Three Decades of Tropospheric Ozone Lidar Development at Garmisch-Partenkirchen
Thomas Trickl, Helmuth Giehl, Frank Neidl, Matthias Perfahl, and Hannes Vogelmann
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-89,2020
Preprint under review for AMT (discussion: open, 0 comments)
Lidar sounding of ozone and other atmospheric constituents has proved to be invaluable tool for atmospheric studies. The ozone lidar systems developed at Garmisch-Partenkirchen have reached an accuracy level almost matching that of in situ sensors. Since the late 1990s numerous important scientific discoveries have been made such as the first observation of intercontinental transport of ozone and the very high occurrence of intrusions of stratospheric air into the troposphere.
Intercomparison of NO2, O4, O3 and HCHO slant column measurements by MAX-DOAS and zenith-sky UV–visible spectrometers during CINDI-2
Karin Kreher, Michel Van Roozendael, Francois Hendrick, Arnoud Apituley, Ermioni Dimitropoulou, Udo Frieß, Andreas Richter, Thomas Wagner, Johannes Lampel, Nader Abuhassan, Li Ang, Monica Anguas, Alkis Bais, Nuria Benavent, Tim Bösch, Kristof Bognar, Alexander Borovski, Ilya Bruchkouski, Alexander Cede, Ka Lok Chan, Sebastian Donner, Theano Drosoglou, Caroline Fayt, Henning Finkenzeller, David Garcia-Nieto, Clio Gielen, Laura Gómez-Martín, Nan Hao, Bas Henzing, Jay R. Herman, Christian Hermans, Syedul Hoque, Hitoshi Irie, Junli Jin, Paul Johnston, Junaid Khayyam Butt, Fahim Khokhar, Theodore K. Koenig, Jonas Kuhn, Vinod Kumar, Cheng Liu, Jianzhong Ma, Alexis Merlaud, Abhishek K. Mishra, Moritz Müller, Monica Navarro-Comas, Mareike Ostendorf, Andrea Pazmino, Enno Peters, Gaia Pinardi, Manuel Pinharanda, Ankie Piters, Ulrich Platt, Oleg Postylyakov, Cristina Prados-Roman, Olga Puentedura, Richard Querel, Alfonso Saiz-Lopez, Anja Schönhardt, Stefan F. Schreier, André Seyler, Vinayak Sinha, Elena Spinei, Kimberly Strong, Frederik Tack, Xin Tian, Martin Tiefengraber, Jan-Lukas Tirpitz, Jeroen van Gent, Rainer Volkamer, Mihalis Vrekoussis, Shanshan Wang, Zhuoru Wang, Mark Wenig, Folkard Wittrock, Pinhua H. Xie, Jin Xu, Margarita Yela, Chengxin Zhang, and Xiaoyi Zhao
Atmos. Meas. Tech., 13, 2169–2208, https://doi.org/10.5194/amt-13-2169-2020, 2020
In September 2016, 36 spectrometers from 24 institutes measured a number of key atmospheric pollutants during an instrument intercomparison campaign (CINDI-2) at Cabauw, the Netherlands. Here we report on the outcome of this intercomparison exercise. The three major goals were to characterise the differences between the participating instruments, to define a robust methodology for performance assessment, and to contribute to the harmonisation of the measurement settings and retrieval methods.
Global Cloud Property Models for Real Time Triage Onboard Visible-Shortwave Infrared Spectrometers
Macey W. Sandford, David R. Thompson, Robert O. Green, Brian H. Kahn, Raffaele Vitulli, Steve Chien, Amruta Yelamanchili, and Winston Olson-Duvall
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-139,2020
Preprint under review for AMT (discussion: open, 0 comments)
We demonstrate an onboard cloud screening approach to significantly reduce the amount of cloud-contaminated data transmitted from orbit. We have produced location-specific models that improve performance by taking into account the unique cloud statistics in different latitudes. We have shown that screening clouds based on their location or surface type will improve the ability for a cloud-screening tool to improve the volume of usable science data.
