Alpha Jet Atmospheric eXperiment

The Alpha Jet Atmospheric eXperiment (AJAX) is a partnership between NASA's Ames Research Center and H211, L.L.C., facilitating routine in-situ measurements over California, Nevada, and the coastal Pacific in support of satellite validation. The standard payload complement includes rigorously-calibrated ozone (O3), formaldehyde (HCHO), carbon dioxide (CO2), and methane (CH4) mixing ratios, as well as meteorological data including 3-D winds. Multiple vertical profiles (to ~8.5 km) can be accomplished in each 2-hr flight. The AJAX project has been collecting trace gas data on a regular basis in all seasons for over a decade, helping to assess satellite sensors' health and calibration over significant portions of their lifetimes, and complementing surface and tower-based observations collected elsewhere in the region.

AJAX supports NASA's Orbiting Carbon Observatory (OCO-2/3) and Japan's GOSAT and GOSAT-2, and collaborates with many other research organizations (e.g. CARB, NOAA, USFS, EPA). AJAX celebrated its 200th science flight in 2016, and previous studies have investigated topics as varied as stratospheric-to-tropospheric transport, forest fire plumes, atmospheric river events, long-range transport of pollution from Asia to the western US, urban outflow, and emissions from gas leaks, oil fields, and dairies.

For more information regarding AJAX data and how to access it, please see the AJAX User Guide.

AJAX Flight Objectives
AJAX Wildfire Data Table
AJAX Wildfire Measurements Compendium (DOI: 10.5067/ASDC/AJAX/Wildfire)

AJAX Project Page

DOI: 10.5067/ASDC/SUBORBITAL/AJAX/DATA001

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Disciplines:   Field Campaigns

Access Campaign Data on
Sub-Orbital Order Tool (SOOT)
Collection Disciplines Spatial Temporal
AJAX_CH2O_1
Alpha Jet Atmospheric eXperiment Formaldehyde Data 		Field Campaigns Spatial Coverage:
(S: 34, N: 42), (W: -125, E: -114)
Temporal Coverage:
2015-12-12 - Present
AJAX_CO2_CH4_1
Alpha Jet Atmospheric eXperiment Carbon Dioxide and Methane Data 		Field Campaigns Spatial Coverage:
(S: 34, N: 42), (W: -125, E: -114)
Temporal Coverage:
2011-06-11 - Present
AJAX_MMS_1
Alpha Jet Atmopsheric eXperiment Meteorological Measurement System (MMS) Data 		Field Campaigns Spatial Coverage:
(S: 34, N: 42), (W: -125, E: -114)
Temporal Coverage:
2013-06-20 - Present
AJAX_O3_1
Alpha Jet Atmospheric eXperiment Ozone Data 		Field Campaigns Spatial Coverage:
(S: 34, N: 42), (W: -125, E: -114)
Temporal Coverage:
2011-02-01 - Present

AJAX Mission Publications

Yates, Emma L.; Iraci, Laura T.; Kulawik, Susan S.; Ryoo, Ju-Mee; Marrero, Josette E.; Parworth, Caroline L.; St. Clair, Jason M.; Hanisco, Thomas F.; Bui, Thao Paul V.; Chang, Cecilia S.; Dean-Day, Jonathan M. (2023). An extensive database of airborne trace gas and meteorological observations from the Alpha Jet Atmospheric eXperiment (AJAX).


Chang, Kai‐Lan; Cooper, Owen R.; Rodriguez, Gavin; Iraci, Laura T.; Yates, Emma L.; Johnson, Matthew S.; Gaudel, Audrey; Jaffe, Daniel A.; Bernays, Noah; Clark, Hannah; Effertz, Peter; Leblanc, Thierry; Petropavlovskikh, Irina; Sauvage, Bastien; Tarasick, David W. (2023). Diverging Ozone Trends Above Western North America: Boundary Layer Decreases Versus Free Tropospheric Increases.


