Validation of in-situ inherent optical properties in the Sargasso Sea

摘要

Abstract: In situ inherent optical properties (IOP) determinations from the US JGOFS Bermuda Atlantic Time-Series (BATS) made from 1994 to 1996 are used to develop processing and correction methods for clear natural waters. Upper bound estimates of precision are 0.0066 and 0.0018 m$+$MIN@1$/ for non-water beam attenuation and absorption coefficient respectively. These are determined by examining the intracruise variability at 190m depth where minimum natural variations exist. The final corrected IOP values show consistent patterns with time, depth and wavelength. A strong correlation is observed between measured beam attenuation and absorption coefficient at 440 nm in the upper 50m. Whereas lower correlation is observed between the scattering coefficient and absorption coefficient. In the upper 50m layer, measured values of a-a$-w$/(440) in the upper 50m compare well with chlorophyll-based bio-optical model. However measured values of c-c$-w$/(440) and b-b$- w$/(440) do not compare well with the modeled values. In particular, the measured b/a(440) shows an inverse relationship compared with estimated b/a(440) ratio in the upper 50m. !13