Global Cloud Property Models for Real Time Triage Onboard Visible-Shortwave Infrared Spectrometers
Macey W. Sandford, David R. Thompson, Robert O. Green, Brian H. Kahn, Raffaele Vitulli, Steve Chien, Amruta Yelamanchili, and Winston Olson-Duvall
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-139,2020
Preprint under review for AMT (discussion: open, 0 comments)
We demonstrate an onboard cloud screening approach to significantly reduce the amount of cloud-contaminated data transmitted from orbit. We have produced location-specific models that improve performance by taking into account the unique cloud statistics in different latitudes. We have shown that screening clouds based on their location or surface type will improve the ability for a cloud-screening tool to improve the volume of usable science data.
Variability of the Brunt-Väisälä frequency at the OH-airglow layer
height at low and mid latitudes
Sabine Wüst, Michael Bittner, Jeng-Hwa Yee, Martin G. Mlynczak, and James M. Russell III
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-73,2020
Preprint under review for AMT (discussion: open, 0 comments)
With airglow spectrometers the temperature in the upper mesosphere/lower thermosphere can be derived each night. The data allow to estimate the amount of energy which is transported by small-scale atmospheric waves, known as gravity waves. In order to do this, information about the Brunt–Väisälä frequency and its evolution during the year is necessary. This is provided here for low and mid latitudes based on 18 years of satellite data.
Three Decades of Tropospheric Ozone Lidar Development at Garmisch-Partenkirchen
Thomas Trickl, Helmuth Giehl, Frank Neidl, Matthias Perfahl, and Hannes Vogelmann
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-89,2020
Preprint under review for AMT (discussion: open, 0 comments)
Lidar sounding of ozone and other atmospheric constituents has proved to be invaluable tool for atmospheric studies. The ozone lidar systems developed at Garmisch-Partenkirchen have reached an accuracy level almost matching that of in situ sensors. Since the late 1990s numerous important scientific discoveries have been made such as the first observation of intercontinental transport of ozone and the very high occurrence of intrusions of stratospheric air into the troposphere.
Climate and marine scientists are observing pervasive warming of the ocean and the land surfaces across the globe. Since the middle of the 19th century, the average global temperature recorded on the land surface has risen by around one degree centigrade, and by 0.6 degrees across the ocean surface. Global warming has been most pronounced in the alpine regions and the Arctic.
Over the period 1982 to 2011, however, a cooling trend was recorded in surface waters in some parts of the Southern Ocean around the Antarctic continent, specifically in the area south of 55 degrees latitude. This cooling was strongest in the Pacific sector of the Southern Ocean, where the ocean surface cooled by around 0.1°C per decade, and the weakest in the Indian and parts of the Atlantic sectors.
Climate and marine scientists have so far been unable to provide satisfactory explanations as to why parts of the Southern Ocean have bucked the trend of global warming. Now a group of scientists led by Nicolas Gruber of the Swiss Federal Institute of Technology in Zürich has solved the puzzle with the help of simulations with a high-resolution ocean model.
Observation‐derived Southern Ocean (south of 40° S) temperature and salinity changes between 1982 and 2011. Left: Sea‐surface temperature changes derived from satellite observations (Reynolds et al., 2007). Left: Surface ocean salinity changes (Levitus et al., 2012). Black lines demark the Pacific, Atlantic, and Indian Ocean sectors, each subdivided into four regions (see section 2.5), by the Subantarctic Front, sea‐ice edge, and the continental shelf. Lower right: Zonal mean temperature and salinity (lower right) changes (Levitus et al., 2012). Credit: Haumann, et al., 2020/AGU.
Simulations highlight the influence of sea ice
In a paper just published in the AGU journal AGU Advances, the scientists use a series of simulations to show that sea-ice changes are the most probable cause for the cooling of the surface waters in the Southern Ocean. Only when Alex Haumann, lead author and Gruber’s former doctoral student, and the team incorporated the observed changes in sea ice into the model were they able to correctly replicate the observed pattern of the temperature changes. When they omitted this effect and only took into account the other potential factors – such as a more vigorous ocean circulation or increased freshwater fluxes from the melting of the Antarctic glaciers – the pattern was not accurately simulated.
