nasa-gesdisc/es-publications-researchareas huggingface dataset:
Interannual variation of reactive nitrogen emissions and their impacts on PM2. 5 air pollution in China during 2005–2015 (2021)

Abstract
            
              Emissions of reactive nitrogen as ammonia (NH
              3
              ) and nitrogen oxides (NO
              
                x
              
              ), together with sulfur dioxide (SO
              2
              ), contribute to formation of secondary PM
              2.5
              in the atmosphere. Satellite observations of atmospheric NH
              3
              , NO
              2
              , and SO
              2
              levels since the 2000s provide valuable information to constrain the spatial and temporal variability of their emissions. Here we present a bottom-up Chinese NH
              3
              emission inventory combined with top-down estimates of Chinese NO
              
                x
              
              and SO
              2
              emissions using ozone monitoring instrument satellite observations, aiming to quantify the interannual variations of reactive nitrogen emissions in China and their contributions to PM
              2.5
              air pollution over 20052015. We find small interannual changes in the total Chinese anthropogenic NH
              3
              emissions during 20052016 (12.013.3 Tg with over 85% from agricultural sources), but large interannual change in top-down Chinese NO
              
                x
              
              and SO
              2
              emissions. Chinese NO
              
                x
              
              emissions peaked around 2011 and declined by 22% during 20112015, and Chinese SO
              2
              emissions declined by 55% in 2015 relative to that in 2007. Using the GEOS-Chem chemical transport model simulations, we find that rising atmospheric NH
              3
              levels in eastern China since 2011 as observed by infrared atmospheric sounding interferometer and atmospheric infrared sounder satellites are mainly driven by rapid reductions in SO
              2
              emissions. The 20112015 Chinese NO
              
                x
              
              emission reductions have decreased regional annual mean PM
              2.5
              by 2.33.8
              
              g m
              3
              . Interannual PM
              2.5
              changes due to NH
              3
              emission changes are relatively small, but further control of agricultural NH
              3
              emissions can be effective for PM
              2.5
              pollution mitigation in eastern China.

Research areas: Air Quality
Concentration Trajectory Route of Air pollution with an Integrated Lagrangian model (C-TRAIL Model v1. 0) derived from the Community Multiscale Air Quality … (2020)

Abstract. This paper introduces a novel Lagrangian model (Concentration Trajectory Route of Air pollution with an Integrated Lagrangian model, C-TRAIL version 1.0) output from a Eulerian air quality model for validating the sourcereceptor direct link by following polluted air masses. To investigate the concentrations and trajectories of air masses simultaneously, we implement the trajectory-grid (TG) Lagrangian advection scheme in the CMAQ (Community Multiscale Air Quality) Eulerian model version 5.2. The TG algorithm follows the concentrations of representative air packets of species along trajectories determined by the wind field. The diagnostic output from C-TRAIL accurately identifies the origins of pollutants. For validation, we analyze the results of C-TRAIL during the KORUS-AQ campaign over South Korea. Initially, we implement C-TRAIL in a simulation of CO concentrations with an emphasis on the long- and short-range transport effects. The output from C-TRAIL reveals that local trajectories were responsible for CO concentrations over Seoul during the stagnant period (1722 May 2016) and during the extreme pollution period (2528 May 2016), highly polluted air masses from China were distinguished as sources of CO transported to the Seoul Metropolitan Area (SMA). We conclude that during the study period, long-range transport played a crucial role in high CO concentrations over the receptor area. Furthermore, for May 2016, we find that the potential sources of CO over the SMA were the result of either local transport or long-range transport from the Shandong Peninsula and, in some cases, from regions north of the SMA. By identifying the trajectories of CO concentrations, one can use the results from C-TRAIL to directly link strong potential sources of pollutants to a receptor in specific regions during various time frames.

