• C KALYANI DEVASANA

      Articles written in Journal of Earth System Science

    • Changing variability of sea surface temperature in the post-WWII era

      KIRIT S YAJNIK C KALYANI DEVASANA

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      Extraordinary multi-seasonal episodes like El Ninos of 1982–1983 and 1997–1998 and their widespread teleconnection effects have spurred varied investigations on the changes in sea surface temperature (SST) variability in the post-WWII period. Most of them have been region-specific. We investigate here change in the variance of SST anomaly (SSTA) in the world oceans from 1951–1980 to 1981–2010. Our search for quantitative patterns, in space and time, is aided by a new decomposition of SSTA annual cycle in three orthogonal components, one time-independent, one low frequency (LF, periods: 4–12 months) and one high frequency (HF, periods: 2–3 months). High SSTA variability occurs in small regions clustered near the equator, middle and high latitudes. Sixteen high variability regions (HVR) are identified on the basis of a threshold. Spread over nearly 10% of the ocean area, they occur in four clusters: two in the equatorial cluster, four each in the northern and the southern mid-latitude clusters and six in the Arctic cluster. We find that the plots of HVR-averaged and zonally averaged SSTA variance in 1951–1980 and 1981–2010 show a general tendency of decrease in SSTA variability south of ${\sim}$15$^{\circ}$S and increase north of ${\sim}$15$^{\circ}$S, and a consequential increase in north–south asymmetry. We further find that HVR-averaged HF variance and HVR-averaged LF variance are strongly correlated.

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