SURFACE-TEMPERATURE DYNAMICS OF LAKE BAIKAL OBSERVED FROM AVHRR IMAGES

Satellite data are important in understanding the relationship between hydrodynamics and biological productivity in a large lake ecosystem. This was demonstrated using NOAA AVHRR, and in situ temperature and ch lorophyll fluorescence data to describe the seasonal temperature cycle and distribution of algal biomass in Lake Baikal (Russia). Features s uch as ice cover, thermal fronts, and the dispersion of river water we re described in a series of images from 1990 and 1991. The northern ba sin retained ice cover until the end of May. In June, thermal fronts e xtending <10 km from shore were observed to be associated with shallow s, bays, and rivers. Offshore surface temperatures in the northern bas in did not exceed 4 degrees C until late June-early July. The southern and middle basins warmed more quickly than the northern basin. In sit u data showed phytoplankton concentrations to be low off-shore and hig h near thermal fronts. The Selenga River, the largest tributary of Lak e Baikal, supplied warm water and nutrients which contributed to local ized increases in chlorophyll fluorescence.