Air pollution disproportionately burdens communities of color and lower‐income communities in US cities. We have generally lacked city‐wide concentration measurements that resolve the steep ...spatiotemporal gradients of primary pollutants required to describe intra‐urban air pollution inequality. Here, we use observations from the recently launched TROPospheric Ozone Monitoring Instrument (TROPOMI) satellite sensor and physics‐based oversampling to describe nitrogen dioxide (NO2) disparities with race, ethnicity, and income in 52 US cities (June 2018–February 2020). We report average US‐urban census tract‐level NO2 inequalities of 28 ± 2% (race‐ethnicity and income combined), with many populous cities experiencing even greater inequalities. Using observations and inventories, we find diesel traffic is the dominant source of NO2 disparities, and that a 62% reduction in diesel emissions would decrease race‐ethnicity and income inequalities by 37%. We add evidence that TROPOMI resolves tract‐scale NO2 differences using relationships with urban segregation patterns and spatial variability in column‐to‐surface correlations.
Plain Language Summary
People of color and people with lower household incomes commonly experience higher levels of air pollution and worsened health burdens from poor air quality in US cities. We have lacked direct observations of air pollution across cities with which to describe, explain, and guide policymaking on air pollution disparities. Nitrogen dioxide is an important combustion pollutant that is co‐emitted with many other toxic pollutants, and its concentrations are highly variable between neighborhoods. Here, we use nitrogen dioxide measurements collected from space by the TROPospheric Ozone Monitoring Instrument (TROPOMI) to describe inequalities within 52 US cities. TROPOMI captures greater spatial detail than previously possible, and the near‐daily data collection allows for interpretation of the specific polluting sources causing nitrogen dioxide inequality, including diesel traffic emissions. Because satellite applications for air pollution inequality analyses are nascent, we build on our past work to advance understanding of the extent to which TROPOMI resolves inter‐neighborhood nitrogen dioxide differences.
Key Points
On average, urban NO2 inequalities of ∼28% are observed with race‐ethnicity and income; disparities are much greater in many cities
Diesel traffic is the dominant source of NO2 disparities; a 62% reduction in diesel emissions would decrease inequalities by more than 37%
TROPOMI observations combined with oversampling resolve surface patterns in NO2 disparities at the census‐tract scale
Aura Microwave Limb Sounder (MLS) measurements show that chemical processing was critical to the observed record‐low Arctic stratospheric ozone in spring 2020. The 16‐year MLS record indicates more ...polar denitrification and dehydration in 2019/2020 than in any Arctic winter except 2015/2016. Chlorine activation and ozone depletion began earlier than in any previously observed winter, with evidence of chemical ozone loss starting in November. Active chlorine then persisted as late into spring as it did in 2011. Empirical estimates suggest maximum chemical ozone losses near 2.8 ppmv by late March in both 2011 and 2020. However, peak chlorine activation, and thus peak ozone loss, occurred at lower altitudes in 2020 than in 2011, leading to the lowest Arctic ozone values ever observed at potential temperature levels from ∼400–480 K, with similar ozone values to those in 2011 at higher levels.
Plain Language Summary
Unlike the Antarctic, the Arctic does not usually experience an ozone hole because temperatures are often too high for the chemistry that destroys ozone. In 2019/2020, satellite measurements show record‐low stratospheric wintertime temperatures and record‐low springtime ozone concentrations in the Arctic lower stratosphere (about 12‐ to 20‐km altitude). Only one other winter/spring season, 2010/2011, in this 16‐year satellite data record comes close. Low temperatures, which result in chlorine being converted from nonreactive forms into forms that destroy ozone, started earlier than in any previous Arctic winter in the record and lingered later than in any year except 2011. The ozone‐destroying chemistry in 2019/2020 occurred at lower altitudes (where more of the ozone that filters out harmful ultraviolet radiation resides) than in 2010/2011. Such extensive ozone loss can have important health and biological impacts because it leads to more ultraviolet radiation reaching the Earths surface. While the success of the Montreal Protocol in limiting human emissions that increase ozone‐destroying gases in the stratosphere has resulted in much less Arctic ozone destruction than we would have otherwise had, future temperature changes could lead to other winters with even more chemical ozone depletion than in 2019/2020.
