U.S. Dept. of Commerce / NOAA / OAR / PMEL / Publications

Observations of Warm Water Volume Changes in the Equatorial Pacific and Their Relationship to El Niño and La Niña

C. S. Meinen1 and M. J. McPhaden2

1Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, Washington
2Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington, 98115

Journal of Climate, 13(20), 3551–3559 (2000).
Copyright ©2000 by the American Meteorological Society. Further electronic distribution is not allowed.

3. Data and methods

The gridded subsurface temperature dataset, prepared by Neville Smith's group at the Australian Bureau of Meteorology Research Centre (BMRC), provides subsurface temperature at 14 depth levels between the surface and 500 m on a 1° lat × 2° long grid at monthly intervals. It was created by an optimal interpolation technique, which combined hydrographic measurements with moored temperature measurements from the Tropical Atmosphere and Ocean (TAO) Array (McPhaden et al. 1998). The development and preparation of the BMRC dataset are discussed in Smith et al. (1991), Smith (1991), Meyers et al. (1991), and Smith (1995a,b). The time series spans from 1980 to the present. The depth of the main thermocline is estimated using the depth of the 20°C isotherm, Z20, which is found in the middle of the main thermocline throughout the region (Kessler 1990). The depth of Z20 is determined by interpolation of the gridded subsurface temperatures.

Two other measured quantities are used in this study: SST and zonal wind stress (x). The SST data used in this study come from Reynolds and Smith (1994, 1995). The gridded SST values represent a blending of satellite-based and in situ SST measurements on a 1° lat × 1° long grid at a weekly time interval. The x used here is derived from The Florida State University (FSU) pseudostress fields, which are gridded on a 2° lat × 2° long grid at a monthly time interval (Stricherz et al. 1992; Stricherz et al. 1997). The gridded winds represent a blending of ship measurements and data from moored buoys, such as the aforementioned TAO array. Pseudostress was converted to stress using a constant air density of 1.2 kg m-3 and a constant drag coefficient of 1.4 × 10-3.

Anomaly time series (Z20, x, SST) shown in this paper have had the mean seasonal cycle removed. They have also been filtered with a five-month running mean to emphasize interannual variability.


Return to previous section or go to next section

PMEL Outstanding Papers

PMEL Publications Search

PMEL Homepage