| Abstract |
Aerosols can affect human health and environment. They provide surfaces for heterogeneous reactions in the atmosphere and they also affect visibility and climate.
The Mediterranean, as a crossroad of air masses from different origin is affected by different aerosol types; anthropogenic pollution, forest fire plumes, desert dust transports from Sahara as well
as natural aerosol from the surrounding continents and ocean contribute to the aerosol loading over this region. Satellite remote sensing techniques provide a great opportunity for the observation and the understanding of the aerosol’s behaviour since they allow systematic and extended spatial and temporal sampling of the atmosphere.
In the present study, the Bremen AErosol Retrieval algorithm (BAER) has been applied to MERIS (Medium Resolution Imaging Spectrometer) and SeaWiFS (Sea-viewing Wide Field-ofview
Sensor) data over the Mediterranean during the years 2002 and 2003. The ability of BAER to retrieve aerosol optical thickness (AOT) over areas affected by various aerosol sources including
dust and fire plumes has been evaluated by comparison with the AERONET (Aerosol Robotic NETwork) observations, ground based measurements and model (TM4) results.
The comparison of the AOT’s retrieved with BAER from MERIS and from SeaWiFs data with the AERONET observations (AOT at 440 nm) at eight different stations in the Mediterranean and during four months of the year 2003 shows large day-to-day variability in the retrieved AOT as well as in the AERONET data and slight underestimation in the AOT retrievals from the sensors compared to the AERONET data. The retrieved AOTs indicate that dust and fire plumes episodes lead to 20% higher values of aerosol optical thickness than observed under background conditions.
The seasonal variability of the derived AOT has been also studied based on the retrieved AOT from MERIS and SeaWiFS and on the MODIS available product version 5. The retrieved AOTs
maximize in summer when the Mediterranean basins are subject to good weather conditions characterized by low content in clouds and higher content in aerosol.
The present study has also demonstrated the reliability of particulate matter (PM) retrievals from satellite remote sensing observations based on the SeaWiFS observations and comparison to
PM10 ground based measurements.
Finally, the aerosols effect on the energy balance of the Mediterranean has been evaluated based on the retrieved optical thickness from MERIS sensor and model results for February, April, August and October 2003. This investigation shows a significant aerosol effect with ΔF varying between -5 and -25 W/m2 and a seasonal variability with the maximum values occurring during summer.
|
Σχηματισμός και κλιματικές επιπτώσεις των αιωρούμενων σωματιδίων στην ανατολική Μεσόγειο
