nasa-gesdisc/es-publications-researchareas huggingface dataset:
Environmental degradation of vegetation cover and water bodies in the semiarid region of the Brazilian Northeast via cloud geoprocessing techniques applied to orbital data (2023)

The spatiotemporal diagnosis of climate variability and environmental changes in arid and semiarid regions is essential to minimize pressures and impacts on natural ecosystems. Remote sensing techniques and satellite images allow the detection of such changes. The study evaluated spatio-temporally the processes of environmental degradation of vegetation cover and water resources via physical-hydric parameters at the surface using remote sensing techniques for the Northeast of Brazil (NEB). Geospatial data from TRMM and MODIS satellites/sensors, digital cloud processing of vegetation indices (NDVI), water (NDWI and MNDWI), and rainfall were performed for the period 2000 to 2019. The patterns identified in the study were evaluated by multivariate statistics and correlation. The NDVI showed the significant vulnerability of vegetation cover in the Northeastern Semiarid region, due to the intensification of droughts. The spectral behavior of NDVI is due to rainfall, confirmed by principal component analysis (PCA) and correlation. The NDWI and MNDWI detected the pattern of water availability in the semiarid region, with a critical reduction in water bodies. In the space-time analysis, the physical-hydric parameters showed a significant water deficit, followed by severe drought and prolonged drought. MNDWI was efficient and sensitive to open water content, especially in areas covered by water bodies concerning NDWI, and correlated with rainfall. The variability of rainfall directly impacted the dynamics and resilience of vegetation and water bodies in the Northeastern Semiarid region. The critical reduction of areas of water bodies, the increase of non-vegetated areas, and the pressures of anthropic activities are favored.

Research areas: Land Surface/Agriculture Indicators, Droughts
Long-Term Variations of Meteorological and Precursor Influences on Ground Ozone Concentrations in Jinan, North China Plain, from 2010 to 2020 (2022)

Ground-level ozone (O3) pollution in the North China Plain has become a serious environmental problem over the last few decades. The influence of anthropogenic emissions and meteorological conditions on ozone trends have become the focus of widespread research. We studied the long-term ozone trends at urban and suburban sites in a typical city in North China and quantified the contributions of anthropogenic and meteorological factors. The results show that urban O3 increased and suburban O3 decreased from 2010 to 2020. The annual 90th percentile of the maximum daily 8-h average of ozone in urban areas increased by 3.01 gm3year1 and, in suburban areas, it decreased by 3.74 gm3year1. In contrast to the meteorological contributions, anthropogenic impacts are the decisive reason for the different ozone trends in urban and suburban areas. The rapid decline in nitrogen oxides (NOX) in urban and suburban areas has had various effects. In urban areas, this leads to a weaker titration of NOX and enhanced O3 formation, while in suburban areas, this weakens the photochemical production of O3. Sensitivity analysis shows that the O3 formation regime is in a transition state in both the urban and suburban areas. However, this tends to be limited to volatile organic compounds (VOCs) in urban areas and to NOX in suburban areas. One reasonable approach to controlling ozone pollution should be to reduce nitrogen oxide emissions while strengthening the control of VOCs.

Research areas: Air Quality, Environmental Impacts
Response of enhanced vegetation index changes to latent/sensible heat flux and precipitation over Pakistan using remote sensing (2022)

