Decadal variability of the tropical Atlantic Ocean surface temperature in shipboard measurements and in a Global Ocean-atmosphere model
- Goddard Space Flight Center, Greenbelt, MD (United States)
- Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States)
Numerous analyses of relatively short (25-30 years in length) time series of the observed surface temperature of the tropical Atlantic Ocean have indicated the possible existence of decadal timescale variability. It was decided to search for such variability in 100-yr time series of sea surface temperature (SST) measured aboard ships and available in the recently published Global Ocean Surface Temperature Atlas (GOSTA). Fourier and singular spectrum analyses of the GOSTA SST time series averaged over 11 subregions, each approximately 1 x 10{sup 6}km{sup 2} in area, show that pronounced quasi-oscillatory decadal ({approximately}-20 yr) and multidecadal ({approximately}30-40 yr) timescale variability exists in the GOSTA dataset over the tropical Atlantic. Motivated by the above results, SST variability was investigated in a 200-yr integration of a global model of the coupled oceanic and atmospheric general circulations developed at the geophysical Fluid Dynamics Laboratory (GFDL). The second 100 yr of SST in the coupled model`s tropical Atlantic region were analyzed with a variety of techniques. Analyses of SST time series, averaged over approximately the same subregions as the GOSTA time series, showed that the GFDL SST anomalies also undergo pronounced quasi-oscillatory decadal and multidecadal variability but at somewhat shorter timescales than the GOSTA SST anomalies. Further analyses of the horizontal structures of the decadal timescale variability in the GFDL coupled model showed the existence of two types of variability in general agreement with results of the GOSTA SST time series analyses. One type, characterized by timescales between 8 and 11 yr, has high spatial coherence within each hemisphere but not between the two hemispheres of the tropical Atlantic. A second type, characterized by timescales between 12 and 20 yr, has high spatial coherence between the two hemispheres. 31 refs., 14 figs., 3 tabs.
- OSTI ID:
- 79387
- Journal Information:
- Journal of Climate, Vol. 8, Issue 2; Other Information: PBD: Feb 1995
- Country of Publication:
- United States
- Language:
- English
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