Key Points
MLS trace gas data show that exceptional polar vortex conditions led to record‐low ozone in the Arctic lower stratosphere in 2019/2020
Early and persistent cold conditions led to the longest period with chlorine in ozone‐destroying forms in the 16‐year MLS data record
Chemical ozone destruction began earlier than in any Arctic winter in the MLS record and ended later than in any year except 2010/2011
One of the multi-facet impacts of lockdowns during the unprecedented COVID-19 pandemic was restricted economic and transport activities. This has resulted in the reduction of air pollution ...concentrations observed globally. This study is aimed at examining the concentration changes in air pollutants (i.e., carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and particulate matters (PM2.5 and PM10) during the period March–April 2020. Data from both satellite observations (for NO2) and ground-based measurements (for all other pollutants) were utilized to analyze the changes when compared against the same months between 2015 and 2019. Globally, space borne NO2 column observations observed by satellite (OMI on Aura) were reduced by approximately 9.19% and 9.57%, in March and April 2020, respectively because of public health measures enforced to contain the coronavirus disease outbreak (COVID-19). On a regional scale and after accounting for the effects of meteorological variability, most monitoring sites in Europe, USA, China, and India showed declines in CO, NO2, SO2, PM2.5, and PM10 concentrations during the period of analysis. An increase in O3 concentrations occurred during the same period. Meanwhile, four major cities case studies i.e. in New York City (USA), Milan (Italy), Wuhan (China), and New Delhi (India) have also shown a similar reduction trends as observed on the regional scale, and an increase in ozone concentration. This study highlights that the reductions in air pollutant concentrations have overall improved global air quality likely driven in part by economic slowdowns resulting from the global pandemic.
•Global NO2 column observations were reduced by approximately 9.19% (March) and 9.57% (April) due to COVID 19 lockdown.•Most monitoring sites in Europe, USA, China, and India showed declines in pollutant concentrations during analysis.•Four major cities case studies also shown a similar reduction trends and an increase in ozone concentration.
Marine low clouds are one of the greatest sources of uncertainty for climate projection. We present an observed climatology of cloud albedo susceptibility to cloud droplet number concentration ...perturbations (S0) with changing sea surface temperature (SST) and estimated inversion strength for single‐layer warm clouds over the North Atlantic Ocean, using eight years of satellite and reanalysis data. The key findings are that SST has a dominant control on S0 in the presence of co‐varying synoptic conditions and aerosol perturbations. Regions conducive to aerosol‐induced darkening (brightening) clouds occur with high (low) local SST. Higher SST significantly hastens cloud‐top evaporation with increasing aerosol loading, by accelerating entrainment and facilitating entrainment drying. In a global‐warming‐like scenario where aerosol loading is reduced, less cloud darkening is expected, mainly as a result of reduced entrainment drying. Our results imply a less positive low‐cloud liquid water path feedback in a warmer climate with decreasing aerosol loading.
Plain Language Summary
Low clouds over the ocean are a poorly quantified component of the climate system. Here we use eight years of space‐based measurements and meteorological data to quantify how the brightness of single‐layer low clouds over the North Atlantic Ocean might respond to cloud droplet number concentration perturbations in a warmer world. We find that under higher sea surface temperatures, increases in drop number tend to reduce cloud brightness by accelerating evaporation of cloud water. Thus in a warmer world, low clouds will reflect less energy to space in response to an increase in aerosol loading. If aerosol sources decrease then we expect more robust clouds and more offsetting of greenhouse gas warming.
