While the evidence of global warming continues to grow, the theory of regional climate change remains less well developed and less well accepted. Because individuals and societies experience only regional and local climates, our lack of knowledge threatens both public awareness of climate change and the design of adaptation strategies. An important science problem with regard to local climate is the role of the earth’s surface.
Over the last twenty years, the important role of local surface properties on weather and climate has been revealed by numerous field, remote sensing and numerical investigations.
Relevant surface properties include:
- albedo: the proportion of the sun’s radiation reflected
- surface roughness: a control on turbulent transport of heat, moisture etc.
- evaporative potential: the availability of water for evaporation
- melting potential: the availability of ice for melting
- emissivity: the efficiency of long wave emission
- heat storage: the ability of the surface to store heat and release it at a later time.
A powerful approach to the study of land surface and climate is the use of satellite remote sensing. Since the 1970s, dozens of increasingly sophisticated environmental earth-orbiting satellite have been launched carrying multi-spectral sensors looking down at the earth. A few examples for land surface studies are Landsat, AVHRR, GOES, MODIS, and Aster. These sensors have global coverage and are able to measure and monitor surface albedo, surface temperature and surface vegetation distribution. Spatial resolution varies from 15 meters to one kilometer. Temporal resolution varies from hourly to yearly. With less precision, they also observe longwave emissivity and surface wetness. When these datasets are combined with standard weather and climate data, many characteristics of the surface heat and moisture budgets can be obtained. Several different aspects of surface climate interaction can be addressed, including surface climate feedbacks, climate change driven by growing cities and the geo-engineering of cities to improve local climate by modifying surface properties.