nasa-gesdisc/es-publications-researchareas huggingface dataset:
Recent advances in satellite mapping of global air quality: evidences during COVID-19 pandemic (2021)

There was a significant decline in air pollution in different parts of the world due to enforcement of lockdown by many countries to check the spread of the coronavirus (COVID-19) pandemic. In particular, commercial and industrial activities had been limited globally with restricted air and surface traffic movements in response to social distancing and isolation. Both satellite remote sensing and ground-based monitoring were used to measure the change in the air quality. There was momentous decline in the averaged concentrations of nitrogen dioxide (NO2), carbon dioxide (CO2), sulphur dioxide (SO2), methane (CH4) and aerosols. Many cities across India, China and several major cities in Europe observed strong reductions in nitrogen dioxide levels dropping by around 4050% owing to lockdowns. Similarly, concentrations of SO2 in polluted areas in India, especially around large coal-fired power plants and industrial areas decreased by around 40% as evidenced by the comparative satellite mapping during April 2019 and April 2020. Recent advances in sensors on board various satellites played a significant role in real-time monitoring of emission regimes over various parts of the world. The satellite data is relying upon single scene profusion for real-time air quality measurements, and also using averaged dataset over certain time-period. The daily global-scale remote sensing data of NO2, as measured through the Copernicus Sentinel-5 Precursor Tropospheric Monitoring Instrument (S5p/TROPOMI) of European Space Agency (ESA), indicated exceptional decreases in tropospheric NO2 pollution in urban areas. Similarly, Greenhouse gases Observing Satellite (GOSAT) of Japan Aerospace Exploration Agency, with a repeat cycle of three days helped in assessing the sources and sinks of CO2 and CH4 on a sub-continental scale.

Research areas: Air Quality
Dry-deposition of inorganic and organic nitrogen aerosols to the Arabian Sea: Sources, transport and biogeochemical significance in surface waters (2021)

Air-to-sea deposition of water-soluble total nitrogen (WSTN) can influence the primary productivity in the coastal oceans. Here, we assessed the concentrations of aerosol inorganic (WSIN: NH4+ + NO3) and WSTN over the Arabian Sea during winter season (SS379:624 December 2018). The mean concentrations of NH4+ (109  83 nmol m3) overwhelm that of NO3 (32  13 nmol m3) and water-soluble organic nitrogen (WSON: WSTN-WSIN: 86  81 nmol m3), and contributing to ~50  31% of WSTN mass. Significant linear relationships of WSON with water-soluble organic carbon and NH4+ with non-sea-salt (nss)-K+ is observed suggesting their common origin from biomass burning and fertilizers. Backward air mass trajectories and satellite-based fire counts further revealed their provenance in the Indo-Gangetic Plain and southern India. The concentration of NO3 moderately correlated with nssCa2+ (dust tracer), indicating heterogeneous reactive uptake on mineral aerosol surface. Despite high concentrations, the deposition fluxes of NH4+ (~9.4  7.1 mol m2 d1) and WSON (7.4  7.0 mol m2 d1) are lower than NO3 (27  11 mol m2 d1) because of their predominant fine nature (i.e., strong correlation with nss-SO42). We also constrained the total annual atmospheric deposition rates of WSIN (0.94 Tg yr1) and WSON (0.08 Tg yr1) to the Arabian Sea during the continental outflow (November-April). The maximum dry-deposition of WSON to the Arabian Sea (0.24 Tg yr1) is twice that of the riverine supply (0.11 Tg yr1), highlighting the significance of aeolian sources. By using Redfield Stoichiometry, the WSTN deposition (2173 mol m2 d1) can account for <5.3% of fixedcarbon by a primary production in the Arabian Sea.

