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An International Year of Planet Earth-2008 Initiative

Current Issue Technical

Year 2017

Volume X

1-1-2017
Process Form Responses of Shoreline Erosion Using Geo-Spatial Techniques: Case Study in Muriganga-Saptamukhi Interfluve, Sundarban
Abhishek Ghosh and Sutapa Mukhopadhyay
Abstract

The numerous tidal river systems have made Sundarban delta one of the most dynamic geomorphic regions of the world. Through time morphological shape and extent of shoreline and river bank configurations have changed considerably through intense erosional and depositional processes by the longshore current and tidal flow pattern in Sundarban. The present study has made an assessment of morpho-dynamic behavior of bank lines for the time-period between 1925-26 and 2014 to identify nature and extent of erosion and deposition of different geomorphic units through consultation and preparation of geo-spatial database comprised of old maps and recent satellite images. Besides, detailed field investigations have also been carried out to understand different processes regarding the bank line changes. Finally different erosion hazard zones have been identified based on the net areal changes.

Keywords: Bank line changes, Erosion hazard zones, Hydro-geomorphic units, Net areal change, Sundarban
1-2-2017
Lighting/Optical Discharges and Climate: A Brief Review
Devendraa Siingh1, Sanjay Kumar2, Upal Saha2, Abhay K. Singh2, R.P. Singh2 and Ashok K. Singh3* 1
Abstract

Lightning is a massive electrostatic discharge between the electrically charged regions within clouds or between a cloud and the Earth's surface. Present paper reviewed various features including generation mechanism of lightning discharges and many transient luminous events (TLEs). Optical discharges like sprites and halos are been caused by the upward developing quasi-electrostatic fields associated with intense cloud-to-ground discharges whereas jets (blue starters, blue jets, gigantic jets, palm tree) are caused by the charge imbalance in the thunderstorms during the intra-cloud and cloud-to-ground discharges and evolve through the process of leaders and streamers. Elves are been generated by the electromagnetic pulse radiated from the return stroke current of lightning discharges. The impact of atmospheric circulation, global electric circuits (GECs), NOx/O3 perturbations (in the troposphere and stratosphere) and aerosols on lightning discharges are discussed and their role on climate change are briefly described.

Keywords: Lightning/thunderstorm, Transient Luminous Events (TLEs), Global Electric Circuit, NOx/O3 perturbation, Aerosols and Climate, Streamers and Leaders