ESSO - Indian National Centre for Ocean Information Services
(An Autonomous Body under the Ministry of Earth Sciences, Govt. of India)
E-Publications
| Paper No | 1 | Publication ID : 540 & Year : 2015 |
| Title | Relation between the upper ocean heat content in the equatorial Atlantic during boreal spring and the Indian summer monsoon rainfall during June-September | |
| Authors | Vijay Pottapinjara, M. S. Girishkumar, M. Ravichandran, and R. Murtugudde | |
| Source | International Journal of Climatology
link to the article on the journal website Nature India highlights this article | |
| Abstract | Earlier studies have identified a teleconnection between the Atlantic Zonal Mode (AZM) and Indian Summer Monsoon Rainfall (ISMR), both of which are active during the boreal summer (AZM: June-August; ISMR: June-September). It is known that El Niño-Southern Oscillation (ENSO)-like coupled dynamics are operational in the tropical Atlantic during the AZM events. Our goal here is to extend this process understanding to seek a predictive relation between the tropical Atlantic and the ISMR based on these known teleconnections. Monthly composite analysis of the zonal surface winds, heat content, and SST in the equatorial Atlantic tells us that signatures of a warm or cold AZM event begin to emerge as early as January of that year. We found significant correlations between the ISMR and the low level zonal winds in the western equatorial Atlantic and heat content in the eastern equatorial Atlantic in the boreal spring season. Tracking coherent changes in these winds and the evolution of the heat content in the deep tropical Atlantic in the boreal spring may offer the potential for skillful predictions of the ensuing summer monsoon anomalies, especially during non-ENSO years when the predictability of ISMR tends to be low. | |
| Paper No | 2 | Publication ID : 505 & Year : 2014 |
| Title | Influence of the Atlantic Zonal mode on monsoon depressions in the Bay of Bengal during boreal summer | |
| Authors | Vijay Pottapinjara, M. S. Girishkumar, M. Ravichandran and R. Murtugudde | |
| Source | Journal of Geophysical Research - Atmosphere
link to the article on the journal website | |
| Abstract | The influence of the Atlantic Zonal Mode (AZM) or the Atlantic Nino on monsoon depressions in the Bay of Bengal during the boreal summer (June-August) is studied. Our analysis shows that there is a statistically significant difference in the number of monsoon depressions in the Bay of Bengal between the warm and cold phases of the AZM; more (fewer) monsoon depressions form during the cold (warm) phase of AZM. It also shows that there are differences in spatial pattern of trajectories of monsoon depressions; during the cold phase of AZM, the tracks are relatively long and seem to cluster along the axis of core monsoon region compared to the warm phase of AZM. The analysis indicates an increase (a reduction) in low-level cyclonic vorticity and mid-tropospheric humidity but a reduction (an increase) in vertical wind shear due to anomalous circulation pattern. All of these changes are favorable for the enhancement (suppression) of monsoon depressions during the cold (warm) phase of the AZM. Our analysis further shows a teleconnection pathway by which the AZM can influence the remote Indian Ocean. This could have implications for enhancing monsoon prediction skill, especially during non-ENSO years. | |
| Paper No | 3 | Publication ID : 484 & Year : 2011 |
| Title | Wavelength Dependence of the Polarization Singularities in a Two-Mode Optical Fiber | |
| Authors | V. V. G. Krishna Inavalli, Vijay Pottapinjara, and Nirmal K. Viswanathan | |
| Source | International Journal of Optics, vol. 2012, Article ID 358093, 7 pages, 2012. doi:10.1155/2012/358093
link to the article on the journal website | |
| Abstract | We present here an experimental demonstration of the wavelength dependence of the polarization singularities due to linear combination of the vector modes excited directly in a two-mode optical fiber. The coherent superposition of the vector modes excited by linearly polarized Gaussian beam as offset skew rays propagated in a helical path inside the fiber results in the generation of phase singular beams with edge dislocation in the fiber output. The polarization character of these beams is found to change dramatically with wavelength from left-handed elliptically polarized edge dislocation to right-handed elliptically polarized edge-dislocation through disclinations. The measured behaviour is understood as being due to intermodal dispersion of the polarization corrections to the propagating vector modes, as the wavelength of the input beam is scanned. | |