Research areas: Air Quality
Distinguishing the roles of meteorology, emission control measures, regional transport, and co-benefits of reduced aerosol feedbacks in “APEC Blue” (2017)

Air quality are strongly influenced by both emissions and meteorological conditions. During the Asia Pacific Economic Cooperation (APEC) week (November 511, 2014), the Chinese government implemented unprecedented strict emission control measures in Beijing and surrounding provinces, and then a phenomenon referred to as APEC Blue (rare blue sky) occurred. It is challenging to quantify the effectiveness of the implemented strict control measures solely based on observations. In this study, we use the WRF-Chem model to distinguish the roles of meteorology, emission control measures, regional transport, and co-benefits of reduced aerosol feedbacks during APEC week. In general, meteorological variables, PM2.5 concentrations and PM2.5 chemical compositions are well reproduced in Beijing. Positive weather conditions (lower temperature, lower relative humidity, higher wind speeds and enhanced boundary layer heights) play important roles in APEC Blue. Applying strict emission control measures in Beijing and five surrounding provinces can only explain an average decrease of 17.7 g/m3 (21.8%) decreases in PM2.5 concentrations, roughly more than half of which is caused by emission controls that implemented in the five surrounding provinces (12.5 g/m3). During the APEC week, non-local emissions contributed to 41.3% to PM2.5 concentrations in Beijing, and the effectiveness of implementing emission control measures hinges on dominant pathways and transport speeds. Besides, we also quantified the contribution of reduced aerosol feedbacks due to strict emission control measures in this study. During daytime, co-benefits of reduced aerosol feedbacks account for about 10.9% of the total decreases in PM2.5 concentrations in urban Beijing. The separation of contributions from aerosol absorption and scattering restates the importance of controlling BC to accelerate the effectiveness of aerosol pollution control.

Research areas: Air Quality
Inverse Modeling of Asian Dust Emissions with POPC Observations: A TEMM Dust Sand Storm 2014 Case Study (2017)

An inverse modeling system for estimating Asian dust emissions was developed by combining the GEOS-Chem chemical transport model with the Green's function method. We applied the system to two heavy dust storms that occurred in 2014 (10-25 March and 24 May to 5 June), using surface-based polarization optical particle counter (POPC) observations at Fukuoka. Validation by independent observation datasets, including POPC measurements and PM10 observations at Seoul, showed that the use of a posteriori dust emissions improved overestimations in the a priori simulation and achieved much better agreement with observations. Satellite observations, surface synoptic observations, and modeled wind fields indicated that the major dust source region differed between the two dust storms; the major dust outbreak of one storm occurred in the northeastern Gobi Desert, whereas that of the other occurred in the southern Gobi Desert. The a posteriori dust emissions successfully reproduced this difference. Thus, the inverse modeling system developed in this study was able to improve the estimation of not only the intensity but also the geographical distribution of dust emissions.

Research areas: Air Quality
Hiroshima and Nagasaki Verification of an Unstructured Mesh-Based Transmutation Toolkit (2020)

In order to model the activated isotopes and resulting dose from a nuclear detonation in an urban environment, the Activation and Transmutation of Isotopes in an Unstructured Mesh (ACTIUM) Python toolkit has been developed to combine the unstructured meshbased particle transport capability of MCNP6.2 with the CINDER2008 transmutation code to produce quantities of interest for the post-detonation nuclear forensics and weapons effects communities. The ACTIUM toolkit has been implemented and validated with a number of test cases from a simple analytic model to a case study of the urban detonation in Nagasaki, Japan. The ACTIUM approach is the first of its kind to couple the latest release of CINDER2008 as a part of the Activation in Accelerator Radiation Environments (AARE) package with MCNP6.2 and produce transmuted quantities per time step on an unstructured mesh for the nuclear forensics and weapon effects communities. ACTIUM uses the latest ENDF/B-VIII.0, TENDL2017, and JENDL4 cross-section libraries for the transmutation calculations and includes methods for producing material cards for the initial MCNP6.2 unstructured mesh calculation based on highly detailed materials often found in urban environments on a city-specific basis.

