nasa-gesdisc/es-publications-researchareas huggingface dataset:
UV Index for Public Health Awareness Based on OMI/NASA Satellite Data at King Abdulaziz University, Saudi Arabia (2021)

Exposure to ultraviolet radiation (UV) is essential for good health and formation of vitamin D while overexposure poses a risk to public health. Therefore, it is important to provide information to the public about the level of solar UV radiation. The ultraviolet index (UVI) is used to help avoid the negative effects of ultraviolet (UV) radiation on humans and to optimize individual exposure. There is limited ground measurement of solar UV radiation, but satellite Ozone Monitoring Instrument (OMIs) satellite products with a spatial resolution of can be used to create UV index climatology at local noon time. In this study, we utilize OMI satellite products collected over the campus of King Abdulaziz University (KAU) (21.5 North and 39.1 East), Jeddah, Saudi Arabia, to estimate changes in exposure to UV over a period of 15 years (2004-2020). The results indicate a significantly increasing trend in UV index over this period. Between 2004 and 2020, daily extreme UV (, as defined by the World Health Organization (WHO)) occurred on 46.60% of days. The frequency of low UVI () was only about 0.06%. These results imply dangerous exposure levels to solar UV radiation on the KAU campus and call for safety measures to increase awareness and decrease direct exposure; for example, by implementing the United States Environmental Protection Agency (EPA) general guidelines.

Research areas: Public Health
Application of satellite data and GIS services for studying air pollutants in Lithuania (case study: Kaunas city) (2020)

Satellite remote sensing, with its relatively short history, is going to play a major role in the fields that encompass topics related to place and space. Through this innovation in technology, real-time monitoring and mapping of changing phenomena on the surface of the earth has been possible. The purpose of this study was to investigate and evaluate the Kaunas city air pollutants between 14 and 25 October 2019 using environmental station data and satellite data (Terra, Aqua, OMI, and Sentinel-5P). The data obtained from satellite and the pollutant data gathered from air quality monitoring stations located in different parts of Kaunas were used. The data was downloaded for days mentioned above for the geographical bound of Kaunas city. Each data file covered an area of the size of Lithuania; hence, we should have extracted data for the area of interest, which was Kaunas city. The overall results of this study confirmed the capability of Sentinel-5P data to be used in monitoring the air quality and air pollution over the Kaunas local area. The existence of strong and acceptable correlations between satellite data and in situ measurements was indicative of the ability of satellite images to monitor air pollution, particularly over Kaunas urban areas during the fire incident in the city of Alytus.

Research areas: Air Quality
The Relationship between Ultraviolet Radiation and Meteorological Factors and Atmospheric Turbidity: Part I. Role of Total Ozone Content, Clouds, and Aerosol Optical Depth (2020)

We analyze the interrelation between the daily UVB radiation and a number of factors determining the absorption of UV radiation in the atmosphere (total ozone content (TOC), cloud amount, and aerosol optical depth (AOD)). This is done using a homogeneous time series of measurements of UVB radiation at the Tropospheric Ozone Research (TOR) station of the Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, from 2003 to 2016, satellite data on TOC, AOD data from the AERONET network, and data on cloud cover from the meteorological site of the Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch, Russian Academy of Sciences. The regression equations are obtained, relating the increment of the diurnal intake of UV-B radiation as a function of the increment of TOC under different cloud conditions and atmospheric transparency.

Research areas: Public Health
Joint Analysis of Anomalies of Different Geophysical Fields, Recorded from Space before Strong Earthquakes in California (2020)