Iraci L T, Parworth C L, Yates E L, Marrero J E, and Ryoo J (2022). A Collection of Airborne Measurements and Analyses of Trace Gases Emitted From Multiple Fires in California. Earth and Space Science, 9 (4), https://doi.org/10.1029/2021EA002116


Langford, Andrew O.; Alvarez II, Raul J.; Kirgis, Guillaume; Senff, Christoph J.; Caputi, Dani; Conley, Stephen A.; Faloona, Ian C.; Iraci, Laura T.; Marrero, Josette E.; McNamara, Mimi E.; Ryoo, Ju-Mee; Yates, Emma L. (2020). Intercomparison of lidar, aircraft, and surface ozone measurements in the San Joaquin Valley during the California Baseline Ozone Transport Study (CABOTS). Atmospheric Measurement Techniques, 12 (3), 1889. https://doi.org/10.5194/amt-12-1889-2019


Faloona, Ian C.; Chiao, Sen; Eiserloh, Arthur J.; Alvarez, Raul J.; Kirgis, Guillaume; Langford, Andrew O.; Senff, Christoph J.; Caputi, Dani; Hu, Arthur; Iraci, Laura T.; Yates, Emma L.; Marrero, Josette E.; Ryoo, Ju-Mee; Conley, Stephen; Tanrikulu, Saffet; Xu, Jin; Kuwayama, Toshihiro (2020). The California Baseline Ozone Transport Study (CABOTS). Bulletin of the American Meteorological Society, 101 (4), https://doi.org/10.1175/BAMS-D-18-0302.1


Ryoo, Ju-Mee; Chiao, Sen; Spackman, J. Ryan; Iraci, Laura T.; Ralph, F. Martin; Martin, Andrew; Dole, Randall M.; Marrero, Josette E.; Yates, Emma L.; Bui, T. Paul; Dean-Day, Jonathan M.; Chang, Cecilia S. (2020). Terrain Trapped Airflows and Precipitation Variability during an Atmospheric River Event. Journal of Hydrometeorology, 21 (2), 355. https://doi.org/10.1175/JHM-D-19-0040.1


Yates E L, Iraci L T, Tarnay L W, Burley J D, Parworth C and Ryoo J-M (2020). The effect of an upwind non-attainment area on ozone in California’s Sierra Nevada Mountains. Atmospheric Environment, 230 117426. https://doi.org/10.1016/j.atmosenv.2020.117426


Baker, K.R.; Woody, M.C.; Valin, L.; Szykman, J.; Yates, E.L.; Iraci, L.T.; Choi, H.D.; Soja, A.J.; Koplitz, S.N.; Zhou, L.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Hair, J.W. (2020). Photochemical model evaluation of 2013 California wild fire air quality impacts using surface, aircraft, and satellite data. Science of The Total Environment, 1137. https://doi.org/10.1016/j.scitotenv.2018.05.048


Leifer, Ira; Melton, Christopher; Chatfield, Robert; Cui, Xinguang; Fischer, Marc L.; Fladeland, Matthew; Gore, Warren; Hlavka, Dennis L.; Iraci, Laura T.; Marrero, Josette; Ryoo, Ju-Mee; Tanaka, Tomoaki; Yates, Emma; Yorks, John E. (2020). Air pollution inputs to the Mojave Desert by fusing surface mobile and airborne in situ and airborne and satellite remote sensing: A case study of interbasin transport with numerical model validation. Atmospheric Environment, 224 117184. https://doi.org/10.1016/j.atmosenv.2019.117184


Cui, Yu Yan; Vijayan, Abhilash; Falk, Matthias; Hsu, Ying-Kuang; Yin, Dazhong; Chen, Xue Meng; Zhao, Zhan; Avise, Jeremy; Chen, Yanju; Verhulst, Kristal; Duren, Riley; Yadav, Vineet; Miller, Charles; Weiss, Ray; Keeling, Ralph; Kim, Jooil; Iraci, Laura T.; Tanaka, Tomoaki; Johnson, Matthew S.; Kort, Eric A.; Bianco, Laura; Fischer, Marc L.; Stroud, Kenneth; Herner, Jorn; Croes, Bart (2020). A Multiplatform Inversion Estimation of Statewide and Regional Methane Emissions in California during 2014–2016. Environmental Science & Technology, 53 (16), 9636. https://doi.org/10.1021/acs.est.9b01769


