key: cord-0795659-mz4zrpdg authors: Lele, Nikhil; Nigam, Rahul; Bhattacharya, Bimal K. title: New findings on impact of COVID lockdown over terrestrial ecosystems from LEO-GEO satellites date: 2021-02-10 journal: Remote Sens Appl DOI: 10.1016/j.rsase.2021.100476 sha: 347dc7d5be5cfbac821d2428333c3f3a2eeb805d doc_id: 795659 cord_uid: mz4zrpdg 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 to 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 fouryear 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 to 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. Majority of the countries of the world were grabbed by severe acute respiratory syndrome coronavirus 2 (SARS-6 CoV-2) which was first reported from China. A novel Corona Virus Disease that was originated in December metropolitan cities as well as densely populated Indo-Gangetic belt (Das et al. 2020 (Das et al. , 2021 . Significant 36 reduction in forest fires was reported by Gupta et al. (2020) in parts of Western Himalayas, India. Not only in 37 air quality, significant improvement was also reported in water quality in lake (Yunus et al., 2020) , rivers (Garg The study utilizes both sun-synchronous polar or low-earth orbiting (LEO) and geostationary (GEO) satellite data and the bio-geophysical products used from these LEO-GEO satellites in the present study, are given in 130 open areas) but also atmospheric constituents like water, ozone and also land surface temperatures (LST). MODIS has ability to observe majority of the earth surface at daily interval and therefore is one of the most 137 widely used instruments for a wide number of applications. Various products and datasets are provided to global 138 user community via multiple data archival systems (e.g. www.earthexplorer.gov). A large number of standard 139 products for land, ocean, air and cryosphere are routinely generated using MODIS data and are distributed to 140 global scientific community. The study adheres to existing operational satellite data and products following the lockdown limitations for 196 ground data collections and impacts on various parameters are primarily studied by detecting anomaly in 197 various products and analyzing spatio-temporal trends with respect to past years. The methodology has been 198 elucidated here: MODIS-GPP product for 2019 and 2020 was studied in order to analyze impact of reduced fires on primary 345 productivity, particularly in forest ecosystem. Non-forest areas were masked from GPP product and productivity 346 amongst only forest pixels were considered. In addition to forests fires, productivity indicates overall effect of 347 other factors as well, that includes forest logging and lopping, which are other anthropogenic activities, though 348 beyond the scope of the present study. Comparison of Gross Primary Productivity (GPP) product for 2019 and production was additionally fixed during this particular period. Ten selected states accounted for 7.8 G g C/8-354 day during this period in 2019, while it accounted for 10.8 G g C/8-day, indicating 38% increase in gross 355 primary production. These estimates thus suggest that there is an improvement in carbon fixation potential by 356 primary producers and emission saving during lockdown period. In Madhya Pradesh and Chhattisgarh states, the estimated rabi crop harvest date showed maximum diversity 400 due to different crop types, sowing patterns and having both irrigated and rainfed rabi crops. In the year 2020, 401 maximum agricultural patches showed 10-20 days delay as compared to past years, except few fragmented 402 patches of north-eastern part that showed early harvest in 2020. In eastern part of India covering West Bengal, Odisha and Jharkhand states only, small pockets showed delay in harvest dates by 5-15 days as shown in Figure 404 8. An assessment of AWD during lockdown periods was made over eleven (11) agriculturally enrich states of The percentage change in AWD for 2020, compared to mean is shown in Figure 9 . year 2020 with overall reductions in volumetric AWD of 14.5% and 14%, respectively for those two periods. The reductions were 10.9%, 11.5% in Gujarat state and 13.9% to 14.9% reduction in Madhya Pradesh state. In The multi-year analysis for harvest date clearly indicated a substantial delay in harvesting dates of rabi crops in 488 northern, north-western, central and parts of eastern India. In India, harvesting depends on availability of 489 workers after crop maturity. The temporary restrictions imposed during initial phase of lockdown due to Betts et al., 1996) . The evapotranspiration is a process which govern both energy and mass exchange. The 522 reduction in mean daily temperatures due cooling in night-time temperature leads to reduction in daily vapor 523 pressure deficit, that further lead to reduction in reference evapotranspiration (Vyas et al., 2016) . As losses in 524 transpiration are reduced, there is a reduction in the demand of water for agriculture use (Allen et al., 1998; account for making future strategy on sustainable environment for achieving related Sustainable Development 532 Goals (SDGs). The major conclusions from the above study are following: • Substantial night-time surface cooling of the order of 2-6K was evident due to lockdown over several 534 cities having continental climate and patches of large industrial congregations when there was no 535 intermittent build-up of surface soil moisture. This is primarily attributed to temporary reduction of 536 heat sources from combustion and partly due to reduction in GHG and pollutant gases. • A substantial reduction in vegetation fire counts in the order of 5 -75% was noticed from space-based 538 data in majority of Indian states during fire-prone period, March -April, of 2020 as compared to mean 539 from previous years'. Increase in primary productivity to the tune of maximum 38% was noticed over 540 Indian forests. • Though a delay in rabi crop harvest for 1 -2 weeks was noticed the overall agricultural productivity 542 increased in north Indian states to a maximum of 34% which is attributed to favorable environmental 543 conditions and increased net carbon assimilation owing to delayed harvest. • Agricultural water demand was found to show substantial reduction to the tune of 5-15% in majority of 545 north Indian states. This can also help in meeting less water requirements either through irrigation or 546 rainfall. In a way, it might have led to a substantial water saving for agriculture. These provide evidence of improvements in various metrics within peri-urban, urban, agriculture and forest 548 ecosystems which are possible if the anthropogenic pressure can be rationally handled for better environment 549 and subsequent impact on ecosystems in terms of better human comfort, low carbon footprint and emissions, 550 reduced forest loss, higher agricultural productivity and water saving. Authorship contribution Statement. J o u r n a l P r e -p r o o f 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221 231 241 251 261 271 281 291 301 Shifting cultivation in North-East India: Trends, Benefits and Challenges COVID-19 forced confinement Global terrestrial gross and net primary 650 productivity from the earth observing system A crop phenology detection method using time-series MODIS data. Remote sensing of 654 Environment Effect of restricted emissions during COVID-19 on air quality in India. Science of The Total 665 The impact of COVID-19 as a 667 necessary evil on air pollution in India during the lockdown. Environmental Pollution, 266, 115080 A baseline regional evapotranspiration (ET) 670 and change hotspots over Indian sub-tropics using satellite remote sensing data. 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