Evaluation of an In Situ Absorption and Beam Attenuation Meter in Clear Open Ocean Water.

摘要

RESEARCH GOALS. Our goal is to assess and characterize in situ inherent optical property (IOP) observations in the clear natural waters of the Sargasso Sea. In situ IOP determinations are difficult in clear waters due to the fact that the signals are extremely small relative to the pure water used to calibrate the instrument. The emphasis of our research is to develop methods for making accurate and precise IOP measurements made with a WETLabs AC-9 spectral absorption and beam attenuation meter in the clear natural waters of the Sargasso Sea and to validate these measurements against independent, in situ apparent optical property (AOP) and in vivo IOP determinations. The development of methodologies for making accurate IOP profiles for this highly demanding environment will lead to an increased understanding of this important instrument for all waters. OBJECTIVES. Our near-term objectives are to 1) characterize the precision of in situ IOP determinations by examining inter- and intra-cruise variations in the measured beam attenuation and absorption spectra, 2) determine the accuracy to which the in situ IOP measurements can be made by comparing with other relevant data sets, 3) evaluate the temporal-depth patterns in IOP values at U.S. JGOFS Bermuda Atlantic Time-series Study (BATS) site and 4) address the relationship between in situ IOP values and simultaneously observed biogeochemical property variations.