Research areas: Validation, Public Health
Evaluation of WRF-Chem predictions for dust deposition in Southwestern Iran (2020)

The relationships between monthly recorded ground deposition rates (GDRs) and the spatiotemporal characteristics of dust concentrations in southwest Iran were investigated. A simulation by the Weather Research and Forecasting Model coupled with the Chemistry modeling system (WRF-Chem) was conducted for dust deposition during 20142015. The monthly dust deposition values observed at 10 different gauge sites (G01G10) were mapped to show the seasonal and spatial variations in dust episodes at each location. An analysis of the dust deposition samples, however, confirmed that the region along the deposition sites is exposed to the highest monthly dust load, which has a mean value of 2.4 mg cm2. In addition, the study area is subjected to seasonally varying deposition, which follows the trend: spring > summer > winter > fall. The modeling results further demonstrate that the increase in dust emissions is followed by a windward convergence over the region (particularly in the spring and summer). Based on the maximum likelihood classification of land use land cover, the modeling results are consistent with observation data at gauge sites for three scenarios [S.I, S.II, and S.III]. The WRF model, in contrast with the corresponding observation data, reveals that the rate factor decreases from the southern [S.IIIG08, G09, and G10] through [S.IIG04, G05, G06, and G07] to the northern points [S.IG01, G02, and G03]. A narrower gap between the modeling results and GDRs is indicated if there is an increase in the number of dust particles moving to lower altitudes or an increase in the dust resident time at high altitudes. The quality of the model forecast is altered by the deposition rate and is sensitive to land surface properties and interactions among land and climate patterns.

Research areas: Air Quality
Strong regional atmospheric
            14
            C signature of respired CO
            2
            observed from a tall tower over the midwestern United States (2016)

Radiocarbon in CO<SUB>2</SUB> (<SUP>14</SUP>CO<SUB>2</SUB>) measurements can aid in discriminating between fast (&lt;1 year) and slower (&gt;5-10 years) cycling of C between the atmosphere and the terrestrial biosphere due to the <SUP>14</SUP>C disequilibrium between atmospheric and terrestrial C. However, <SUP>14</SUP>CO<SUB>2</SUB> in the atmosphere is typically much more strongly impacted by fossil fuel emissions of CO<SUB>2</SUB>, and, thus, observations often provide little additional constraints on respiratory flux estimates at regional scales. Here we describe a data set of <SUP>14</SUP>CO<SUB>2</SUB> observations from a tall tower in northern Wisconsin (USA) where fossil fuel influence is far enough removed that during the summer months, the biospheric component of the <SUP>14</SUP>CO<SUB>2</SUB> budget dominates. We find that the terrestrial biosphere is responsible for a significant contribution to <SUP>14</SUP>CO<SUB>2</SUB> that is 2-3 times higher than predicted by the Carnegie-Ames-Stanford approach terrestrial ecosystem model for observations made in 2010. This likely includes a substantial contribution from the North American boreal ecoregion, but transported biospheric emissions from outside the model domain cannot be ruled out. The <SUP>14</SUP>CO<SUB>2</SUB> enhancement also appears somewhat decreased in observations made over subsequent years, suggesting that 2010 may be anomalous. With these caveats acknowledged, we discuss the implications of the observation/model comparison in terms of possible systematic biases in the model versus short-term anomalies in the observations. Going forward, this isotopic signal could be exploited as an important indicator to better constrain both the long-term carbon balance of terrestrial ecosystems and the short-term impact of disturbance-based loss of carbon to the atmosphere.

