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Date: Thu, 6 Oct 1994 11:34:01 +0000 (GMT)

We are at the end of the intercalibration and training cruise, and are pleased to report that everything has gone very well. The ship's crew and scientists have worked hard to solve problems as they arose and most systems have been thoroughly "wrung out". High quality, edited data is available from 24 stations (46 casts) as we leave the ship and copies will be forwarded to the chief scientists of each U.S. JGOFS leg within the next month to aid them in planning their cruises. There are three Seabird CTDs aboard, two with dual sensors, two 24-bottle Seabird carousels, and back up General Oceanics rosettes. All sensors and cable have been used in 4000 m casts. The hydro team (CTD, salinity, oxygen, nutrients) has been generating superb data, cross checking for consistency, and developing protocols that will be used on all subsequent U.S. JGOFS cruises. A protocol manual is being written which will be distributed for your comments soon. The aft conducting cable (.68) worked flawlessly on 11 MOCNESS tows. We have internet connectivity at a cost of $1 per 1000 characters. The ship has many computers linked by ethernet; the science computer has three years of TOPEX data (10 day composites) for the region, and three years of model output from Mark Luther (monthly averages). These were brought out and installed by John Morrison. The ship's acoustic Doppler current profiler is being configured by Charlie Flagg to operate autonomously, displaying the standard ADCP profiles each 5 minutes and also displaying cumulative 12 hour plots of current and range corrected backscatter intensity. Charts, reprints, and atlases reside in the science office. Lou Codispoti plans to send preliminary copies of the bottle data to the chief scientists of each leg within the next month. These data were collected at 24 stations beginning at 8 deg N, 65 deg E and continuing along the eastern and northern portions of the U.S. JGOFS cruise track into Muscat. The hydro team has intercompared standards from SIO/ODF, Old Dominion Univeresity and the National Institute of Oceanography in Goa, India, with excellent results. Comparisons of the SIO/ODF automated Winkler titrations with a colorimetric method optimized for low concentrations produced excellent agreement (+/-0.003ml/l) down to concentrations of about 0.015 ml/l. Wajih Naqvi and Ted Yoshinari collected data on nitrous oxide and its isotopic composition, and other isotopic data (in collaboration with M. Altabet) with support from the ONR-managed bi-lateral USA/India program. The trainees from Oman and Pakistan have provided much needed assistance. A series of seminars presented by S. Smith, G. White, J. Morrison, C. Flagg, L. Codispoti, T. Yoshinari and W. Naqvi was organized for their benefit; most of the scientific complement and some of the ship's crew attended. The system for automatic ADCP data collection has been installed and has been enhanced to show the previous 12 hours of velocity and backscatter data in real time. The installation of the ADCP on the Thompson generates superior results throughout the ship's speed range. ADCP highlights include a remarkably clear indicatiion of equatorial waves along 5 deg N, east of 80 deg E, currents in the central Arabian Sea that resemble Luther's model output from October 1993, and vivid pictures of the diel plankton migration. The range of the ADCP in the Arabian Sea varies with location and time, being about 400 m during the day, even in the low oxygen region, and decreasing to 200 m during the night when the plankton migrate to the surface. We used the MOCNESS to investigate the layer that resides in the low oxygen region in the day and comes to the surface at night; the preliminary impression is that it is composed of euphausiids and myctophid-like fish. There are areas in the low oxygen region where there appeared to be nothing, judging by the ADCP's backscatter, and these layers did indeed seem to be devoid of "ordinary" plankton. We also found the animals that dominate the Somali upwelling area (Calanoides carinatus) present in the areas where phytoplankton was more abundant. These areas are consistent with our understanding based on CZCS images. A vexing problem with excessive noise in some of the CTD casts remains to be completely resolved, but it had only a minor effect on the quality of the data. Work on this problem continues and we expect it to be solved by the first U.S. JGOFS process cruise in January. The intercalibration and training cruise has achieved its goals and heads for Muscat satisfied. Winds were never above 14 knots and the seas were calm for 21 days. The sun shines without mercy. Sharon, Lou, John and Charlie