Atmospheric and Climate Science Lab.
Extreme Weather Events and Atmospheric Chemistry
Coastal zone of India is vulnerable and highly-susceptible to extreme weather events, tropical cyclones (TCs) and storms. According to national disaster management authority (NDMA) out of 7516 km long coastline, about 5700 km is prone to cyclones and Tsunamis. The enhanced cyclonic activity derived by climate change over the north Indian Ocean increases the coastal hazards and vulnerability
. Colonialism and international trade increased the coastal population causing the cyclone losses to become enormous. So it is necessary to record the economic losses (to be normalised) and the role of atmospheric parameters to expose the temporal changes of damage for different cyclones.
The unique bimodal pattern of tropical cyclones with peaks is observed during the pre-monsoon and post-monsoon seasons. Our team researches the impact of extreme weather events and atmospheric chemistry with International Collabs such as European Centre for Medium-Range Weather Forecast (ECMWF), University of Reading and Indian Collabs such as Indian Institute of Tropical Meteorology (IITM) Pune, India Meteorological Department (IMD), National Institute of Ocean Technology (NIOT) and Indian National Centre for Ocean Information Services (INCOIS). The intraseasonal variabilities like Madden Jullian oscillation dominate the North Indian Ocean region during the post-monsoon season. There has been a substantial interannual variability in TC activity with a farrago of the trend in their frequency, period, Power Dissipation Index (PDI) and the Accumulated cyclone energy(ACE). The increased moisture in a warm climate modulates the intraseasonal variability (convective phase of MJO favours cyclogenesis) and alters the cyclonic activity and the spatial distribution. So it is crucial to study the variation of cyclonic activity over the NIO region caused by the MJO.
The greenhouse gases can trigger the moisture anomalies in convection in a warmer climate. This can alter the cyclonic activity that implies the necessity of including the study of the role of atmospheric constituents, which emphasises the influence of anthropogenic forcings that has a vital role in cyclogenesis and activity. El Nino Southern Oscillation (ENSO) also plays a crucial role in cyclones formation and intensity. The simultaneous occurrence of El Nino with Indian Ocean Dipole can positively influence the NIO cyclones (especially in the Arabian Sea) and exhibit a positive correlation with ACE.
Several man-made trace gases, accumulating in the Earth's atmosphere, may lead to global warming in the future or may cause a depletion of stratospheric ozone. Although increased amounts of individual trace gases may add little to the Earth's natural greenhouse effect, together they may rival the expected impact from the increasing levels of CO2. The primarily natural trace gases, N2O and CH4, now increasing because of human activities, are likely to add to the Earth's greenhouse effect. In the past decades, there has been an explosive increase in studies of the chemistry of the atmosphere. Many studies have shown that the chemical composition of the global atmosphere is far from constant. There is a discernible chemical ‘weather’, and ‘climate’ and the latter is changing.
Global atmospheric chemistry is at a relatively embryonic stage thus far. Much of the effort has been directed towards establishing an observational basis upon which a sound theoretical understanding of chemical weather and climate can be built. Without this framework, we will remain unable to assess the consequences of, or even distinguish between rationally, natural and human-made perturbations to the chemistry of the atmosphere or understand the instabilities that already exist. Parallel with this development is the significant upsurge of interest in the warming of the planet now expected with high probability due to the increase of the atmospheric levels of the so-called greenhouse gases. Such changes, although not the only environmental anticipated changes are likely to have far-reaching effects on society and the natural environment. Serious decisions are ahead as we strive to adapt to and avoid climatically induced change.