Research areas: Air Quality
Regional Impact of Ozone Precursor Emissions on NOX and O3 Levels at ZOTTO Tall Tower in Central Siberia (2021)

Seasonal variations of the near-surface NO<SUB>X</SUB> (= NO + NO<SUB>2</SUB>) and ozone (O<SUB>3</SUB>) mixing ratios at Zotino Tall Tower (ZOTTO), a remote site in central Siberia, are described for years 2007-2014. Conditional probability function analysis and back trajectories are used to determine the origins of clean (continental baseline, CB) and regional emissions-influenced air. High NO<SUB>X</SUB> levels at the site are observed for air from industrial regions of western Siberia and Ural Mountains, whereas CB air originates from remote areas of North Eurasia within 55°-70°N. The estimated annual means of daytime O<SUB>3</SUB> and NO<SUB>X</SUB> mixing ratios for CB air are 27.0 and 0.44 ppbv, correspondingly, versus the similar quantities of 27.9 and 0.79 ppbv for all data. Monthly ozone for CB air shows a distinct maximum in April, as is the case for Northern Hemisphere midlatitude baseline (NHMLB) air at the European inflow boundary according to the surface ozone data for Mace Head and Norwegian monitoring sites, and a minimum in late summer-early autumn reflecting a weak continental-scale ozone production from biogenic sources of ozone precursors and wildfire emissions throughout the warm season. During spring and early summer under hot weather conditions, regional anthropogenic and wildfire emissions are an important source for ozone in the continental boundary layer over southern and central Siberia, resulting in surface ozone levels compared to or larger than those observed in NHMLB air. Throughout the remaining part of year, the central North Eurasia represents a sink for tropospheric ozone on a hemispheric scale.

Research areas: Air Quality
Historical (17502014) anthropogenic emissions of reactive gases and aerosols from the Community Emissions Data System (CEDS) (2018)

Abstract. We present a new data set of annual historical (17502014) anthropogenic chemically reactive gases (CO, CH4, NH3, NOx, SO2, NMVOCs), carbonaceous aerosols (black carbon  BC, and organic carbon  OC), and CO2 developed with the Community Emissions Data System (CEDS). We improve upon existing inventories with a more consistent and reproducible methodology applied to all emission species, updated emission factors, and recent estimates through 2014. The data system relies on existing energy consumption data sets and regional and country-specific inventories to produce trends over recent decades. All emission species are consistently estimated using the same activity data over all time periods. Emissions are provided on an annual basis at the level of country and sector and gridded with monthly seasonality. These estimates are comparable to, but generally slightly higher than, existing global inventories. Emissions over the most recent years are more uncertain, particularly in low- and middle-income regions where country-specific emission inventories are less available. Future work will involve refining and updating these emission estimates, estimating emissions' uncertainty, and publication of the system as open-source software.

Research areas: Air Quality
Groundwater arsenic contamination in Burkina Faso, West Africa: Predicting and verifying regions at risk (2017)

Arsenic contamination in groundwater from crystalline basement rocks in West Africa has only been documented in isolated areas and presents a serious health threat in a region already facing multiple challenges related to water quality and scarcity. We present a comprehensive dataset of arsenic concentrations from drinking water wells in rural Burkina Faso (n=1498), of which 14.6% are above 10g/L. Included in this dataset are 269 new samples from regions where no published water quality data existed. We used multivariate logistic regression with arsenic measurements as calibration data and maps of geology and mineral deposits as independent predictor variables to create arsenic prediction models at concentration thresholds of 5, 10 and 50g/L. These hazard maps delineate areas vulnerable to groundwater arsenic contamination in Burkina Faso. Bedrock composed of schists and volcanic rocks of the Birimian formation, potentially harbouring arsenic-containing sulphide minerals, has the highest probability of yielding groundwater arsenic concentrations >10g/L. Combined with population density estimates, the arsenic prediction models indicate that ~560,000 people are potentially exposed to arsenic-contaminated groundwater in Burkina Faso. The same arsenic-bearing geological formations that are positive predictors for elevated arsenic concentrations in Burkina Faso also exist in neighbouring countries such as Mali, Ghana and Ivory Coast. This study's results are thus of transboundary relevance and can act as a trigger for targeted water quality surveys and mitigation efforts.

