National reports

Other TIP pages

TIP homepage

Other TIP 4 pages

TIP 4 Table of contents

Summary

Opening of the meeting

Summary of current conditions in the Tropical Pacific

National reports

Brazilian Ocean-Climate programs

Program status reports

Science reports

Discussions

Acknowledgments

United States
L. Mangum/M. Koehn, NOAA/PMEL
Completion of the Array. The TAO Array was completed on 17 December 1994, with the deployment of an ATLAS mooring at 8°N,156°E by the Taiwanese R/V Ocean Researcher I. At the time of the meeting, the Array consisted of moorings at 67 sites, 64 of which were instrumented with ATLAS moorings and 5 of which were instrumented with current meter moorings (Figure 2). In two instances (0°,147°E and 0°,170°W) subsurface ADCP mooring were collocated with ATLAS moorings. Completion of the array marks the culmination of a 10-year effort under the auspices of the TOGA program to develop an observing system in the tropical Pacific for climate studies. Most rapid growth of the array occurred during the second half of TOGA, and in particular since mid-1990 when the array was only 30% complete (Figure 3).

TAO Array Support Vessel Update. As reported at the second and third TAO Panel meetings, NOAA is in the process of converting a former U.S. Navy vessel to a dedicated support vessel for the TAO Array. Presently, the vessel is in the midst of a nine-month conversion and is expected to begin service in March 1996. The vessel is being modified with the TAO support mission as her primary task and she is expected to be dedicated solely to that effort for the foreseeable future.

At the last TAO Panel meeting, Panel members and meeting attendees sent a letter to Dr. D. James Baker, NOAA Administrator, supporting a proposal to name the vessel in honor of the late Dr. Stan Hayes. Subsequently, a petition to name the ship S.P. Hayes was signed by 175 participants of the final TOGA conference in Melbourne, Australia in April 1995. Unfortunately, this support was not enough, and the vessel has been named Ka'imimoana, a Hawaiian term meaning "The Ocean Seeker".

TAO Array Annual Operating Plan. A review of mooring work accomplished and support of the Array since TIP-3 was presented. For the period October 1994 through September 1995, JAMSTEC provided 49 days at sea to support the TAO Array, Taiwan's National Science Council provided 44 days, and NOAA contributed 209 days.

It was shown that while the TAO moorings is the eastern and central Pacific were generally replaced at 12 month intervals, this average rises in the western Pacific as cruise tracks are often unable to reach various outlying mooring locations. This has led to some moorings remaining in place beyond their design lifetime (12 months for ATLAS and subsurface ADCP moorings; 6 months for PROTEUS moorings) resulting in lost data and sometimes lost equipment due to failed moorings. More importantly, when the western Pacific vandalism problem is factored in, a much lower data return rate results compared to the eastern and central Pacific.

Looking ahead to the next year, there are firm commitments to provide 223 sea days in the eastern and central Pacific from NOAA, 4 days (as a part of a JGOFS cruise) to maintain the 180ø line from France (ORSTOM), and 21 days for a February 1996 cruise from JAMSTEC. It is anticipated that JAMSTEC will continue to provide two cruises per year, with a second cruise aboard R/V Kaiyo planned tentatively for the boreal summer. Furthermore, Dr. Tang is confident that a mooring cruise can be arranged through Taiwan's National Science Council on one of their available research vessels.

Combating Vandalism. At last year's meeting, Dr. Sangbok Hahn of the Korean Fisheries Research and Development Agency provided valuable insights into the issues of fisheries interference with the TAO Array and the vandalism problem. Since that time, the TAO Project Office has developed an informational brochure written for the fishing industry operating in the equatorial Pacific. Preliminary copies of the brochure were distributed to Panel members and meeting attendees for comments. We also asked certain Panel members to translate the text of the brochure into different languages prevalent throughout the equatorial Pacific fishery. It is planned that the translated versions of the brochure will be mass produced along with English versions and distributed to fishing associations and organizations.

Panel members were asked to assist in this effort by learning more about potential audiences for this brochure in their countries.

In addition to the brochure, articles describing the TAO Array and its benefits to fishermen were submitted to "Fishing News International" and the South Pacific Commission's "Fisheries Newsletter." These articles are expected to appear in print soon.

Data Dissemination over the Global Telecommunications System (GTS). TAO data continues to be relayed in real-time through the Service Argos to operational centers around the world via the Global Telecommunications System (GTS). Recent statistics suggest that more than 90% of the TAO data made available is being inserted onto the GTS on a daily basis. Routine monitoring of the data flow to various operational centers is ongoing at the NOAA/National Ocean Service/Observing Networks Branch. In this way, problems can be addressed as they occur, eliminating long data gaps to operational centers.

