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2. Societal shifts due to COVID-19 reveal large-scale complexities and feedbacks between atmospheric chemistry and climate change

Author

Laughner, Joshua L, Neu, Jessica L, Schimel, David, Wennberg, Paul O, Barsanti, Kelley, Bowman, Kevin W, Chatterjee, Abhishek, Croes, Bart E, Fitzmaurice, Helen L, Henze, Daven K, Kim, Jinsol, Kort, Eric A, Liu, Zhu, Miyazaki, Kazuyuki, Turner, Alexander J, Anenberg, Susan, Avise, Jeremy, Cao, Hansen, Crisp, David, de Gouw, Joost, Eldering, Annmarie, Fyfe, John C, Goldberg, Daniel L, Gurney, Kevin R, Hasheminassab, Sina, Hopkins, Francesca, Ivey, Cesunica E, Jones, Dylan BA, Liu, Junjie, Lovenduski, Nicole S, Martin, Randall V, McKinley, Galen A, Ott, Lesley, Poulter, Benjamin, Ru, Muye, Sander, Stanley P, Swart, Neil, Yung, Yuk L, and Zeng, Zhao-Cheng

Subjects
Climate Action, Air Pollution, Atmosphere, COVID-19, Carbon Dioxide, Climate Change, Greenhouse Gases, Humans, Methane, Models, Theoretical, Nitrogen Oxides, Ozone, air quality, greenhouse gases, earth system, mitigation
Abstract

The COVID-19 global pandemic and associated government lockdowns dramatically altered human activity, providing a window into how changes in individual behavior, enacted en masse, impact atmospheric composition. The resulting reductions in anthropogenic activity represent an unprecedented event that yields a glimpse into a future where emissions to the atmosphere are reduced. Furthermore, the abrupt reduction in emissions during the lockdown periods led to clearly observable changes in atmospheric composition, which provide direct insight into feedbacks between the Earth system and human activity. While air pollutants and greenhouse gases share many common anthropogenic sources, there is a sharp difference in the response of their atmospheric concentrations to COVID-19 emissions changes, due in large part to their different lifetimes. Here, we discuss several key takeaways from modeling and observational studies. First, despite dramatic declines in mobility and associated vehicular emissions, the atmospheric growth rates of greenhouse gases were not slowed, in part due to decreased ocean uptake of CO2 and a likely increase in CH4 lifetime from reduced NO x emissions. Second, the response of O3 to decreased NO x emissions showed significant spatial and temporal variability, due to differing chemical regimes around the world. Finally, the overall response of atmospheric composition to emissions changes is heavily modulated by factors including carbon-cycle feedbacks to CH4 and CO2, background pollutant levels, the timing and location of emissions changes, and climate feedbacks on air quality, such as wildfires and the ozone climate penalty.

Published
2021

3. The Improvement of the Air Quality due to Traffic Halting in Los Angeles and Potential Health Care Risk during the COVID-19 Outbreak

Author

Yang, Jiani, Wang, Yuan, Pinto, Joseph, Kuai, Le, Li, King-Fai, Sander, Stanley P, and Yung, Yuk L

Subjects
Physics - Atmospheric and Oceanic Physics, Statistics - Applications
Abstract

Background: On March 19, 2020, the government of California ordered all 40 million Californians to stay at home in the coming weeks as the result of the escalation of the coronavirus disease 2019 (COVID-19) pandemic. As lockdowns were implemented, the significant changes caused by these restrictions brought a dramatic improvement in air quality in metropolitan cities such as Los Angeles (LA Basin).Methods: We use real-time data from The South Coast Air Quality Management District (South Coast AQMD), and the California Department of Transportation to evaluate the drivers of the pollution sources. We also mapped monthly spatial variations and constructed hourly heatmaps of those pollutants in 2020 to understand the impacts of the lockdown on different locations and times of day in the LA Basin. Results: Compared to the same dates in 2019, traffic flow on highways in the Los Angeles Basin dropped by 20.86 % when the stay at home order was initiated and it continued to decrease along with dramatic declines in NO2, CO, and PM2.5. The correlation (Pierson r) between truck flow change and changes of NO2, CO, and PM2.5 is statistically significant. Conclusion: The declines in truck flow are mainly responsible for the drop of NO2 and CO, with traffic having a slightly smaller effect on PM2.5. The lockdowns provided a large-scale experiment into air quality research. The result of this research would provide an important reference for the policy markers regarding truck management in light of air quality control to prepare for the 2028 Summer Olympics in LA.

