La radiazione solare globale nei modelli di Produzione Primaria dei mari della Toscana

Marine Primary Production (PP) is mostly based on the absorption of photosynthetically active radiation (PAR) by phytoplankton chlorophyll. The solar beams passing through the marine surface activate photosynthesis and the production of new living matter. In this work we evaluate the use of different sources of solar radiation for estimating PP in the Tuscany seas from 2005 to 2008. These sources comprise the solar radiation measured at some meteorological stations and the solar radiation estimated from satellite observations. The considered satellite products are the daily Surface Solar Irradiance (SSI), derived from the Ocean & Sea Ice Satellite Application Facility (O&SI SAF), and the PAR product of the SeaWiFS sensor, derived from the Ocean Color site of the National Aeronautics and Space Administration (NASA). A local model of PP has finally been fed with the PAR obtained from the two satellite products. The comparisons between the radiation data from the three sources show the slight superiority of the O&SI SAF over the SeaWiFS product. The former is in fact more consistent with the data taken at the weather stations, without showing the degradation patterns which are typical of land radiation measurements. The PP differences obtained by using the two PAR products are, however, marginal and limited to particular cases. The main features of the radiation sources examined are finally discussed in view of their possible utilization within an operational system for monitoring PP in the study area.