• Jai Singh Parihar

      Articles written in Journal of Earth System Science

    • Radiation and energy balance dynamics over young chir pine (Pinus roxburghii) system in Doon of western Himalayas

      Nilendu Singh Bimal K Bhattacharya M K Nanda Prafulla Soni Jai Singh Parihar

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      The regional impacts of future climate changes are principally driven by changes in energy fluxes. In this study, measurements on micrometeorological and biophysical variables along with surface energy exchange were made over a coniferous subtropical chir pine (Pinus roxburghii) plantation ecosystem at Forest Research Institute, Doon valley, India. The energy balance components were analyzed for two years to understand the variability of surface energy fluxes, their drivers, and closure pattern. The period covered two growth cycles of pine in the years 2010 and 2011 without and with understory growth. Net short wave and long wave radiative fluxes substantially varied with cloud dynamics, season, rainfall induced surface wetness, and green growth. The study clearly brought out the intimate link of albedo dynamics in chir pine system with dynamics of leaf area index (LAI), soil moisture, and changes in understory background. Rainfall was found to have tight linear coupling with latent heat fluxes. Latent heat flux during monsoon period was found to be higher in higher rainfall year (2010) than in lower rainfall year (2011). Higher or lower pre-monsoon sensible heat fluxes were succeeded by noticeably higher or lower monsoon rainfall respectively. Proportion of latent heat flux to net radiation typically followed the growth curve of green vegetation fraction, but with time lag. The analysis of energy balance closure (EBC) showed that the residual energy varied largely within ±30% of net available energy and the non-closure periods were marked by higher rainspells or forced clearance of understory growths.

    • Trend analysis of evapotranspiration over India: Observed from long-term satellite measurements

      Sheshakumar Goroshi Rohit Pradhan Raghavendra P Singh K K Singh Jai Singh Parihar

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      Owing to the lack of consistent spatial time series data on actual evapotranspiration (ET), very few studies have been conducted on the long-term trend and variability in ET at a national scale over the Indian subcontinent. The present study uses biome specific ET data derived from NOAA satellite’s advanced very high resolution radiometer to investigate the trends and variability in ET over India from 1983 to 2006. Trend analysis using the non-parametric Mann–Kendall test showed that the domain average ET decreased during the period at a rate of 0.22 mm year−1. A strong decreasing trend (m=−1.75 mm year−1, F=17.41, P 0.01) was observed in forest regions. Seasonal analyses indicated a decreasing trend during southwest summer monsoon (m=−0.320 mm season−1year−1) and post-monsoon period (m=−0.188 mm season−1year−1). In contrast, an increasing trend was observed during northeast winter monsoon (m=0.156 mm season−1year−1) and pre-monsoon (m=0.068mm season−1year−1) periods. Despite an overall net decline in the country, a considerable increase ( 4 mm year−1) was observed over arid and semi-arid regions. Grid level correlation with various climatic parameters exhibited a strong positive correlation (r> 0.5) of ET with soil moisture and precipitation over semi-arid and arid regions, whereas a negative correlation (r−0.5) occurred with temperature and insolation in dry regions of western India. The results of this analysis are useful for understanding regional ET dynamics and its relationship with various climatic parameters over India. Future studies on the effects of ET changes on the hydrological cycle, carbon cycle, and energy partitioning are needed to account for the feedbacks to the climate.

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