Lake Malawi is the second largest lake in Africa by volume and an important regional
source of food. Seasonal fluctuations in the primary production of the lake are principally
controlled by the lake's thermal structure, which modulates the mixing of nutrient-rich deep
water with that of the phytoplankton-rich near-surface layer. Satellites potentially offer
an efficient, low cost method of providing information on the lake's thermal structure over
the longer term via remote sensing observations of lake surface temperature. Here we
investigate the accuracy of remotely sensed lake surface temperatures derived using data
from the NOAA-11 AVHRR over a two-year period (1992-1993). Optimised triple window atmospheric
correction algorithms are shown to provide an accuracy of around 0.5°C when compared
to in situ water temperatures. The effect of the 1994 switch in operational night-time
satellite from NOAA-11 to NOAA-14 is assessed using modelling of the transfer of radiation
through the Malawian atmosphere, combined with detail on the differences in the satellite
spectral response functions. These simulations indicate that lake surface temperatures derived
from NOAA-14 are warmer than those that would be derived from NOAA-11 under the same conditions.
The magnitude of the temperature difference is estimated at 0.27°± 0.07°C,
depending on the viewing zenith angle. Finally, we illustrate the ability of the remotely
derived surface temperature maps to provide information relevant to the lake's 3-D thermal
structure. Evaluations of the annual mixing regime of the lake can be based on this
information, this mixing being directly relevant to the seasonal variations in lake primary
production.