scholarly journals Assessing Measurements of Pollution in the Troposphere (MOPITT) carbon monoxide retrievals over urban versus non-urban regions

2020 ◽  
Vol 13 (3) ◽  
pp. 1337-1356 ◽  
Author(s):  
Wenfu Tang ◽  
Helen M. Worden ◽  
Merritt N. Deeter ◽  
David P. Edwards ◽  
Louisa K. Emmons ◽  
...  
Keyword(s):  
Air Quality ◽  
Correlation Coefficients ◽  
Atmospheric Composition ◽  
Aircraft Measurements ◽  
Urban Regions ◽  
Model Based ◽  
Chemistry Research ◽  
Aircraft Observations ◽  
Co Concentrations

Abstract. The Measurements of Pollution in the Troposphere (MOPITT) retrievals over urban regions have not been validated systematically, even though MOPITT observations are widely used to study CO over urban regions. Here we compare MOPITT products over urban and non-urban regions with aircraft measurements from the Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ – 2011–2014), Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS – 2013), Air Chemistry Research In Asia (ARIAs – 2016), A-FORCE (2009, 2013), and Korea United States Air Quality (KORUS-AQ – 2016) campaigns. In general, MOPITT agrees reasonably well with the in situ profiles, over both urban and non-urban regions. Version 8 multispectral product (V8J) biases vary from −0.7 % to 0.0 % and version 8 thermal-infrared product (TIR) biases vary from 2.0 % to 3.5 %. The evaluation statistics of MOPITT V8J and V8T over non-urban regions are better than those over urban regions with smaller biases and higher correlation coefficients. We find that the agreement of MOPITT V8J and V8T with aircraft measurements at high CO concentrations is not as good as that at low CO concentrations, although CO variability may tend to exaggerate retrieval biases in heavily polluted scenes. We test the sensitivities of the agreements between MOPITT and in situ profiles to assumptions and data filters applied during the comparisons of MOPITT retrievals and in situ profiles. The results at the surface layer are insensitive to the model-based profile extension (required due to aircraft altitude limitations), whereas the results at levels with limited aircraft observations (e.g., the 600 hPa layer) are more sensitive to the model-based profile extension. The results are insensitive to the maximum allowed time difference criterion for co-location (12, 6, 3, and 1 h) and are generally insensitive to the radius for co-location, except for the case where the radius is small (25 km), and hence few MOPITT retrievals are included in the comparison. Daytime MOPITT products have smaller overall biases than nighttime MOPITT products when comparing both MOPITT daytime and nighttime retrievals to the daytime aircraft observations. However, it would be premature to draw conclusions on the performance of MOPITT nighttime retrievals without nighttime aircraft observations. Applying signal-to-noise ratio (SNR) filters does not necessarily improve the overall agreement between MOPITT retrievals and in situ profiles, likely due to the reduced number of MOPITT retrievals for comparison. Comparisons of MOPITT retrievals and in situ profiles over complex urban or polluted regimes are inherently challenging due to spatial and temporal variabilities of CO within MOPITT retrieval pixels (i.e., footprints). We demonstrate that some of the errors are due to CO representativeness with these sensitivity tests, but further quantification of representativeness errors due to CO variability within the MOPITT footprint will require future work.

scholarly journals Validation of MOPITT Carbon Monoxide (CO) retrievals over urban regions

2019 ◽  
Author(s):  
Wenfu Tang ◽  
Helen M. Worden ◽  
Merritt N. Deeter ◽  
David P. Edwards ◽  
Louisa K. Emmons ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Correlation Coefficients ◽  
Urban Regions ◽  
Model Based ◽  
Sensitivity Tests ◽  
Aircraft Observations ◽  
Future Work ◽  
Co Concentrations ◽  
Better Than

