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TIP 3 National reports | |
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National reports
United States TAO Mooring Annual Operating Plan. A review of the mooring work accomplished since TTIP-2 was presented. During the past year, 5 ATLAS moorings deployed for the TOGA-COARE Intensive Observing Period (IOP) were recovered and seven new ATLAS sites were inaugurated, resulting in a current total of 61 ATLAS moorings and 6 ADCP moorings deployed in the Pacific TAO Array. To accomplish this work, 325 days at sea were expended from the United States (235 days from NOAA and 31 days from the UNOLS vessel Moana Wave) and Japan (59 days). The plan for the period 1 October 1994 to 30 September 1995 was presented. NOAA will expend 211 days to support the TAO array from 95W to the date line. The JAMSTEC R/V Kaiyo will spend 25 days in December - January and a similar number of days in late boreal spring to service the Western Pacific TAO array. The Taiwanese R/V Ocean Researcher I will provide 32 days in November - December to deploy the last two moorings in the TAO array along with several others. Taiwan may also provide ship time in boreal summer 1995 for mooring maintenance work in the western Pacific aboard the Fishery Researcher I. A potential shortfall in the western Pacific in spring 1995 is being addressed. One potential solution under discussion within NOAA is to have NOAA Ship Discoverer tend to the 165E line in boreal spring as an extension of her scheduled central Pacific TAO maintenance cruise. The panel was informed about the tenuous nature of ship time in the western Pacific. With the end of TOGA-COARE and the demise of the IFREMER fleet in the Pacific, availability of ship time to support the western Pacific has become an acute problem, particularly along the 165E and 156E meridians, where several heavily instrumented moorings are in place. TAO Data Calibrations and Sampling. There are presently 61 ATLAS moorings and 4 PROTEUS moorings, with over 1100 sensors, deployed by PMEL as part of the TAO program. The majority of sensors are calibrated at PMEL by TAO technicians prior to deployment and after recovery. A technical report describing the calibration procedures and accuracy estimates is in preparation. A new automated humidity calibration chamber has been added at PMEL which continues the improvement in calibration equipment and procedures. A review of the onboard sampling for the moorings, averaging schemes, and data transmissions was presented. TAO Data Dissemination. During the past year, major improvements were seen in the GTS data transmissions by ARGOS for the TAO buoys. Nearly 100% of all available data is now being sent out to the GTS network. Typically, approximately 1500 hourly surface messages (winds, air, and SST) and 400 daily averaged subsurface temperature reports are available on GTS each week. Daily quality checking of the GTS data, consisting of disabling distribution from questionable sensors, is performed by PMEL to maintain the highest possible data quality on the GTS. A new release of the TAO Workstation Display Software was announced in October 1994. Enhancements include access to current meter data, historical data, hourly time series, improved flexibility in axes scales, and data subscription service. No software purchases are necessary to run the Display Software package. NetCDF files are updated daily at PMEL. Improvements have also been made to the anonymous FTP files that are maintained at PMEL, with the addition of quality words and the availability of hourly data by site. Anonymous FTP files are updated monthly. During the period of November 1993 to October 1994, 105 requests for TAO data were received at PMEL. Data and information regarding the TAO array are also available through recent development efforts on MOSAIC. The home page address for the TAO project at PMEL is http://www.pmel.noaa.gov/toga-tao/home.html. Data subscription service is also available. TAO Moorings in the Indian Ocean. The ATLAS mooring that had been deployed at 0,80.5E in the Indian Ocean in August 1993 by the R/V Sonne broke free from its anchor in early January 1994. After drifting for several weeks, it was retrieved by the M/V SEAFDEC of the Phuket Marine Biological Center in Phuket, Thailand. Unknown to the vessel personnel, the transmitter on the buoy continued to operate during the ship transit to Phuket, allowing TAO personnel to pinpoint its exact position. Relying on personal contacts initiated by Ms. Vallapha Cass of the TAO Project Office, the buoy was secured until Ms. Cass visited Phuket and was able to recover the complete hourly time series of the surface data. From inspection of the recovered buoy and analysis of the sequence of events following the buoy's initial drift, it was judged that the buoy had been vandalized and the mooring line cut well before the SEAFDEC retrieved the buoy. Next Generation ATLAS Mooring. Development efforts continued during the past year in testing a prototype mooring where subsurface measurements are transmitted to the surface buoy via inductive coupling technology rather than the conventional thermistor cable. A test mooring was deployed in June off the Washington coast and several weeks of subsurface data were received. Preliminary results were encouraging and two prototype