nasa-gesdisc/es-publications-researchareas huggingface dataset:
Spatial and temporal variation of aerosol optical depths over six major cities in Bangladesh (2021)

The Aerosol Optical Depth (AOD) is a crucial parameter for assessing aerosol content and determining the level of air pollution. In this study, we represent almost seven years' aerosol optical behavioral patterns of six major cities in Bangladesh with emphasis on trends, seasonal variations, sources characterization, comparison between ground (AERONET) and satellite (MODIS Terra and Aqua) measurements, and relation with particulate matter (PM). High AOD values (>0.70) were obtained in most of the western parts of the country in all seasons. Decreasing patterns were observed from northwest to southeast. Average values of AOD for Dhaka, Chattagram, Rajshahi, Khulna, Barishal, and Sylhet were 0.71  0.08, 0.50  0.08, 0.78  0.06, 0.72  0.14, 0.64  0.08, 0.60  0.07 (Terra), and 0.59  0.07, 0.48  0.05, 0.69  0.08, 0.64  0.12, 0.56  0.05, 0.56  0.07 (Aqua), respectively. AERONET AODs at 870, 500, and 340 nm, and Angstrom Exponent (AE440870) values for Dhaka city were 0.40, 0.78, 1.06, and 1.18, respectively. Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Correlation coefficient (r) values were 0.23, 0.30, 0.64 (Terra) and 0.12, 0.29, 0.76 (Aqua), respectively. Both PM2.5 and PM10 were well correlated with all AODs but weakly correlated with AE. AODs, AE, and PM were negatively associated with meteorological variables such as rainfall, relative humidity, wind speed, and temperature. Anthropogenic and biomass burning aerosols were dominated in all four seasons, but dust and mixed type aerosols were only dominated in pre-monsoon and monsoon seasons. This research would help researchers further know the nature of atmospheric aerosols and how they affect seasonal patterns.

Research areas: Environmental Impacts
A closer look at factors governing landslide recovery time in post-seismic periods (2021)

Earthquakes increase landslide susceptibility in post-seismic periods. The time required for restoring pre-earthquake susceptibility levels is defined as landslide recovery time. Overall, stronger earthquakes are associated with relatively long recovery times in the literature. However, the seismic effect does not explain the whole process. This paper provides insight into factors governing this process. We hypothesize that the dominant post-seismic landsliding process (i.e., new or remobilized landslides), which is governed by the interactions between co-seismic landslide deposits and seismotectonic, morphologic and climatic conditions of a site, is the key to understand the physics behind the landslide recovery time. To test this argument, we analyze 11 earthquake-affected areas associated with seismic variables (i.e., earthquake magnitude and peak ground acceleration) and four environmental factors: (1) the fraction of area affected by co-seismic landslides (FAAL), (2) local relief, (3) average daily precipitation of extreme events (mm/day) and (4) rainfall seasonality. Our findings show that in areas with limited co-seismic landslide deposits (FAAL  ~1%), then remobilization of material takes the role of the dominant mechanism and recovery may take longer than a year.

Research areas: Land Surface/Agriculture Indicators, Earthquakes
Prevalence and Associated Risk Factor of COVID-19 and Impacts of Meteorological and Social Variables on Its Propagation in Punjab, Pakistan (2021)

The current study identifies the spatial distribution of COVID-19 cases and its association with meteorological and social variables in Punjab (densely populated province of Pakistan). To identify the COVID-19 propagation, the weekly growth, recovery, and deaths rate have also been calculated. The geographic information system (GIS) has used to determine COVID-19 impacts on gender (male/female), age groups, and causalities over an affected population (km2) for the period of 11th March to 12th August, 2020 in each district of province. Our results show that 43 peak days (where daily positive cases were above 900) have been observed in Punjab during 27th May to 8th July, 2020. The high population density districts, i.e., Lahore and Islamabad, have been affected (five persons per square kilometers) due to COVID-19, whereas the maximum death tolls (> 50 persons per millions) have also been observed in these urban districts. The meteorological variables (temperature, humidity, heat index, and ultraviolet index) show negative significant relationship to basic reproduction number (R0), whereas daily COVID-19 cases are positively correlated to aerosols concentration at 95% confidence level. The government intervention (stringency index) shows a positive impact to reduce the COVID-19 cases over the province. Keeping in view the COVID-19 behavior and climatology of the region, it has been identified that the COVID-19 cases may likely to increase during the dry period (high concentration of aerosols) i.e., OctoberDecember, 2020 and post-spring season (April to June), 2021 in urban areas of Pakistan. This study provides an overview on districts vulnerability that would help the policy makers, health agencies to plan their activities to reduce the COVID-19 impacts.