Results are presented from using satellite data to study anomalies of different geophysical fields due to the interaction of the lithosphere, atmosphere, and ionosphere. The anomalies are mid- and short-term precursors of strong earthquakes in California that occurred on July 4 and 5, 2019 (M = 6.4 and M = 7.1). Precursory changes in the lithosphere are analyzed using lineament system characteristics obtained by processing satellite imagery (Terra/Aqua satellites and MODIS instrument), along with variations in the Earths surface temperature (the Aqua satellite and the AIRS instrument). Fluctuations in the temperature of the near-surface atmospheric layer are studied to detect atmospheric anomalies during preparation of seismic events, as are fluctuations in the air temperature now at an altitude of 1000 hPa and changes in outgoing longwave radiation recorded by the AIRS instrument on the Aqua satellite. Variations in the ionospheric electron density in the F2-layer maximum are studied with GPS data to reveal ionospheric anomalies during the precursors and occurrence of earthquakes. Joint analysis of anomalies in different geophysical fields, identified via satellite monitoring, allow precursory changes in the lithosphere to be detected a month before strong earthquakes. Precursory changes in the atmosphere and ionosphere can be detected 36 days and 35 or 10 days before earthquakes, respectively.

Research areas: Earthquakes
Comparison of INSAT-3D retrieved total column ozone with ground-based and AIRS observations over India (2021)

Ozone plays an important role in the thermal structure and chemical composition of the atmosphere. The present study compares the temporal and spatial distributions of Total Column Ozone (TCO) over the Indian sub-continent retrieved from a geostationary Indian National Satellite (INSAT-3D) and Atmospheric Infrared Sounder (AIRS). The INSAT-3D TCO values are also evaluated against the Dobson spectrophotometer observations at two locations. The inter-comparison results reveal a good correlation of 0.8, the bias of 5 DU, and Root Mean Square Error (RMSE) of 15 DU approximately between the TCO retrieved from INSAT-3D and AIRS. The lowest RMSE and highest correlation coefficient were found in the pre-monsoon season. The INSAT-3D and AIRS show reasonable agreement with the RMSE varying between 10 and 30 DU. On the other hand, evaluation of the INSAT-3D TCO with the ground-based observations from Dobson spectrophotometers located at New Delhi and Varanasi showed fair agreement with a maximum monthly mean correlation coefficient of 0.68 and 0.76, respectively, and RMSE varying from 11 to 16 DU for both the stations. The seasonal distribution of TCO and its variation over the Indian region has also been studied using INSAT-3D and AIRS data. The analysis exhibits strong seasonal variations, with higher values in pre-monsoon season and minimum values in winter season. The noticeable seasonal variability of TCO can be attributed to complex combination of photochemical and dynamical processes in the troposphere and stratosphere. The main objectives of the study are to compare the INSAT-3D TCO with two independent ground-based Dobson spectrophotometer observations and Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite.

Research areas: Validation
Temporal patterns of remote-sensed tropospheric carbon dioxide and methane over an urban site in Malawi, Southeast Africa: Implications for climate effects (2021)

Carbon dioxide (CO2) and Methane (CH4) are considered the most crucial climate forcing greenhouse gases due to their significant impacts on climate systems. The present study is aimed at analyzing the long-term (20042016) concentration patterns of CO2 and CH4 over Malawi located in Southeast Africa using the observations from Atmospheric Infrared Sounding (AIRS). The study found an annual increase concentration of CO2 and CH4, with a rate of 7.08% and 1.66%, respectively; whereas, the respective concentration levels of CO2 and CH4 in 2016 were noted as >400 ppm and >750 ppb, which is comparable to that reported by IPCC (2014) over the globe. The monthly and seasonal analyses revealed that high patterns are associated with biomass burning season, changes in vegetation cover, and long-range transport. The two trace gases were seasonally correlated with carbon-containing compounds produced from incomplete combustion and biomass burning. The trace gases and pollutants are emitted from the burning of crop residues during the harvesting season, besides, open burning of forests and vehicular emissions. The present study also detected a seasonal increase in CO2 and CH4 concentrations during JJA and SON seasons. The temperature (T C) exhibited profound correlation with CO2 (r = 0.75, p 

Research areas: Greenhouse Gases, Environmental Impacts
Retrieval of total columnar precipitable water vapour using radio occultation technique over the Indian region (2021)