Ryoo, Ju-Mee; Iraci, Laura T.; Tanaka, Tomoaki; Marrero, Josette E.; Yates, Emma L.; Fung, Inez; Michalak, Anna M.; Tadić, Jovan; Gore, Warren; Bui, T. Paul; Dean-Day, Jonathan M.; Chang, Cecilia S. (2020). Quantification of CO2 and CH4 emissions over Sacramento, California, based on divergence theorem using aircraft measurements. Atmospheric Measurement Techniques, 12 (5), 2949. https://doi.org/10.5194/amt-12-2949-2019


Langford, Andrew O.; Alvarez, Raul J.; Brioude, J.; Caputi, Dani; Conley, Stephen A.; Evan, S.; Faloona, Ian C.; Iraci, Laura T.; Kirgis, Guillaume; Marrero, Josette E.; Ryoo, Ju‐Mee; Senff, Christoph J.; Yates, Emma L. (2020). Ozone Production in the Soberanes Smoke Haze: Implications for Air Quality in the San Joaquin Valley During the California Baseline Ozone Transport Study. Journal of Geophysical Research: Atmospheres, 125 (11), https://doi.org/10.1029/2019jd031777


Langford, A.O.; Alvarez, R.J.; Brioude, J.; Evan, S.; Iraci, L.T.; Kirgis, G.; Kuang, S.; Leblanc, T.; Newchurch, M.J.; Pierce, R.B.; Senff, C.J.; Yates, E.L. (2019). Coordinated profiling of stratospheric intrusions and transported pollution by the Tropospheric Ozone Lidar Network (TOLNet) and NASA Alpha Jet experiment (AJAX): Observations and comparison to HYSPLIT, RAQMS, and FLEXPART. Atmospheric Environment, 174 1. https://doi.org/10.1016/j.atmosenv.2017.11.031


Leifer, Ira; Melton, Christopher; Fischer, Marc L.; Fladeland, Matthew; Frash, Jason; Gore, Warren; Iraci, Laura T.; Marrero, Josette E.; Ryoo, Ju-Mee; Tanaka, Tomoaki; Yates, Emma L. (2019). Atmospheric characterization through fused mobile airborne and surface in situ surveys: methane emissions quantification from a producing oil field. Atmospheric Measurement Techniques, 11 (3), 1689. https://doi.org/10.5194/amt-11-1689-2018


Ryoo, Ju-Mee; Johnson, Matthew S.; Iraci, Laura T.; Yates, Emma L.; Gore, Warren (2018). Investigating sources of ozone over California using AJAX airborne measurements and models: Assessing the contribution from long-range transport. Atmospheric Environment, 155 53. https://doi.org/10.1016/j.atmosenv.2017.02.008


Tadić, Jovan M.; Michalak, Anna M.; Iraci, Laura; Ilić, Velibor; Biraud, Sébastien C.; Feldman, Daniel R.; Bui, Thaopaul; Johnson, Matthew S.; Loewenstein, Max; Jeong, Seongeun; Fischer, Marc L.; Yates, Emma L.; Ryoo, Ju-Mee (2018). Elliptic Cylinder Airborne Sampling and Geostatistical Mass Balance Approach for Quantifying Local Greenhouse Gas Emissions. Environmental Science & Technology, 51 (17), 10012. https://doi.org/10.1021/acs.est.7b03100


Yates, E.L.; Iraci, L.T.; Singh, H.B.; Tanaka, T.; Roby, M.C.; Hamill, P.; Clements, C.B.; Lareau, N.; Contezac, J.; Blake, D.R.; Simpson, I.J.; Wisthaler, A.; Mikoviny, T.; Diskin, G.S.; Beyersdorf, A.J.; Choi, Y.; Ryerson, T.B.; Jimenez, J.L.; Campuzano-Jost, P.; Loewenstein, M.; Gore, W. (2018). Airborne measurements and emission estimates of greenhouse gases and other trace constituents from the 2013 California Yosemite Rim wildfire. Atmospheric Environment, 127 293. https://doi.org/10.1016/j.atmosenv.2015.12.038


