PMEL Programs and Plans
Accomplishments in FY 99 and Plans for FY 00

Tropical Atmosphere-Oceans Program

The Tropical Atmosphere-Ocean (TAO) Array consists of approximately 70 deep-ocean moorings spanning the equatorial Pacific Ocean between 8N and 8S from 95W to 137E. The purpose of the array is to provide high quality, in-situ, real-time data in the equatorial Pacific Ocean for short-term climate studies, most notably those relating to the El Niño/Southern Oscillation (ENSO) phenomenon. The moored measurements consist primarily of surface winds, sea surface temperature, upper ocean temperature and currents, air temperature, and relative humidity. Data are telemetered in real time via Service Argos. A subset of these data is placed on the Global Telecommunications System (GTS) for distribution to operational centers where they are assimilated into weather and climate forecast models. The NOAA Ship Ka'imimoana, commissioned in 1996, is dedicated to servicing the array between 95W and 165E. The array is part of the operational ENSO Observing System, supported by NOAA's Office of Oceanic and Atmospheric Research.

Accomplishments in FY 99

Work at PMEL during the past year has included description and diagnosis of physical mechanisms responsible for the 1997-98 El Niño, which was among the strongest on record. This work has highlighted the importance of intraseasonal atmospheric forcing in affecting the amplitude and onset of the event. A cover story in Science magazine described the interplay between the physics, biology, and chemistry of the tropical Pacific during the 1997-98 El Niño using data from the TAO array, NOAA ships, and from spaceborne sensors. Other studies have examined the upper ocean mass, heat, momentum, and fresh water balances in the upper equatorial Pacific Ocean using TAO and related data sets. These studies have illustrated the complex mix of mechanisms that give rise to observed variability on a wide range of time scales (diurnal, intraseasonal, seasonal, and interannual) of relevance to climate.

In FY 99, refinements of the Next Generation ATLAS moorings continued, and the number of sites in the array instrumented with this new technology increased from 11 to 24. Moored bio-optical, nutrient and chemical sensors were maintained at a few sites in collaboration with the NOAA Ocean Atmosphere Carbon Exchange Studies (OACES) Program and the NASA SeaWifs (ocean color) satellite program. The TAO project also continued a short wave radiation measurement program in the western Pacific in collaboration with the US Department of Energy/Atmospheric Radiation Measurements (DOE/ARM) program, and an in situ rainfall and surface salinity measurement program with the NASA Tropical Rainfall Measuring Mission (TRMM) program. The TAO project also participated in two special field studies in FY 99, the DOE/ARM NAURU99 Experiment and the NASA/TRMM KWAJEX Experiment. Surface salinity measurements were maintained between 156E and the date line, supported in part by the French Institut de Recherche pour le Developement. Implementation of the Pilot Research Moored Array in the Tropical Atlantic (PIRATA) continued in collaboration with Brazil and France, with the array expanding from five to eleven sites. Two high latitude ATLAS moorings, transmitting via GOES, were successfully deployed in the North Pacific at Ocean Station PAPA (50N, 145W) and Station MOMMA (35N, 165W) as part of the National Ocean Partnership Program.

In all, TAO used 434 sea days on 7 ships from 5 countries to deploy 93 moorings. TAO personnel spent 932 person days at sea on cruises during this time.

Tropical Atmosphere-Oceans Program

Plans for FY 00

• Maintain the array as part of the ENSO Observing System in support of NOAA's Seasonal to Interannual Climate Prediction Program (SICPP), GOOS, GCOS, and CLIVAR.
• Transition the TAO array to the TAO/TRITON array, with TRITON moorings maintained by the Japan Science and Technology Center (JAMSTEC) west of 165E.
• Continue transition to Next Generation ATLAS moorings east of 165E; upgrade ATLAS moorings for real-time velocity, longwave radiation, and barometric pressure.
• Continue moored radiation, rainfall, bio-optical, chemical, and salinity measurements as part of collaborative studies.
• Expand and enhance the array in the eastern tropical Pacific along 95W in support of NOAA's Pan American Climate Studies (PACS)/Eastern Pacific Investigation of Climate Processes (EPIC).
• Conduct a special month-long land-based intercomparison study between ATLAS, TRITON, and WHOI/IMET moorings at Woods Hole Oceanographic Institute.
• Complete the PIRATA array in the tropical Atlantic (12 sites); expand and enhance PIRATA with new moorings in "hurricane alley" (10-20N).
• Conclude NOPP field program with recovery of moorings at Stations PAPA and MOMMA.
• Maintain and enhance on-line access to TAO data sets.
• Continue scientific analyses of TAO, PIRATA, and NOPP data, in conjunction with shipboard, satellite, historical, and model based data sets.