Abstract. The performance of the Measurements of Pollution in the Troposphere (MOPITT) retrievals over urban regions has not been validated systematically, even though MOPITT observations are widely used to study CO over urban regions. Here we validate MOPITT products over urban regions using aircraft measurements from DISCOVER-AQ, SEAC4RS, ARIAs, A-FORCE, and KORUS-AQ campaigns. Overall, MOPITT performs reasonably well over both urban and non-urban regions, overall biases for V8J and V8T vary from −0.7 % to 0.0 %, and from 2.0 % to 3.5 %, respectively. The evaluation statistics of MOPITT V8J and V8T over non-urban regions are better than that over urban regions with smaller biases and higher correlation coefficients. We find that the performance of MOPITT V8J and V8T at high CO concentrations is not as good as that at low CO concentrations, although CO variability may tend to exaggerate retrieval biases in heavily-polluted scenes. We test the sensitivities of validation results to assumptions and data filters applied during the comparisons of MOPITT retrievals and in-situ profiles. The results at the surface are insensitive to the model-based profile extension (required due to aircraft altitude limitations) whereas the results at levels with limited aircraft observations are more sensitive to the model-based profile extension. The validation results are insensitive to the allowed maximum time difference as criteria for co-location (12 hours, 6 hours, 3 hours, and 1 hour), and are generally insensitive to the radius for co-location, except for the case where the radius is small (25 km) and hence the MOPITT retrievals included in the validation become very small. Daytime MOPITT products have overall smaller biases than nighttime MOPITT products when comparing both MOPITT daytime and nighttime retrievals to the daytime aircraft observations. However, it would be premature to draw conclusions on the performance of MOPITT nighttime retrievals without nighttime aircraft observations. Applying signal-to-noise ratio (SNR) filters does not necessarily improve the overall agreement between MOPITT retrievals and in-situ profiles, likely due to the reduced number of MOPITT retrievals that result for comparison. Comparisons of MOPITT retrievals and in-situ profiles over complex urban or polluted regimes are inherently challenging due to spatial and temporal variabilities of CO within MOPITT retrieval pixels (i.e., footprints). We demonstrate the some of that errors are due to CO representativeness with these sensitivity tests, but further quantification of validation errors due to CO variability within the MOPITT footprint will require future work.

scholarly journals Characterizing mega-city pollution with TES O<sub>3</sub> and CO measurements

2007 ◽  
Vol 7 (5) ◽  
pp. 15189-15212 ◽  
Author(s):  
C. Shim ◽  
Q. Li ◽  
M. Luo ◽  
S. Kulawik ◽  
H. Worden ◽  
...  
Keyword(s):  
Mexico City ◽  
Metropolitan Area ◽  
Correlation Coefficients ◽  
In Situ Measurements ◽  
Vertical Profiles ◽  
Aircraft Measurements ◽  
Aircraft Observations ◽  
In Situ Observations ◽  
Pollution Events

Abstract. Concurrent tropospheric O3 and CO vertical profiles from the Tropospheric Emission Spectrometer (TES) during the MILAGRO/INTEX-B aircraft campaigns over the Mexico City Metropolitan Area (MCMA) allow us to characterize mega-city pollution. Outflow from the MCMA occurred predominantly at 600–800 hPa, evident in O3, CO, and NOx enhancements in the in situ observations. We examined O3, CO, and their correlation at 600–800 hPa from TES retrievals, aircraft measurements, and GEOS-Chem model results over the aircraft coverage (within a radius of ~700 km around MCMA). The enhancements in O3 and CO seen in the in situ measurements are not apparent in TES data, due to the lack of TES coverage during several strong pollution events. However, TES O3 and CO data are consistent with the aircraft observations on a daily mean basis (50–60 ppbv and 100–130 ppbv for O3 and CO respectively). The O3-CO correlation coefficients and enhancement ratios (ΔO3/ΔCO) derived from TES data are in good agreements with those derived from the aircraft observations and GEOS-Chem model results (r : 0.5–0.9; ΔO3/ΔCO: 0.3–0.4), reflecting significant springtime photochemical production over MCMA and the surrounding region.

scholarly journals Response of atmospheric composition to COVID-19 lockdown measures during Spring in the Paris region (France)

2021 ◽  
Author(s):  
Jean-Eudes Petit ◽  
Jean-Charles Dupont ◽  
Olivier Favez ◽  
Valérie Gros ◽  
Yunjiang Zhang ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Meteorological Conditions ◽  
In Situ Monitoring ◽  
Pollutant Emissions ◽  
Atmospheric Composition ◽  
Secondary Pollutants ◽  
The Impact ◽  
Mitigation Policies

