Lightning is one of the main sources of NOx in the Earth's atmosphere. However, there is a large variability in NOx production during the lifetime of thunderstorms. In this study, we used the ...TROPOspheric Monitoring Instrument (TROPOMI) cloud and NO2 research products along with Lightning Mapping Array (LMA) measurements to investigate the possible relation between the amount of NOx produced per lightning flash and flash channel length in the Ebro Valley. We found that there is a positive relationship between both variables. In turn, the vertical structure of the analyzed lightning flashes indicates that longer flashes could release more LNOx at lower altitudes than shorter flashes, while higher flash rates produce less LNOx per flash.
Plain Language Summary
Lightning produces significant amounts of NOx in the Earth's atmosphere. However, the quantity of NOx generated during thunderstorms exhibits significant variation. In this study, we used a space‐based instrument called TROPOMI to look at clouds and measure NO2, and we also used a network of antennas called Lightning Mapping Array to map the spatial structure of lightning strikes. Our main goal was investigating if there is a connection between the amount of NOx produced by lightning and how long the lightning flashes were in the Ebro Valley. We found that there is a positive relationship between the two variables. We also looked at the structure of the lightning flashes and found that longer flashes release more NOx at lower altitudes compared to shorter flashes. Additionally, when there are more frequent lightning flashes, each flash produces less NOx.
Key Points
Lightning Mapping Array data reveals a positive correlation between lightning NOx production efficiency and the lightning flash lengths
The investigation of space‐based data demonstrates a negative correlation between lightning NOx production efficiency and flash frequency
Mean NOx per flash length obtained in this work vary between 1.9 × 1021 and 3.8 × 1021 molec NOx/m
Over the past 24 years, the AErosol RObotic NETwork (AERONET) program has provided highly accurate remote-sensing characterization of aerosol optical and physical properties for an increasingly ...extensive geographic distribution including all continents and many oceanic island and coastal sites. The measurements and retrievals from the AERONET global network have addressed satellite and model validation needs very well, but there have been challenges in making comparisons to similar parameters from in situ surface and airborne measurements. Additionally, with improved spatial and temporal satellite remote sensing of aerosols, there is a need for higher spatial-resolution ground-based remote-sensing networks. An effort to address these needs resulted in a number of field campaign networks called Distributed Regional Aerosol Gridded Observation Networks (DRAGONs) that were designed to provide a database for in situ and remote-sensing comparison and analysis of local to mesoscale variability in aerosol properties. This paper describes the DRAGON deployments that will continue to contribute to the growing body of research related to meso- and microscale aerosol features and processes. The research presented in this special issue illustrates the diversity of topics that has resulted from the application of data from these networks.
Based on multiple linear regression (MLR) models, we estimated the PM2.5 at Seoul using a number of aerosol optical depth (AOD) values obtained from ground-based and satellite remote sensing ...observations. To construct the MLR model, we consider various parameters related to the ambient meteorology and air quality. In general, all AOD values resulted in the high quality of PM2.5 estimation through the MLR method: mostly correlation coefficients >~0.8. Among various polar-orbit satellite AODs, AOD values from the MODIS measurement contribute to better PM2.5 estimation. We also found that the quality of estimated PM2.5 shows some seasonal variation; the estimated PM2.5 values consistently have the highest correlation with in situ PM2.5 in autumn, but are not well established in winter, probably due to the difficulty of AOD retrieval in the winter condition. MLR modeling using spectral AOD values from the ground-based measurements revealed that the accuracy of PM2.5 estimation does not depend on the selected wavelength. Although all AOD values used in this study resulted in a reasonable accuracy range of PM2.5 estimation, our analyses of the difference in estimated PM2.5 reveal the importance of utilizing the proper AOD for the best quality of PM2.5 estimation.
An intriguing natural phenomenon occurs every polar spring, namely the bromine explosion, in which plumes of tropospheric bromine monoxide (BrO) are formed. These plumes are observed in the BrO ...vertical column densities (VCDs), retrieved from satellite sensors. Tropospheric BrO depletes tropospheric ozone and facilitates the deposition of mercury. Bromine molecules are mainly released from young sea ice, and meteorological parameters determine the formation and evolution of enhanced BrO VCD plumes. Due to the complexity of the physicochemical processes involved in the bromine explosion, the modeling of tropospheric BrO VCDs in chemical transport models is challenging and not yet adequate. The first of its type, this study demonstrates the potential of using an artificial neural network (ANN), which uses meteorological parameters and sea ice age as inputs to simulate and predict tropospheric BrO VCDs in the Arctic. The ANN is trained and validated using a 22-year satellite remote sensing dataset of Arctic tropospheric BrO VCDs. A generally satisfactory spatial agreement between observed and simulated tropospheric BrO VCDs is observed. However, the magnitude of the observed BrO VCD plumes is underestimated. Air temperature and mean sea level pressure are the most important parameters influencing the magnitude of tropospheric BrO VCD simulations. Although the changing spatial distribution of tropospheric BrO VCDs over time is well captured, the trend reported in the observations of tropospheric BrO VCDs is not reproduced by the ANN, suggesting that additional parameters not included in the ANN also influence the formation of tropospheric BrO VCD plumes.
