engleski

OPTICAL PROPERTIES IN THE GARGANO-MANFREDONIA GULF REGION

In-situ measurements of inherent and apparent optical properties during the two DART cruises 19-20, March and 26-27, August 2006, in addition to laboratory measurements of total suspended matter and chlorophyll concentrations were analysed. Optical properties vary in space and time in the research area due to horizontal and vertical water mass displacement, currents, seasonal changes etc. Irradiance and radiance measurements with PRR800 allowed determination of attenuation downward/upward coefficients for 14 wavelengths. From AC9 measurements absorption and total attenuation coefficients were calculated for 9 wavelengths. Coefficients were compared accross the wavelengths and through vertical distribution at the stations for the two periods of measurements. The investigated waters are characterized by a sharp water color gradient from coastal to the open sea, covering a full range of optical properties. Optical water types determined through qualitative spectrum characterisation and PAR attenuation measurements vary across the spectrum of optical water types. Range of attenuation coefficients in the area dominate over seasonal differences between the two seasons. High attenuation coefficients indicate that suspended sediments significantly influence optical properties of the region, in addition to high concentrations of dissolved colored substances. Linear relation is observed between absorption and total ectinction coefficients in most of the cases, and correspondence exist between suspended matter concentrations and total extinction coefficients. Relationship is explored between optical properties and chlorophyll concentrations.

inherent and apparent optical properties; absorption; attenuation

nije evidentirano