Their considering of the role of sea ice in causing the surface cooling was based on the observation that over the same period as the cooling took place, i.e., from 1982 to 2011, the sea-ice extent steadily increased in the Southern Ocean around Antarctica, while in the Arctic it shrunk significantly over the same period.
A few years ago, Haumann and Gruber and various colleagues already discovered the reason for this expansion of sea ice in the Southern Ocean. They noticed that stronger southerly winds over this period propelled more of the sea ice that is being formed along the coast out into the open sea, enhancing the melting there. The resulting stronger conveyor-belt enhanced the transport of freshwater from near the continent out into the open ocean. This is because when sea ice is being formed from seawater, the salt is left behind, whereas when the sea ice melts in the summer well away from the coast, the freshwater is released into the surface, reducing the salinity of the seawater there.
This reduction in surface salinity strengthened the vertical stratification of the seawater: the fresher, and in this part of the ocean lighter water stays in the upper 100 m, while the denser saltier water remains below. In general, the saltier and colder the water, the greater its density and the greater its depth in the ocean.
Smaller heat exchange between the water layers
The stronger stratification reduced the exchange of heat between the deeper layers and the surface water, causing the heat to remain trapped at depth. In addition, the air above the Southern Ocean during winter is generally colder than the temperature of the seawater. Combined with the reduction of the vertical exchange of heat in the ocean, this ultimately created the observed situation where the surface water cooled and the subsurface warmed.
The strong role of salinity in controlling the vertical stratification is a peculiarity of the Southern Ocean, since there is actually very little difference in temperature between the ocean’s surface water and the subsurface: only a few tenths of a degree. The strong salinity driven stratification also explains why the surface cooling did not induce deep mixing.
No material to feed global-warming skeptics
“The cooling of the Southern Ocean over three decades is really unusual, bearing in mind that otherwise all other parts of the planet, especially the land surface, have warmed up,” Gruber said.
Cooling in just one area of the ocean should not be interpreted as a reduction of the long-term warming of the global climate system as a whole. It is merely a redistribution of heat in the Southern Ocean from the surface to the deeper layers of the ocean. “We assume the strong winds pushing the sea ice in the Southern Ocean northward are potentially a side-effect of climate change,” Gruber stresses. “Climate change is clearly man-made and cannot be disputed simply because one area of the ocean shows signs of cooling.”
In addition, the current study went only up to 2011. “We have observed a trend reversal since 2015. The sea ice around the Antarctic is now starting to recede at a rapid rate,” Gruber said. “And this is very much in line with the overall trend of continuing global warming.”
This post was originally published on the Swiss Federal Institute of Technology in Zürich website.
The post Going against the trend appeared first on GeoSpace.
The influence of the baseline drift on the resulting extinction values of a cavity attenuated phase shift-based extinction monitor (CAPS PMex)
Sascha Pfeifer, Thomas Müller, Andrew Freedman, and Alfred Wiedensohler
Atmos. Meas. Tech., 13, 2161–2167, https://doi.org/10.5194/amt-13-2161-2020, 2020
The effect of the baseline drift on the resulting extinction values of three CAPS PMex monitors with different wavelengths was analysed for an urban background station. A significant baseline drift was observed, which leads to characteristic measurement artefacts for particle extinction. Two alternative methods for recalculating the baseline are shown. With these methods the extinction artefacts are diminished and the effective scattering of the resulting extinction values is reduced.
How to estimate total differential attenuation due to hydrometeors with ground-based multi-frequency radars?
Frédéric Tridon, Alessandro Battaglia, and Stefan Kneifel
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-159,2020
Preprint under review for AMT (discussion: open, 0 comments)
At millimeter wavelengths, attenuation by hydrometeors, such as liquid droplets or large snowflakes, is generally not negligible. When using multi-frequency ground-based radar measurements, it is common practice to use the Rayleigh targets at cloud top as a reference in order to derive attenuation-corrected reflectivities and meaningful dual-frequency ratios (DFR). By capitalizing on this idea, this study describes a new quality-controlled approach aiming at identifying regions of the cloud where particle growth is negligible. The core of the method is the identification of a Rayleigh plateau, i.e. a large enough region near cloud top where the vertical gradient of DFR remains small.