Velocity measurements. PMEL has maintained PROTEUS moorings at three sites along the equator (110°W, 140°W, and 165°E). JAMSTEC maintains a subsurface ADCP mooring at the 0°,147°E TAO site; and the University of South Florida (USF) maintains a subsurface mooring at 0°,170°W. Problems which have plagued the PROTEUS surface moorings are vandalism in the western Pacific and fish bias problems in the eastern Pacific. Schools of fish congregate near the surface moorings and bias the ADCP speed measurements to lower values. A technical report (Plimpton et al., 1995) is available describing this effect and the corrections that are made to the ADCP data. Corrections applied can be up to 50% of the actual current speed.

In view of these continued problems, PMEL will switch to subsurface ADCP moorings at each of the three sites it maintains. An upward looking ADCP will be mounted in a float at depths of 250 - 300 m depending on site. These subsurface moorings, the first two of which were deployed in September 1995 at 0°,110°W and 0°,140°W, have a design lifetime of one year. Traditional current meter moorings will be located nearby to provide backup, internally recorded mechanical current meter measurements at few depths as well as velocity measurements near the surface where the ADCP data are contaminated by surface reflections. The subsurface mooring data will not be available in real-time. However, data collected in delayed mode will be of increased quality and quantity: neither fish nor fishermen will find the subsurface moorings since biological productivity and food supply are concentrated near the surface.

Salinity Monitoring. A plan was presented at TIP-3 (q.v. Koehn et al, 1995) for an enhanced western Pacific salinity monitoring array utilizing a pool of SEACAT temperature/salinity recorders provided by ORSTOM in Noumea, University of Hawaii, and PMEL. During the first year of the project, 45 SEACATs were deployed at 10 TAO sites along 156°E and 165°E, with 10 SEACATs on each of the equatorial moorings, 5- 6 on the 2°N and 2°S moorings, and 1 surface SEACAT at 5°N and 5°S. SEACAT data are not transmitted in real-time except for surface measurements on the equatorial moorings, so for the most part data are only available after the instrument is recovered.

This past year was not successful for the salinity monitoring program. A total of 34 SEACATs were lost on 4 separate moorings due to a combination of mooring failure and fishing vandalism. Two heavily instrumented PROTEUS moorings were lost at 0°,165°E with a total of 20 SEACATs. One had already been deployed for nearly 12 months (twice the mooring design time) before it was lost. Additionally, an ATLAS mooring at 2°N,156°E stopped transmitting 14 months after deployment and was not found by the Kaiyo in July 1995. The last mooring lost was at 0°,156°E which had the surface buoy cut free from the mooring line by a visiting boat. The drifting surface buoy with one SEACAT on the bridle was recovered by the Ocean Researcher I but the bottom part of the mooring with 9 SEACATs was lost. In view of these losses, the need for University of Hawaii SEACATs in other programs, and the prospect of future losses due to fishing activity, a revised salinity monitoring network has been proposed (Figure 4). This network consists of 24 SEACATs deployed on 16 moorings. Surface coverage is extended zonally to the dateline, and subsurface monitoring is reduced to only 1 mooring (0°,165°E) where long subsurface time series extend back to 1988. SEACATs at 1 m are already in place at 14 sites and the last two sites will be instrumented by December 1995. Next generation ATLAS moorings with low-cost conductivity sensors (see below) will allow real-time transmissions of up to 4 subsurface conductivities, allowing for expansion of the salinity subsurface array as these moorings become operational.

Rainfall. Since the end of the TOGA-COARE experiment, PMEL has maintained 4 sites with optical rain gauges (ORG) in the western Pacific (Figure 4). Hourly rainfall rates are transmitted to shore in real-time. A best estimate at present for ORG accuracy is ñ30% as delivered from the manufacturer, although this uncertainty can be reduced (to perhaps ñ10%) by calibration in natural rain before deployment. Hence, PMEL established a rain gauge calibration facility during the past year in the Olympic Rain Forest on the coast of Washington. Besides ORGs, testing and calibration of RM Young capacitance rain gauges is underway, and a distrometer will be added to the suit of gauges in 1996.

SST Measurements. The optimal depth for SST sensors on the TAO moorings was discussed during the past year via e-mail correspondence. There can be a large temperature gradient close to the surface during light winds, particularly in the western Pacific. Hence, bulk SST measurements at a nominal depth of 1 m may not be representative of the surface at all times (even if skin temperature effects are taken into account). Nonetheless, for continuity with previous SST measurements, standard TAO SST sensors will continue to be located at 1 m depth. In addition, an internally recording Mini-Temperature Recorder (MTR) has been deployed at 0°,165°E at 0.6 m depth (shallowest possible with present buoy configuration) to further investigate the magnitude and variability in the near-surface temperature gradients in the warm pool.

