Aeresol Variability in the Adriatic Sea from Automated Optical Field Measurements and SeaWiFS

The aerosol optical properties in the Adriatic Sea are presented using a 9-year time series (1996-2005) of automated measurements collected on the Acqua Alta Oceanographic Tower (AAOT) in the northern part of the basin and a coincident satellite record obtained from an atmospheric correction scheme adapted for European seas and applied to SeaWiFS. At AAOT, the overall averages of aerosol optical thickness taua at 500 nm and Angstrom exponent alpha are 0.29+/-0.21 and 1.51+/-0.34, respectively. The average single scattering albedo varies from 0.957 at 440 nm to 0.910 at 1020 nm. The aerosol size distribution derived by optical data inversion exhibits an increase of the radius of the accumulation mode with taua. From 402 coincident data records, the agreement between satellite and field taua is remarkable, with mean relative absolute differences of 17-20% in the 412-870 nm spectral range. On the other hand, the satellite record tends to filter out occurrences of high taua. The satellite products are used to analyze the seasonal cycle over the Adriatic basin, showing minima in winter and maxima in summer (taua(500) from 0.06 to 0.23). Then, the results of radiative transfer simulations are combined with the satellite derived seasonal cycles of taua and cloud fraction to determine the clear-sky aerosol direct radiative effect for the Adriatic Sea. At the surface, the aerosol load results in a monthly average cooling effect ranging from -1 W.m-2 in winter up to -9.6 W.m-2 in August and a corresponding atmospheric warming from 0.5 to 4.6 W.m-2.

MELIN Frederic;  CLERICI Marco;  ZIBORDI Giuseppe;  BULGARELLI Barbara; 

2006-11-20

AMER GEOPHYSICAL UNION

JRC32868

https://publications.jrc.ec.europa.eu/repository/handle/JRC32868,