Abstract. Since early 2020, the COVID-19 pandemic has led to lockdowns at national scales. These lockdowns resulted in large cuts of atmospheric pollutant emissions, notably related to the vehicular traffic source where daily commuting of light-duty vehicles was almost completely stopped in numerous urban areas worldwide, especially during Spring 2020. As a result, air quality changed in manners that are still currently under investigation. Long-term in-situ monitoring of atmospheric composition provides, to this perspective, essential information. However, a robust quantitative assessment of the impact of lockdown measures on ambient concentrations is hindered by weather variability. Basic comparisons with previous years may thus be flawed, especially regarding secondary pollutants, whose concentrations strongly depends on meteorological conditions. In order to circumvent this difficulty, an innovative methodology has been developed. The Analog Application for Air Quality (A3Q) method is based on the comparison of each day of lockdown to a group of analog days having similar meteorological conditions. The A3Q method has been successfully evaluated and applied to a comprehensive in-situ dataset of primary and secondary pollutants obtained at the SIRTA observatory, a suburban background site of the Paris megacity (France). The overall slight decrease of PM1 concentrations (−14 %) compared to business-as-usual conditions conceals contrasting behaviours. Primary traffic tracers (NOx and traffic-related carbonaceous aerosols) dropped by 42–66 % during the lockdown period. Further, the A3Q method enabled us to characterize of changes triggered by NOx decreases. Particulate nitrate and secondary organic aerosols (SOA), two of the main springtime aerosol components in North-Western Europe, decreased by −45 % and −25 %, respectively. A NOx-relationship emphasizes the interest of NOx mitigation policies at the regional (i.e. city) scale, although long-range pollution advection sporadically overcompensated regional decreases. Variations of the oxidation state of SOA suggests discrepancies in SOA formation processes. At the same time, the expected ozone increase (+20 %) underlines the negative feedback of NO titration. These results provide a quasi-comprehensive observation-based insight on mitigation policies regarding air quality in future low-carbon urban areas.

scholarly journals Retrieval of Metop-A/IASI N2O Profiles and Validation with NDACC FTIR Data

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 219
Author(s):  
Brice Barret ◽  
Yvan Gouzenes ◽  
Eric Le Flochmoen ◽  
Sylvain Ferrant
Keyword(s):  
Vertical Profile ◽  
Correlation Coefficients ◽  
Atmospheric Composition ◽  
Spectral Window ◽  
Mixing Ratios ◽  
Geographical Variability ◽  
Composition Changes ◽  
Better Than ◽  
Good Agreement

This paper reports atmospheric profiles of N2O retrieved from Metop/IASI with the Software for the Retrieval of IASI Data (SOFRID) for the 2008–2018 period and their validation with FTIR data from 12 stations of the Network for the Detection of Atmospheric Composition Changes (NDACC). SOFRID retrievals performed in the 2160–2218 cm−1 spectral window provide 3 independent pieces of information about the vertical profile of N2O. The FTIR versus SOFRID comparisons display a better agreement in the mid-troposphere (MT, 700–350 hPa) than in the lower (LT, Surface–700 hPa) and upper (UT, 350–110 hPa) troposphere with correlation coefficients (R) in the 0.49–0.83 range and comparable variabilities (3–5 ppbv). The agreement for oceanic and coastal stations (R > 0.77) is better than for continental ones (R < 0.72). The SOFRID MT N2O mixing ratios are significantly biased high (up to 16.8 ppbv) relative to FTIR at continental stations while the biases remain below 4.2 ppbv and mostly unsignificant when oceanic data are considered. The average MT decadal trends derived from SOFRID at the 8 NDACC stations with continuous observations during the 2008–2018 period (1.05 ± 0.1 ppbv·yr−1) is in good agreement with the corresponding FTIR trends (1.08 ± 0.1 ppbv·yr−1) and the NOAA-ESRL trends from surface in-situ measurements (0.95 ± 0.02 ppbv·yr−1). In the Northern Hemisphere where they are clearly detected, the N2O MT seasonal variations from SOFRID and FTIR are phased (summer minima) and have similar amplitudes. SOFRID also detects the UT summer maxima indicating independent MT and UT information. The global MT N2O oceanic distributions from SOFRID display low geographical variability and are mainly characterized by enhanced tropical mixing ratios relative to mid and high latitudes.

