Data from the Tropical Moored Buoy Array is provided by multiple data collection systems.  The older "Next Generation ATLAS" systems have been replaced in TAO by NDBC's TAO Refresh system and are in the process of being replaced by PMEL's recently developed "T-Flex" systems in PIRATA and RAMA. Oldest  "Standard ATLAS" systems were previously replaced in TAO  by "Next Generations ATLAS" systems. JAMSTEC's TRITON moorings replaced some TAO moorings in the western Pacific and M-TRITON moorings are deployed at some RAMA sites.

Next Gen ATLAS systems provide near-real-time daily-averaged surface and subsurface data from ATLAS moorings as our standard product for climate research. Daily averages are computed starting at 0000UTC and are assigned an observation "time stamp" of 1200UTC. Higher resolution data are recorded onboard the moorings and are made available after mooring recoveries, which are scheduled on an annual basis. High resolution data from older ATLAS moorings prior to 1991 (Mangum et al., 1995) and Current Meter moorings through spring 1999 (Freitag et al., 1991) consisted of a variety of sampling and averaging periods.With the advent of the T-Flex moorings,  temporal resolution of internally recorded data has changed due to technological improvements and evolving scientific priorities.

The tables below describe the present sampling schemes for TFlex, Next Generation and Standard ATLAS moorings. Observation times in data files are assigned to the center of the averaging interval unless otherwise noted. Sampling details for TAO Refresh systems are available at at http://tao.ndbc.noaa.gov/proj_overview/sampling_ndbc.shtml . Sampling details for TRITON systems are available at http://www.jamstec.go.jp/jamstec/TRITON/real_time/overview/po-t4 . Sampling details for M-TRITON systems are available at http://www.jamstec.go.jp/iorgc/iomics/projectoverview/1_b4_eng.html.

Basic measurements on T-Flex and ATLAS moorings are wind, air temperature, relative humidity, SST, and 10 subsurface temperatures. Next Generation ATLAS and T-Flex moorings have the flexibility for additional sensors (rainfall, shortwave and longwave radiation, barometric pressure, salinity and ocean currents) All PIRATA and RAMA moorings include rainfall, shortwave and salinity sensors. Additional sensors are deployed at selected mooring sites often in collaboration with other research programs, e.g., OceanSITES. Basic data from ATLAS and T-Flex moorings are also available on the GTS network. . Basic and additional data from T-Flex moorings are also available on the GTS network.

T-Flex Sampling

Next Generation ATLAS Sampling

[1] To reduce instrumental noise, internally recorded 1-minute rain accumulation values are smoothed with a 16-minute Hanning filter upon recovery. These smoothed data are then differenced at 10-minute intervals and converted to rain rates in mm hr^-1. The resultant rain rate values are centered at times coincident with other 10-minute data (0000, 0010, 0020...). For further information see Serra et al (2001).

[2] To minimize spiking in the salinity record due to sensor response time mismatches, the internally recorded 10-minute conductivity and temperature values are smoothed with a 13-point Hanning filter and subsampled at hourly intervals. Salinities are calculated from the smoothed hourly conductivity and temperature values using the method of Fofonoff and Millard (1983). These hourly data constitute the high-resolution salinity time series in the data base. High-resolution temperatures are offered at their original 10-minute sampling increment.

Standard ATLAS Sampling

Subsurface ADCP Mooring Sampling

In addition to surface moorings, subsurface upward-looking ADCP (Acoustic Doppler Current Profiler) moorings are deployed along the equator within the TAO/TRITON and RAMA Arrays. TAO ADCP moorings originally maintained by PMEL and the University of South Florida (USF) are now maintained by NDBC and the Japan Agency for Marine-earth Science and Technology (JAMSTEC).  RAMA ADCP sites are maintained by PMEL and JAMSTEC.  Early TAO ADCP moorings were instrumented with RDI, Inc., narrowband profilers.  Later TAO/TRITON and all RAMA ADCP moorings are instrumented with RDI, Inc., broadband Long Ranger profilers.

Data from these moorings are available only after mooring recoveries, which are scheduled on a 1 to 2 year basis. The sampling scheme for ADCP moorings maintained by PMEL are listed below.

ADCP data from moorings maintained by PMEL have been corrected for variations in sound velocity. The ADCP nominal bin width and pulse length were set to 8m, resulting in a velocity measurement that represents a weighted average over a nominal 16m depth, sampled at approximately 8m-depth intervals. The data available here have been remapped by linear interpolation to 5m depth intervals. Daily average data are computed as an average of 0000 to 2300 hr, requiring a minimum of 6 good hourly values.

In contrast to the present upward-looking subsurface moorings, some downward-looking surface moorings were deployed in the past. ADCP data from these moorings (named PROTEUS) at 170W, 140W, and 110W were at times significantly biased due to the presence of fish near the moorings. Corrections to the 140W and 110W ADCP data have been made using coincident mechanical current meter data (Plimpton et al., 2000). Corrections to the 170W data have been made by analysis of the ADCP echo intensity (Plimpton et al., 1997). Corrections were made to daily mean velocity profiles only. Hourly data have not been corrected, but erroneous hourly values have been edited out of the original time series.

ADCP data from PROTEUS moorings at 0, 156E and 0, 165E did not appear to have significant bias due to fish.

PROTEUS moorings were deployed for the following time periods: May 1991 to August 1995 at 110W; May 1990 to September 1995 at 140W; April 1993 to March 1994 at 170W; March 1991 to January 1996 at 165E; August 1991 to March 1993 and April to December 1994 at 156E.

For details on the JAMSTEC data see Kutsuwada and Inaba (1995). For the USF data see Weisberg and Hayes (1995), and Plimpton et al. (1997). Sampling schemes from earlier generation TAO ADCP moorings can be found in Plimpton et al. (2000).

References:
Fofonoff, P., and R. C. Millard Jr.: Algorithms for computation of fundamental properties of seawater, Tech. Pap. Mar. Sci., 44, 53 pp., Unesco, Paris, 1983.

Freitag, H.P., M.J. McPhaden, C.S. Coho, and A.J. Shepherd (1991): Equatorial wind, current and temperature data: 108W to 140W; April 1983 to October 1987. NOAA Data Report ERL PMEL-35 (PB92-119817), 116 pp.

Kutsuwada, K. and H. Inaba, (1995): "Long-Range Measurement of Surface Oceanic Current in the Western Equatorial Pacific by Acoustic Doppler Current Profiler", J. of Meteor. Soc. of Japan, 73, No. 1, pp. 1-11, 1995.

Mangum, L.J., H.P. Freitag, and M.J. McPhaden (1995): TOGA TAO array sampling schemes and sensor evaluations. Proceedings, Oceans '94 OSATES, 13-16 September 1994, Parc de Penfeld, Brest, France, II-402-II-406.

Plimpton, P.E., H.P. Freitag, and M.J. McPhaden (2000): Correcting moored ADCP data for fish-bias errors at 0, 110W and 0, 140W from 1993 to 1995. NOAA Tech. Memo. OAR PMEL-117, 35 pp.

Plimpton, P.E., H.P Freitag, M.J McPhaden, and R.H. Weisberg, (1997): "Using echo intensity to correct moored ADCP data for fish-bias error at 0, 170W", NOAA Technical Memorandum ERL PMEL-111, 17pp.

Weisberg, R.H. and S.P. Hayes (1995): "Upper ocean variability on the equator in the west-central Pacific at 170W", J. Geophys. Res., 100, pp. 20485-20498.