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TIP 6 National reports | |
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National reports United States
The locations of the present moorings in the TAO array are shown in Figure 2. In addition to the standard ATLAS moorings throughout the array, thirteen sites are instrumented with next generation ATLAS moorings. At three of these sites, reverse catenary next generation moorings were deployed nearby traditional ATLAS moorings for intercomparison. Long-term current measurements are being made at five sites along the equator; one site off the equator (8°N,125°W) was instrumented with a subsurface ADCP by PMEL in April 1997 for a one-year study in support of PACS. TAO Array Annual Operation Plan. Ship time support for the TAO array in calendar year 1997 is summarized in Figure 3 and the following table. During 1997, three ships were used in support of the array: the NOAA ship Ka'imimoana, JAMSTEC's research vessel Kaiyo, and Taiwan's research vessel Ocean Researcher. NOAA provided 252 days of ship time between 95°W and 165°E with JAMSTEC providing 65 days and Taiwan provided 9 days west of the date line. The new NOAA vessel Ron Brown also serviced one of the TAO moorings at 8°N, 125°W during a PACS cruise. In 1998, a major change will be the start of Japan's Mirai cruises in March 1998 to deploy TRITON moorings along 156E. In addition to 1998 TAO cruises on the Ka'imimoana, 30 days of time on the Ron Brown is anticipated.
Ship Time Summary
1997 1998
Western Pacific (137°E - 165°E)
Japan (Kaiyo) 65 63
Japan (Mirai) -- 26 (TRITON)
Taiwan (Fisheries Researcher) 9 ?
U.S. (Ka'imimoana) 15 15
TOTAL 89 104 (includes TRITON)
East Pacific (95°W - 180°W)
U.S. (Ka'imimoana) 237 207
U.S. (Ron Brown) -- 30
TOTAL 237 237
Maintenance Requirements.
The TAO array has specific scheduling and ship time requirements to ensure
continuity of the data and maintenance of equipment. Surface current meter
moorings require recovery/deployment every six months, whereas ATLAS and
subsurface ADCP moorings require recovery/deployment every twelve months.
All sites should be visited at least every six months to check the status
of the instruments, verify data quality, and make any necessary repairs.
Flexibility in cruise plans is necessary so as to allow for recovery of
drifting moorings or unscheduled repairs. On three cruises in 1997, the
Ka'imimoana diverted from their cruise track, twice to pick up ATLAS moorings
that were adrift and also once to recover a malfunctioning LODYC (France)
CARIOCA drifter near 110°W. Sufficient time must be build into schedules
to allow for unexpected problems with moorings, bad weather, and strong
currents.
Vandalism. Vandalism and damage caused by commercial vessels continue to be a significant problem which effect data return and instrument loss. Efforts continued in the past year to work with national and international fishing agencies to find solutions to the problems. Brochures were send to Latin American fishing boats and also to agencies in ten Pacific Rim countries for distribution to local fishing fleets. The TAO Operations Manager, CDR Tim Wright, attended the South Pacific Commission (SOPAC) meeting in Fiji in October 1997 along with JAMSTEC personnel to enlist the assistance of island nations in the region. Last year at TIP-5, the decision was made to call a moratorium at three sites in the western Pacific until progress has been made in combating vandalism. At 2°N, 147°E, the data return was below 40%, four out of eight moorings were lost, and the remaining four were damaged. At 5°N, 137°E, five out of five moorings were lost and no equipment has ever been recovered at that site. Similar problems were also seen in the short history of 7°N, 137°E, which has also proven to be a difficult site to service by the Kaiyo due to bad weather and cruise length restrictions. Two other sites being watched closely include 0°, 147°E and 2°N, 137°E where instrument damage and data return continue to be a problem. Velocity Measurements. PMEL continued to maintain Acoustic Doppler Current Meter moorings at three sites along the equator at 110°W, 140°W, and 170°W. Additional current measurements were made at 8°N, 125°W by PMEL during the past year as an enhancement to the PACS program. Each subsurface ADCP mooring is deployed for one year. JAMSTEC continued to maintain a subsurface ADCP mooring 0°, 147°E and also took over responsibility for the subsurface current mooring at 0, 165°E as discussed in the proceedings from TIP-5. Processing has been recently completed for all of PMEL's ADCP data recovered during the past year and these are available on the TAO Web data delivery