For a sustainable development and ecological integrity, it is of worth importance to monitor land use/ land cover (LULC) changes and related landatmosphere fluxes. To serve this purpose, we have used moderate resolution imaging spectroradiometer (MODIS) retrievedenhanced vegetation index (EVI), MERRA-2 re-analysis surface heat fluxes (latent heat flux, sensible heat flux and specific humidity), TRMM rainfall data, and OMI retrieved aerosol index (AI) over Pakistan during 2000 to 2021. High EVI (0.66) is observed in May 2021 as compared to May 2000 over Muzaffarabad, Srinagar, north and northwest of Khyber Pakhtunkhwa, east of Punjab and along the Indus River in Sindh. The highest increase in vegetative area is observed in Baluchistan (~ 366%), followed by Manavadar (~ 60%), Khyber Pakhtunkhwa (~ 41%), Sindh (~ 37%), and Punjab (~ 20%) whereas Gilgit-Baltistan and Jammu and Kashmir show reduction in vegetative area by 21% and 11% respectively. The coefficient of determination (R2) is found to be highest between rainfall and latent heat flux (R2 = 0.59) followed by rainfall and specific humidity (R2 = 0.35), and rainfall and sensible heat flux (R2 = 0.06). The latent heat flux shows increasing trend at the rate of 0.003 Wm2 winter1, 0.0065 Wm2 pre-monsoon1 and 0.0272 Wm2 post-monsoon1 during 19802021 whereas sensible heat flux shows decreasing trend at the rate of 0.00056 Wm2 winter1, 0.00249 Wm2 pre-monsoon1 and 0.0037 Wm2 post-monsoon1 during 19802021. Specific humidity depicts increasing trend at the rate of 0.0002 Wm2 winter1, 0.0038 Wm2 pre-monsoon1 and decreasing trend at the rate of 0.0080 Wm2 post-monsoon1 during 19802021. The interannual variations in AI show highest AI of 2.28 in 2021 with maximum positive percentage anomaly of 28.06% during 2007.

Research areas: Land Surface/Agriculture Indicators, Habitat Conversion/Fragmentation
Impact of mobility restrictions on NO2 concentrations in key Latin American cities during the first wave of the COVID-19 pandemic (2023)

Between March and June 2020, activity in the major cities of Latin America declined due to containment efforts implemented by local governments to avoid the rapid spread of COVID-19. Our study compared 2020 with the previous year and demonstrated a considerable drop in tropospheric NO2 levels obtained by the SENTINEL 5P satellite in major Latin American cities. Lima (47.5%), Santiago (36.1%), Sao Paulo (27%), Rio de Janeiro (23%), Quito (18.6%), Bogota (17.5%), Buenos Aires (16.6%), Guayaquil (15.3%), Medellin (14.2%), La Paz (9.5%), Belo Horizonte (7.8%), Mexico (7.6%) and Brasilia (5.9%) registered statistically significant decreases in NO2 concentrations during the study period. In addition, we analyzed mobility data from Google and Apple reports as well as meteorological information from atmospheric reanalysis data along with satellite fields between 2011 and 2020, and performed a refined multivariate analysis (non-negative matrix approximation) to show that this decrease was associated with a reduction in population mobility rather than meteorological factors. Our findings corroborate the argument that confinement scenarios may indicate how air pollutant concentrations can be effectively reduced and managed.

Research areas: Air Quality, Environmental Impacts
Aerosol Variability at Coastal Bhola Island (Bangladesh), an IGP Outflow Region (2023)

The aerosol optical depth (AOD) and Angstrom parameters are recognised to be pivotal factors in understanding the status of ambient aerosol concentrations over a certain place and depend not only on the local but also on large-scale atmospheric dynamics. Aerosol climatology was undertaken across coastal Bhola Island for 7 years (20142021), using data from the Aerosol Robotic Network (AERONET). This study provides a protracted scrutiny of daily, monthly, seasonal and inter-annual variations of the AOD and Angstrom parameters for Bhola. The observed columnar AOD was analysed to offer a hitherto unknown temporal picture of trends in aerosol pollution over Bhola. During the study period (20142021), the AOD value increased from 20152019 to 20202021. The AOD value was  0.70 except for 20142015 and 20192020. The seasonal mean AOD over Bhola was > 0.3, highest in January and February (winter) and lowest in July (monsoon). Coarse-mode fractions during winter and fine-mode fractions during rest, corroborate the seasonal pattern of AODs and  (Angstrom wavelength exponent). The average  was found to be > 1 during the inter-annual comparison, implying the ubiety and predominance of fine-mode aerosol. The average ' (second order Angstrom exponent) value was positive, with an overall cumulative count of 90% of the data having positive ' validating the pre-eminence of fine-mode aerosols. The  (Angstrom turbidity coefficient) value proportionally varied with respect to AOD, whereas it was inversely proportional to the    at a broader wavelength. The average  varied between 0.2 and 0.4. The aerosols detected over the Bhola are of metropolitan/industrial, maritime, biomass combustion and dust origins, with proportionate inputs varying in various seasons. The current study data will be used for future investigations of Bholas aerosols, pollution load, climate and atmospheric environment. Thus, this study is important as it facilitates the baseline data for policymakers and model simulation for pollution load and climate change analysis.

