Investigation on heat transfer in the Laptev Sea with respect to regional climate changes

The Laptev Sea around the Lena River delta in northern Siberia is a very remote area that in-situ measurements are only sparsely available. Polar night and long lasting ice coverage until the end of June makes it difficult to investigate the area all year round. Here satellite investigations of radiances measured e.g. with Envisat MERIS satellite and derived inherent optical properties (IOP) may help to generate a time series of changing water constituents, e.g. chlorophyll and coloured organic matter which can be split further into coloured dissolved organic matter (CDOM) and suspended particles (SPM). However, large solar zenith angles as well as thin cloud coverage in summer after ice break-off makes it difficult to investigate this region by remote sensing applications. Therefore modelling approaches seems to be a useful first approximation to identify the feedback to the radiation budget in these remote areas. With the current studies we investigate the influence of CDOM and SPM on the radiative heat transfer into the shelf regions of the Laptev Sea. As a first step we use the coupled atmosphere-ocean radiative transfer model SCIATRAN to assess energy input into coastal waters of this region dependent on different concentrations of CDOM varying significantly for different times of the year. Low solar elevations and high absorption by water constituents in this area extremely reduces the light penetration depth in the water body. An increased absorption in the surface water leads to higher sea surface temperatures and a high energy release into the atmosphere often occurring in late autumn and consequently influences the ice development process. In the context of climate change and thawing permafrost in Siberia the riverine input of those highly absorbing particles by Lena river may increase in the future. Therefore, a better understanding of these processes is necessary to predict possible future changes for that remote area