Sampling

All data collected from the KEO mooring are publicly available. Daily averaged surface and subsurface data from the KEO mooring are made available in near real-time. In addition, spot values of high resolution surface meteorological data transmitted opportunistically are also made available in near real-time. Higher resolution data are recorded onboard the mooring and are made available 6 months after sensor recovery. Sensor recovery is scheduled on an annual basis.

The table below describes the sampling schemes for the KEO moorings. Observation times in data files are assigned to the center of the averaging interval unless otherwise noted. For example, daily averages are computed starting at 0000 GMT and are assigned an observation "time stamp" of 1200 GMT.

KEO measures winds, air temperature, relative humidity, sea surface temperature and salinity (SST and SSS), and subsurface temperatures and salinity as well as rainfall, shortwave and longwave radiation. KEO will measure CO₂ beginning June 2005. KEO CO₂ data and metadata will be available through the PMEL CO₂time series web pages. Data from KEO will be available on the GTS network starting in June 2005.

[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.

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: 108°W to 140°W; 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°, 110°W and 0°, 140°W 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.

Serra, Y.L., P.A'Hearn, H.P. Freitag, and M.J. McPhaden, 2001: ATLAS self-siphoning rain gauge error estimates. J. Atmos. Ocean. Tech., 18, 1989-2002.

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.