Total precipitable water vapour (PWV) is retrieved using radio occultation retrievals of water vapour from COSMIC satellites over four regions of India. This analysis is carried out to assess the accuracy of the radio occultation technique for estimating PWV and to observe the PWV variation over these regions. The impact points of radio occultation are investigated for one year to select those points which are very near to the surface for the four regions. Total column PWV is estimated using these points data and further compared to the PWV values obtained from AIRS instrument and reanalysis data from MERRA2. The findings obtained using the radio occultation technique show that the vertical profile of PWV from COSMIC provides almost similar results at different pressure levels with AIRS and MERRA2 PWVs. The PWV values obtained from COSMIC are 22 mm, 17 mm, 27 mm, and 52 mm approximately for region1, region2, region3, and region4 respectively having differences in the range of 2 mm7 mm with respect to PWV values estimated from AIRS and MERRA2. On the surface level, the average difference is estimated to be less than 1 mm. It is inferred that a good estimation of total column PWV is obtained using the radio occultation technique which can be further used for rainfall prediction, its impact on climate change and to study hydrological cycle more efficiently.

Research areas: Validation
A Machine-Learning Based Tool for Diagnosing Inland Tropical Cyclone Maintenance or Intensification Events (2022)

Tropical Cyclone Maintenance and Intensification (TCMI) is a generalized definition of tropical cyclones that strengthen or maintain intensity inland while maintaining tropical characteristics. Herein, a novel methodology, using a machine learning method was created to examine the tropical cyclone record to improve climatological representation of such cases. Using the International Best Track Archive for Climate Stewardship (IBTrACS) dataset, individual times of inland tropical cyclones were classified into TCMI and non-TCMI (weakening) events. The MERRA-2 dataset was applied to develop a prototypical machine-learning model to help diagnose future TCMI events. A list of possible TCMI storms for case studies in future analyses is provided. Two of these storms were examined for attributes characteristic of the Brown Ocean Effect, a hypothesized mechanism for TCMI centered on warm, moist soils. It was revealed that variables that were important at the time of storm arrival were important the prior day, which indicates that a TCMI event is a reaction to the environment. Moreover, the variables that were finally selected show a heavy emphasis on land-surface processes. This supports the idea that the accurate representation of the land surface state is critical to the accurate diagnosis of TCMI.

Research areas: Validation
Investigation of seasonal variability of atmospheric columnar CO2 over India in relation to environmental parameters using OCO-2 observation and vertical redistribution model (2021)

This work re-explores the seasonal change of atmospheric carbon dioxide (CO2) concentration, a subject of renewable interest over half a century, in both time and frequency domain and identifies the atmospheric surface pressure and the surface air temperature as key factors for the temporal variation. The annual variability of CO2 dry-air mole fraction derived from the National Aeronautics and Space Administration Jet Propulsion Laboratory (NASA-JPL) Orbiting Carbon Observatory-2 (OCO-2) database for the region bounded by 22 N to 23 N and 86 E to 89 E was found to increase in summer, to decrease in winter and to exhibit a tendency of increase at the end of the year consistently for the years 2016 and 2017 whereas the corresponding variations of solar-induced fluorescence, surface pressure and air temperature showed partial consistency with that. The trends of these findings were cross-checked with the long-time gross variations of CO2, Normalized Difference Vegetation Index, surface pressure and surface temperature for 25 urban regions within approximately 20 N to 29 N and 69 E to 89 E obtained from NASA-Giovanni database for a period of 2010 to 2017. The periodic variations of these parameters were pin-pointed by Fourier transform. Field measurements were carried out for ground level and column-averaged CO2 concentrations in parts per million (ppm) at the region around Kolkata city (22.55 N, 88.35 E). Based on the above findings, a simple atmospheric model is developed for vertical redistribution of CO2 molecules under changed temperature and pressure causing a changed atmospheric path for radiation absorption and an apparent change in the gas concentration at any specific altitude.

