Nieke, B. Dalhousie University, bnieke@raptor.ocean.dal.ca
Cullen, J. Dalhousie University, john.cullen@dal.ca

 
VERTICAL DIFFUSE ATTENUATION COEFFICIENT KD(UV) FROM WATER-LEAVING RADIANCES (400-700 NM) IN OCEANIC AND COASTAL WATERS
 
In order to assess the biological and photochemical effects of UV (280-400 nm) in aquatic systems, the spatial and temporal variability of downwelling irradiance (Ed) in the UV needs to be quantified, and consequently, vertical diffuse attenuation coefficients (Kd) for UV wavelengths in oceanic (Case1) and coastal (Case2) waters must be determined. Because the constituents of surface waters that influence ocean color (CDOM, inorganic/organic particulate matter), also determine attenuation at UV and visible wavelengths, observations of upwelling radiance (Lu) in the visible, from a number of platforms, such as satellites, drifters and moorings, can potentially offer means to estimate Kd in the UV. We used principal component and stepwise multiple regression analyses to develop empirical algorithms relating Kd in the UV to Lu at satellite wavebands (e.g. SeaWiFS) for data from the St. Lawrence system, Canada (September 1997). Different algorithms were found for Case1 and Case2 waters, due to the influence of CDOM. We also discuss the importance of the Lu(412)/Lu(555) ratio as a predictor for absorption at UV wavelengths.
 
Day: Thursday, Feb. 4
Time: 02:15 - 02:30pm
Location: Eldorado Hotel
 
Code: CS61TH0215E