By analyzing collocated Ka-W band radar and microwave radiometer (MWR) observations taken at two European sites under various meteorological conditions, it is shown how the resulting estimates of differential path-integrated attenuation (DeltaPIA) can be used to characterize hydrometeor properties. When the DeltaPIA is predominantly produced by cloud liquid droplets, this technique alone can provide accurate estimates of the liquid water path. When combined with MWR observations, this methodology paves the way towards profiling the cloud liquid water and/or quality flagging the MWR retrieval for rain/drizzle contamination and/or estimating the snow differential attenuation.
The influence of the baseline drift on the resulting extinction values of a cavity attenuated phase shift-based extinction monitor (CAPS PMex)
Sascha Pfeifer, Thomas Müller, Andrew Freedman, and Alfred Wiedensohler
Atmos. Meas. Tech., 13, 2161–2167, https://doi.org/10.5194/amt-13-2161-2020, 2020
The effect of the baseline drift on the resulting extinction values of three CAPS PMex monitors with different wavelengths was analysed for an urban background station. A significant baseline drift was observed, which leads to characteristic measurement artefacts for particle extinction. Two alternative methods for recalculating the baseline are shown. With these methods the extinction artefacts are diminished and the effective scattering of the resulting extinction values is reduced.
How to estimate total differential attenuation due to hydrometeors with ground-based multi-frequency radars?
Frédéric Tridon, Alessandro Battaglia, and Stefan Kneifel
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-159,2020
Preprint under review for AMT (discussion: open, 0 comments)
At millimeter wavelengths, attenuation by hydrometeors, such as liquid droplets or large snowflakes, is generally not negligible. When using multi-frequency ground-based radar measurements, it is common practice to use the Rayleigh targets at cloud top as a reference in order to derive attenuation-corrected reflectivities and meaningful dual-frequency ratios (DFR). By capitalizing on this idea, this study describes a new quality-controlled approach aiming at identifying regions of the cloud where particle growth is negligible. The core of the method is the identification of a Rayleigh plateau, i.e. a large enough region near cloud top where the vertical gradient of DFR remains small.
By analyzing collocated Ka-W band radar and microwave radiometer (MWR) observations taken at two European sites under various meteorological conditions, it is shown how the resulting estimates of differential path-integrated attenuation (DeltaPIA) can be used to characterize hydrometeor properties. When the DeltaPIA is predominantly produced by cloud liquid droplets, this technique alone can provide accurate estimates of the liquid water path. When combined with MWR observations, this methodology paves the way towards profiling the cloud liquid water and/or quality flagging the MWR retrieval for rain/drizzle contamination and/or estimating the snow differential attenuation.
An inter-laboratory comparison of aerosol in organic ion measurements by Ion Chromatography: implications for aerosol pH estimate
Jingsha Xu, Shaojie Song, Roy M. Harrison, Congbo Song, Lianfang Wei, Qiang Zhang, Yele Sun, Lu Lei, Chao Zhang, Xiaohong Yao, Dihui Chen, Weijun Li, Miaomiao Wu, Hezhong Tian, Lining Luo, Shengrui Tong, Weiran Li, Junling Wang, Guoliang Shi, Yanqi Huangfu, Yingze Tian, Baozhu Ge, Shaoli Su, Chao Peng, Yang Chen, Fumo Yang, Aleksandra Mihajlidi-Zelić, Dragana Đorđević, Stefan J. Swift, Imogen Andrews, Jacqueline F. Hamilton, Ye Sun, Agung Kramawijaya, Jinxiu Han, Supattarachai Saksakulkrai, Clarissa Baldo, Siqi Hou, Feixue Zheng, Kaspar R. Daellenbach, Chao Yan, Yongchun Liu, Markku Kulmala, Pingqing Fu, and Zongbo Shi
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-156,2020
Preprint under review for AMT (discussion: open, 0 comments)
An inter-laboratory comparison exercise was conducted for the first time to examine the difference of water-soluble inorganic ions (WSII) measured by 10 labs using Ion Chromatography and by 2 online Aerosol Chemical Speciation Monitor method. Major ions including SO42−, NO3−, NH4+ agreed well in 10 IC labs, and correlated well with ACSM. WSII inter-lab variability strongly affected aerosol acidity results based on ion balance, but aerosol pH computed by ISORROPIA-II were very similar.
