Publications by authors named "Bimal K Bhattacharya"

2 Publications

  • Page 1 of 1

New findings on impact of COVID lockdown over terrestrial ecosystems from LEO-GEO satellites.

Remote Sens Appl 2021 Apr 10;22:100476. Epub 2021 Feb 10.

Agriculture and Land Eco-system Division, Biological and Planetary Sciences and Applications Group, Earth, Ocean, Atmosphere Planetary Sciences and Applications Area, Space Applications Centre (ISRO), Ahmedabad, 380015, Gujarat, India.

The COVID 19 pandemic led to lockdown and restrictions on anthropogenic activities not only in India but all over the world. This provided an opportunity to study positive effects on environment and subsequent impact on terrestrial ecosystems such as urban, peri-urban, forest and agriculture. A variety of studies presented so far mainly include improved air quality index, water quality, reduced pollutants etc. The present study focused on few novel parameters from both polar and geostationary satellites that are not studied in context to India, and also attempts deriving/quantifying benefits rather than merely indicating qualitative improvements. Due to lack of anthropogenic activities during complete lockdown-1 (21 days from 25 March 2020) in India nighttime cooling of land surface temperature (LST) of the order of 2-6 K was observed. Amongst 10 major cities, Bhopal showed highest nighttime cooling. The cooling effect in LST was evident in 80% of industrial units distinctly indicating cooling trend. Vegetation fires were analyzed in 10 fire-prone states of India. Compared to past four-years average number of occurrences, only 45% fire occurrences occurred during lockdown, indicating strong effect of lockdown. The study also revealed that, there is increase in gross primary production in forest ecosystem to the tune of maximum 38%, during this period. Though delay in rabi crop harvest date by 1-2 weeks in majority of north Indian states was observed rise in rabi crop productivity of the order of maximum 34% was observed which is attributed to favorable environmental conditions for net carbon uptake. About 18% reduction in volumetric agricultural water demand was estimated in Indo-Gangetic region, parts of Gujarat and Rajasthan. Apart from controlling the spread of the disease, the lockdown restrictions were thus also able to show positive effects on the environment and ecosystem which might influence to rethink on strategies for sustainable development.
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http://dx.doi.org/10.1016/j.rsase.2021.100476DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7874975PMC
April 2021

Agricultural drought early warning from geostationary meteorological satellites: concept and demonstration over semi-arid tract in India.

Environ Monit Assess 2020 Apr 23;192(5):311. Epub 2020 Apr 23.

Agriculture and Land Ecosystem Division (AED), Space Applications Centre, ISRO, Ahmedabad, Gujarat, 380015, India.

Remote sensing data from Indian geostationary satellites (Kalapana-1, INSAT 3A) were used for the first time for early warning of agricultural drought and forewarning of crop vigour. An Early warning indicator (EWI) was developed from operational product of rainfall and reference evapotranspiration from observations of Kalpana-1 very high resolution radiometer (VHRR). The effectiveness of EWI was evaluated for the two drought years (2009 and 2012). The positive correlation (r = 0.66-0.68 for 2009 and r = 0.64-0.70 for 2012) between the EWI in the month of June-July and standardized precipitation index-1 (SPI-1) averaged over administrative unit (called district) indicates that EWI can be used successfully for drought early warning. Lag-response behaviour between EWI and crop vigour in terms of normalized difference vegetation index (NDVI) and LAI (leaf area index) over cropland was studied. Systematic patterns emerged for 30 days lag period between negative EWI and NDVI at both grid-scale (0.25°) and at district level. Linear relations were found between 10-day EWI and NDVI or LAI at 30 days lag during June-July period. Linear models were developed to forewarn crop vigour which was validated with realized NDVI from INSAT 3A charge-coupled device (CCD) observations within 95% accuracy. The EWI is recommended as potential indicator for early-season agricultural drought assessment and can be used for sub-district scale with finer scale rainfall and evaporation products from advanced next-generation geostationary meteorological satellites.
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http://dx.doi.org/10.1007/s10661-020-08272-8DOI Listing
April 2020