Published
2020

4. The 2020 COVID-19 pandemic and atmospheric composition: back to the future

Author

Laughner, Joshua L, Neu, Jessica L, Schimel, David, Wennberg, Paul O, Barsanti, Kelley, Bowman, Kevin, Chatterjee, Abhishek, Croes, Bart, Fitzmaurice, Helen, Henze, Daven, Kim, Jinsol, Kort, Eric A, Liu, Zhu, Miyazaki, Kazuyuki, Turner, Alexander J, Anenberg, Susan, Avise, Jeremy, Cao, Hansen, Crisp, David, de Gouw, Joost, Eldering, Annmarie, Fyfe, John C, Goldberg, Daniel L, Gurney, Kevin R, Hasheminassab, Sina, Hopkins, Francesca, Ivey, Cesunica E, Jones, Dylan BA, Lovenduski, Nicole S, Martin, Randall V, McKinley, Galen A, Ott, Lesley, Poulter, Benjamin, Ru, Muye, Sander, Stanley P, Swart, Neil, Yung, Yuk L, and Zeng, Zhao-Cheng

Published
2021

5. Constraining the vertical distribution of coastal dust aerosol using OCO-2 O2 A-band measurements

Author

Zeng, Zhao-Cheng, Chen, Sihe, Natraj, Vijay, Le, Tianhao, Xu, Feng, Merrelli, Aronne, Crisp, David, Sander, Stanley P., and Yung, Yuk L.

Subjects
Physics - Atmospheric and Oceanic Physics
Abstract

Quantifying the vertical distribution of atmospheric aerosols is crucial for estimating their impact on the Earth energy budget and climate, improving forecast of air pollution in cities, and reducing biases in the retrieval of greenhouse gases (GHGs) from space. However, to date, passive remote sensing measurements have provided limited information about aerosol extinction profiles. In this study, we propose the use of a spectral sorting approach to constrain the aerosol vertical structure using spectra of reflected sunlight absorption within the molecular oxygen (O2) A-band collected by the Orbiting Carbon Observatory-2 (OCO-2). The effectiveness of the approach is evaluated using spectra acquired over the western Sahara coast by comparing the aerosol profile retrievals with lidar measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Using a radiative transfer model to simulate OCO-2 measurements, we found that high-resolution O2 A-band measurements have high sensitivity to aerosol optical depth (AOD) and aerosol layer height (ALH). Retrieved estimates of AOD and ALH based on a look up table technique show good agreement with CALIPSO measurements, with correlation coefficients of 0.65 and 0.53, respectively. The strength of the proposed spectral sorting technique lies in its ability to identify spectral channels with high sensitivity to AOD and ALH and extract the associated information from the observed radiance in a straightforward manner. The proposed approach has the potential to enable future passive remote sensing missions to map the aerosol vertical distribution on a global scale., Comment: 35 pages, 17 figures

Published
2019

6. Remote sensing of angular scattering effect of aerosols in a North American megacity

Author

Zeng, Zhao-Cheng, Xu, Feng, Natraj, Vijay, Pongetti, Thomas J., Shia, Run-Lie, Zhang, Qiong, Sander, Stanley P., and Yung, Yuk L.

