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Ahmadābād, India

Ganguly N.D.,St Xaviers College | Tzanis C.,Technological Educational Institute of Athens
Meteorological Applications

Stratosphere-troposphere Exchange (STE) is an important factor controlling the budget of ozone in the upper troposphere and lower stratosphere. Studies of STE events in India are so far restricted to co-ordinated campaigns, and measurements over longer periods are relatively scarce. In the light of this observation, this paper aims to identify the Indian latitudes most likely to be affected by STE, the frequency of occurrence of shallow and deep STE events, the depth up to which the ozone from the stratosphere descends into the troposphere during STE events and the resultant trend of ozone in the troposphere under the possible influence of STE over the 24 years from 1982 to 2006. In addition, a case study of the STE of ozone, which occurred during a cut-off low event at Athens, Greece, is presented in order to understand the parameters that may contribute to the evolution of these events. It is concluded that STE plays a minor role in the Indian tropospheric ozone budget. On the whole, the occurrence of STE events in India is found to increase with increase in latitude and occur more frequently during winter followed by summer. The occurrence of deep STE is higher at high latitudes while the occurrence of shallow STE is higher at low latitudes. © 2011 Royal Meteorological Society. Source

The contribution of transport processes to the observed ozone concentration following the 26 January 2001 and 7 March 2006 earthquakes in the Kutch region of Gujarat is presented. The analysis of back trajectories at different altitudes and vertical pressure velocities at the tropopause indicated the transport of ozone-rich air from higher latitudes in the tropospheric and lower stratospheric regions apart from stratospheric intrusion of ozone into the troposphere along the path of the back trajectory and its transport to the epicentre during these earthquakes. © 2011 Taylor & Francis. Source

Ganguly N.D.,St Xaviers College
International Journal of Remote Sensing

India's climate is changing gradually from one year to another. A significant increase in surface air temperature in different Indian regions was observed from 1998 onwards, which became all the more pronounced in 2009. Monthly mean maximum and minimum temperatures were higher than normal values over the whole of India, accompanied by a sharp increase in the duration and frequency of hot days and heatwave conditions. In the light of these observations the paper is aimed at investigating the spatial and temporal variation of air temperature at different altitudes and the interannual trend for different months over the Indian region for a period of 108 years from 1901 to 2008. It is observed that the variation in air temperature is not uniform at all places in India. The yearly mean air temperature for the period 1948-2008 exhibits an increasing trend at all atmospheric layers from the surface up to 10 km. The recently observed increase in surface air temperature and longer periods of heatwaves and hot days in India may be due to a higher occurrence of dust storms and forest fires and the influence of local factors, such as a sharp population growth accompanied by uncontrolled urbanization and rapid industrialization, resulting in high levels of pollution and imbalances in the regional climate. © 2011 Taylor & Francis. Source

Pant P.,Florida International University | Pant S.,St Xaviers College
Journal of Environmental Sciences

Research works in the recent past have revealed three major biodegradation processes leading to the degradation of trichloroethylene. Reductive dechlorination is an anaerobic process in which chlorinated ethenes are used as electron acceptors. On the other hand, cometabolism requires oxygen for enzymatic degradation of chlorinated ethenes, which however yields no benefit for the bacteria involved. The third process is direct oxidation under aerobic conditions whereby chlorinated ethenes are directly used as electron donors by microorganisms. This review presented the current research trend in understanding biodegradation mechanisms with regard to their field applications. All the techniques used are evaluated, with the focus being on various factors that influence the process and the outcome. © 2010 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Source

Ganguly N.D.,St Xaviers College
Journal of Atmospheric and Solar-Terrestrial Physics

A massive earthquake shook Nepal on 25 April 2015, with a moment magnitude of 7.9 Mw, its hypocenter at a depth of 10 km. Atmospheric changes that precede an earthquake might offer the hope of early warning and evacuation. Although the existence of such precursory signals is highly controversial, an attempt has been made to investigate the atmospheric changes from two months prior, to five months following this deadly earthquake. Aerosol optical depth (AOD) and columnar ozone were found to be higher by 40% and 6% respectively prior to the occurrence of the earthquake. The UV aerosol index (UVI), AOD and columnar NO2 increased, while columnar ozone and sea level pressure dropped following the earthquake. © 2016 Elsevier Ltd. Source

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