•The prediction of BrO plumes is required to assess the loss of tropospheric ozone•We present an artificial neural network, which simulates Arctic tropospheric BrO•The neural network reproduces spatial patterns of many tropospheric BrO plumes•The trend reported in the observations is not evident in the simulations
Every polar spring, phenomena called bromine explosions
occur over sea ice. These bromine explosions comprise photochemical
heterogeneous chain reactions that release bromine molecules, Br2, to
the ...troposphere and lead to tropospheric plumes of bromine monoxide, BrO.
This autocatalytic mechanism depletes ozone, O3, in the boundary layer
and troposphere and thereby changes the oxidizing capacity of the
atmosphere. The phenomenon also leads to accelerated deposition of metals
(e.g., Hg). In this study, we present a 22-year (1996 to 2017) consolidated
and consistent tropospheric BrO dataset north of 70∘ N, derived from
four different ultraviolet–visible (UV–VIS) satellite instruments (GOME, SCIAMACHY, GOME-2A and
GOME-2B). The retrieval data products from the different sensors are
compared during periods of overlap and show good agreement (correlations of
0.82–0.98 between the sensors). From our merged time series of
tropospheric BrO vertical column densities (VCDs), we infer changes in the
bromine explosions and thus an increase in the extent and magnitude of
tropospheric BrO plumes during the period of Arctic warming. We determined
an increasing trend of about 1.5 % of the tropospheric BrO VCDs per year
during polar springs, while the size of the areas where enhanced
tropospheric BrO VCDs can be found has increased about 896 km2 yr−1. We infer from comparisons and correlations with sea ice age data that
the reported changes in the extent and magnitude of tropospheric BrO VCDs
are moderately related to the increase in first-year ice extent in the
Arctic north of 70∘ N, both temporally and spatially, with a
correlation coefficient of 0.32. However, the BrO plumes and thus bromine
explosions show significant variability, which also depends, apart from sea
ice, on meteorological conditions.
During polar spring, ozone depletion events (ODEs) are often observed in combination with bromine explosion events (BEEs) in Ny-Ålesund. In this study, two long-term ozone data sets (2010–2021) from ...ozonesonde launches and in situ ozone measurements have been evaluated between March and May of each year to study ODEs in Ny-Ålesund. Ozone concentrations below 15 ppb were marked as ODEs. We applied a composite analysis to evaluate tropospheric BrO retrieved from satellite data and the prevailing meteorological conditions during these events. During ODEs, both data sets show a blocking situation with a low-pressure anomaly over the Barents Sea and anomalously high pressure in the Icelandic Low area, leading to transport of cold polar air from the north to Ny-Ålesund with negative temperature and positive BrO anomalies found around Svalbard. In addition, a higher wind speed and a higher, less stable boundary layer are noticed, supporting the assumption that ODEs often occur in combination with polar cyclones. Applying a 20 ppb ozone threshold value to tag ODEs resulted in only a slight attenuation of the BrO and meteorological anomalies compared to the 15 ppb threshold. Monthly analysis showed that BrO and meteorological anomalies are weakening from March to May. Therefore, ODEs associated with low-pressure systems, high wind speeds, and blowing snow more likely occur in early spring, while ODEs associated with low wind speed and stable boundary layer meteorological conditions seem to occur more often in late spring. Annual evaluations showed similar weather patterns for several years, matching the overall result of the composite analysis. However, some years show different meteorological patterns deviating from the results of the mean analysis. Finally, an ODE case study from the beginning of April 2020 in Ny-Ålesund is presented, where ozone was depleted for 2 consecutive days in combination with increased BrO values. The meteorological conditions are representative of the results of the composite analysis. A low-pressure system arrived from the northeast to Svalbard, resulting in high wind speeds with blowing snow and transport of cold polar air from the north.