Research areas: Air Quality, Energy Production/Use
Evaluation of MODIS combined DT and DB AOD retrievals and their association with meteorological variables over Qena, Egypt (2023)

The purpose of this study is to validate the daily Terra-MODIS level 2 combined dark target (DT) and deep blue (DB) aerosol optical depth (AOD) retrievals with a spatial resolution of 10 km against the ground-based AERONET AOD data to be used in evaluating the air pollution and impact of meteorological variables over Qena, Egypt, in 2019. The regression analysis demonstrated an accepted agreement between the MODIS and AERONET AOD data with a correlation coefficient (R) of 0.7118 and 74.22% of the collocated points fall within the expected error (EE) limits. Quality flag filtering and spatial and temporal collocation were found to have a significant impact on the regression results. Quality flag filtering increased R by 0.2091 and % within EE by 17.97, spatial collocation increased R by 0.0143 and % within EE by 1.13, and temporal collocation increased R by 0.0089 and % within EE by 4.43. By validating the MODIS AOD data seasonally and analyzing the temporal distribution of the seasonal AOD data to show the retrieval accuracy variations between seasons, it was found that the MODIS AOD observations overestimated the AERONET AOD values in all seasons, and this may be because of underestimating the surface reflectance. Perhaps the main reason for the highest overestimation in summer and autumn is the transportation of aerosols from other regions, which changes the aerosol model in Qena, making accurate aerosol-type assumptions more difficult. Therefore, this study recommends necessary improvements regarding the aerosol model selection and the surface reflectance calculations. Temperature and relative humidity were found to have a strong negative relationship with a correlation of  0.735, and both have a moderate association with AOD with a correlation of 0.451 and  0.356, respectively. Because Qena is not a rainy city, precipitation was found to have no correlation with the other variables.

Research areas: Validation
Exploring the Impact of Winter Storm Uri on Power Outage, Air Quality, and Water Systems in Texas, USA (2023)

Texas was hit by a record-setting cold snap from the 1417 February 2021 after three decades that resulted in power outages, disruption of the public water systems, and other cascading effects. This study investigates the unprecedented impact of winter storm Uri on power outages, air quality, and water systems in Texas, USA. Analysis of the Parameter Regression of Independent Slopes Model (PRISM) gridded climate data showed that the average daily freezing temperature range was 019 C on 14 February 2021, with severe levels (1719 C) occurring in the Texas High Plains. Our results showed that the extreme freezing temperature persisted from 1417 February 2021, significantly affecting power operation and reliability, and creating power outages across Texas. Uri impacted the public water systems and air quality on time scales ranging from a few minutes to several days, resulting in 322 boiling notices. The air quality index level exceeded the standard limit by 51.7%, 61.7%, 50.8%, and 60% in DallasFort Worth, HoustonGalveston, Austin, and Lubbock regions. The level of the pollutants exceeded the EPA NAAQS standard allowable limits during winter storm Uri. In general, this study gives information on the governments future preparedness, policies, communication, and response to storm impacts on vulnerable regions and communities.

Research areas: Atmospheric/Ocean Indicators, Air Quality
COVID-19 Pandemic: Impacts on Air Quality during Partial Lockdown in the Metropolitan Area of Sao Paulo (2023)