Next Generation ATLAS. Development and testing of the next generation ATLAS moorings has continued during the past year. Two moorings are presently deployed adjacent to traditional ATLAS moorings in the eastern Pacific. Although, there are still some sensor problems to be solved, preliminary results are very encouraging. The next generation moorings offer four real-time conductivities, more flexibility for additional sensors, higher resolution internally recorded data, and are much easier to construct and deploy. Surface meteorological variables (air, humidity, and winds) are sampled every 10 minutes for 2 minutes at 2 Hz and recorded internally. The most recent hourly average as well as the previous daily average are transmitted to shore in real-time via Service Argos. Ocean data including SST, 9 subsurface temperatures, 4 conductivities, and 3 subsurface pressures are spot-sampled every ten minutes. These data are recorded internally and the most recent daily average is transmitted to shore in real-time. Future plans will include 6 - 10 deployments of the next generation moorings in spring 1996.

Data Availability. Data from the TAO array is available through a variety of sources including GTS, anonymous FTP file transfer, World Wide Web, and the TAO Workstation software. The area of most growth during the past year was on
the TAO Web home page (http://www.pmel.noaa.gov/toga-tao/home.html),
the data delivery page (http://www.pmel.noaa.gov/toga-tao/data-delivery.html), and
the real-time display page (/tao/realtime.html).

References:

Plimpton, P.E., H.P. Freitag, and M.J. McPhaden, 1995: Correcting moored ADCP data for fish-bias errors att 0°, 110°W and 0°,140°W from 1990 to 1993. NOAA Technical Memorandum ERL PMEL-107, 49 pp.

Koehn, M., L.J. Mangum, and M.J. McPhaden, 1995: Proceeding of the third TOGA-TAO Implementation Panel Meeting, Seoul, South Korea, 18 20 October 1994, 61 pp.

The data from the shipboard ADCP and CTD observations of the July 1995 cruise show the enhancement of the New Guinea Coastal Under Current. The warm water accumulated over the equatorial western Pacific indicates a return to normal conditions in the context of ENSO.

The buoy network project of JAMSTEC is progressing. However, the total number of buoys was reduced to 21 from 35, due to budgetary limitations.

A new research vessel (R/V Mutsu) will be launched in October 1997 and one of its major missions will be to maintain the newly developed mooring buoy network. The present development schedule is as follows:
FY 1995: Basic design and field test of a prototype mooring in February 1996.
FY 1996: A new mooring system design will be completed. One complete mooring will be constructed. International workshop for the buoy network will be held in 29 31 May 1996 in Mutsu City before the CLIVAR SSG in Sapporo, Japan.
FY 1997: The new research vessel will be launched. The deployment of the buoy network will begin in early 1998.
FY 1998: Thirteen moorings will be in operation.
FY 1999: Twenty one moorings will be in operation.

This buoy array, designed to obtain long term data for research, will begin with deployment in the western tropical Pacific in conjunction with the TAO array and expand over the Indian Ocean and Pacific mid/higher latitudes. JAMSTEC will start a comprehensive research program (triangle) for ocean climate studies including ENSO, Monsoonal and decadal scale variability, and in which the new research vessel and the buoy array will be involved.

The Hidaka Ocean Science Foundation has recently been established to promote ocean science to be conducted on the R/V Mutsu. The foundation plans to develop a mass spectrometer, to be used to study geochemical cycles in the ocean. The main laboratory is located at Mutsu City in the northern part of Honshu Island.

The Korean Ocean Research and Development Institute (KORDI) continues its interests in open ocean observations, especially in the Western Pacific region. Unfortunately, KORDI's long-term science plan has been rejected again this year by the approving agency. However, the plan has a very high possibility of being funded under newly appointed KORDI leadership. Furthermore, there is a group of scientists who want to create a national CLIVAR committee to stimulate climate related studies in Korea.

The second cruise was from August 28 to September 9, performed by R/V Fishery Researcher I. One buoy was repaired and three buoys were re-deployed. No mooring recoveries were accomplished because of buoys that drifted off station. The work at one proposed site was canceled due to the limited ship time. The inoperative CTD on Fishery Researcher I was replaced by a SEACAT unit for hydrographic measurements. A joint NTU/PMEL cruise report will be issued soon.

