The sensitivity of MEdium Resolution Imaging Spectrometer (MERIS) for detecting chlorophyll and seston dry weight in coastal and inland waters

MERIS will enable monitoring of water quality in Case I and II waters. A sensitivity analysis is presented to assess the performance of MERIS for detecting chlorophyll and seston dry weight for case II waters which are optically more complex. For two case II water types (coastal and inland) an analytical bio-optical model is specified that generates the subsurface irradiance reflectance R(0-) from the water constituent concentrations. The R(0-) is propagated through the air-water interface and the atmosphere to the radiance at the sensor L_rs. Changes in R(0-) and L_rs due to a 10% increase of chlorophyll and seston dry weight are simulated. The results are compared with the noise equivalent R(0-) as specified for MERIS ocean colour applications. The results show that the sensitivity depends on the water composition and should be evaluated for different water types separately. From the case study in Lake Ijsselmeer it is concluded that MERIS will be able to estimate chlorophyll-a with an accuracy of 10% for CHL values between 10 to 100 mg m^-3 and seston dry weight with an accuracy of 2% for DW from 10 to 70 g m^-3. For the North Sea the CHL can be estimated with an accuracy of 5-15% depending on the DW concentration and the predicted accuracy for DW retrieval is approximately 1-5%