An overview of ACTRIS observational data in relation to the 2020 lockdown period in Europe

2021 ◽  
Author(s):  
Giulia Saponaro ◽  
Cathrine Lund Myhre ◽  
Markus Fiebig ◽  
Ewan O'Connor ◽  
Lucia Mona ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Air Quality ◽  
Trace Gases ◽  
Research Infrastructure ◽  
Atmospheric Composition ◽  
World Health ◽  
Quality Data ◽  
Data Set ◽  
Aerosol Remote Sensing

&lt;p&gt;The identification of the severe COVID-19 virus in December 2019 led the World Health Organization to declare a global pandemic by March 2020. Up till recently with the first available vaccines, the only prevention measures include strict social, travel and working restrictions in a so-called lockdown period that lasted for several weeks (mid-March to the end of April 2020 for most of Europe). This abrupt change in social behaviour is expected to impact local but also regional atmospheric composition, and the environmental impact is highly interesting to study.&lt;/p&gt;&lt;p&gt;The Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS) is a pan-European research infrastructure producing high-quality data and information on short-lived atmospheric constituents and on the processes leading to the variability of these constituents in natural and controlled atmospheres. ACTRIS integrates, harmonizes, and distributes datasets, activities, and services provided by the Central Facilities and National Facilities, located in 22 European countries.&amp;#160;&lt;/p&gt;&lt;p&gt;During the lockdown period in spring 2020 most of the ACTRIS observational were operational. The National Facilities performing the ambient measurements are generally regional background sites, with the aim to detect changes on regional level. Within the context of the current COVID-19 outbreak, ACTRIS has been continuously providing access to data on air quality and atmospheric composition. This is of particular interest and importance as it provides unique information measured from the ground to assess the European air quality and atmospheric composition during the lockdown complementing, in a fundamental way, satellite observations and modelling analysis.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;ACTRIS released a comprehensive and quality assured set of atmospheric measurement data during the COVID-19 pandemic spring 2020 &amp;#8211; January&amp;#8211; May 2020. This includes:&lt;/p&gt;&lt;ul&gt;- 30 sites with aerosol in situ measurements providing mainly absorption and scattering coefficient, size and/or number distribution. A few sites with high time solution aerosol chemical composition;&lt;/ul&gt;&lt;ul&gt;- 12 sites with trace gases in situ data providing VOCs and NOX measurements;24 sites with aerosol remote sensing data providing profiles with backscattering and extinction coefficient;&lt;/ul&gt;&lt;ul&gt;- 11 cloud remote sensing sites providing profile information of 9 various cloud properties.&lt;/ul&gt;&lt;p&gt;To facilitate studies, ACTRIS has compiled the data and coined a DOI for the data sets measured during the COVID-19 spring lockdown period, including an intensive aerosol remote sensing campaign in May. This presentation will present the data set and the potential applications and benefits using ACTRIS COVID-19 dataset for studying atmospheric composition changes during COVID-19 lockdown periods.&lt;/p&gt;

scholarly journals In Situ Aircraft Measurements of CO2 and CH4: Mapping Spatio-Temporal Variations over Western Korea in High-Resolutions

2020 ◽  
Vol 12 (18) ◽  
pp. 3093
Author(s):  
Shanlan Li ◽  
Youngmi Kim ◽  
Jinwon Kim ◽  
Samuel Takele Kenea ◽  
Tae-Young Goo ◽  
...  
Keyword(s):  
Correlation Coefficients ◽  
Background Level ◽  
Temporal Variations ◽  
Central China ◽  
The Yellow Sea ◽  
Aircraft Measurements ◽  
Short Term ◽  
Regression Slope ◽  
North Western

