REMOTELY SENSED TIME SERIES OF CHLOROPHYLL-α, TOTAL SUSPENDED MATTER AND SEA SURFACE TEMPERATURE FOR MONITORING WATER QUALITY OF THERMAIKOS GULF (GREECE)

During the last decades, remote sensing has been accepted as a useful tool for monitoring marine and coastal environments. The most notable advantages of using satellite imagery are the detailed coverage of large areas at low cost, the ability to collect data repeatedly and nonintrusively, and the multispectral nature of the observations. The aim of this work was to assess the use of satellite images for creating a time series of water quality parameters in Thermaikos Gulf (Greece), a dynamic aquatic ecosystem. The specific objectives included the evaluation of the spatial and temporal distributions of the produced maps, and the evaluation of the accuracy of the estimated parameters. Using ENVISAT MERIS and Aqua MODIS satellite images, a time series of two hydrological years was put together for chlorophyll-alpha (Chl-alpha), total suspended matter (TSM) and sea surface temperature (SST). The results show that the satellite images covered the study Site with some data gaps due to cloud coverage and orbit shift of the ENVISAT satellite. Comparisons show a very good correlation with measurements of samples taken in the field. The produced maps illustrate the spatial distribution of Chl-alpha and TSM, specifically, the maxima were observed on the plumes of the three major rivers and the minima in the open sea. The time series produced by the temporal interpolation may be adequate for monitoring the water quality parameters of the area on an operational basis.