Variations in colored dissolved organic matter between boreal lakes studied by satellite remote sensing

There have been major improvements in our understanding of the role of lakes and impoundments in global carbon cycle. Estimating the true role of lakes as sentinels, regulators and integrators of climate change requires analyzing carbon content of vast number of lakes. This is not realistic without using remote sensing methods. There are no satellite sensors at the moment that provide full global coverage and at the same time have spatial and radiometric resolutions suitable for lake color dissolved organic matter (CDOM) mapping. Therefore, the global study has to be performed using more sensitive sensors to create regional lake CDOM statistics for as many sites as possible and extrapolating the results on global lake map that can be created from less sensitive sensor data with full global coverage (Landsat). As a first step towards the global lake carbon mapping we show that the Advanced Land Imager (ALI) allows to study regional variations in lake CDOM content and consequently estimate closely correlated DOC (dissolved organic carbon) and CO2 saturation values. The results show also that there may be regional differences in lake CDOM content even if the study sites are geographically relatively close to each other and occupying zones with similar land cover and annual runoff. In one occasion the difference can be explained with human impact that has caused acidification of lakes but the other occasion needs further studies.