Research areas: Environmental Impacts, Ecosystems
Dispersion of Smoke Plumes over South America (2021)

AbstractSatellite and reanalysis products are used to study the atmospheric environment, aerosols, and trace gases in smoke plumes over South America in the period 200018. Climatic conditions and fire density maps provide context to link biomass burning across the southern Amazon region (515S, 5070W) to thick near-surface plumes of trace gases and fine aerosols. Intraseasonal weather patterns that underpin greater fire emissions in the dry season (JulyOctober) are exacerbated by high pressure over a cool eastern Pacific Ocean, for example in September 2007. Smoke-plume dispersion simulated with HYSPLIT reveals a slowing of westward transport between sources in eastern Brazil and the Andes Mountains. During cases of thick smoke plumes over southern Amazon, an upper ridge and sinking motions confine trace gases and fine aerosols below 4 km. Long-term warming, which tends to coincide with the zone of biomass burning, is +0.03C yr1 in the air and +0.1C yr1 at the land surface. Our study suggests that weather conditions promoting fire emissions also tend to limit dispersion.

Research areas: Wildfires, Atmospheric/Ocean Indicators
Diatom response to alterations in upwelling and nutrient dynamics associated with climate forcing in the California Current System (2021)

The California Current System displays a strong seasonal cycle in water properties, circulation, and biological production. Interactions of the alongshore current with coastal and topographic features lead to high spatial variability forced by seasonal winds that displace surface coastal water offshore. This process also supplies nutrients to the euphotic zone by Ekman transport and eventually supports phytoplankton blooms typically dominated by diatoms. Here, we investigate the relationship between biogenic silica production and mesoscale upwelling dynamics along the central region of the California Current System between 2013 and 2015, a period affected by a warm anomaly known as the Blob. Changes in the upwelling phenology along California caused by this marine heatwave are investigated using an innovative index and related to patterns of diatom production during upwelling events to evaluate diatom resilience. Based on this new index, we estimated that the nutrient supply to the euphotic zone declined by 50% during the Blob, but the Blob had little impact on local production during individual upwelling events. A statistical analysis evaluating the relationship between production and environmental conditions reveals persistent biological hotspots characterized by high biomass, depleted nutrients, and high specific production rates (up to 0.7 d1) throughout the study period. Lower observed biogenic silica to Chlorophyll a ratios during the Blob suggested a taxonomic shift from siliceous to nonsiliceous phytoplankton and/or lightly silicified diatoms signaling a change at the base of the food chain that could have ramifications for productivity in this eastern boundary coastal upwelling system.

Research areas: Atmospheric/Ocean Indicators, Ecosystems
Spatiotemporal observations of CH4 and CO2 over Iraq using Atmospheric Infrared Sounder (AIRS) data (2020)

Methane (CH4) and carbon dioxide (CO2) are the most important greenhouse gases and most important climate forcing agents due to their significant impact on climate, and their concentrations have been increased since the pre-industrial time by 150 and 40 % respectively, basically from fossil fuel combustion and land-use change emissions. In this research, the atmospheric concentration of CH4 and CO2 over Iraq is measured by the Atmospheric Infrared Sounder (AIRS). Time series and time-averaged maps were generated to study and analyse the distribution of CH4 and CO2 concentrations. The results show a significant increase of these two gases with an average increase (3.5 and 5.11 ppbv/ year ) in a rate of (2.69 % and 4 %) for CH4 at  SPL 925 hPa and 400 hPa, respectively ; the average increase of CO2 is (1.85 ppm/ year) represent (3.31%) for the whole period. The considerable increase of CH4 and CO2 concentration can affect human healthiness and earth radiative balance. Also, the Satellite observation of AIRS can efficiently show the spatiotemporal variations of CH4 and CO2 for the study area.

Research areas: Greenhouse Gases, Energy Production/Use
Decadal record of satellite carbon monoxide observations (2013)

Abstract. Atmospheric carbon monoxide (CO) distributions are controlled by anthropogenic emissions, biomass burning, transport and oxidation by reaction with the hydroxyl radical (OH). Quantifying trends in CO is therefore important for understanding changes related to all of these contributions. Here we present a comprehensive record of satellite observations from 2000 through 2011 of total column CO using the available measurements from nadir-viewing thermal infrared instruments: MOPITT, AIRS, TES and IASI. We examine trends for CO in the Northern and Southern Hemispheres along with regional trends for Eastern China, Eastern USA, Europe and India. We find that all the satellite observations are consistent with a modest decreasing trend ~ 1 % yr1 in total column CO over the Northern Hemisphere for this time period and a less significant, but still decreasing trend in the Southern Hemisphere. Although decreasing trends in the United States and Europe have been observed from surface CO measurements, we also find a decrease in CO over E. China that, to our knowledge, has not been reported previously. Some of the interannual variability in the observations can be explained by global fire emissions, but the overall decrease needs further study to understand the implications for changes in anthropogenic emissions.