Research areas: Validation
xCO2 temporal variability above Brazilian agroecosystems: A remote sensing approach (2021)

Agriculture and soil management practices are closely related to CO2 emissions in crop fields. These practices directly interfere on the carbon dynamics between the land and atmosphere. In this study, we investigated the temporal variability of the column-averaged dry-air mole fraction of atmospheric CO2 (xCO2), solar-induced chlorophyll fluorescence (SIF), and the normalized difference vegetation index (NDVI) in areas with the main agroecosystems in southern-central Brazil as a way to understand if and how crops cycle and agricultural management could be associated with the temporal variability of NDVI, SIF and xCO2. The study was carried out in areas corresponding to the three agroecosystems: sugarcane (Pradopolis, State of Sao Paulo, Brazil), cropland with soybean-corn succession (Santo Antonio do Paraiso, State of Parana, Brazil), and grassland (Aguas Claras, State of Mato Grosso do Sul, Brazil). Air temperature, precipitation, NDVI, and SIF and xCO2 were retrieved from NASA-POWER, NASA-GIOVANNI, SATVeg-EMBRAPA, and OCO-2, respectively, during a two-year study. Trends were removed from the NDVI, SIF, and xCO2 time series applying the regression method. A negative correlation between SIF and xCO2 was found in sugarcane and cropland areas, but in grasslands, no correlation showed up. Higher SIF values were observed in grassland (2.24 W m2 sr1 m1), and lower xCO2 values were observed above grains, which varied from 396.8 to 404.2 ppm. Both xCO2 and SIF followed more a seasonal pattern in sugarcane and annual crops, but over pasture this presented an unusual pattern related to higher precipitation events. Our results indicate a potential use of SIF and xCO2 which could help identifying potential sources and sinks of the main additional greenhouse gas over agricultural areas.

Research areas: Greenhouse Gases, Agriculture
Modified Flood Potential Index (MFPI) for Flood Monitoring in Terrestrial Water Storage Depletion Basin Using GRACE Estimates (2022)

The Gravity Recovery and Climate Experiment (GRACE) and Follow-On (GRACE-FO) missions offer great potential for large-scale flood event monitoring. However, the effectiveness of current GRACE-based indices may be limited in areas with significant Terrestrial Water Storage (TWS) decline. In this study, a Modified Flood Potential Index (MFPI) was proposed to improve the monitoring capability for flood events in the Yarlung Tsangpo-Brahmaputra River Basin (YBRB). First, the GRACE/FO Terrestrial Water Storage Anomaly (TWSA) data gap was filled with a Multilayer Perceptron Artificial Neural Network Model (MLP-ANN). Based on the gap-filled data, the performance of the MFPI was compared with five selected indices: Flood Potential Index (FPI), Total Storage Deficit Index (TSDI), Modified Total Storage Deficit Index (MTSDI), Water Storage Deficit Index (WSDI), and Combined Climatologic Deviation Index (CCDI). Finally, the spatiotemporal monitoring ability of the MFPI was evaluated for typical and atypical flood events. We found that (1) MLP-ANN was able to predict the GRACE/FO data gap with a performance of Very Good; (2) the MFPI outperformed the FPI, TSDI, MTSDI, WSDI, and CCDI in capturing flood events, and could also reflect their spatiotemporal processes; and (3) the MFPI avoids long-term TWSA trend effects on flood event monitoring and is available for areas with significant TWSA trends. This study can provide a reference for using GRACE data to monitor large-scale flood events.

Research areas: Floods
On the relationship between eastern China aerosols and western North Pacific tropical cyclone activity (2023)

How aerosols affect the weather and climate system has received increasing attention. This study finds a significant negative correlation between MarchMay eastern China aerosol optical depth (AOD) and JulyNovember western North Pacific (WNP) tropical cyclone (TC) frequency during 20032020. This time period spans when several aerosol reanalyses are available and both Terra and Aqua Moderate Resolution Imaging Spectroradiometer AOD retrievals are assimilated therein. Composite analyses and budget analyses of dynamical genesis potential indices indicate the importance of large-scale environmental factors, especially vertical velocity and vertical wind shear, associated with changes in AOD that in turn modulate changes in WNP TC frequency. Increased eastern China AOD may facilitate negative Pacific meridional mode development via modulation of the westerly jet, which then forces an anticyclonic circulation over the WNP basin. Increased AOD can also directly decrease the inter-hemispheric temperature differential and increases the intra-hemispheric temperature differential between the equator and the mid-latitudes, thus weakening ascending motion and enhancing vertical wind shear over the WNP, especially the southeastern portion of the basin. All of these large-scale environment changes induced by increased eastern China AOD tend to suppress WNP TCs. This study highlights the potential influence of eastern China aerosol loadings on WNP TCs, thus improving our understanding of TC climate variability over the WNP.