Subjects
Physics - Atmospheric and Oceanic Physics
Abstract

The angle-dependent scattering effect of aerosols in the atmosphere can be used to infer their compositions, which in turn is important to understand their impacts of human health and Earth climate. The aerosol phase function, which characterizes the angular signature of scattering, has been continuously monitored from ground-based and space-borne observations. However, the range of scattering angles these instruments can sample is very limited. There is a dearth of research on the remote sensing of aerosol angular scattering effect at a city scale that analyzes diurnal variability and includes a wide range of scattering angles. Here, we quantify the aerosol angular scattering effect using measurements from a mountain-top remote sensing instrument: the California Laboratory for Atmospheric Remote Sensing Fourier Transform Spectrometer (CLARS-FTS). CLARS-FTS is located on top of the Mt. Wilson (1.67km above sea level) overlooking the Los Angeles (LA) megacity and receives reflected sunlight from targeted surface reflection points. The observational geometries of CLARS-FTS provide a wide range of scattering angles, from about 20 degrees (forward) to about 140 degrees (backward). The O2 ratio, which is the ratio of retrieved O2 Slant Column Density (SCD) to geometric O2 SCD, quantifies the aerosol transmission with a value of 1.0 represent aerosol-free and with a value closer to 0.0 represents stronger aerosol loadings. The aerosol transmission quantified by the O2 ratio from CLARS measurements provides an effective indicator of the aerosol scattering effect., Comment: 29 pages; 4 figures

Published
2019

7. Societal shifts due to COVID-19 reveal large-scale complexities and feedbacks between atmospheric chemistry and climate change

Author

rest of the Keck Institute for Space Studies “COVID-19: Identifying Unique Opportunities for Earth System Science” study team, Laughner, Joshua L., Neu, Jessica L., Schimel, David, Wennberg, Paul O., Barsanti, Kelley, Bowman, Kevin W., Chatterjee, Abhishek, Croes, Bart E., Fitzmaurice, Helen L., Henze, Daven K., Kim, Jinsol, Kort, Eric A., Liu, Zhu, Miyazaki, Kazuyuki, Turner, Alexander J., Anenberg, Susan, Avise, Jeremy, Cao, Hansen, Crisp, David, de Gouw, Joost, Eldering, Annmarie, Fyfe, John C., Goldberg, Daniel L., Gurney, Kevin R., Hasheminassab, Sina, Hopkins, Francesca, Ivey, Cesunica E., Jones, Dylan B. A., Liu, Junjie, Lovenduski, Nicole S., Martin, Randall V., McKinley, Galen A., Ott, Lesley, Poulter, Benjamin, Ru, Muye, Sander, Stanley P., Swart, Neil, Yung, Yuk L., and Zeng, Zhao-Cheng

Published
2021

19. Los Angeles megacity: a high-resolution land–atmosphere modelling system for urban CO2 emissions

Author

Feng, Sha, Lauvaux, Thomas, Newman, Sally, Rao, Preeti, Ahmadov, Ravan, Deng, Aijun, Díaz-Isaac, Liza I, Duren, Riley M, Fischer, Marc L, Gerbig, Christoph, Gurney, Kevin R, Huang, Jianhua, Jeong, Seongeun, Li, Zhijin, Miller, Charles E, O'Keeffe, Darragh, Patarasuk, Risa, Sander, Stanley P, Song, Yang, Wong, Kam W, and Yung, Yuk L

Subjects
Earth Sciences, Atmospheric Sciences, Climate Action, Astronomical and Space Sciences, Meteorology & Atmospheric Sciences, Atmospheric sciences, Climate change science
Abstract

