Surface radiation budget in a Subalpine lake using a combined modelling/remote sensing method

Four Landsat-5 Thematic Mapper (TM) images acquired between May 1996 and June 1998 were selected in order to define a procedure to compute the surface temperatures and the daily energy budgets of Lake Iseo, located in northern Italy. TM data were atmospherically corrected by using the radiative transfer code LOWTRAN 6 (Low Resolution Transmittance Code), and results in some locations were evaluated comparing satellite derived temperatures with in situ measurements collected simultaneously to the TM overpasses. The root mean square error (ESQM) between satellite and measured temperatures was lower than 1 degrees C. Then, a method combining modelled values of incoming short and longwave radiation, remotely sensed measurements of surface temperatures and albedo was used to retrieve the instantaneous surface radiation budget and the net radiation of the basin. Using hourly meteorological measurements and a model founded in literature the daily energy budget and its accuracy were finally evaluated and compared to reference values.