Posts Tagged ‘GCM’

Climate Models: Albedo, Earthshine

Thursday, November 5th, 2009

NASA

Measuring Earthshine: How New Terra Data are Improving Weather and Climate Forecast Models

A sensor aboard NASA’s Terra satellite is helping scientists map how much sunlight the Earth’s surface reflects back up into the atmosphere, and this new detailed information should help to greatly improve weather and forecast models.

The Moderate Resolution Imaging Spectroradiometer (MODIS) now routinely provides daily global and local measurements of albedo, or the total amount of light reflected from Earth’s surface out to space. These precise data may allow scientists to better understand and predict how various surface features absorb and reflect solar radiation, which influence both short-term weather patterns and longer-term climate trends.

American Meteorological Society

Land surface albedo is a critical parameter affecting the earth’s climate. For many general circulation models (GCMs), both visible (0.4–0.7 μm) and near-infrared (0.7–5.0 μm) albedos are needed, whereas the surface energy balance studies typically require broadband shortwave (0.25–5.0 μm) albedo. Although surface albedo has been routinely observed for a long time and different approaches have been explored, a global map of surface albedo with high accuracy is not simply available right now. It has been well recognized that surface albedo is among the main radiative uncertainties in current climate modeling. Most GCMs are still using prescribed fields of surface albedo that are often 5%–15% in error from place to place and time to time.