Current Science

K. S. Yajnik ¹

Affiliations
1 CSIR Fourth Paradigm Institute, Wind Tunnel Road, Bengaluru 560 037, IN

Abstract

Detection of small decadal-scale variation amidst larger variations on smaller timescales is carried out here by geometrical segregation rather than filtering. Sea surface temperature (SST) annual cycle is represented as a point in a 12-dimensional space and thermal history as a path connecting successive points. Drift of the domain of decadal variations in the state space is taken as a measure of change from one decade to another. Visualization of the path in the 12- dimensional space is achieved by projecting it on planes. A matrix transformation gives an orthogonal decomposition of the annual cycle resembling Fourier series. The specific problem investigated here is the response of the Northern, the Tropical and the Southern Oceanic Regions (NOR, 30°-90°N; TOR, 30°S-30°N; SOR, 90°-30°S) to global warming during 1951-2010. The results are based on the Extended Reconstructed Sea Surface Temperature version 4 (ERSSTv4) database. Several interesting findings are obtained. The decadal scale warming has a seasonal variation, the largest being in the NOR (~0.26°C to ~0.57°C), in 2001-10. The consequential change in the annual cycle is increase in the amplitude of the annual mode in addition to increase in the annual mean. Decade-on-decade SST increase has peaked first in the SOR in 1971-80, and last in the NOR in 2001-10.

Keywords

Normal Modes, Ocean Warming, Seasonal Cycle, Sea Surface Temperature, State Space Analysis.

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R. Sunder ¹, K. S. Yajnik ², R. Narasimha ³

Affiliations
1 BISS (P Ltd), Bengaluru 560 058, IN
2 CSIR-Fourth Paradigm Institute, Bengaluru 560 027, IN
3 Jawarhlal Nehru Centre for Advanced Scientific Research, Bengaluru 560 064, IN

Abstract

On 23 January 2019, the Indian scientific community lost Dr S. R. Valluri, former Director of the (then) National Aeronautical Laboratory (NAL) and Director- General (DG) of the Aeronautical Development Agency (ADA), Bengaluru. Seldom does an outstanding young researcher morph into an institutionbuilder, manager and formulator of administrative policy, whose legacy will continue to be cherished and admired by future generations. Most would agree that Valluri was indeed an exceptional leader. The few who may hesitate, would have to admire the resoluteness of a young engineering student who decided he would ‘go to the US for further studies, and return to head a research institution here’. As mentioned in his memoirs, that is precisely what young Valluri resolved to do into his third year as an engineering student of Banaras Hindu University (BHU), Varanasi.

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