Key Points
Sea surface temperature (SST) has a strong influence on the relative occurrence of aerosol‐induced brightness of clouds over the North Atlantic Ocean
Aerosol perturbations are locally confined and have less influence on the brightness of clouds compared to SST
In a warmer climate where aerosol loading is reduced, we expect a less positive liquid water path feedback
Electron heating at collisionless shocks in space is a combination of adiabatic heating due to large‐scale electric and magnetic fields and non‐adiabatic scattering by high‐frequency fluctuations. ...The scales at which heating happens hints to what physical processes are taking place. In this letter, we study electron heating scales with data from the Magnetospheric Multiscale (MMS) spacecraft at Earth's quasi‐perpendicular bow shock. We utilize the tight tetrahedron formation and high‐resolution plasma measurements of MMS to directly measure the electron temperature gradient. From this, we reconstruct the electron temperature profile inside the shock ramp and find that the electron temperature increase takes place on ion or sub‐ion scales. Further, we use Liouville mapping to investigate the electron distributions through the ramp to estimate the deHoffmann‐Teller potential and electric field. We find that electron heating is highly non‐adiabatic at the high‐Mach number shocks studied here.
Plain Language Summary
Shock waves appear whenever a supersonic medium, such as a plasma, encounters an obstacle. The plasma, which consists of charged ions and free electrons, is heated by the shock wave through interactions with the electromagnetic fields. In this work, we investigate how electrons are heated at plasma shocks. A key parameter to electron heating is the thickness of the layer where the heating takes place. Here, we use observations from the four Magnetospheric Multiscale spacecraft that regularly cross the standing bow shock that forms when the supersonic plasma, known as the solar wind, encounters Earth's magnetic field. We find that the thickness of the shock is larger than previously reported and is on the scales where ion physics dominate. We also find that the electron heating deviates significantly from simple adiabatic heating.
Key Points
Using multipoint data from Magnetospheric Multiscale, we find that electron heating takes place on ion scales in the quasi‐perpendicular shock ramp
We show that the time series of the temperature does not represent the spatial profile due to varying shock ramp speed
Electron distributions in the ramp and downstream of the shock show that electrons are heated non‐adiabatically
Numerical circulation modeling and observational studies have been conducted to understand the Loop Current (LC) system behaviors in the Gulf of Mexico (GoM). One of the factors that may influence ...the LC are upstream eddies from within the Caribbean Sea. By combining satellite altimetry, sea surface salinity and ocean color data, we demonstrate that mesoscale eddies from the western tropical Atlantic Ocean can eventually make their way to the Gulf of Mexico and likely affect the LC. In addition, our study shows that freshwater of Amazon and Orinoco River origin trapped within mesoscale eddies can also enter the GoM, potentially affecting the GoM stratification. This study provides insights into understanding variations of the LC system and showcases the roles of mesoscale eddies in connecting the open ocean and regional seas.
Plain Language Summary
The Loop Current (LC) is the dominant large‐scale oceanic process in the Gulf of Mexico (GoM). However, the mechanism for variations of the LC system is still unsolved. Here, we show that some mesoscale eddies originated in the tropical Atlantic Ocean can pass through the Caribbean Sea and eventually enter the GoM. These remotely generated eddies could be an important upstream factor affecting the behavior of the LC. Also, freshwater and other materials (e.g., chlorophyll) trapped in the eddies could reach the GoM as well. In addition to advancing the understanding of the LC system, this study provides an explicit example showing eddies can serve as a route connecting regional seas and the open ocean.
Key Points
Some eddies from the Atlantic Ocean can ultimately reach the Gulf of Mexico and likely affect the Loop Current
Freshwater of Amazon and Orinoco River origin and other materials trapped in eddies could reach the Gulf of Mexico
Weakening and strengthening of the long‐propagating eddies are mostly related to the variation of bathymetry
Much effort has been made to increase the integration of solar photovoltaic (PV) systems to reduce the environmental impacts of fossil fuels. An essential process in PV systems is the forecasting of ...solar irradiance to avoid safety and stability problems due to its intermittent nature. Most of the research has been focused on improving the prediction accuracy based on the assumption that enough on-site training data are available. However, in many situations, it is required for the implementation of PV systems in locations where not enough solar irradiance measurements have been collected. Our hypothesis is that measurements from other sites can be used to train accurate forecasting models, given an appropriate definition of site similarity. We propose a methodology that takes information from exogenous variables that are correlated to on-site solar irradiance and constructs a multidimensional space equipped with a metric. Each site is a point in this space, and the learned metric is used to select those sites that can provide measurements to train an accurate forecasting model on an unobserved site. We show through experiments with real data that using the learned metric provides better predictions than using the measurements collected from the whole set of available sites.