Research areas: Atmospheric/Ocean Indicators
Chemical characterization of marine aerosols from two cruises over the South China Sea: Importance of biomass burning and secondary formation (2023)

Total suspended particle (TSP) samples were collected during JuneJuly 2015 in the northern South China Sea (NSCS) and AugustSeptember 2016 in the western South China Sea (WSCS). Water-soluble ions (WSIs), organic carbon (OC), elemental carbon (EC), and organic compounds were measured. The average concentrations of WSIs, OC, EC and organic compounds were 19.4  10.9 g m3, 2.48  1.54 gC m3, 0.31  0.25 gC m3 and 789  217 ng m3 in the NSCS, and were 10.2  4.71 g m3, 1.76  1.82 gC m3, 0.43  0.32 gC m3 and 781  342 ng m3 in the WSCS. In both cruises, sea salt ions (Na+ and Cl) and secondary inorganic ions (SO42, NO3, and NH4+) were the main species of WSIs, accounting for 54.0 % and 43.6 % in the NSCS, and for 35.0 % and 54.0 % in the WSCS. The secondary products (dicarboxylic acids and aromatic acids) (NSCS: 73.3 %; WSCS: 73.9 %) and saccharides (NSCS: 19.0 %; WSCS: 18.0 %) accounted large fractions of organic compounds in aerosol particles over the SCS. These results suggest sea salt emissions and secondary formation are the main sources of the aerosols over the SCS in summer. The positive correlations between the biomass burning tracers (nss-K+ and levoglucosan) and OC as well as organic compounds indicated that biomass burning from nearby continents was also an important source of organic aerosols over the SCS. Based on back-trajectory analysis and satellite fire spots, Indochina Peninsula and China were proposed as the main continental source areas of non-sea salt WSIs and organic compounds. Our results highlight the significant contribution of continental outflow especially biomass burning and photochemical secondary oxidation to the organic compositions of aerosol particles over the SCS in summertime.

Research areas: Ecosystems, Environmental Impacts
Enhanced aerosols over the southeastern Tibetan Plateau induced by open biomass burning in spring 2020 (2023)

The Tibetan Plateau is the third pole of the world, with an essential role in regulating Northern Hemisphere climate. Previous studies showed that atmospheric aerosols over the Tibetan Plateau are influenced by biomass burning (BB) products from South and Southeast Asia. In fact, open biomass burning (OBB) is also an important form of BB in Southeast Asian countries, causing serious springtime air pollution yearly. However, there are still scientific gaps in the contribution of OBB to surrounding regional aerosols, especially on the Tibetan Plateau. In order to quantify this contribution, we collected samples of fine particulate matter and derived the concentrations of major water soluble ion, water soluble organic carbon (WSOC), and total carbon (TC) and total nitrogen (TN) as well as the dual isotopic compositions of carbon and nitrogen (13C and 15N) during MarchJune on the southeastern Tibetan Plateau. 13C and 15N showed no significant difference (p > 0.05) between the OBB and non-OBB periods. Furthermore, both 13C and 15N (25.7  0.7  and 8.0  3.6 ) values calculated during the whole sampling period were similar to the BB value, indicating that the primary source of TC and TN in aerosols was BB, whether OBB or non-OBB burning periods. TC and TN concentrations during the OBB period (6.5  2.9 g m3 and 1.2  0.4 g m3, respectively) were significantly higher than during the non-OBB period (4.1  1.7 g m3, with p = 0.014, and 0.7  0.3 g m3, with p = 0.013, respectively). Active fire data and surface smoke concentrations further indicated that BB emissions from Southeast Asia were higher during the OBB period. This suggests that OBB-related high BB emissions significantly enhanced atmospheric aerosols concentrations on the southeastern Tibetan Plateau.

Research areas: Air Quality, Environmental Impacts