A cavity ring-down spectroscopy (CRDS) G-2401m analyzer onboard a Beechcraft King Air 350, a new Korean Meteorological Administration (KMA) research aircraft measurement platform since 2018, has been used to measure in situ CO2, CH4, and CO. We analyzed the aircraft measurements obtained in two campaigns: a within-boundary layer survey over the western Republic of Korea (hereafter Korea) for analyzing the CO2 and CH4 emission characteristics for each season (the climate change monitoring (CM) CM mission), and a low altitude survey over the Yellow Sea for monitoring the pollutant plumes transported into Korea from China (the environment monitoring (EM) mission). This study analyzed CO2, CH4, and CO data from a total of 14 flights during 2019 season. To characterize the regional combustion sources signatures of CO2 and CH4, we calculated the short-term (1-min slope based on one second data) regression slope of CO to CO2 and CH4 to CO enhancements (subtracted with background level, present as ∆CO, ∆CO2, and ∆CH4); slope filtered with correlation coefficients (R2) (<0.4 were ignored). These short-term slope analyses seem to be sensitive to aircraft measurements in which the instrument samples short-time varying mixtures of different air masses. The EM missions all of which were affected by pollutants emitted in China, show the regression slope between ∆CO and ∆CO2 with of 1.8–6% and 0.3–0.7 between ∆CH4 and ∆CO. In particular, the regression slope between ∆CO and ∆CO2 increased to >4% when air flows from east-central China such as Hebei, Shandong, and Jiangsu provinces, etc., sustained for 1–3 days, suggesting pollutants from these regions were most likely characterized by incomplete fossil fuel combustions at the industries. Over 80% of the observations in the Western Korea missions were attributed to Korean emission sources with regression slope between ∆CO and ∆CO2 of 0.5–1.9%. The CO2 emissions hotspots were mainly located in the north-Western Korea of high population density and industrial activities. The higher CH4 were observed during summer season with the increasing concentration of approximately 6% over the background level, it seems to be attributed to biogenic sources such as rice paddies, landfill, livestock, and so on. It is also noted that occurrences of high pollution episodes in North-Western Korea are more closely related to the emissions in China than in Korea.

A Comparison of NMC and GWC Analysis Field Temperatures with Aircraft Measurements

1984 ◽  
Vol 23 (10) ◽  
pp. 1421-1426 ◽  
Author(s):  
William H. Jasperson ◽  
Gregory D. Nastrom
Keyword(s):  
Aircraft Measurements ◽  
Aircraft Observations ◽  
Standard Deviations ◽  
Flight Route

Abstract Comparison between in situ aircraft observations of temperature and National Meteorological Center and Global Weather Central analysis fields of temperature is presented for a continental and oceanic flight route. The standard deviations of the temperature differences over several hundred flights are found to be 2.5 and 3.5°C for the continental and oceanic route, respectively. A bias towards warm temperatures of about 0.85°C for the analysis fields was found for the oceanic route. Only small differences are found between the NMC and GWC analysis field temperatures.

scholarly journals Investigation on the Impacts of COVID-19 Lockdown and Influencing Factors on Air Quality in Greater Bangkok, Thailand

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Parichat Wetchayont
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Influencing Factors ◽  
Anthropogenic Emissions ◽  
Emission Sources ◽  
Pollution Levels ◽  
Absolute Reduction ◽  
The Impact ◽  
Co Concentrations

