Browsing by Author "Maurya, Archana"

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    Assessment of climate change of different meteorological state variables during Indian summer monsoon season
    (Springer, 2022) Bhatla, R.; Maurya, Archana; Sinha, Palash; Verma, Shruti; Pant, Manas
    Long-term assessment of basic meteorological field variability is an important factor that influences the Indian summer monsoon and consequently affects the socio-economic aspects of India. In this study, the spatial and temporal variation of meteorological parameters during summer monsoon season using NCEP/NCAR reanalysis datasets for the period of 70�years (1948�2017) has been analyzed in climatology, early-late phase and multidecadal epochs over India and its regions. Statistical techniques such as the standardized anomaly index of surface temperature, rainfall and zonal and meridional wind (at 850 and 200�hPa) and temporal analysis of Mann�Kendall trend test over six selected regions, viz., North India (NI), Central India (CI), Southern India (SI), Arabian Sea (AS), Bay of Bengal (BoB) and Equatorial Indian Ocean (EIO) reveal higher variability during summer monsoon season from 1948 to 2017. The significant spatial changes in the value of standard deviation and coefficient of variation confirm the early-late phase and multidecadal modulation of the seasonal variability of selected climatic parameters. The results indicate that the escalation in the surface temperature multidecadal variability and trend has dominating characteristics over NI, CI and SI regions at an alarming range (0.5�1.0�C). The major hotspots of increasing early-late phase and multidecadal variability and average precipitation have been found over BoB, EIO and SI (~1�3.5 mm/day). The decreasing changes in the mean rainfall pattern and associated variability is strongly linked with increasing surface warming and significant reduction in the strength of surface zonal wind over BoB, IO, SI and CI region which cause the weakening of important atmospheric circulations such as the role of Somali jet and strong low-level jet (LLJ) during Indian summer monsoon season. Also, the meridional wind at the surface and upper level has shown significant enhancement over AS and EIO. The recent decadal anomaly (2008�2017) is really a matter of concern as precipitation and wind circulation anomaly at 850 and 200�hPa have shown decreasing trends over all the regions. In recent years, the variation in meteorological parameters and distribution are asymmetrical during summer monsoon season in changing climate. � 2022, Indian Academy of Sciences.
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    Epochal Changes in the Intrinsic Nature/Dynamics of Flood and Drought During Indian Summer Monsoon
    (John Wiley and Sons Inc, 2023) Maurya, Archana; Verma, Shruti; Pant, Manas; Bhatla, R.
    The basic and derived meteorological parameters, are important factors that affect the epochal changes of monsoonal drought/flood events which consequently influence the socio-economic aspects of India. The anomalous tricade departure of parameters namely rainfall, surface pressure, surface temperature, zonal and meridional wind, cloud cover (CC), outgoing longwave radiation, latent heat flux (LHF), sensible heat flux, net incoming shortwave radiation flux and net heat flux (NHF) have been considered between past, and recent tricade respectively drought and flood events. An anomalous decrease (?3 to ?2�mm/d) in rainfall over the southern Arabian sea (AS), southern peninsular India and Bay of Bengal during past and recent tricade, on the other side increase (2�2.5�mm/d) in rainfall over the equatorial Indian ocean (EIO) during drought. The drought episode of the recent tricade is showing basin wise significant increase in LHF (20�30�W/m2) and decrease in NHF (?30 to ?60�W/m2) from the Somali coast to Indonesian region which is linked with changing oceanic processes linked with the Indian ocean warming. The comparison of past and recent monsoonal flood has shown decrease in the CC over EIO and AS region which supported anomalous highest departure in LHF (12�W/m2) over EIO. A direct association of dry and moist static energy variations have been found to be linked with the surface fluxes during Indian summer monsoon season. Further, epochal differences of vertically integrated moisture flux convergence is consistent with flood/drought rainfall anomaly. Thus, radiative imbalance also plays a secondary role in determining epochal nature of drought/flood variability and its nature. � 2023 The Authors. Earth and Space Science published by Wiley Periodicals LLC on behalf of American Geophysical Union.