Research areas: Air Quality, Environmental Impacts
Metagenomic Sequencing and Quantitative Real-Time PCR for Fecal Pollution Assessment in an Urban Watershed (2021)

Microbial contamination of recreation waters is a major concern globally, with pollutants originating from many sources, including human and other animal wastes often introduced during storm events. Fecal contamination is traditionally monitored by employing culture methods targeting fecal indicator bacteria (FIB), namely E. coli and enterococci, which provides only limited information of a few microbial taxa and no information on their sources. Host-associated qPCR and metagenomic DNA sequencing are complementary methods for FIB monitoring that can provide enhanced understanding of microbial communities and sources of fecal pollution. Whole metagenome sequencing (WMS), quantitative real-time PCR (qPCR), and culture-based FIB tests were performed in an urban watershed before and after a rainfall event to determine the feasibility and application of employing a multi-assay approach for examining microbial content of ambient source waters. Cultivated E. coli and enterococci enumeration confirmed presence of fecal contamination in all samples exceeding local single sample recreational water quality thresholds (E. coli, 410 MPN/100 mL; enterococci, 107 MPN/100mL) following a rainfall. Test results obtained with qPCR showed concentrations of E. coli, enterococci, and human-associated genetic markers increased after rainfall by 1.52-, 1.26-, and 1.11-log10 copies per 100 mL, respectively. Taxonomic analysis of the surface water microbiome and detection of antibiotic resistance genes, general FIB, and human-associated microorganisms were also employed. Results showed that fecal contamination from multiple sources (human, avian, dog, and ruminant), as well as FIB, enteric microorganisms, and antibiotic resistance genes increased demonstrably after a storm event. In summary, the addition of qPCR and WMS to traditional surrogate techniques may provide enhanced characterization and improved understanding of microbial pollution sources in ambient waters.

Research areas: Water Quality
Capturing the footprints of ground motion in the spatial distribution of rainfall-induced landslides (2021)

The coupled effect of earthquakes and rainfall is rarely investigated in landslide susceptibility assessments although it could be crucial to predict landslide occurrences. This is even more critical in the context of early warning systems and especially in cases of extreme precipitation regimes in post-seismic conditions, where the rock masses are already damaged due to the ground shaking. Here, we investigate this concept by accounting for the legacy of seismic ground shaking in rainfall-induced landslide (RFIL) scenarios. We do this to identify whether ground shaking plays a role in the susceptibility to post-seismic rainfall-induced landslides and to identify whether this legacy effect persists through time. With this motivation, we use binary logistic regression and examine time series of landslides associated with four earthquakes occurred in Indonesia: 2012 Sulawesi (Mw = 6.3), 2016 Reuleut (Mw = 6.5), 2017 Kasiguncu (Mw = 6.6) and 2018 Palu (Mw = 7.5) earthquakes. The dataset includes one co-seismic and three post-seismic landslide inventories for each earthquake. We use the peak ground acceleration map of the last strongest earthquake in each case as a predisposing factor of landslides representing the effect of ground shaking. We observe that, at least for the study areas under consideration and in a probabilistic context, the earthquake legacy contributes to increase the post-seismic RFIL susceptibility. This positive contribution decays through time. Specifically, we observe that ground motion is a significant predisposing factor controlling the spatial distribution of RFIL in the post-seismic period 110 days after an earthquake. We also show that this effect dissipates within 3 years at most.