moorings will be deployed in the central equatorial Pacific in late 1994. Vandalism in the TAO Array. Vandalism continues to be a problem in the TAO Array, particularly on the eastern and western boundaries. At least 19 sites were damaged during the past year with three along 95W in the eastern Pacific, three in the central Pacific at 2S, and the remainder west of the date line. Wind sensors are most commonly vandalized, but damage is also done to the electronics packages, other sensors, and even the buoy towers. The percent of good data return for western Pacific winds has been below 70% at most sites, while it is typically 80 - 90% in the central and eastern Pacific. Attempts to reduce the damage to the instrumentation include the installation of a hardened cage which protects the base of the wind sensor and the electronics tube. Japan Past observations have shown that current and salinity variability is very large in the western Pacific. The buoy design is therefore planned to be compatible with the ATLAS buoy, but with a capability to observe subsurface salinity in addition to temperature. Current observations are planned to be made by independent ADCP moorings. The design for this buoy network is being undertaken this year (1994) at JAMSTEC and the University of Tokyo. The research vessel Mutsu was officially authorized to be rebuilt to support the Buoy Network Programme. This ship is 130 m long with a gross tonnage of around 8600 tonnes. This ship will be equipped for deployment and retrieval of the planned buoys, and will enter service in the winter of 1997. Dr. Sumi briefed the group on GAME (GEWEX Asian Monsoon Experiment), sponsored by GEWEX/CLIVAR. This multi-year program will be divided into two phases: Phase 1, (1997 - 1999) will examine land surface processes in four regions (Siberian tundra, Tibetan plateau, tropical rainfall region, and the subtropical rainfall region of Southeastern China. This program will be collaborative with the TRMM Validation program and the Bay of Bengal project. Phase 2, (2000 and beyond) focusses on remote sensing platforms such as ADEOS, TRMM, and ADEOS-2. Dr. Sumi announced that the Second International Study Conference on GAME will be held March 6 - 9, 1995 in Pattaya, Thailand. Also, the CLIVAR Asian Monsoon Workshop will be held in Melbourne, Australia, on April 10 - 11, 1995, following the TOGA conference.
Korea The present Korea TAO projects will be terminated in November 1994 with the end of TOGA. However, the Korean Meteorological Research Institute (MRI) will start a new three-year project in December 1994 for the development of regional long-range forecasts. The monitoring branch in the project will continue to contribute some resources to the TAO. We hope to continue the operation of the 137E line in cooperation with the United States and other countries. However, the funding situation for next year is very bad: the first year of a new project usually starts with a rather small amount of research funding in Korea. Moreover, a KORDI proposal for ship time in 1995 was not approved. Overall, the Korean TAO program will suffer in 1995. However, we will work to make 1996 a successful year for Korean TAO and will concentrate on the analysis of TAO data to produce good scientific results. Dr. Suk outlined KORDI's ambitious plans to annually survey the western Pacific between 137E and 147E, requiring 100 days of ship time. Unfortunately, these plans were rejected by the approving agency. KORDI will submit a plan for 1996 support in April 1995. Dr. Hahn, director of the Oceanography Division of the Korean National Fisheries Research and Development Agency, addressed the problem of vandalism in the western Pacific by presenting the views of offshore fishermen. He meets with Korean fishing captains regularly. He blamed much of the vandalism problem on supporters and developers of TAO for not working with the various fishing groups before the Array was established to explain the purpose and benefits of the Array in order to perhaps minimize conflict. He contends that fishermen hold right of priority claim for their livelihoods and the mooring group should communicate with the fishing community to establish mooring station. It is hoped that Dr. Hahn's perspectives on fishing vandalism will lead to constructive dialogue with the fishing community to help mitigate this problem. Taiwan Several TOGA-related research projects are in progress including data analyses, such as "Relationship between tropical heating and global circulation: interannual variability" by Hsu et al. (1994); numerical model studies, such as "Development of an air-sea coupled boundary" by Wu (1994); and analytical model studies, such as "Basin-wide wind field analysis and its corresponding ocean response" by Tang (1994). The remote influence of ENSO on Taiwan's climate has been noted by domestic scientists. A data report (in Chinese) of TOGA-TAO has been issued to facilitate domestic research. A 30-day research cruise to support the TAO program may possibly be available in the summer of 1995, provided by the Taiwan Fishery Institute. Firm commitments can not be made at the present time, however. References Hsu, H.-H., 1994:
Relation between tropical heating and global circulation: interannual