Research areas: Public Health, Air Quality
Dust and tropical PMx aerosols in Cape Verde: Sources, vertical distributions and stratified transport from North Africa (2021)

We investigated the sources and processes affecting the vertical distribution of tropical PMx aerosols (particulate matter -PM- smaller than 10, 2.5 and 1 m, PM10, PM2.5 and PM1, respectively) in the low troposphere of Santo Antao and Sao Vicente islands, in Cape Verde archipelago, a region where a better understanding of aerosols is needed due to their involvement in tropical meteorology and their impact on air quality, ocean and climate. We found that local sources had a low-scale impact. From transect measurements at ground level, we found that PMx levels were predominantly low, except near to PMx sources, where distinctive PM1 / PM2.5 ratios were measured, linked to vehicle exhaust (0.96), biomass burning (0.67) and Cape Verdean dust (0.36) emissions. The depth of the marine boundary layer (MBL) and the vertical distributions of PMx showed wide variability prompted by meteorological conditions. The trade winds prevailed in the MBL, whereas other airflows were situated above it: North-Atlantic, African easterly airflow and Saharan Air Layer. Under North-Atlantic airflow conditions, the MBL extended to 1400 m above sea level (m.a.s.l.). Above this altitude, PMx concentrations decreased quickly (< 3 g/m3) due to the free troposphere conditions. Under Saharan dust conditions, the MBL was confined to just 70 m.a.s.l., whereas a complex dust stratification was observed above, characterized by alternating dry air layers with high dust loads (PM10 ~ 100 g/m3) and more humid air layers with lower aerosol loads (PM10 ~ 40 g/m3). Within the dry easterly African airflow occurring above the marine stratocumulus typical of the MBL top (placed at 500 m.a.s.l.), we detected layers enriched in hydrophilic aerosols (PM10: ~ 8 g/m3). These were imbedded in relatively humid air (RH ~48%), probably linked to secondary aerosol formation by in-cloud processes in the marine stratocumulus situated below. We found that PMx transport from North Africa, both under dust and dust-free conditions, is associated with complex vertical stratifications, even within the dusty Saharan Air Layer.

Research areas: Environmental Impacts
Overview and Seasonality of PM10 and PM2.5 in Guayaquil, Ecuador (2021)

The focus of this study is the assessment of total suspended particles (TSP) and particulate matter (PM) with various aerodynamic diameters in ambient air in Guayaquil, a city in Ecuador that features a tropical climate. The urban annual mean concentrations of TSP (Total Suspended Particles), and particle matter (PM) with various aerodynamic diameters such as: PM10, PM2.5 and PM1 are 31  14 g m3, 21  9 g m3, 7  2 g m3 and 1  1 g m3, respectively. Air mass studies reveal that the city receives a clean Southern Ocean breeze. Backward trajectory analysis show differences between wet and dry seasons. During the dry season, most winds come from the south and southwest, while air masses from the peri urban may contribute as pollutant sources during the wet season. Although mean values of PM10 and PM2.5 were below dangerous levels, our year-round continuous monitoring study reveals that maximum values often surpassed those permissible limits allowed by the Ecuadorian norms. A cluster analysis shows four main paths in which west and southwest clusters account for more than 93% of the pollution. Total vertical column of NO2 shows the pollution footprint is strongest during the dry season, as opposed to the wet season. A microscopic morphological characterization of ambient particles within the city during the wet and the dry season reveals coarse mode particles with irregular and rounded shapes. Particle analysis reveals that samples are composed of urban dust, anthropogenic and organic debris during the dry season while mainly urban dust during the wet season.