Research areas: Land Surface/Agriculture Indicators, Earthquakes, Atmospheric/Ocean Indicators
Impact of COVID-19 lockdown on ground-based airglow observations over India (2021)

Airglow emissions which originate from the mesospheric and thermospheric altitudes have been routinely being monitored at Kolhapur (16.8 N, 74.2 E), Maharashtra, India, using ground base remote sensing imagers. We note that the observable amplitudes of very small-scale waves during April 2020 were significantly smaller than the regular observations. We investigate the reason for these low observable amplitudes. It is noted that drastic improvement in the quality of images was due to better contrast, which is attributed to significant reduction in greenhouse gases and aerosol loading in the atmosphere by the complete shutdown of local man-made emissions. Results suggest that lockdown had an important repercussion on the visibility through the improved air quality and thus better viewing conditions, which were reflected in the remotely sensed observations made with airglow imager.

Research areas: Greenhouse Gases
Surface Urban Heat Island (SUHI) Over Riverside Cities Along the Gangetic Plain of India (2021)

Rapid urbanisation in India has led to increased land use and energy demand, and the consequent uncontrolled development and increased human-induced activities are changing the micrometeorology and the local environment. Of late, the surface urban heat island (SUHI) effect is quite evident in India. It is known that river banks are where the most densely populated cities can be found around the globe, and the River Ganga (Ganges)  in India is no exception. Town/cities located over the Gangetic Plain are witnessing a fast urbanisation, and associated perturbation is taking place in the micro/meso-scale meteorology/environment. Discussion about the influence of the river on the SUHI and dynamics over different cities along a single major river is needed, and therefore this study is undertaken to investigate the SUHI effect on riverside towns/cities over the Gangetic Plain, India. For this purpose, the observation data for the period of 20012014 from the Terra-MODIS satellite are used. The study quantifies the land surface temperature (LST) under different zones  namely urban, suburban, and rural,  delineated on the basis of  International Geosphere Biosphere Programme-Land Cover (IGBP-LC) products. The intensity and trend of SUHI are measured as an indicator of environmental and micro-climate change. The study found a prevailing regime of nighttime SUHI intensity (SUHII) as well as the daytime formation of SUHI. The interaction of the wind blowing from the river and other land cover to towns/cities was examined with respect to the SUHII of Kanpur and Patna and was found to be quite important.

Research areas: Heat, Habitat Conversion/Fragmentation
Temperature patterns along an arid coastline experiencing extreme and rapid urbanization, case study: Dubai (2021)

Today more than one billion people are living in coastal regions, and coastal urbanization is rapidly growing worldwide. Here, we explore the impact of an extreme and rapid coastal urbanization on temperature patterns, based on MODIS data. We study Dubai, one of the fastest growing cities in the world over the last two decades. Dubai's urbanization centers along its coastline  in land, massive skyscrapers and infrastructure have been built, while in sea, just nearby, unique artificial islands have been constructed. Studying the coastline during the years of intense urbanization, we show that the coastline exhibits surface urban heat island characteristics, where the urban center experiences higher temperatures, by as much as 2.5 C and more, compared to the adjacent less urbanized zones. During development, the coastal surface urban heat island has nearly doubled its size, expanding towards the newly developed areas. This newly developed zone also exhibits the largest temperature trend along the coast of over 0.1 C/year on average. In addition, an opposite linear relation was found between the surface temperature and albedo trends. In sea, temperature decreases were observed, particularly over the artificial islands, exceeding 0.1 C/year, in one of them. The positive trends in land along with the negative trends in sea decreased the coastal sea-land temperature gradient by up to about 30% in only 12 years, which also decreased the land breeze intensity. The findings shown here directly affect the local coastal population and ecosystem, exacerbate the thermal comfort, and add additional burden to this area, which is already considered as one of the warmest in the world.

