SUMMARY OF COAST FLIGHT 18

COAST Flight Number 18 was flown on August 13, 2001. This flight was the second in a planned multi-flight time series during a period of northerly winds. Measurements were made of: SST, subsurface ocean temperature and upper-ocean color; atmospheric temperature, humidity and horizontal winds. Data were collected on all eight Big Box Lines, flying from south to north.

AXBTs were deployed as follows:

Line 2: 6 AXBTs
Line 4: 6 AXBTs
Line 6: 7 AXBTs
Line 8: 7 AXBTs

We altered our flight execution somewhat on this flight due to the widespread stratus cloud layer in the region, which had a base at around 1,200 feet. To obtain better coverage for SST and ocean color, we flew Lines 3 and 5 at 500 feet instead of making sawtooth profiles for atmospheric variables. This would have put us in or above the clouds for more than half of each of those lines, thereby obscuring the remote sensors' views of the sea surface. It seemed especially important to obtain SST information, as the study area had been covered with clouds for a few days, resulting in no satellite imagery. We did atmospheric profiles on Lines 1 and 7 as usual. We also flew the AXBT lines at 1,000 feet, as that gave improved reception of the BT radio transmissions as the aircraft flew away from a BT drop site. Winds at 500 feet were measured on Lines 3 and 5 instead of the BT lines on this flight.

Oceanic and atmospheric conditions observed on this flight seemed much the same as those seen on the previous flight two days before. An atmospheric temperature inversion was observed on both lines where meteorological profiles were made (Lines 1 and 7). It was a sharp inversion but did not have the overall temperature change of the one measured on the 11th. The delta-T was about 4 C at around 500m height. There was a mild wind jet below the inversion, but for the most part the winds were northerly at about 10-15 knots in the marine layer. Surfacw winds appeared to be below 15 knots throughout the study area.

The SST field showed slightly cooler water near the coast. Nearshore SSTs were generaly about 13C. The low surface winds allowed us to see several sets of "bands" on the surface over the southern half of the Big Box. They seem to be over the banks and not in the northern half of the BB, although there are the more typical slick patterns almost everywhere.

We saw both ships on this flight and did a few low passes past each. With the overcast skies we did not attemopt to gather optical calibration data.

Data products will be available from http://www.marine.unc.edu/cool/COAST or they may be retrieved from the real-time results or 4-days-plus results areas. All of these are buttons off of the main COAST site.

Submitted by:
John Bane
August 14, 2001