variability. J. Geophys. Res., 99, 10,473 10,489. France A collaborative effort between the University of Hawaii, NOAA/PMEL, and ORSTOM-Noumea to collect near surface salinity measurements from the TAO array using 40 - 50 SEACAT temperature/salinity sensors was begun in 1994. A corresponding data bank is being established at PMEL. These newly instrumented TAO moorings are very complementary to the recent SURTROPAC array of thermosalinographs installed onboard several merchant ships operating in the western Pacific. TOGA-TAO data were intensively used by the SURTROPAC group and some other research groups in France-mainland. In particular, the TOGA-TAO data were used for comparative studies with 1986 - 89 GEOSAT and 1992 - 93 TOPEX/Poseidon sea level data over the equatorial band (Delcroix et al., 1994; Menkes et al., 1994). These studies led to interesting findings about the ENSO mechanism and the lack of equatorial wave reflection on the western Pacific boundary (Picaut and Delcroix, 1994; Boulanger and Menkes, 1994). The dedicated TOPEX/Poseidon open-ocean validation study, using two heavily instrumented ATLAS moorings from August 1992 to March 1993, was completed at the end of 1994 (see section 6.9 of this report for an abstract of this study). Discussions are underway in France for the preparation of a French GOOS program, and it will take a year or two before knowing the degree of French involvement in the tropical Pacific ocean observing system. In any case, a French CLIVAR/Pacific program has just been proposed to the ad hoc French scientific committees, by a group of scientists from ORSTOM-Noumea and the University of Paris VI. Most probably, this program will result in keeping up a significant French research effort in the tropical Pacific for the coming years. As for the critical need of research vessel time for the coming years in order to maintain all the western Pacific TOGA-TAO moorings, it is hoped that a few days of R/V l'Atalante would be devoted to this array, with her return in the Pacific in 1996. References Delcroix, T., J.-P.
Boulanger, F. Masia, and C. Menkes, 1994: GEOSAT-derived sea-level and
surface-current anomalies in the equatorial Pacific, during the 1986 89
El Nino and La Nina. J. Geophys. Res., in press. S.P. Kumar, National Institute of Oceanography It is known that the north Indian Ocean is dynamically an interesting area for physical oceanographers. The physiographic setting and monsoonal forcing coupled with the inflow of the warm high saline waters of Persian Gulf and Red Sea origin and the large quantities of fresh water influx from peninsular India (~1.5 x 1012 m3/yr) make the upper ocean circulation complex. It is known that large-scale, low-frequency forcings associated with the monsoons generate Rossby and Kelvin waves along the equator and transfer the wind energy to unforced areas. Some indications are available, based on numerical models, that these long period waves on encountering a boundary (such as the eastern Bay of Bengal) propagate their energy as "coastally trapped Kelvin waves" (Potemra et al., 1991; McCreary, 1993). A recent study using the climatology of the temperature of the eastern Indian Ocean indicated: (1) signatures of the zonal propagation of Kelvin waves in the equatorial region, (2) a northward propagation of coastally trapped Kelvin waves in the eastern periphery, and (3) the westward propagating Rossby waves into the Bay of Bengal (Prasanna Kumar and Unnikrishnan, personal communication). This study also revealed that the seasonal monsoon signal does not penetrate deeper than 300 m depth in the Bay of Bengal, clearly indicating the importance of this surface layer for energy transfer. Although there exists a broad understanding about the general circulation of the north Indian Ocean, various aspects of circulation and its seasonal dependence to finer details including the interannual variations are still not well understood. Neither do we know the role of the planetary waves in modifying the circulation of the eastern Indian Ocean and the Bay of Bengal. This is primarily because of the poor data coverage, in time and space, in the Indian Ocean, particularly the area encompassing the Bay of Bengal and the eastern Indian Ocean. It is in this context that a proposed jointly sponsored TAO field program provides an unique opportunity to study and monitor the spatio-temporal variability and the response of the eastern Indian Ocean to: (1) the monsoonal forcing(s), (2) fresh water forcing from the Bay of Bengal and the Pacific Ocean through-flow, and (3) the remote forcing via equatorial planetary waves. In addition, long time series data that would be generated would aid in addressing the deep ocean climate related to monsoons and also the trans-equatorial movement of water masses. In response to a request from Dr. McPhaden, Chairman, TOGA-TAO Implementation Panel regarding the possible cooperation in maintaining the proposed instrumented moorings (3 in all) to be deployed in the eastern Indian Ocean, National Institute of Oceanography, India, proposes to provide the technical and logistic support by way of deployment and recovery of the instrumented moorings from the Indian research ship OR/V Sagar Kanya. References Potemra, J.T., M.E.
Luther, and J.J. O'Brien, 1991: The seasonal circulation of the upper
ocean in the Bay of Bengal. J. Geophys. Res., 96, 12,667
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