| overlay in Google Maps | ||
|---|---|---|
| Years | Annual Mean Concentration | September Mean Concentration |
| 2003 | 
|
 |
| 2002 | 
|
 |
| 2001 | 
|
 |
| 2000 | 
|
 |
| 1999 | 
|
 |
| 1998 | 
|
 |
| 1997 |  |
|
* this page is designed for (at least) 1280 x 1080 resolution
Chlorophyll-a concentration is an index of phytoplankton biomass and it is one of the most common properties that characterize marine productivity. Satellite remote-sensing images of ocean colour, calibrated as chlorophyll-a concentration provides a unique synoptic view of the marine ecosystem.
A major value of ocean colour lies in the long term monitoring of the marine environment which will improve the understanding of the ecosystem functioning. Chlorophyll-a concentration, as the principle deliverable from ocean colour, has a dynamic range of at least four orders of magnitude over regions and seasons (0.01 to 100 mg.m-3).
In many regional sea ecosystems a considerable increase in the concentration of nutrients in coastal waters has been recorded in the last decades. A major source of these nutrients is agriculture and intensive farming which releases these substances into the drainage basin. Nutrient enrichment of the waters stimulates the farming which releases these substances into the drainage basin. Nutrient enrichment of the waters stimulates the growth of phytoplankton, leading, in certain circumstances, to the phenomenon of algal blooms and to anoxia in the lower part of the water column with destruction of the benthic fauna and flora.
The maps given here are produced at the European Commission - Joint Research Centre (http://ec.europa.eu/dgs/jrc/index.cfm). They are derived from SeaWiFS satellite images and show annual (1998 – 2003) and September (1997 – 2003) mean concentration of chlorophyll-like pigments in the Black Sea (Note: September 1997 has been the first month when data from the SeaWiFS satellite have become available; data have not been available for the full month of September 1997). Annual means as well as September means reveal significant variability between the years. Throughout all the years the north-western part of the Black Sea with the Danube, Dnjestr and Dnjepr river mouths shows higher values in chlorophyll concentration compared to other Black Sea coastal areas and the ‘open’ Black Sea in all the years given here. For both the annual means and the September means the year 2000 shows the largest spatial extent of higher chlorophyll values in the north-western Black Sea. The higher values in the Azov Sea have to be taken with care because the area is very shallow and the majority of the signal received by the sensor is due to bottom reflectance.Validity of the chlorophyll-a product
The chlorophyll-a algorithm OC4-V4 is designed for oceanic waters and it can lead to large uncertainties in river influenced areas due to the presence of dissolved organic matter and suspended particulate matter. The spatial gradients should be therefore interpreted with caution. The temporal variability must also be analysed accounting for the number of valid observations.
The chlorophyll-a algorithm OC4-V4 is designed for oceanic waters and it can lead to large uncertainties in river influenced areas due to the presence of dissolved organic matter and suspended particulate matter. The spatial gradients should be therefore interpreted with caution. The temporal variability must also be analysed accounting for the number of valid observations.
