Jyoti Bhate

Analysis of variability and trends of extreme rainfall events over India using 104 years of gridded daily rainfall data

In this study, using 104 years (1901-2004) of high resolution daily gridded rainfall data, variability and long-term trends of extreme rainfall events over central India have been examined. Frequency of extreme rainfall events shows significant inter-annual and inter-decadal variations in addition to a statistically significant long term trend of 6% per decade. Detailed analysis shows that inter-annual, inter-decadal and long-term trends of extreme rainfall events are modulated by the SST variations over the tropical Indian Ocean. The present study supports the hypothesis that the increasing trend of extreme rainfall events in the last five decades could be associated with the increasing trend of sea surface temperatures and surface latent heat flux over the tropical Indian Ocean. In the global warming scenario, the coherent relationship between Indian Ocean SST and extreme rainfall events suggests an increase in the risk of major floods over central India.

Correction to “Analysis of variability and trends of extreme rainfall events over India using 104 years of gridded daily rainfall data”

[1] In this study, using 104 years (1901–2004) of high resolution daily gridded rainfall data, variability and long-term trends of extreme rainfall events over central India have been examined. Frequency of extreme rainfall events shows significant inter-annual and inter-decadal variations in addition to a statistically significant long term trend of 6% per decade. Detailed analysis shows that inter-annual, inter-decadal and long-term trends of extreme rainfall events are modulated by the SST variations over the tropical Indian Ocean. The present study supports the hypothesis that the increasing trend of extreme rainfall events in the last five decades could be associated with the increasing trend of sea surface temperatures and surface latent heat flux over the tropical Indian Ocean. In the global warming scenario, the coherent relationship between Indian Ocean SST and extreme rainfall events suggests an increase in the risk of major floods over central India. Citation: Rajeevan, M., J. Bhate, and A. K. Jaswal (2008), Analysis of variability and trends of extreme rainfall events over India using 104 years of gridded daily rainfall data, Geophys. Res. Lett., 35, L18707, doi:10.1029/2008GL035143.

Appraisal of recent theories to understand cyclogenesis pathways of tropical cyclone Madi (2013)

The present study aims to examine the new understanding of cyclogenesis by analyzing the genesis sequence of formation of a very severe cyclonic storm Madi (6–13 December 2013) that occurred over the Bay of Bengal. We have generated a high-resolution (18 km, 6 km, and 2 km) analysis using three-dimensional variational data assimilation technique and Weather Research and Forecasting model. The genesis sequence of Madi cyclone is analyzed using the concepts in the marsupial theory and other theories of tropical cyclone formation. Major results are as follows: the developed analysis is found useful for tracking the movement of westward moving parent disturbance from 15 days prior to the genesis; identifying developed pouch region in the Lagrangian frame of reference; understanding the evolution of the pouch and convection within the pouch region and for the study of intensification inside the pouch region. Also, large-scale priming of environment concurs with the hypotheses of the marsupial theory of tropical cyclogenesis. The analysis of dynamical and thermodynamical processes within the pouch region showed gradual moistening, uplifting of moisture, diabatic heating causing buoyant convection in the vorticity-rich environment followed by vortex tube stretching, development of convection, heavy precipitation, strengthening of lower level convergence, and hence spin-up during a day or two preceding the genesis of Madi cyclone. In general, it is concluded that intensification within pouch region during the cyclogenesis phase followed the marsupial paradigm and bottom-up mechanism.

BATAL: The Balloon Measurement Campaigns of the Asian Tropopause Aerosol Layer

AbstractWe describe and show results from a series of field campaigns that used balloonborne instruments launched from India and Saudi Arabia during the summers 2014–17 to study the nature, formati...