Research areas: Heat, Habitat Conversion/Fragmentation
Evaluating Antarctic marine protected area scenarios using a dynamic food web model (2020)

Marine protected areas, especially when they are or include no-take zones, can support conservation objectives by creating an area where marine organisms are protected from human disturbances, particularly fishing. The coast of the Antarctic continent is the only habitat of the iconic Adelie penguin, whose main diet is Antarctic krill. Current threats to Adelie Penguins, other Antarctic krill predators and Antarctic krill itself include sea-ice loss as a result of climate change and krill fishing. We use a spatially and temporally dynamic food web model of the region surrounding the Western Antarctic Peninsula to evaluate the potential impacts of various marine protected area scenarios in the context of climate change. We examine the effects of sustained sea-ice loss on krill and seven monitored krill predators. We evaluate four marine protected area scenarios given two scenarios that describe future changes in sea ice and three scenarios that describe future changes in krill fishing effort. Our results indicate that establishing no-take zones where krill might aggregate in the future and where some krill predators forage could positively affect biomass accumulation of krill and the predators. No-take zones may be particularly important for enhancing the resilience of species that have recently experienced population decline and ensuring positive outcomes from establishing a marine protected area in the region. Our simulations suggest that establishing protected areas in the right locations can play an important role in mitigating the negative effects of climate change on iconic species that many people want to conserve.

Research areas: Cryospheric Indicators, Ecosystems, Agriculture
Fifty-six years of Surface Solar Radiation and Sunshine Duration at the Surface in Sao Paulo, Brazil: 19612016 (2020)

Abstract. Fifty-six years (19612016) of daily surface downward solar irradiation, sunshine duration, diurnal temperature range and the fraction of the sky covered by clouds in the city of Sao Paulo, Brazil, were analyzed. The main purpose was to contribute to the characterization and understanding of the dimming and brightening effects on solar global radiation in this part of South America. As observed in most of the previous studies worldwide, in this study, during the period between 1961 up to the early 1980's, more specifically up to 1983, a negative trend in surface solar irradiation was detected in Sao Paulo, characterizing the occurrence of a dimming effect. A similar behavior, a negative trend, was also observed for sunshine duration and the diurnal temperature range, the three variables in opposition to the trend in the sky cover fraction. However, a brightening effect, as observed in western industrialized countries in more recent years, was not observed. Instead, for surface downward irradiation, the negative trend persisted and still in consonance to the cloud cover fraction increasing trend. The trends for sunshine duration and the diurnal temperature range, by contrast, changed signal. Some possible causes for the discrepancy were discussed, such as the frequency of fog occurrence, urban heat island effects, aerosol changes and greenhouse gas concentration increase. Future studies on aerosol effect are encouraged, particularly with higher temporal resolution as well as modeling studies, to better analyze the contribution of each possible causes.

Research areas: Sun-Earth Interactions
Spatio-temporal assessment of ambient air quality, their health effects and improvement during COVID-19 lockdown in one of the most polluted cities of India (2020)

The present work aims to investigate seasonal variations in air pollution levels in Lucknow and assess the ambient air quality of the city together with highlighting the health impacts of major pollutants like PM10, PM2.5, SO2, NO2, Pb, Ni and aerosols from 2010 to 2019. The maximum and minimum values of PM10, PM2.5, SO2, NO2, Pb and Ni were found to be 270.75 and 122.45 g/m3, 124.95 and 95.52 g/m3, 25.60 and 8.05 g/m3, 75.65 and 23.85 g/m3, 0.66 and 0.03 g/m3 and 0.07 and 0.01 ng/m3, respectively. Health impact of particulate matter has also been assessed with AirQ+, and it was estimated that long-term exposure of PM10 was attributed to between 37 and 48% for post-neonatal (age 112 months) mortality rate due to all causes, whereas long-term attributable proportions in mortality due to exposure of PM2.5 were to about 19 to 28% from all causes. Further, an attempt has also been made to evaluate the impact of lockdown amid COVID-19 on the ambient air quality of Lucknow. During the lockdown, PM2.5 levels reduced by 65% (at Gomti Nagar), 23% (at central school), 79% (at Lalbagh) and 35% (at Talkatora), due to which, air quality index of Gomti Nagar came down to 43, well below 50 which falls in the healthy range. NO2 levels also came down. However, levels of SO2 did not show significant reduction. Correlating the data between aerosol optical depth and Angstrom exponent by Pearson correlation analysis revealed a significant positive correlation (r = 0.65, P 

Research areas: Air Quality, Public Health