• VINAY KUMAR DADHWAL

      Articles written in Journal of Earth System Science

    • Analysis of carbon dioxide, water vapour and energy fluxes over an Indian teak mixed deciduous forest for winter and summer months using eddy covariance technique

      Chandra Shekhar Jha Kiran Chand Thumaty Suraj Reddy Rodda Ajit Sonakia Vinay Kumar Dadhwal

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      In the present study, we report initial results on analysis of carbon dioxide (CO2), water vapour (H2O), and energy fluxes (sensible and latent heat flux) over teak mixed deciduous forests of Madhya Pradesh, central India, during winter (November 2011 and January 2012) and summer (February–May 2012) seasons using eddy covariance flux tower datasets. During the study period, continuous fast response measurements of CO2, H2O and heat fluxes above the canopy were carried out at 10 Hz and averaged for 30 minutes. Concurrently, slow response measurements of meteorological parameters are also being carried out. Diurnal and seasonal variations of CO2, H2O and heat fluxes were analysed and correlated with the meteorological variables. The study showed strong influence of leaf off and on scenario on the CO2, H2O and energy fluxes due to prevalence of deciduous vegetation type in the study area. Maximum amount of CO2 was sequestered for photosynthesis during winter (monthly mean of −25 𝜇 mol/m2/s) compared to summer (monthly mean of −2 𝜇 mol/m2/s). Energy flux analysis (weekly mean) showed more energy being portioned into latent heat during winter (668 W/m2) and sensible heat during summer (718 W/m2).

    • Understanding the interactions between meteorological and soil moisture drought over Indian region

      PRABIR KUMAR DAS SUSHANT CHANDRA DILIP KUMAR DAS SUBRATA KUMAR MIDYA ARATI PAUL SOUMYA BANDYOPADHYAY VINAY KUMAR DADHWAL

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      The present study aims at analysing the relationship between meteorological and soil moisture droughts over different meteorological regions of India based on change-point, trends and probability analysis. The long term gridded standardized-precipitation-evapotranspiration-index (SPEI) and standardized-soil-moisture-index (SSMI) data during 1980–2015 were used to address the meteorological and soil-moisture drought, respectively. The significant changes in the time-series SPEI and SSMI data at different time-scales were estimated using Pettitt’s test. The variations in change-points among different time-scales of SSMI were much lower than SPEI, specifically in parts of NW and central India. The inter-annual variability of drought parameters, i.e., duration and magnitude, showed good agreement between meteorological and soil moisture droughts for mild drought conditions. However, under moderate drought conditions, the behaviour of meteorological and soil moisture drought was different, specifically over peninsular India. The trend analysis revealed that SSMI based drought occurrences were significantly decreasing over all the four meteorological regions, whereas in case of SPEI, significant trends were observed only over peninsular India for mild drought condition. The probability of occurrences of both meteorological and soil moisture droughts were higher over major parts of India in case of mild droughts, whereas the values were lower for moderate drought conditions.

      $\bf{Highlights}$

      $\bullet$The Pettitt’s change point analysis revealed that variations of the period of significant changes among different time scale SSMI was much lower comparison to SPEI.

      $\bullet$In major parts of the country, good agreement between SPEI and SSMI derived drought parameters, i.e., duration and magnitude, were observed for mild drought conditions. However, it was quite low in moderate drought conditions, more specifically over peninsular and central India.

      $\bullet$The trend analysis revealed that the soil moisture drought was decreasing during the study period. Similar observations were recorded in meteorological drought also, but with some increasing drought duration and magnitude in parts of NW and NE India.

      $\bullet$The probability of occurrences of both meteorological and soil moisture droughts were higher over major parts of India in case of mild droughts, whereas the values were lower for moderate drought conditions.

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