With the outbreak of the COVID-19 pandemic around the world, many countries announced lockdown measures, including Thailand. Several scientific studies have reported on improvements in air quality due to the impact of these COVID-19 lockdowns. This study aims to investigate the effects of the COVID-19 lockdown and its driving influencing factors on air pollution in Greater Bangkok, Thailand, using in situ measurements. Overall, PM2.5, PM10, O3, and CO concentrations presented a significant decreasing trend during the COVID-19 outbreak year based on three periods: the Before Lockdown, Lockdown, and After Lockdown periods, for PM2.5: −0.7%, −15.8%, and −20.7%; PM10: −4.1%, −31.7%, and −6.1%; and O3: −0.3%, −7.1%, and −4.7%, respectively, compared to the same periods in 2019. CO concentrations, especially which had increased by 14.7% Before Lockdown, decreased by −8.0% and −23.6% during the Lockdown and After Lockdown periods, respectively. Meanwhile, SO2 increased by 54.0%, 41.5%, and 84.6%, and NO2 increased by 20.1%, 3.2%, and 26.6%, respectively, for the Before Lockdown, Lockdown, and After Lockdown periods. PCA indicated a significant combination effect of atmospheric mechanisms that were strongly linked to emission sources such as traffic and biomass burning. It has been demonstrated that the COVID-19 lockdown did pause some of these anthropogenic emissions, i.e., traffic and commercial and industrial activities, but not all of them. Even low traffic emissions, on their own, did not cause an absolute reduction in air pollution since there are several primary emission sources that dominate the air quality over Greater Bangkok. Finally, these findings highlight the impact of COVID-19 lockdown measures not only on air pollution levels but on their effects on air pollution characteristics, as well.

Real-life Field Studies of the NOx Removing Properties of Photocatalytic Surfaces in Roskilde and Copenhagen Airport, Denmark

2020 ◽  
Vol 01 ◽  
Author(s):  
Henrik Jensen ◽  
Pernille D. Pedersen
Keyword(s):  
Air Quality ◽  
High Stability ◽  
Reference Site ◽  
Real Life ◽  
Field Studies ◽  
The Real ◽  
Before And After ◽  
Parking Lot ◽  
Photocatalytic Concrete

Aims: To evaluate the real-life effect of photocatalytic surfaces on the air quality at two test-sites in Denmark. Background: Poor air quality is today one of the largest environmental issues, due to the adverse effects on human health associated with high levels of air pollution, including respiratory issues, cardiovascular disease (CVD), and lung cancer. NOx removal by TiO2 based photocatalysis is a tool to improve air quality locally in areas where people are exposed. Methods: Two test sites were constructed in Roskilde and Copenhage airport. In Roskilde, the existing asphalt at two parking lots was treated with TiO2 containing liquid and an in-situ ISO 22197-1 test setup was developed to enable in-situ evaluation of the activity of the asphalt. In CPH airport, photocatalytic concrete tiles were installed at the "kiss and fly" parking lot, and NOx levels were continuously monitored in 0.5 m by CLD at the active site and a comparable reference site before and after installation for a period of 2 years. Results: The Roskilde showed high stability of the photocatalytic coating with the activity being largely unchanged over a period of 2 years. The CPH airport study showed that the average NOx levels were decreased by 12 % comparing the before and after NOx concentrations at the active and reference site. Conclusion: The joined results of the two Danish demonstration projects illustrate a high stability of the photocatalytic coating as well as a high potential for improvements of the real-life air quality in polluted areas.

scholarly journals In Situ exploration of the giant planets

2021 ◽  
Author(s):  
O. Mousis ◽  
D. H. Atkinson ◽  
R. Ambrosi ◽  
S. Atreya ◽  
D. Banfield ◽  
...  
Keyword(s):  
Solar System ◽  
Giant Planets ◽  
Atmospheric Composition ◽  
Formation History ◽  
History Of ◽  
Composition Structure ◽  
Galileo Probe ◽  
Probe Measurements

AbstractRemote sensing observations suffer significant limitations when used to study the bulk atmospheric composition of the giant planets of our Solar System. This impacts our knowledge of the formation of these planets and the physics of their atmospheres. A remarkable example of the superiority of in situ probe measurements was illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases’ abundances and the precise measurement of the helium mixing ratio were only made available through in situ measurements by the Galileo probe. Here we describe the main scientific goals to be addressed by the future in situ exploration of Saturn, Uranus, and Neptune, placing the Galileo probe exploration of Jupiter in a broader context. An atmospheric entry probe targeting the 10-bar level would yield insight into two broad themes: i) the formation history of the giant planets and that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. An atmospheric probe could represent a significant ESA contribution to a future NASA New Frontiers or flagship mission to be launched toward Saturn, Uranus, and/or Neptune.

Sign in / Sign up

Export Citation Format

Share Document