Megacities are major sources of anthropogenic fossil fuel CO2 (FFCO2) emissions. The spatial extents of these large urban systems cover areas of 10 000 km2 or more with complex topography and changing landscapes. We present a high-resolution land-atmosphere modelling system for urban CO2 emissions over the Los Angeles (LA) megacity area. The Weather Research and Forecasting (WRF)-Chem model was coupled to a very high-resolution FFCO2 emission product, Hestia-LA, to simulate atmospheric CO2 concentrations across the LA megacity at spatial resolutions as fine as ∼ 1 km. We evaluated multiple WRF configurations, selecting one that minimized errors in wind speed, wind direction, and boundary layer height as evaluated by its performance against meteorological data collected during the CalNex-LA campaign (May-June 2010). Our results show no significant difference between moderate-resolution (4 km) and high-resolution (1.3 km) simulations when evaluated against surface meteorological data, but the high-resolution configurations better resolved planetary boundary layer heights and vertical gradients in the horizontal mean winds. We coupled our WRF configuration with the Vulcan 2.2 (10 km resolution) and Hestia-LA (1.3 km resolution) fossil fuel CO2 emission products to evaluate the impact of the spatial resolution of the CO2 emission products and the meteorological transport model on the representation of spatiotemporal variability in simulated atmospheric CO2 concentrations. We find that high spatial resolution in the fossil fuel CO2 emissions is more important than in the atmospheric model to capture CO2 concentration variability across the LA megacity. Finally, we present a novel approach that employs simultaneous correlations of the simulated atmospheric CO2 fields to qualitatively evaluate the greenhouse gas measurement network over the LA megacity. Spatial correlations in the atmospheric CO2 fields reflect the coverage of individual measurement sites when a statistically significant number of sites observe emissions from a specific source or location. We conclude that elevated atmospheric CO2 concentrations over the LA megacity are composed of multiple fine-scale plumes rather than a single homogenous urban dome. Furthermore, we conclude that FFCO2 emissions monitoring in the LA megacity requires FFCO2 emissions modelling with ∼ 1 km resolution because coarser-resolution emissions modelling tends to overestimate the observational constraints on the emissions estimates.

Published
2016

20. A portable reflected-sunlight spectrometer for CO2 and CH4

Author

Löw, Benedikt A., primary, Kleinschek, Ralph, additional, Enders, Vincent, additional, Sander, Stanley P., additional, Pongetti, Thomas J., additional, Schmitt, Tobias D., additional, Hase, Frank, additional, Kostinek, Julian, additional, and Butz, André, additional

Published
2023
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22. Airships: A New Horizon for Science

Author

Miller, Sarah H., Fesen, Robert, Hillenbrand, Lynne, Rhodes, Jason, Baird, Gil, Blake, Geoffrey, Booth, Jeff, Carlile, David E., Duren, Riley, Edworthy, Frederick G., Freeze, Brent, Friedl, Randall R., Goldsmith, Paul F., Hall, Jeffery L., Hoffman, Scott E., Hovarter, Scott E., Jensen-Clem, Rebecca M., Jones, Ross M., Kauffmann, Jens, Kiessling, Alina, King, Oliver G., Konidaris, Nick, Lachenmeier, Timothy L., Lord, Steven D., Neu, Jessica, Quetin, Gregory R., Ram, Alan, Sander, Stanley, Simard, Marc, Smith, Mike, Smith, Steve, Smoot, Sara, Susca, Sara, Swann, Abigail, Young, Eliot F., and Zambrano, Thomas

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Galaxy Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

The "Airships: A New Horizon for Science" study at the Keck Institute for Space Studies investigated the potential of a variety of airships currently operable or under development to serve as observatories and science instrumentation platforms for a range of space, atmospheric, and Earth science. The participants represent a diverse cross-section of the aerospace sector, NASA, and academia. Over the last two decades, there has been wide interest in developing a high altitude, stratospheric lighter-than-air (LTA) airship that could maneuver and remain in a desired geographic position (i.e., "station-keeping") for weeks, months or even years. Our study found considerable scientific value in both low altitude (< 40 kft) and high altitude (> 60 kft) airships across a wide spectrum of space, atmospheric, and Earth science programs. Over the course of the study period, we identified stratospheric tethered aerostats as a viable alternative to airships where station-keeping was valued over maneuverability. By opening up the sky and Earth's stratospheric horizon in affordable ways with long-term flexibility, airships allow us to push technology and science forward in a project-rich environment that complements existing space observatories as well as aircraft and high-altitude balloon missions., Comment: This low resolution version of the report is 8.6 MB. For the high resolution version see: http://kiss.caltech.edu/study/airship/