Satellite observations have shown large areas of elevated bromine monoxide (BrO) covering several thousand square kilometres over the Arctic and Antarctic sea ice regions in polar spring. These ...enhancements of total BrO columns result from increases in stratospheric or tropospheric bromine amounts or both, and their occurrence may be related to local meteorological conditions. In this study, the spatial distribution of the occurrence of total BrO column enhancements and the associated changes in meteorological parameters are investigated in both the Arctic and Antarctic regions using 10 years of Global Ozone Monitoring Experiment-2 (GOME-2) measurements and meteorological model data. Statistical analysis of the data presents clear differences in the meteorological conditions between the 10-year mean and episodes of enhanced total BrO columns in both polar sea ice regions. These differences show pronounced spatial patterns. In general, atmospheric low pressure, cold surface air temperature, high surface-level wind speed, and low tropopause heights were found during periods of enhanced total BrO columns. In addition, spatial patterns of prevailing wind directions related to the BrO enhancements are identified in both the Arctic and Antarctic sea ice regions. The relevance of the different meteorological parameters on the total BrO column is evaluated based on a Spearman rank correlation analysis, finding that tropopause height and surface air temperature have the largest correlations with the total BrO vertical column density. Our results demonstrate that specific meteorological parameters can have a major impact on the BrO enhancement in some areas, but in general, multiple meteorological parameters interact with each other in their influence on BrO columns.
For more than 2 decades, satellite observations from instruments such as GOME, SCIAMACHY, GOME-2, and OMI have been used for the monitoring of bromine monoxide (BrO) distributions on global and ...regional scales. In October 2017, the TROPOspheric Monitoring Instrument (TROPOMI) was launched on board the Copernicus Sentinel-5 Precursor platform with the goal of continuous daily global trace gas observations with unprecedented spatial resolution. In this study, sensitivity tests were performed to find an optimal wavelength range for TROPOMI BrO retrievals under various measurement conditions. From these sensitivity tests, a wavelength range for TROPOMI BrO retrievals was determined and global data for April 2018 as well as for several case studies were retrieved. Comparison with GOME-2 and OMI BrO retrievals shows good consistency and low scatter of the columns. The examples of individual TROPOMI overpasses show that due to the better signal-to-noise ratio and finer spatial resolution of 3.5×7 km2, TROPOMI BrO retrievals provide good data quality with low fitting errors and unique information on small-scale variabilities in various BrO source regions such as Arctic sea ice, salt marshes, and volcanoes.
In recent decades, there has been an increasing interest in making use of satellite measurements for identifying trends in atmospheric composition and climate. Instruments like GOME-2 and TROPOMI are ...dedicated to air-quality and global trace gas monitoring. For the accurate retrieval of columnar information of the trace gases, cloud correction is necessary. This work is meant to examine the quality of the GOME-2 operational cloud product from AC SAF and to propose enhancements of the current dataset to improve the retrieval of the NO2 and HCHO tropospheric gases.
Bromine monoxide (BrO) plays an important role in tropospheric chemistry. The state‐of‐the‐science TROPOspheric Monitoring Instrument (TROPOMI) offers the potential to monitor atmospheric composition ...with a fine spatial resolution of up to 5.5 × 3.5 km2. We present here the retrieval of tropospheric BrO columns from TROPOMI. We implement a stratospheric correction scheme using a climatological approach based on the latest GEOS‐Chem High Performance chemical transport model, and improve the tropospheric air mass factor calculation with TROPOMI surface albedo data accounting for the geometrical dependency. Our product presents a good level of consistency in comparison with measurements from ground‐based zenith‐sky differential optical absorption spectroscopy (r = 0.67), aircrafts (r = 0.46), and satellites (similar spatial distributions of BrO columns). Furthermore, our retrieval captures BrO enhancements in the polar springtime with values up to 7.8 × 1013 molecules cm−2 and identifies small‐scale emission sources such as volcanoes and salt marshes. Based on TROPOMI data, we probe a blowing snow aerosol bromine mechanism in which the snow salinity is reduced to better match simulation and observation. Our TROPOMI tropospheric BrO product contributes high‐resolution global information to studies investigating atmospheric bromine chemistry.
Plain Language Summary
Bromine monoxide (BrO) is an important species that affects the global chemistry of the troposphere. However, global observations of tropospheric BrO remain challenging and limited due to the short lifetime and low abundance. In this study, we present a global high‐spatial‐resolution tropospheric BrO column product from the TROPOspheric Monitoring Instrument. We describe the retrieval algorithm and present a comprehensive verification and evaluation. In addition, we use the data set to investigate sources and sinks on a daily scale for measurement scenarios of BrO enhancements, such as polar sea ice, volcanic plumes, and salt marshes. We additionally optimize salinity, the key parameter in modeling blow snow aerosol bromine emissions, by comparing simulation and observation. Our work provides unique information to studies exploring atmospheric bromine chemistry.
Key Points
We present the retrieval and evaluation of tropospheric BrO columns from TROPOspheric Monitoring Instrument (TROPOMI)
Our high‐resolution BrO product identifies small‐scale emission sources on a daily scale
A blowing snow aerosol bromine scheme with reduced snow salinity improves agreement between the model and TROPOMI
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