Research areas: Air Quality
Solar Potential in Saudi Arabia for Inclined Flat-Plate Surfaces of Constant Tilt Tracking the Sun (2021)

The objective of the present work is to investigate the optimally performing tilt angles in Saudi Arabia of solar panels that follow the daily motion of the Sun. To that end, the annual energy sums are estimated for surfaces with tilt angles in the range 555 at 82 locations covering all Saudi Arabia. All calculations use a surface albedo of 0.2 and a near-real value, too. It is found that tilt angles of 40, 45, and 50, respectively, are optimal for the three recently defined solar energy zones in Saudi Arabia. The variation of the energy sums in each energy zone on annual, seasonal and monthly basis is given for near-real ground albedos; the analysis provides regression equations for the energy sums as functions of time. A map of the annual global inclined solar energy for Saudi Arabia is derived and presented. The annual energy sums are found to vary between 2159 kWhm2year1 and 4078 kWhm2year1. Finally, a correction factor, introduced in a recent publication, is used; it is confirmed that the relationship between the correction factor and either the tilt angle or the ground-albedo ratio has a general application and it may constitute a nomogram.

Research areas: Energy Production/Use, Sun-Earth Interactions
Monitoring spatial-temporal dynamics of small lakes based on SAR Sentinel-1 observations: a case study over Nui Coc Lake (Vietnam) (2021)

For the first time, this study estimates the variation of surface water extent of Nui Coc Lake located in Thai Nguyen province in North Vietnam at high spatial (20 m) and temporal resolution (bi-weekly). The classification methodology was developed based on the use of the Otsu threshold algorithm on the histogram of the backscatter coefficient of the SAR Sentinel-1 signal. Totally, more than 150 SAR Sentinel-1 images have been processed for the 2016-2020 period. Except for extreme drought and flood conditions, the average minimum and maximum of the lakes surface water extent are 17 km2 (in May) and 24 km2 (in September/October), respectively, and Nui Coc Lakes surface water was stable during the last five years. Classification results are in good agreement with the corresponding surface water extent maps derived from free-cloud Sentinel-2 images, with the occurrence map derived from the Landsat-derived Global Surface Water (GSW) product, and with in situ precipitation data. Compared to Sentinel-2, the lakes surface water extent detected from Sentinel-1 is 4-4.5% less. The water occurrence is similar between our results and that derived from the GSW product, but Sentinel-1 data provide more details as its spatial resolution is higher than Landsat. This study clearly shows the great potential of SAR Sentinel-1 data for monitoring small lakes water surface at low costs, especially over tropical regions.

Research areas: Validation
Environmental parameters associated with incidence and transmission of pathogenic Vibrio spp. (2021)

Vibrio spp. thrive in warm water and moderate salinity, and they are associated with aquatic invertebrates, notably crustaceans and zooplankton. At least 12 Vibrio spp. are known to cause infection in humans, and Vibrio cholerae is well documented as the etiological agent of pandemic cholera. Pathogenic non-cholera Vibrio spp., e.g., Vibrio parahaemolyticus and Vibrio vulnificus, cause gastroenteritis, septicemia, and other extra-intestinal infections. Incidence of vibriosis is rising globally, with evidence that anthropogenic factors, primarily emissions of carbon dioxide associated with atmospheric warming and more frequent and intense heatwaves, significantly influence environmental parameters, e.g., temperature, salinity, and nutrients, all of which can enhance growth of Vibrio spp. in aquatic ecosystems. It is not possible to eliminate Vibrio spp., as they are autochthonous to the aquatic environment and many play a critical role in carbon and nitrogen cycling. Risk prediction models provide an early warning that is essential for safeguarding public health. This is especially important for regions of the world vulnerable to infrastructure instability, including lack of water, sanitation, and hygiene (WASH), and a less resilient infrastructure that is vulnerable to natural calamity, e.g., hurricanes, floods, and earthquakes, and/or social disruption and civil unrest, arising from war, coups, political crisis, and economic recession. Incorporating environmental, social, and behavioural parameters into such models allows improved prediction, particularly of cholera epidemics. We have reported that damage to WASH infrastructure, coupled with elevated air temperatures and followed by above average rainfall, promotes exposure of a population to contaminated water and increases the risk of an outbreak of cholera. Interestingly, global predictive risk models successful for cholera have the potential, with modification, to predict diseases caused by other clinically relevant Vibrio spp. In the research reported here, the focus was on environmental parameters associated with incidence and distribution of clinically relevant Vibrio spp. and their role in disease transmission. In addition, molecular methods designed for detection and enumeration proved useful for predictive modelling and are described, namely in the context of prediction of environmental conditions favourable to Vibrio spp., hence human health risk.

