| Popis: |
A suite of bio-optical sensors is to be deployed by the National Data Buoy Center (NDBC) in coastal waters in anticipation of the launch of the SeaWiFS instrument aboard the SeaStar satellite. Surface-referenced solar irradiance, upwelling radiance, chlorophyll concentration, pressure, temperature, conductivity, and oxygen concentration will be measured at depth. Hourly reports of time averages of these quantities will be made available through GOES satellite messages which will be disseminated through normal NDBC data channels as well as through the Internet in near-real time. High resolution (6 Hz) time series data will be collected for post-processing to evaluate the hourly measurements. These data will provide valuable ground-truth information for SeaWiFS calibration. The bio-optical sensors and the data recording and transmission systems have been installed for field testing at the Army Corps of Engineers facility in Duck, North Carolina. The final installation of the sensor system has been delayed by damage suffered by the targeted platform (Ambrose Light Tower in the New York Bight) as well as by a review of sensor mounting strategies inspired by a tower shadowing study conducted by NDBC. Radiometric measurements taken by NDBC near the Apache 990 oil production platform located in the northern Gulf of Mexico show evidence of significant shadowing effects from such large ( 24 m square, elevation 22.0 m) ocean structures. Approximations derived from the least-squares fit of an analytical function to data collected during overcast conditions indicate that distances from the structure of greater than 100 m must be achieved to avoid any shadowing effects. |