page. PMEL also continued to maintain traditional surface current meter moorings at 0°, 110°W; 0°, 140°W; and 0°, 165°E. Salinity Monitoring. At the TIP-4 meeting in September 1995, a revised salinity monitoring plan was adopted for the western Pacific. During the past year, surface SEACATs were in place on 16 TAO moorings between 156°E and 180°W. Instrumentation was provided by ORSTOM and PMEL. Data return from the past year was 85%. These data are being quality-controlled and should be available in early 1998 on the Web. It is planned to continue these surface salinity measurements during the next year. Next Generation ATLAS Moorings. Next generation ATLAS moorings use inductive coupling technology to transmit the subsurface data to the surface electronics package, eliminating the need for the thermistor cable. These moorings are described in Milburn et al. (1996). Standard sensors on the next generation ATLAS buoys include wind speed and direction, air temperature, relative humidity, sea surface temperature, ten subsurface temperatures and up to three subsurface pressures to monitor vertical excursions of the subsurface modules. Additional sensors such as conductivity, rainfall, and radiation can be added as special projects require. From the standard suite of sensors, the data that are available in real time consist of several values of the surface measurements updated hourly each day as well as the previous day's average of both the surface and subsurface data. Ten minute data is stored onboard for all sensors and will be available after the mooring is recovered. Daily-averaged conductivities can be transmitted in real time from four depths and ten minute samples are also stored in the sensor modules. An RM Young capacitance rain gauge can be interfaced to the data stream; one minute accumulations are stored onboard and the daily mean, standard deviation, maximum rate, and the percent time raining are transmitted back. Radiation measurements can be made using an Eppley PSP radiometer sampled at 1 Hz; 2 minute averages are stored and the transmitted data will consist of a daily mean, maximum, and standard deviation (computed for daylight hours). In support of the DOE/ARM program, four next generation ATLAS moorings with radiation sensors were deployed along 165°E in June 1997. The TRMM Project Office is supporting rainfall and surface salinity measurements on selected moorings, the first ones of which were also deployed in 1997. Two next generation ATLAS moorings were also deployed as part of PIRATA in the eastern Atlantic and one was deployed in the South China Sea as part of Taiwan's contribution to the SCSMEX experiment. There have been failures with the salinity sensors and PMEL is working with the manufacturer (Sea-Bird) to determine the cause of the problems. Next generation ATLAS moorings will continue to be phased into the TAO array during the next year as funding permits. Reference: Data Availability. TAO data continues to be available to the international community through anonymous FTP file transfer, the World Wide Web (http://www.pmel.noaa.gov/toga-tao/), and the GTS. New web pages were set up for SCSMEX, PIRATA, TRMM, and DOE/ARM to allow for display of the additional sensors funded by these programs. The TAO Project Office is working with Brazil and France to set up a mirror site for the PIRATA Web pages in each country. With the present El Niño event underway, information from TAO Web pages has been in great demand, with over three million hits each in September and October 1997. The TAO Project will continue to add new displays and data during the next year, including the high resolution data from the next generation ATLAS sensors (10-minute data) and special sensors (rain, radiation, salinity, and currents). An additional area of work during the upcoming year will be a detailed comparison of data from the TAO and TRITON moorings which are scheduled to be co-located along 156°E starting in March 1998. TAO personnel are working with JAMSTEC personnel to set up mirror Web sites in both Japan and at PMEL to coordinate data quality control and processing. The TAO Project Office continues to work closely with Service Argos and the Buoy Quality Control Network sponsored by the Data Buoy Coordination Panel to ensure high quality realtime GTS data. With a new NOAA satellite available through Service Argos, an approximate increase of 50% was seen the numbers of GTS hourly surface messages starting in late September 1997. During the month of October 1997, over 1800 subsurface temperature profiles and over 7000 surface observations were distributed on the GTS network. TAO Real-Time Data Monitoring: An Update. Our ability to