Research areas: Public Health
The geographic disparity of historical greenhouse emissions and projected climate change (2021)

One challenge in climate change communication is that the causes and impacts of global warming are unrelated at local spatial scales. Using high-resolution datasets of historical anthropogenic greenhouse emissions and an ensemble of 21st century surface temperature projections, we developed a spatially explicit index of local climate disparity. This index identifies positive (low emissions, large temperature shifts) and negative disparity regions (high emissions, small temperature shifts), with global coverage. Across all climate change projections we analyzed, 99% of the earths surface area has a positive index value. This result underscores that while emissions are geographically concentrated, warming is globally widespread. From our index, the regions of the greatest positive disparity appear concentrated in the polar arctic, Central Asia, and Africa with negative disparity regions in western Europe, Southeast Asia, and eastern North America. Straightforward illustrations of this complex relationship may inform on equity, enhance public understanding, and increase collective global action.

Research areas: Greenhouse Gases, Atmospheric/Ocean Indicators
Studies of heat fields before strong fields earthquakes in Turkey March 8, 2010 (M = 6.1) and January 24, 2020 (M = 6.7). (2020)

Thermal field anomalies during preparation and occurrence of strong earthquakes in Turkey on March 8, 2010 (M = 6.1) and January 24, 2020 (M = 6.7) were studied using satellite data. Temperatures of the surface and the atmosphere's near surface layer, as well as outgoing longwave radiation registered by the AIRS sensor of the Aqua satellite were used for the analysis. The processing results have allowed us to find out that 712 days before the studied seismic events with  = 6.1 and  = 6.7 magnitudes there appeared positive variations of surface and atmosphere temperatures that set the stage for the formation of outgoing longwave radiation anomalies registered over the North and East Anatolian tectonic faults. The thermal field anomalies detected during the preparation of the earthquakes in Turkey confirm the presence of heat generation effects between the surface and the upper cloud edge. These effects can be used as short-term precursors of strong seismic events that can be registered from space.

Research areas: Earthquakes
Assessment of dust major ions and suspended heavy metal contents in atmospheric particulate matter of Port Said city, Egypt (2021)

Deposited particulate matter (dust fall) was collected in an urban and industrial city, Port Said, Egypt, from March 2018 to February 2019, and analyzed for water-soluble ions. In addition, suspended particulate matter (SPM) was collected from March to August 2018, and the filtrate samples were analyzed for heavy metal concentrations using ICP-OES. The depositional rates of dust fall and SPM in sampling sites were compared with meteorological (e.g., temperature, wind speed and direction) and satellite-based datasets. GIS-based interpolated maps were delineated for concentrations of major ions and heavy metals to determine their spatial and temporal variations within sampling sites. The analyzed anions (meq/L) have the decreasing order: SO42 (5.86) > Cl (4.54) > HCO3 (1.57) > NO3 (0.10) and Ca2+ (4.20) > Na+ (4.00) > Mg2+ (2.10) > K+ (1.51) > NH4+ (0.37) for cations. Low ratios of NO3/SO42 indicate the predominance of stationary pollution sources in Port Said city. The SPM-associated heavy metals (g/m3) have the decreasing order: Fe (2.7) > Cr (1.64) > Ni (1.35) > Pb (1.3) > Cd (0.17). The mean concentration of SPM (258 g/m3) exceeds the European (150 g/m3) and Egyptian (230 g/m3) air quality standards. Statistically, Cd and Cr were positively correlated with Fe (R2 = 0.86), while Pb and Ni were not. Overall, findings show that high rates of dust fall and heavy metals in Port Saids atmosphere can be attributed to urbanization (construction sites), sea-salt spray, and anthropogenic sources (e.g., industrial and vehicle emissions).

