Space Science and Engineering Center

This project is a continuing effort to compile statistics on global cloud occurrence using the High-resolution Infrared Radiation Sounder (HIRS) sensors on NOAA polar orbiting weather satellites. Clouds play a critical role in Earth's energy balance because they control absorption of solar radiation and emission of the Earth's infrared radiation, a far greater impact than controlling atmospheric greenhouse gases. To predict changes in climate, numerical models need to predict changes in clouds. For this reason global statistics on clouds and their changes in the last 22 years are being compiled. The project complements and contrasts with a similar project, the International Satellite Cloud Climatology Project (ISCCP), which does not use HIRS data. By using the HIRS sensors, which contain channels that partially absorb CO2 from 13 to 15 microns (wavelength), SSEC's statistics provide better sensitivity to semitransparent clouds, which have been difficult to detect with other sensors.