Published
2014

28. Background levels of methane in Mars’ atmosphere show strong seasonal variations

Author

Webster, Christopher R., Mahaffy, Paul R., Atreya, Sushil K., Moores, John E., Flesch, Gregory J., Malespin, Charles, McKay, Christopher P., Martinez, German, Smith, Christina L., Martin-Torres, Javier, Gomez-Elvira, Javier, Zorzano, Maria-Paz, Wong, Michael H., Trainer, Melissa G., Steele, Andrew, Archer, Doug, Sutter, Brad, Coll, Patrice J., Freissinet, Caroline, Meslin, Pierre-Yves, Gough, Raina V., House, Christopher H., Pavlov, Alexander, Eigenbrode, Jennifer L., Glavin, Daniel P., Pearson, John C., Keymeulen, Didier, Christensen, Lance E., Schwenzer, Susanne P., Navarro-Gonzalez, Rafael, Pla-García, Jorge, Rafkin, Scot C. R., Vicente-Retortillo, Álvaro, Kahanpää, Henrik, Viudez-Moreiras, Daniel, Smith, Michael D., Harri, Ari-Matti, Genzer, Maria, Hassler, Donald M., Lemmon, Mark, Crisp, Joy, Sander, Stanley P., Zurek, Richard W., and Vasavada, Ashwin R.

Published
2018

30. Conformer-Dependent Chemistry: Experimental Product Branching of the Vinyl Alcohol + OH + O2 Reaction

Author

Rösch, Daniel, primary, Jones, Gregory H., additional, Almeida, Raybel, additional, Caravan, Rebecca L., additional, Hui, Aileen, additional, Ray, Amelia W., additional, Percival, Carl J., additional, Sander, Stanley P., additional, Smarte, Matthew D., additional, Winiberg, Frank A. F., additional, Okumura, Mitchio, additional, and Osborn, David L., additional

Published
2023
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36. A portable reflected-sunlight spectrometer for CO2 and CH4

Author

Löw, Benedikt A., Kleinschek, Ralph, Enders, Vincent, Sander, Stanley P., Pongetti, Thomas J., Schmitt, Tobias D., Hase, Frank, Kostinek, Julian, and Butz, André

Abstract

Mapping the greenhouse gases carbon dioxide (CO2) and methane (CH4) above source regions such as urban areas can deliver insights into the distribution and dynamics of the local emission patterns. Here, we present the prototype development and an initial performance evaluation of a portable spectrometer that allows for measuring CO2 and CH4 concentrations integrated along a long (>10 km) horizontal path component through the atmospheric boundary layer above a target region. To this end, the spectrometer is positioned at an elevated site from which it points downward at reflection targets in the region collecting the reflected sunlight at shallow viewing angles. The path-integrated CO2 and CH4 concentrations are inferred from the absorption fingerprint in the shortwave-infrared (SWIR) spectral range. While mimicking the concept of the stationary CLARS-FTS (California Laboratory for Atmospheric Remote Sensing - Fourier Transform Spectrometer) at Los Angeles, our portable setup requires minimal infrastructures and is straightforward to duplicate and to operate at various places. For performance evaluation, we deployed the instrument, termed EM27/SCA, side-by-side with the CLARS-FTS at Mt. Wilson observatory (1670 m a.s.l.) above Los Angeles for a month-long period in Apr./May 2022. We determined the relative precision of the retrieved slant column densities (SCDs) for urban reflection targets to 0.36–0.55 % for O2, CO2 and CH4, where O2 is relevant for lightpath estimation. For the partial vertical columns (VCDs) below instrument level, which is the quantity carrying the emission information, the propagated precision errors amount to 0.75–2 % for the three gases depending on the distance to the reflection target and solar zenith angle. The comparison to simultaneous CLARS-FTS measurements shows good consistency, but the observed diurnal patterns highlight the need for taking into account light scattering to enable detection of emission patterns.