Research areas: Air Quality, Environmental Impacts
Characteristics of Ethiopia Air Chemistry and Its Meteorological Context (2018)

The concentration of trace gases and aerosols in Ethiopia is
poorly characterized due to a limited history of surface measurements. Here,
satellite measurements and model estimates of atmospheric composition are
employed to understand spacetime distributions in the period 200016. Methane
(CH 4 ) and carbon monoxide (CO) display high concentrations over the highlands
and provide a focus for analysis of monthly and daily data. CH 4 emissions from
livestock peak at the beginning of the dry season, while CO from biomass burning
rises at the end of the dry season. The seasonal cycle of dust, aerosol optical depth
(AOD), and CO 2 is inversely related with CH 4 , while CO closely follows sensible
heat flux, thus linking drying and rural biomass burning. Stable easterly flow in
the dry season accumulates local emissions, so near-surface concentrations of CO
and CH 4 are high then. The weather pattern underlying an episode of high ni-
trogen dioxide (NO 2 ) concentrations was studied. In addition to a stable lapse rate
and dry anticyclonic weather, midtropospheric subsidence was related to intrusion
of the northern subtropical jet stream on 2426 December 2010. The wind shadow
was cast by the Rift Escarpment limited dispersion, particularly with the dry,
stable weather conditions. A key outcome of this work is that CH 4 concentrations over Ethiopia are high in global context and have increased .0.1 ppm from 2002
to 2016; hence, there is a need to improve livestock management and production efficiency.

Research areas: Air Quality, Environmental Impacts
Features of atmospheric disturbances in temperate latitudes before strong earthquakes (M> 7) according to satellite measurements (2020)

An ATOVS and MERRA data archive containing
temperature values at isobaric levels from 1000 to 50 hPa was formed
to study the atmospheric effects observed over the foci of two strong
earthquakes with magnitudes M = 7,3. The first seismic event was
recorded on August 19, 1992 in the northern Tien Shan and the second
on November 12, 2017 in the border areas of the Zagros folded
mountain belt. According to USGS intense aftershock activity in these
regions began with these seismic events. Using correlation and spectral
analysis we studied the vertical profiles of temperature and pressure in
a disturbed atmosphere over seismically active regions. The modified
anomaly index was calculated at isobaric levels from 500 to 50 hPa and
on its basis the registered temperature anomalies were investigated.

Research areas: Earthquakes
Solar extinction map in Chile for applications in solar power tower plants, comparison with other places from sunbelt and impact on LCOE (2021)

Direct normal solar irradiation is a crucial parameter for site selection and design of solar power tower plants. It also has a high impact on economic studies, such as the levelized cost of electricity (LCOE). However, direct solar irradiation can be partially extinguished in its path between heliostats and receivers. Therefore, considering only direct normal solar irradiation in the solar resource assessment for tower plant projects is insufficient and leads to errors. This paper presents an improved methodology to estimate the extinction of radiation in the first 150 m of the lower atmosphere, where solar power tower plants are located. This work also shows the first atmospheric extinction maps, which in this case are elaborated for Chilean territory, and the intercomparison of extinction values with other places of interest in the sunbelt. Chile stands out for having the lowest annual atmospheric extinction values, below 4% for 1 km of slant range, while elsewhere annual losses can reach up to 17%. These values limit the amount of local useful solar resource available directly impacting on the LCOE values calculated for solar tower power plants. A new equation for the calculation of the LCOE considering atmospheric extinction is proposed in this paper.

Research areas: Energy Production/Use, Sun-Earth Interactions