Air pollution has become one of the factors that most affect the quality of life, human health, and the environment. Gaseous pollutants from motor vehicles have a significantly harmful effect on air quality in the Metropolitan Area of Sao Paulo (MASP)Brazil. Motor vehicles emit large amounts of particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), and volatile organic compounds (VOCs), the last three acting as the main tropospheric ozone (O3) precursors. In this study, we evaluated the effects of these pollutants on air quality in the MASP during the partial lockdown that was imposed to ensure the social distancing necessitated by the COVID-19 pandemic. We compared the monthly data for nitrogen dioxide (NO2) from the Ozone Monitoring Instrument (OMI) and CO, SO2, and BC from MERRA-2 for the period between April and May 2020 (during the pandemic) with the average for the same period for the (pre-pandemic) years 2017 to 2019 in the southeast region of Brazil. The meteorological and pollutant concentration data from the CETESB air quality monitoring stations for the MASP were compared with the diurnal cycle of three previous years, with regard to the monthly averages of April and May (2017, 2018, and 2019) and the same period in 2020, when the partial lockdown was first imposed in southeast Brazil. Our findings showed that there was a decrease in NO2 concentrations ranging from 10% to more than 60% in the MASP and the Metropolitan Area of Rio de Janeiro (MARJ), whereas in the Metropolitan Area of Belo Horizonte and Vitoria (MABH and MAV, respectively), there was a reduction of around 10%. In the case of the concentrations of CO and BC from MERRA-2, there was a considerable decrease (approx. 10%) during the period of partial lockdown caused by COVID-19 throughout almost the entire state of Sao Paulo, particularly in the region bordering the state of Rio de Janeiro. The concentration of SO2 from MERRA-2 was 5 to 10% lower in the MASP and MARJ and the west of the MABH, and there was a decrease of 30 to 50% on the border between the states of Sao Paulo and Rio de Janeiro, while in the MAV region, there was an increase in pollutant levels, as this region was not significantly affected by the COVID-19 pandemic. Sharp reductions in the average hourly concentrations of CO (38.8%), NO (44.9%), NO2 (38.7%), and PM2.5 (6%) were noted at the CETESB air quality monitoring stations in the MASP during the partial lockdown in 2020 compared with the hourly average rate in the pre-pandemic period. In contrast, there was an increase of approximately 16.0% in O3 concentrations in urban areas that are seriously affected by vehicular emissions, which is probably related to a decrease in NOx.

Research areas: Air Quality, Energy Production/Use
Earth Observation Data Synergy for the Enhanced Monitoring of Ephemeral Water Bodies to Anticipate Karst-Related Flooding (2023)

With the increasing availability and diversity of satellite imagery, the multisensor fusion of data can more effectively address the improved monitoring of temporary water bodies. This study supports the attempt to apply well established methods to detect spatial and temporal changes in ephemeral shallow lakes in lowland karst terrain, as well as to improve the understanding concerning the dynamics of water storage and hydrological mechanisms during extreme precipitation events. Based on the joint analysis of Copernicus Sentinel SAR and optical mission data, as well as soil moisture and EO-based rainfall observations over the period of 20152020, we demonstrated the control of the karst system on the ephemeral lake appearances in the broader area of Chalkida (Evvia, Greece). A connection between the prolonged and extended water coverage in the ephemeral lakes and flooding in the area is documented. Our EO-supported findings may serve as indicators for flood alerts in future extreme precipitation events, improving responses in cases of emergencies.

Research areas: Floods, Atmospheric/Ocean Indicators
NASA Giovanni: A Tool for Visualizing, Analyzing, and Intercomparing Soil Moisture Data (2014)

As part of two NASA-funded projects, with team members who are end users from the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) and the U.S. Department of Agriculture (USDA) World Agricultural Outlook Board (WAOB), a number of level 3 (gridded) soil moisture products have been incorporated into a beta prototype Giovanni portal. The purpose of this effort, beyond satisfying the requirements of the projects, is to create an environment, as part of the NASA Giovanni family of portals that facilitates intercomparisons and other uses of soil moisture products. This chapter provides some additional details on Giovanni. It describes the data products currently available in the Giovanni Intercomparison of Soil Moisture Products portal, and illustrates the portal's user interface and currently available services. The chapter then focuses on two examples of how the portal might be used for and facilitate hydrologic applications.

Research areas: Validation
Impact of COVID-19 on the Air Quality over China and India Using Long-term (2009-2020) Multi-satellite Data (2021)