Three-dimensional radiative transfer effects on airborne, satellite
and ground-based trace gas remote sensing
Marc Schwaerzel, Claudia Emde, Dominik Brunner, Randulph Morales, Thomas Wagner, Alexis Berne, Brigitte Buchmann, and Gerrit Kuhlmann
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-146,2020
Preprint under review for AMT (discussion: open, 0 comments)
Horizontal homogeneity is often assumed for trace gases remote sensing, although it is not valid where trace gas concentrations have high spatial variability, e.g. in cities. We show the importance of 3D effects for MAX-DOAS and airborne imaging spectrometers using 3D-box air mass factors implemented in the MYSTIC radiative transfer solver. In both cases, 3D information is invaluable for interpreting the measurements, as not considering 3D effects can lead to misinterpretation of measurements.
Ground-based FTIR O3 retrievals from the 3040 cm−1 spectral
range at Xianghe, China
Minqiang Zhou, Pucai Wang, Bavo Langerock, Corinne Vigouroux, Christian Hermans, Nicolas Kumps, Ting Wang, Yang Yang, Denghui Ji, Liang Ran, Jinqiang Zhang, Yuejian Xuan, Hongbin Chen, Françoise Posny, Valentin Duflot, Jean-Marc Metzger, and Martine De Mazière
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-127,2020
Preprint under review for AMT (discussion: open, 0 comments)
We study O3 retrievals in the 3040 cm−1 spectral range from FTIR measurements at Xianghe China (39.75N, 116.96E, 50 m a.s.l.) between June 2018 and December 2019. It is found that the FTIR O3 (3040 cm−1) retrievals capture very well the seasonal and synoptic variations of O3. The systematic and random uncertainties of FTIR O3 (3040 cm−1) total column are about 5.5–9.0 % and 1.4%, respectively. The DOF is 2.4±0.3 (1σ), with 2 individual pieces of information in surface-20 km and 20–40 km.
Three-dimensional radiative transfer effects on airborne, satellite
and ground-based trace gas remote sensing
Marc Schwaerzel, Claudia Emde, Dominik Brunner, Randulph Morales, Thomas Wagner, Alexis Berne, Brigitte Buchmann, and Gerrit Kuhlmann
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-146,2020
Preprint under review for AMT (discussion: open, 0 comments)
Horizontal homogeneity is often assumed for trace gases remote sensing, although it is not valid where trace gas concentrations have high spatial variability, e.g. in cities. We show the importance of 3D effects for MAX-DOAS and airborne imaging spectrometers using 3D-box air mass factors implemented in the MYSTIC radiative transfer solver. In both cases, 3D information is invaluable for interpreting the measurements, as not considering 3D effects can lead to misinterpretation of measurements.
Ground-based FTIR O3 retrievals from the 3040 cm−1 spectral
range at Xianghe, China
Minqiang Zhou, Pucai Wang, Bavo Langerock, Corinne Vigouroux, Christian Hermans, Nicolas Kumps, Ting Wang, Yang Yang, Denghui Ji, Liang Ran, Jinqiang Zhang, Yuejian Xuan, Hongbin Chen, Françoise Posny, Valentin Duflot, Jean-Marc Metzger, and Martine De Mazière
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-127,2020
Preprint under review for AMT (discussion: open, 0 comments)
We study O3 retrievals in the 3040 cm−1 spectral range from FTIR measurements at Xianghe China (39.75N, 116.96E, 50 m a.s.l.) between June 2018 and December 2019. It is found that the FTIR O3 (3040 cm−1) retrievals capture very well the seasonal and synoptic variations of O3. The systematic and random uncertainties of FTIR O3 (3040 cm−1) total column are about 5.5–9.0 % and 1.4%, respectively. The DOF is 2.4±0.3 (1σ), with 2 individual pieces of information in surface-20 km and 20–40 km.