Presently, our scientific research is mainly concentrated on the analysis of TOGA-COARE data, such as Hsu's (1994) study of the interannual variability on the relationship between tropical heating and global circulation. The long-term current data on 0øN,170øW which was a part of NTU/USF joint work, was also studied. Preliminary results show that interannual variations of the Equatorial Undercurrent have a period longer than 7 years; and that the reversal of the South Equatorial Current at this location seems to be an indicator of the occurrence of El Nino. Further study and monitoring of these currents is ongoing.

Our national interest during the next 5 years will concentrate on the South China Sea Monsoon Experiment (SCSMEX), studying the East Asian Monsoon and its influence on Taiwan. Since the western tropical Pacific Ocean has large impact on the South China Sea, our national funding agency, National Science Council (NSC), would like to combine the TAO and SCSMEX investigations. Such integration would be of benefit to both programs.

References:

Hsu, H.-H., 1994: Relationship between tropical heating and global circulation: interannual variability. J. Geophys. Res., 99, 10,473 10,489.

Shiah, F.-K., S.-J. Ko, and K.-K. Liu, 1995: The dependency of bacterial consumption of glucose on inorganic nutrients in the western equatorial Pacific. Limnol. Oceanogr., submitted.

In order to replace the small and old R/V Andre Nizery, which for over a decade was based in Lome, Togo, ORSTOM has just launched the R/V Antea. The Antea is a catamaran of significant size (35 m long, 11.7 m wide) and will be based at first in Abidjan, Ivory Coast. It will be devoted to various research programs of the TOA (Terre Ocean Atmosphere) Department of ORSTOM, including the extensive PICOLO program. PICOLO will focus on the role of long tropical instability waves centered around 2°N 4°N, 10°W 20°W, in order to understand why there is high fishing activity in a region outside of the usual nutrient-rich areas. Two cruises a year in summer and winter will be conducted during the 1996 - 98 period. Discussions for expanding this program on a multinational level are underway. In any case, mooring deployments from this new research vessel are certainly feasible as part either of the PICOLO program or the more general French Atlantic CLIVAR program.

Several scientists from ORSTOM, LODYC/Paris and the University of Brest, have put together a science report, in order to develop a tropical Atlantic program, as part of the more general French CLIVAR program. Discussions will continue over the first half of 1996, and it is expected that the general CLIVAR program will be submitted to the PNEDC (Programme National d'Etudes de la Dynamique du Climat) science committee in Fall 1996. A project to install a pilot array of TAO moorings should be included in the tropical Atlantic program. Discussions about the preparation of a French GOOS program are continuing, and a group of experts for the climate module has been formed with J. Picaut serving as chairman. The TAO array, in the equatorial Pacific and eventually in the equatorial Atlantic and Indian Oceans, should be a milestone of this module, which at first will focus on interannual time scale variability. However, one might expect progress towards a well developed international GOOS program in the near future to be slow, knowing the financial difficulties of the developed countries which are taking the lead in this program.

Strategy for the cooperative western Pacific salinity monitoring project, originally supported by ORSTOM/Noumea, NOAA/PMEL, and the University of Hawaii was reviewed. With the loss of two heavily instrumented TAO moorings and a significant loss of SEACATs, emphasis will shift away from moorings with vertical arrays of SEACATs to primarily measurements of surface salinity. Also, due to the need of SEACATs for other programs, the University of Hawaii has decided to begin a phased withdrawal from this cooperative effort. However, effort will be continued by NOAA/PMEL and ORSTOM/Noumea, with three meridians instrumented in the western and central Pacific (156°E, 165°E, and 180°). A TAO salinity data bank will be maintained under the direction of Paul Freitag at NOAA/PMEL.

French scientists are regularly using TAO data for multiple purposes. ERS-1 winds were validated by the Space Oceanography Group at IFREMER/Brest. TAO winds were also used to improve tropical wind products produced jointly by NASA/GSFC and ORSTOM/Noumea. Output of the LODYC/Paris tropical Pacific ocean general circulation model has been compared to TAO current and temperature measurements. At ORSTOM/Noumea, TOPEX/POSEIDON sea level and derived surface currents are being validated with TAO data. Current measurements from the TAO moorings along the equator have been merged with circulation drifter data to construct a tropical Pacific near-surface velocity field for the period 1987 - 93. Studies of the importance of zonal currents in advecting the eastern edge of the warm pool during El Nino and La Nina episodes spanning 1986 to 1994 are also being conducted using velocity fields inferred from GEOSAT, TOPEX/POSEIDON, drifter data, and TAO near-surface current measurements. During the TOGA-COARE Enhanced Monitoring Phase, temperature measurements in the upper 20 m from about 30 French drifters were calibrated with the closest TAO moorings. Also during TOGA-COARE, sea surface salinity variations were studied from a combination of merchant ship and TAO measurements.

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