•On-site measurements required to forecast solar irradiance are not always available.•Data from observed sites can be used to train accurate models for an unobserved one.•Distance between sites can be measured using geographical and weather conditions.•Feature importance can be used to determine the sites to consider on the training.
•Differences in the Samsung Galaxy series smartphones positioning accuracy.•Brand-new smartphone models do not always provide better positioning results.•No clear positioning accuracy improvement ...with the third GNSS system (BeiDou).•Compliance with the IMO and FRP17 maritime navigation accuracy thresholds.
One of the most popular functions of modern mobile phones is determining the coordinates of the device using built-in GNSS receivers. By using map images extensively available on the Internet, today's smartphones have become basic navigation devices of the average user.
Mobile devices with built-in GNSS receivers are primarily used in land navigation. However, marine sailing, tourism and recreation are fields where the use of mobile phones as navigation devices is also very common. The average position errors of GNSS receivers mounted on smartphones decisively influence the ability and accuracy of navigation based on those devices.
This publication analyses the accuracy of the dynamic positioning of six Samsung Galaxy smartphones during vessel manoeuvring. As part of the parallel tracking studies, the telephone positions were compared to those of precise GNSS receivers, using corrections from an active geodetic network with an accuracy of 2–3 cm (p = 0.95). As a result of the 4-h measurement, the accuracy statistics for each of the phone models were defined based on approximately 10,000 positions. Studies indicate that there are significant differences in the accuracy of positioning as performed by the models in question.
Urban air pollution disproportionately harms communities of color and low-income communities in the U.S. Intraurban nitrogen dioxide (NO2) inequalities can be observed from space using the ...TROPOspheric Monitoring Instrument (TROPOMI). Past research has relied on time-averaged measurements, limiting our understanding of how neighborhood-level NO2 inequalities co-vary with urban air quality and climate. Here, we use fine-scale (250 m × 250 m) airborne NO2 remote sensing to demonstrate that daily TROPOMI observations resolve a major portion of census tract-scale NO2 inequalities in the New York City–Newark urbanized area. Spatiotemporally coincident TROPOMI and airborne inequalities are well correlated (r = 0.82–0.97), with slopes of 0.82–1.05 for relative and 0.76–0.96 for absolute inequalities for different groups. We calculate daily TROPOMI NO2 inequalities over May 2018–September 2021, reporting disparities of 25–38% with race, ethnicity, and/or household income. Mean daily inequalities agree with results based on TROPOMI measurements oversampled to 0.01° × 0.01° to within associated uncertainties. Individual and mean daily TROPOMI NO2 inequalities are largely insensitive to pixel size, at least when pixels are smaller than ∼60 km2, but are sensitive to low observational coverage. We statistically analyze daily NO2 inequalities, presenting empirical evidence of the systematic overburdening of communities of color and low-income neighborhoods with polluting sources, regulatory ozone co-benefits, and worsened NO2 inequalities and cumulative NO2 and urban heat burdens with climate change.
The main objective of this work was to evaluate the nearshore wind resources in the Black Sea area by using a high resolution wind database (ERA-Interim). A subsequent objective was to estimate what ...type of wind turbines and wind farm configurations would be more suitable for this coastal environment. A more comprehensive picture of these resources was provided by including some satellite measurements, which were also used to assess the wind conditions in the vicinity of some already operating European wind projects. Based on the results of the present work, it seems that the Crimea Peninsula has the best wind resources. However, considering the current geopolitical situation, it seems that the sites on the western part of this basin (Romania and Bulgaria) would represent more viable locations for developing offshore wind projects. Since there are currently no operational wind projects in this marine area, some possible configurations for the future wind farms are proposed.
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