An inter-laboratory comparison of aerosol in organic ion measurements by Ion Chromatography: implications for aerosol pH estimate
Jingsha Xu, Shaojie Song, Roy M. Harrison, Congbo Song, Lianfang Wei, Qiang Zhang, Yele Sun, Lu Lei, Chao Zhang, Xiaohong Yao, Dihui Chen, Weijun Li, Miaomiao Wu, Hezhong Tian, Lining Luo, Shengrui Tong, Weiran Li, Junling Wang, Guoliang Shi, Yanqi Huangfu, Yingze Tian, Baozhu Ge, Shaoli Su, Chao Peng, Yang Chen, Fumo Yang, Aleksandra Mihajlidi-Zelić, Dragana Đorđević, Stefan J. Swift, Imogen Andrews, Jacqueline F. Hamilton, Ye Sun, Agung Kramawijaya, Jinxiu Han, Supattarachai Saksakulkrai, Clarissa Baldo, Siqi Hou, Feixue Zheng, Kaspar R. Daellenbach, Chao Yan, Yongchun Liu, Markku Kulmala, Pingqing Fu, and Zongbo Shi
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-156,2020
Preprint under review for AMT (discussion: open, 0 comments)
An inter-laboratory comparison exercise was conducted for the first time to examine the difference of water-soluble inorganic ions (WSII) measured by 10 labs using Ion Chromatography and by 2 online Aerosol Chemical Speciation Monitor method. Major ions including SO42−, NO3−, NH4+ agreed well in 10 IC labs, and correlated well with ACSM. WSII inter-lab variability strongly affected aerosol acidity results based on ion balance, but aerosol pH computed by ISORROPIA-II were very similar.
Detecting turbulent structures on single Doppler lidar large datasets: an automated classification method for horizontal scans
Ioannis Cheliotis, Elsa Dieudonné, Hervé Delbarre, Anton Sokolov, Egor Dmitriev, Patrick Augustin, and Marc Fourmentin
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-82,2020
Preprint under review for AMT (discussion: open, 0 comments)
The current study presents an automated method to classify turbulent structures near the surface, based on the observations recorded by a single scanning Doppler lidar. This methodology combines texture analysis with a supervised machine learning algorithm in order to study large datasets. The algorithm classified correctly about 91 % cases of a training ensemble (150 scans). Furthermore the results of a two-months classified dataset (4577 scans) by the algorithm are presented.
Assessment of the quality of TROPOMI high-spatial-resolution NO2 data products in the Greater Toronto Area
Xiaoyi Zhao, Debora Griffin, Vitali Fioletov, Chris McLinden, Alexander Cede, Martin Tiefengraber, Moritz Müller, Kristof Bognar, Kimberly Strong, Folkert Boersma, Henk Eskes, Jonathan Davies, Akira Ogyu, and Sum Chi Lee
Atmos. Meas. Tech., 13, 2131–2159, https://doi.org/10.5194/amt-13-2131-2020, 2020
Pandora NO2 measurements made at three sites located in the Toronto area are used to evaluate the TROPOspheric Monitoring Instrument (TROPOMI) NO2 data products, including standard NO2 and research data developed using a high-resolution regional air quality forecast model. TROPOMI pixels located upwind and downwind from the Pandora sites were analyzed by a new wind-based validation method, which revealed the spatial patterns of local and transported emissions and regional air quality changes.
Assessment of the quality of TROPOMI high-spatial-resolution NO2 data products in the Greater Toronto Area
Xiaoyi Zhao, Debora Griffin, Vitali Fioletov, Chris McLinden, Alexander Cede, Martin Tiefengraber, Moritz Müller, Kristof Bognar, Kimberly Strong, Folkert Boersma, Henk Eskes, Jonathan Davies, Akira Ogyu, and Sum Chi Lee
Atmos. Meas. Tech., 13, 2131–2159, https://doi.org/10.5194/amt-13-2131-2020, 2020
Pandora NO2 measurements made at three sites located in the Toronto area are used to evaluate the TROPOspheric Monitoring Instrument (TROPOMI) NO2 data products, including standard NO2 and research data developed using a high-resolution regional air quality forecast model. TROPOMI pixels located upwind and downwind from the Pandora sites were analyzed by a new wind-based validation method, which revealed the spatial patterns of local and transported emissions and regional air quality changes.