sustain the long-term operation of components of the ocean observing system depends increasingly on our ability to document applications for the data and to quantify the usage and value of the data in those applications. Previous analyses of the use of TAO data in the global atmospheric models at NCEP indicated that only two-thirds of the real- time data available from the TAO array was being used. One third of the observations was not arriving in time at NCEP to be assimilated into their global system. Because the value and impact of the TAO observations (and other ocean observations) increases as more data is available, it is important to maximize the quantity, quality and timeliness of the real-time data. Consequently the NOAA GOOS Center at AOML is establishing a data tracking capability for the real-time TAO data pipeline. The availability and usage of the TAO observations will be routinely monitored and documented in an effort aimed at maximizing their use and value in the NCEP global models. Results from these monitoring activities will be reported at subsequent TIP meetings. Japan(M. Hishida and Y. Kuroda, JAMSTEC) Summary of Frontier Research Program (FRP) for Global Change:
Activities of TOCS and TRITON at JAMSTEC. Tropical Ocean Climate Study (TOCS): JAMSTEC begun the Tropical Ocean Climate Study (TOCS) program in 1993 which continued work began in JAPACS (Japanese Pacific Climate Study, 1987 - 1993). The objective of TOCS is to achieve the better understanding of ocean circulation in the warm pool and its relationship to the ENSO phenomena and global climate change.
FY 1996: A new mooring system design was completed. One complete prototype TRITON mooring was constructed and two sea trials near Ogasawara Islands were completed. International workshop for the buoy network was held in May 1997 in Mutsu city. TRITON program was acknowledged as one of CLIVAR's observational systems at CLIVAR SSG held in June 1997 in Sapporo. FY 1997: JAMSTEC started the operation of R/V Mirai beginning in October 1997. Third sea trial of the prototype buoy was conducted in October 1997 at 37.5°E,152°E (east of Japan). Buoy sensor calibration system and buoy maintenance facilities were completed and equipped in a new buoy maintenance building at JAMSTEC Mutsu-Branch at the home port of R/V Mirai. The TRITON buoy data processing and buoy parts management software has been installed in the buoy maintenance building. TAO/TRITON data integration and distribution software will be completed by PMEL in February 1998. The TRITON buoy deployments will start in March 1998 by R/V Mirai at the four sites of (8°N,156°E), (5°N,156°E), (2°N,156°E), and (0°,156°E) where intercomparison between ATLAS and TRITON buoys will be carried out. JAMSTEC started a new collaboration program with BPPT (Indonesia) on climate studies with an emphasis on buoy network. JAMSTEC also started to discuss with SOPAC and FFA how to advertise and provide education regarding the TRITON buoy program to fishermen, in order to avoid conflict with fishing activities in the western tropical Pacific. FY 1998: Four TRITON buoys will be constructed and four sites will be in operation. FY 1999: Nine sites will be in operation. FY 2000: Thirteen sites will be in operation. FY 2001: Fifteen sites will be in operation. FY 2002: Eighteen sites will be in operation. The TRITON buoy array will be started in the western tropical Pacific harmonized with the TAO array and will later be expanded to the Indian Ocean and mid/higher latitudes. JAMSTEC has already prepared basic facilities to maintain TRITON buoys and some technical staff are employed. The deployment plan, however, has been lengthened because of the difficult financial status in Japan. We need further international support and cooperation to develop and accelerate the TRITON program. Taiwan (D. Tang, National Taiwan University) In the past year, Taiwan has put most effort into the study of ocean variability in South China Sea (SCS). To monitor the upper ocean thermal variation in the SCS, an ATLAS mooring was deployed at 115.6°E, 18.1°N. It was the first time that an ATLAS mooring was deployed at such high latitude in the western Pacific. Generally speaking, the mooring worked well and survived at least through two typhoons. The wind sensor is presently not working due to a hardware problem. The data are transmitted daily back to PMEL and then to NTU, and is available to the general community. The hourly data will be available after the mooring is recovered in April 1998. Six current meter
moorings, including four self-contained Acoustic Doppler Current Profilers
(SC-ADCP), were deployed in the northern SCS, mainly in the Luzon Strait.
