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On the Variability of Winds, Sea Surface Temperature, and Surface Layer Heat Content in the Western Equatorial Pacific

Michael J. McPhaden and Stanley P. Hayes

NOAA/Pacific Marine Environmental Laboratory, Seattle, Washington

Journal of Geophysical Research, 96, supplement, 3331-3342 (1991)
This paper is not subject to U.S. copyright. Published in 1991 by the American Geophysical Union.

Gallery of Figures and Tables

Fig. 1. (a) Average SST and (b) SST anomaly in the western tropical Pacific for December 1986 to October 1987, based on data from the National Meteorological Center [Reynolds, 1988]. Contour interval is 1C in Figure 1a, except that the 29.5C isotherm is shown as dashed curve. Contour interval in Figure 1b is 0.5C, with positive values shown as solid contours and negative values shown as dashed contours. Hatching in Figure 1b indicates regions of negative SST anomaly. The current meter mooring (solid square) and ATLAS moorings (solid diamonds) are also indicated.

Fig. 2. (a) Zonal and (b) meridional winds for December 13, 1986, to October 14, 1987, at 2N, 0 and 2S along 165E.

Fig. 3. Contours of daily averaged temperatures at 2S, 0, and 2N along 165E for December 13, 1986, to October 14, 1987. Contour interval is 2C, except that the 29C contour is shown as a dashed curve. Sensor depths are indicated on the left axis; 7 days of missing data are indicated by crosses.

Fig. 4. (a) Mean and (b) standard deviation of temperature between 2N and 2S, 165E for December 13, 1986 to April 16, 1987. Contour interval in Figure 4a is 2C (except for the 29C isotherm shown as a dashed line); contour interval in Figure 4b is 0.2C, with contours less than 1C dashed.

Fig. 5. (a) Temperature empirical orthogonal eigenfunctions (EOF) mode 1 and (b) mode 2 for the period December 13, 1986, to April 16, 1987. Percent variance explained by each EOF is indicated. Hatching indicates negative eigenvector values.

Fig. 6. Mode 1 wind EOFs for the period December 13, 1986, to April 16, 1987, in (a) the zonal direction and (b) the meridional direction. Percent variance explained by each EOF is indicated.

Fig. 7. Time series of daily averaged wind speed (|U|), zonal wind pseudostress (|U|U), wind pseudowork (|U|), SST, and temperature at 50 m (dashed curve) from the current meter mooring at 0, 165E for the period December 13, 1986, to October 14, 1987. Note that 50-m temperatures are off-scale frequently after August 1987 because the upper thermocline has risen to this depth by then (see Figure 3).

Table 1. Summary of means and standard deviations for wind speed, zonal wind pseudostress, pseudowork, and sea surface temperature from the current meter mooring at 0, 165E for the period from December 13, 1986, to October 14, 1987.

Fig. 8. Cross correlations between SST and wind speed, zonal wind pseudostress, and wind pseudowork. Cross correlation extrema (r) and the lag (in days) at which they occur are shown. In each case, the lag indicates that cold SST follows high winds by 1 day. The 95% confidence limits for the null hypothesis of uncorrelated variability are indicated by horizontal bars on the abscissa.

Fig. 9. Coherence and phase spectra for SST and wind speed, zonal wind pseudostress, and wind pseudowork at 0, 165E for the period December 13, 1986, to October 14, 1987. Positive phase indicates that high winds lead high SST, and negative phase indicates that high winds lead low SST. Horizontal lines superimposed on coherence estimates indicate 95% confidence limits for the null hypothesis of incoherent variability, based on five (15) frequency band averages at periods longer (shorter) than about 8 days.

Fig. 10. Coherence amplitude as a function of depth averaged over periods of approximately 3-8 days (encompassing 36-65 frequency bands depending on depth) for SST and wind speed, zonal wind pseudostress, and wind pseudowork at 0, 165E. The 95% confidence limits for the null hypothesis of incoherent variability are indicated by the dashed lines. Note that the temperature record lengths for this analysis were chosen such that the statistics were stationary; for example, the period June-October 1987 was excluded at 50 m and 75 m. Shown on the right are the mean temperature profile (solid curve) and the standard deviation of temperature variations at periods of approximately 3-8 days (dashed curve) for December 13, 1986, to October 14, 1987.

Fig. 11. Coherence amplitude as a function of depth averaged over periods of approximately 30-60 days (that is 4-6 frequency bands, depending on depth) for SST and wind speed, zonal wind pseudostress, and wind pseudowork at 0, 165E. The 95% confidence limits for the null hypothesis of incoherent variability are indicated by the dashed lines. Shown on the right are the mean temperature profile (solid curve) and the standard deviation of temperature variations at periods of approximately 30-60 days (dashed curve) for December 13, 1986, to October 14, 1987.

Fig. 12. Coherence amplitude and phase as a function of depth averaged over periods of approximately 3-8 days (encompassing 36-65 frequency bands, depending on depth) for SST and zonal wind pseudostress at 0, 165E. The 95% confidence limits for the null hypothesis of incoherent variability are indicated by the dashed curve.

Fig. 13. Time series of H/t for depth ranges of (a) 0-10 m for the period December 13, 1986, to July 20, 1987, and (b) 0-75 m for the period December 13, 1986, to May 31, 1987. The standard deviation of heat content variations () and cross correlation with wind speed at zero lag (r) are shown.

Fig. 14. Zonal velocity (u), meridional velocity (v), and time rate of change of temperature (T/T) at 50 m from December 13, 1986, to May 31, 1987, at 0, 165E. Daily averaged data are shown by thin curves and 15-day Hanning filtered data are shown by thick curves.


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