Research areas: Water Quality, Public Health
COVID-19 lockdown closures of emissions sources in India: Lessons for air quality and climate policy (2022)

Reduced anthropogenic activities during the COVID-19 pandemic caused significant reductions in ambient fine particulate matter (PM2.5), SO2 and NOx concentrations across India. However, tropospheric O3 concentrations spiked over many urban regions. Moreover, reductions in SO2 and NOx (atmospheric cooling agents) emissions unmask heating exerted by warming forcers. Basing governmental guidelines, we model daily emissions reductions in CO2 and short-lived climate forcers (SLCFs) during different lockdown periods using bottom-up regional emission inventory. The transport sector, with maximum level of closure, followed by power plants and industry reduced nearly 50% to 75% emissions of CO2, primary PM2.5, SO2 and NOx, while warming SLCFs (black carbon, CH4, CO and non-methane VOCs) showed insignificant reduction from continuing activity in residential and agricultural sectors. Consequently, the analysis indicates that reduction in the emission ratio of NOx to NMVOC coincided spatially with observed increases in O3, consistent with reduced uptake of O3 from night-time NOx reactions. Also, similar reductions, occurring for longer timescales (say, a year), can potentially increase the annual warming rate over India from the positive regional temperature response, estimated using climate metric. Further, by linking ongoing policies to sectoral reductions during lockdown, this study shows that the relative pacing of implementation among policies is crucial to avoid counter-productive results. A key policy recommendation is introduction and improving efficacy of programs targeting reduction of NMVOC and warming SLCF emissions (shifts away from biomass cooking technologies, household electrification and curbing open burning of crop residues), must precede the strengthening of policies targeting NOx and SO2 dominated sectors.

Research areas: Air Quality
Droughts augment youth migration in Northern Latin America and the Caribbean (2016)

While evidence on the linkages between migration and climate is starting to emerge, the subject remains largely under-researched at regional scale. Knowledge on the matter is particularly important for Northern Latin America and the Caribbean, a region of the world characterized by exceptionally high migration rates and substantial exposure to natural hazards. We link individual-level information from multiple censuses for eight countries in the region with natural disaster indicators constructed from georeferenced climate data at the province level to measure the impact of droughts and hurricanes on internal mobility. We find that younger individuals are more likely to migrate in response to these disasters, especially when confronted with droughts. Youth exhibit a stronger inclination towards relocating to rural and small town settings, motivated possibly by opportunities for nearby off-farm employment and financing limitations for urban transport and living expenses. Migration decisions are mediated by national institutional arrangements. These findings highlight the importance of social protection and regional planning policies to reduce the vulnerability of youth to droughts in the future and secure their economic integration.

Research areas: Droughts
SMAP L4 assessment of the US northern plains 2017 flash drought (2019)

A rapidly developing "flash drought" occurred over the US Northern Plains in the summer of 2017, spurred by unusually high temperatures and strong evaporative demand. The impacts of the drought included widespread reductions in rangeland and agricultural productivity that cascaded into significant economic losses. Here, we used satellite information from the NASA Soil Moisture Active Passive (SMAP) mission to clarify the nature and impact of the drought on regional vegetation growth. The model enhanced SMAP Level 4 Soil Moisture (L4SM) and Carbon (L4C) products were used with other ancillary data to examine spatial and seasonal anomalies in surface to root zone soil moisture and vegetation productivity (GPP). We find that the flash drought was triggered by a mid-July heat wave, conditioned by exceptionally low spring rainfall. The drought resulted in anomalous low soil moisture levels and regional GPP collapse, coinciding with severe (D3) to exceptional (D4) drought conditions indicated from the US Drought Monitor. The SMAP L4C GPP anomalies closely tracked reported county-level crop production anomalies for the major regional crop types, indicating generally larger productivity decline in managed croplands than surrounding natural areas. The SMAP L4 global products provide an effective indicator of vegetation growth changes and moisture-related restrictions on ecosystem productivity that are complementary with more traditional drought assessment tools.

Research areas: Droughts