The new measurements showed quite different features from the early studies
which mostly were based upon the ship observations and numerical model
results. Since the SCS is a nearly closed basin, the early studies showed
that the water circulation was relatively simple. It was mainly driven
by the monsoon which was southwesterly (northeasterly) in summer (winter),
respectively. The Luzon Strait is the main channel connecting the SCS
and Pacific Ocean. The early studies showed that the Kuroshio water intruded
into the northern SCS in winter and the SCS water flowed out to the Pacific
Ocean in summer. The intruded water did not have much effect on the SCS
mainly owing to the insufficient amount of volume transport. Unfortunately,
these studies are not supported by the current measurements. The new data
shows that Kuroshio current consistently intrudes into the northern SCS.
The seasonal variation of current velocity is unclear. The estimated volume
transport of intrusion is around 8 Sv. This large amount intruded water
should have a significant impact at least on the circulation of northern
SCS where the circulation may not be dominated only by the monsoon. Moreover,
the data itself is interesting. The observed maximum speed at 1000 m was
around 100 cm s Taiwan also provided assistance for maintaining the TAO array in the western tropical Pacific Ocean last year. From Guam to Taiwan during September 1997, the Fishery Researcher I recovered one and deployed two ATLAS moorings. Taiwan will continue to provide the necessary assistance to TAO array. India(P. Kumar, NIO) JGOFS India Arabian Sea Process Study and Current Observational Programmes in the Indian Ocean JGOFS Arabian Sea Study: Under the Indian JGOFS program, extensive multi-disciplinary field measurements were carried out in the central and eastern Arabian Sea to understand how closely the chemical and biological changes are coupled to the physical forcing. The field measurements started in 1994 and lasted until February 1997, during which two cruises were held during winter (February 1995 and 1997) and during summer (1995 and 1996; July - August) and one during the inter-monsoon (April - May). These cruises were carried out onboard Indian research vessel R/V Sagar Kanya. These measurements provided some interesting new insight into the tight coupling between the physical forcing and chemical/biological response during the winter and summer monsoon. During the summer monsoon (June - September), high biological production was observed in the interior Arabian Sea away from the coastal upwelling zones of Somalia and Arabia. The nutrients which supported the observed high production and biomass resulted from physical processes. Physical data suggested that the lateral advection of fluid in the Ekman layer transports the nutrient rich upwelled waters of Somalia into the interior Arabian Sea which supports the observed high production in the southern regions. In the north, a combination of lateral advection from the Arabian coast as well as upward Ekman pumping, under the influence of cyclonic wind stress curl north of the Findlater Jet, is responsible for the high pigment concentrations. During the winter monsoon (November - February), a combination of reduced solar insolation and enhanced evaporation under the influence of dry continental air brought into the northern Arabian sea by the north-east trade cools the upper layers. Accordingly, the northern Arabian Sea (north of 15°N), experiences densification and convective mixing, which in turn result in the injection of nutrients from the thermocline region. This nutrient availability into the nutrient depleted upper layers triggers winter bloom. Thus the Indian JGOFS measurement programme revises our conventional picture of Arabian Sea productivity which stated that a tropical ocean is always nutrient limited, and gives us some new insight into the close coupling between the physical forcing and chemical and biological responses. Present and Planned Observational Programmes in the Indian Ocean: Considering the importance of the eastern Indian Ocean to climatically critical ocean-atmospheric interaction, a number of observational programmes are in future plan to monitor this region. To start with, as a part of the National Data Buoy Programme, four buoys (Norwegian) are deployed in the Bay of Bengal, measuring the wind speed and direction, air and water temperature, conductivity, wave height and direction, and current speed and direction. These