ABSTRACT We have examined the air quality over China, India and demonstrated marked differences in levels of air pollution resulted from the COVID-19 restrictions during DecemberApril, 201920 to that of 11 years mean of 200919. The criteria air quality indicators i.e., nitrogen dioxide (NO2), sulphur dioxide (SO2), Aerosol Index (AI) and aerosol optical depth (AOD) data are retrieved from the Ozone Monitoring Instrument (OMI), TROPOspheric Monitoring Instrument (TROPOMI), and MODerate Resolution Imaging Spectroradiometer (MODIS) sensor on the Terra and Aqua satellites, respectively. Over China, during COVID-19 lockdown a significant drop in columnar abundances of tropospheric NO2 (37%), SO2 (64%) and AOD (8%) for 2020 in comparison to 11 years mean (200919) has been observed. A noticeable difference in NO2 column burden is seen over SE (35%), NE (33%), NW (13%) and SW (5%) China. Over the SE and NE China, both NO2 and SO2 levels decreased dramatically in 2020 from that of 200919, by more than 40% and 65%, respectively, because of both stricter regulations of emissions and less traffic activity due to reduced social and industrial activities during COVID-19 restrictions. In contrast, the curve of monthly mean tropospheric columnar burden of NO2 and SO2 over India has shown moderate reduction of 16% and 20%, respectively because lockdown came into effect much later in March 2020. The mean NO2 and SO2 over IGP region is found to be 25% higher than whole Indias mean concentration due to large scale urban settlement and crop burning events. The statistical t-test analysis results confirm significant (p < 0.05) improvements in AQ during lockdown. The COVID-19 pandemic provided an unprecedented opportunity to investigate such large-scale reduction in emissions of trace gases and aerosols. Therefore, it is important to further strengthen environmental policies to tackle air quality, human health, and climate change in this part of the world.

Research areas: Air Quality, Environmental Impacts
Mapping the landslide susceptibility considering future land-use land-cover scenario (2022)

The landslide susceptibility (LS) of any mountainous region is significantly affected by the land-use land-cover (LULC) change. Recently, LULC change effects on landslides have been investigated by many researchers. However, the future prediction of the LS using these LULC changes has not been quantified. The main objective of this study is to predict the future LS map considering the future LULC change scenario for the Tehri region, India. To achieve this objective, we first prepared a geospatial database of past landslide events. These events data were clustered into three major temporal categories, 20052010, 20102015, and 20152020. Second, the artificial neural network (ANN) approach was adopted to prepare LS maps for the years 2010, 2015, and 2020. Then, for the same years, LULC maps were also developed. Third, the future scenario of LULC for the year 2030 was simulated using the ANN-cellular automata model, and the future LULC changes were derived using the change detection technique. Finally, the future LS map for 2030 was projected using derived future LULC changes. The LULC change results reveal that the region is expected to see a significant growth in the built-up area by 34.1%, water body by 6.3%, and agriculture land by 1%. Further, a shrink in dense forest area by 2.4% and sparse forest area by 0.9% is expected in the future. Additionally, the projected LS results reveal a 33% increment in the very high LS zone. This information about the increase in future LS due to rapid urban growth in the mountains can help the various government agencies to scientifically plan the various developmental activities.

Research areas: Land Surface/Agriculture Indicators, Habitat Conversion/Fragmentation
Mid-Century Changes in the Mean and Extreme Climate in the Kingdom of Saudi Arabia and Implications for Water Harvesting and Climate Adaptation (2020)

The Kingdom of Saudi Arabia (KSA) is a water-scarce region with a dry, desert climate, yet flood-producing precipitation events and heat extremes lead to loss of life and damages to local infrastructure, property and economy. Due to its distinctive natural and man-made spatial features (e.g., coastal features, wadis, agricultural areas) studying changes in the mean climate and extreme events requires higher-resolution climate projections than those available from the current generation of Earth System Models. Here, a high-resolution convection-permitting regional climate model is used to downscale the middle of the 21st century (20412050) climate projections of the Community Earth System Model (CESM) under representative concentration pathway (RCP) 8.5 and for a historical time period (20082017) focusing on two months (August and November) within KSAs dry-hot and wet seasons, where extreme events have historically been observed more frequently. Downscaling of climate reanalysis is also performed for the historical time period (20082017) to evaluate the downscaling methodology. An increase in the intensity and frequency of precipitation events is found in August by mid-century, particularly along the mountainous western coast of KSA, suggesting potential for water harvesting. Conversely, the northern flank of the Empty Quarter experiences a noticeable reduction in mean and extreme precipitation rates during the wet season. Increasing August heat index is found to particularly make regional habitability difficult in Jeddah by mid-century.

Research areas: Atmospheric/Ocean Indicators, Heat