other satellite observations as well as the critical surface, field experiment, and laboratory data needed to address the role of clouds in the climate system. It is concluded that the EOS data are a necessary but insufficient condition for solution of the scientific cloud/radiation issues. A balanced approach of satellite, field, and laboratory data will be required. These combined data can span the necessary spatial scales of global, regional, cloud cell, and cloud particle physics (i.e., from 1 O* to 1 O-’ m). *Atmospheric Sciences Division, NASA Langley Research Center, Hampton, Virginia. ‘InstituteforTerrestrial and Planetary Atmospheres, State University of New York, Stony Brook, New York. #Earth Sciences Directorate, NASA Goddard Space Flight Center, Greenbelt, Maryland. “Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado. Corresponding author address: Dr. Bruce A. Wielicki, Radiation Sciences Branch, Atmospheric Sciences Division, NASA Langley Research Center, Mail Stop 420, Hampton, VA 23681-0001. In final form 31 March 1995.