buoys are equipped with global positioning system and communicate with the shore station through Inmarsat-C. Six such buoys are also planned for deployment in the Arabian Sea. As with the Arabian Sea JGOFS study, a Bay of Bengal Process study is planned during 1998-99 and would last for three years during which extensive water column and surface meteorological measurements will be carried out on five cruises. As a part of the Acoustic Thermometry and Ocean Climate (ATOC) program, there are plans to deploy acoustic receivers in the Bay of Bengal. Under the Indian Climate Research Programme (ICRP) as a part of the ocean component, two ATLAS type moorings are projected to be deployed in the eastern equatorial Indian Ocean and the proposal is now with the Department of Science & Technology (DST) for funding consideration. If accepted, it will start off by the year 1999 - 2000. France J. Picaut, ORSTOM and NASA/GSFC Since the disappearance of a permanent R/V at Noumea in 1993, the maintenance of the TAO array in the Pacific by France was done through the occasional venues of a French R/V in the Pacific. This was possible in 1994 and 1996 and it is very likely that the R/V L'Atalante will return in the Pacific in 1999. Nevertheless, the permanent contribution of France in TAO since 1993 is through the contribution of two dozen of SEACAT thermosalinographs to a pool of instruments handled by NOAA/PMEL, in order to monitor near-surface salinity in the western equatorial Pacific. Over the last years, the ORSTOM and NOAA pool of thermosalinographs has decreased by 40% with the loss of several moorings, and it is expected that the new generation of ATLAS will ensure the continuation, development and, most of all, the data transmission in real time (something not possible with the present thermosalinographs) of near surface salinity in the western equatorial Pacific. Together with the data provided by the ORSTOM-Noumea sea surface salinity merchant ship network, these salinity measurements appear more and more important for understanding the warm pool climate system (see for example section 6.8). However the French participation in TAO has taken a more global turn since 1997 with the installation of the first PIRATA moorings in the tropical Atlantic, as part of a pilot experiment handled by Brazil, U.S. and France (see PIRATA report in section 5.1). In the same way as the preliminary TOGA-TAO array in the Pacific (installed in 1985 - 88 by NOAA/PMEL and ORSTOM-Noumea), this pilot array in the tropical Atlantic should be part of a global TAO observing system over the three tropical oceans in the first years of the second millennium. As stated in the TIP-5 report, the French CLIVAR/GOALS program is building up, with in particular the continuation of the modeling effort in the tropical Pacific and of the XBT and surface salinity merchant networks from ORSTOM-Noumea. However, after being somewhat neglected during the 10 years of TOGA, the tropical Atlantic Ocean will be the focus of several French modeling and field programs, associated in particular with PIRATA. As shown in section 6.3, the French meteorologists are using the TAO data. With the coupling of the OPA/LODYC OGCM with the Meteo-France ARPEGE AGCM, TAO appears useful in testing the behavior of the coupled system. Process studies from several versions of the OPA OGCM, such as the formation of the barrier layer in the Pacific warm pool, are helped tremendously by the use of TAO data. Other research groups in France are using TAO data, like the Groupe de Meteorologie a Moyenne Echelle at Meteo-France for their own TOGA-COARE research, the Space Oceanographic group at IFREMER for extracting winds from the ERS-1/2 satellites, and the JGOFS group for their analyses of two recent cruises in the equatorial Pacific. Within the ORSTOM Pacific Ocean SURTROPAC group (now spilt in half between Noumea and Toulouse), TAO is used extensively in order to improve the assimilation of TOPEX/Poseidon data in the Gent & Cane model, through a reduce Kalman filter. The combination of salinity measurements from the TAO array of SEACATs and the ORSTOM merchant ship network appears very useful for understanding the behavior of the displacement of the eastern edge of the warm pool during ENSO. Most of all, the TAO data was proved important for the recent discovery of an oceanic zone of convergence on this edge which led to a new concept for the oscillatory nature of ENSO. |
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