Published
2023

43. Absorption cross-sections of ozone in the ultraviolet and visible spectral regions: Status report 2015

Author

Orphal, Johannes, Staehelin, Johannes, Tamminen, Johanna, Braathen, Geir, De Backer, Marie-Renée, Bais, Alkiviadis, Balis, Dimitris, Barbe, Alain, Bhartia, Pawan K., Birk, Manfred, Burkholder, James B., Chance, Kelly, von Clarmann, Thomas, Cox, Anthony, Degenstein, Doug, Evans, Robert, Flaud, Jean-Marie, Flittner, David, Godin-Beekmann, Sophie, Gorshelev, Viktor, Gratien, Aline, Hare, Edward, Janssen, Christof, Kyrölä, Erkki, McElroy, Thomas, McPeters, Richard, Pastel, Maud, Petersen, Michael, Petropavlovskikh, Irina, Picquet-Varrault, Benedicte, Pitts, Michael, Labow, Gordon, Rotger-Languereau, Maud, Leblanc, Thierry, Lerot, Christophe, Liu, Xiong, Moussay, Philippe, Redondas, Alberto, Van Roozendael, Michel, Sander, Stanley P., Schneider, Matthias, Serdyuchenko, Anna, Veefkind, Pepijn, Viallon, Joële, Viatte, Camille, Wagner, Georg, Weber, Mark, Wielgosz, Robert I., and Zehner, Claus

Published
2016
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45. A portable reflected-sunlight spectrometer for CO2 and CH4.

Author

Löw, Benedikt A., Kleinschek, Ralph, Enders, Vincent, Sander, Stanley P., Pongetti, Thomas J., Schmitt, Tobias D., Hase, Frank, Kostinek, Julian, and Butz, André

Subjects
FOURIER transform spectrometers, ATMOSPHERIC boundary layer, SPECTROMETERS, IR spectrometers, ZENITH distance, GREENHOUSE gases, SUNGLASSES
Abstract

Mapping the greenhouse gases carbon dioxide (CO2) and methane (CH4) above source regions such as urban areas can deliver insights into the distribution and dynamics of the local emission patterns. Here, we present the prototype development and an initial performance evaluation of a portable spectrometer that allows for measuring CO2 and CH4 concentrations integrated along a long (> 10km) horizontal path component through the atmospheric boundary layer above a target region. To this end, the spectrometer is positioned at an elevated site from which it points downward at reflection targets in the region collecting the reflected sunlight at shallow viewing angles. The path-integrated CO2 and CH4 concentrations are inferred from the absorption fingerprint in the shortwave-infrared (SWIR) spectral range. While mimicking the concept of the stationary CLARS-FTS (California Laboratory for Atmospheric Remote Sensing - Fourier Transform Spectrometer) at Los Angeles, our portable setup requires minimal infrastructures and is straightforward to duplicate and to operate at various places. For performance evaluation, we deployed the instrument, termed EM27/SCA, side-by-side with the CLARS-FTS at Mt. Wilson observatory (1670 m a.s.l.) above Los Angeles for a month-long period in Apr./May 2022. We determined the relative precision of the retrieved slant column densities (SCDs) for urban reflection targets to 0.36-0.55% for O2, CO2 and CH4, where O2 is relevant for lightpath estimation. For the partial vertical columns (VCDs) below instrument level, which is the quantity carrying the emission information, the propagated precision errors amount to 0.75-2% for the three gases depending on the distance to the reflection target and solar zenith angle. The comparison to simultaneous CLARS-FTS measurements shows good consistency, but the observed diurnal patterns highlight the need for taking into account light scattering to enable detection of emission patterns. [ABSTRACT FROM AUTHOR]

Published
2023
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50. Simulated multispectral temperature and atmospheric composition retrievals for the JPL GEO-IR Sounder

Author

Natraj, Vijay, primary, Luo, Ming, additional, Blavier, Jean-Francois, additional, Payne, Vivienne H., additional, Posselt, Derek J., additional, Sander, Stanley P., additional, Zeng, Zhao-Cheng, additional, Neu, Jessica L., additional, Tremblay, Denis, additional, Wu, Longtao, additional, Roman, Jacola A., additional, Wu, Yen-Hung, additional, and Dorsky, Leonard I., additional

Published
2022
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