St. Clair, Jason M.; Swanson, Andrew K.; Bailey, Steven A.; Wolfe, Glenn M.; Marrero, Josette E.; Iraci, Laura T.; Hagopian, John G.; Hanisco, Thomas F. (2018). A new non-resonant laser-induced fluorescence instrument for the airborne in situ measurement of formaldehyde. Atmospheric Measurement Techniques, 10 (12), 4833. https://doi.org/10.5194/amt-10-4833-2017


Kulawik, Susan S.; O'Dell, Chris; Payne, Vivienne H.; Kuai, Le; Worden, Helen M.; Biraud, Sebastien C.; Sweeney, Colm; Stephens, Britton; Iraci, Laura T.; Yates, Emma L.; Tanaka, Tomoaki (2018). Lower-tropospheric CO2 from near-infrared ACOS-GOSAT observations. Atmospheric Chemistry and Physics, 17 (8), 5407. https://doi.org/10.5194/acp-17-5407-2017


Tanaka, Tomoaki; Yates, Emma; Iraci, Laura T.; Johnson, Matthew S.; Gore, Warren; Tadic, Jovan M.; Loewenstein, Max; Kuze, Akihiko; Frankenberg, Christian; Butz, Andre; Yoshida, Yukio (2018). Two-Year Comparison of Airborne Measurements of CO2 and CH4 With GOSAT at Railroad Valley, Nevada. IEEE Transactions on Geoscience and Remote Sensing, 54 (8), 4367. https://doi.org/10.1109/TGRS.2016.2539973


Hamill, Patrick; Iraci, Laura T.; Yates, Emma L.; Gore, Warren; Bui, T. Paul; Tanaka, Tomoaki; Loewenstein, Max (2018). A New Instrumented Airborne Platform for Atmospheric Research. Bulletin of the American Meteorological Society, 97 (3), 397. https://doi.org/10.1175/BAMS-D-14-00241.1


Johnson, Matthew S.; Yates, Emma L.; Iraci, Laura T.; Loewenstein, Max; Tadić, Jovan M.; Wecht, Kevin J.; Jeong, Seongeun; Fischer, Marc L. (2018). Analyzing source apportioned methane in northern California during Discover-AQ-CA using airborne measurements and model simulations. Atmospheric Environment, 99 248. https://doi.org/10.1016/j.atmosenv.2014.09.068


Fine, Rebekka; Miller, Matthieu B.; Yates, Emma L.; Iraci, Laura T.; Gustin, Mae Sexauer (2017). Investigating the influence of long-range transport on surface O3 in Nevada, USA, using observations from multiple measurement platforms. Science of The Total Environment, 530 493. https://doi.org/10.1016/j.scitotenv.2015.03.125


Yates, E. L.; Iraci, L. T.; Roby, M. C.; Pierce, R. B.; Johnson, M. S.; Reddy, P. J.; Tadić, J. M.; Loewenstein, M.; Gore, W. (2017). Airborne observations and modeling of springtime stratosphere-to-troposphere transport over California. Atmospheric Chemistry and Physics, 13 (24), 12481. https://doi.org/10.5194/acp-13-12481-2013


Yates E L, Johnson M S, Iraci L T, Ryoo J-M, Pierce R B, Cullis P D, Gore W, Ives M A, Johnson B J, Leblanc T, Marrero J E, Sterling C W and Tanaka T (2017). An Assessment of Ground Level and Free Tropospheric Ozone Over California and Nevada. Journal of Geophysical Research: Atmospheres, 122 (18), 10089. https://doi.org/10.1002/2016JD026266


Yates, Emma L.; Iraci, Laura T.; Austerberry, David; Pierce, R. Bradley; Roby, Matthew C.; Tadić, Jovan M.; Loewenstein, Max; Gore, Warren (2017). Characterizing the impacts of vertical transport and photochemical ozone production on an exceedance area. Atmospheric Environment, 109 342. https://doi.org/10.1016/j.atmosenv.2014.09.002


Johnson M S, Xi X, Jeong S, Yates E L, Iraci L T, Tanaka T, Loewenstein M, Tadić J M and Fischer M L (2016). Investigating seasonal methane emissions in Northern California using airborne measurements and inverse modeling. Journal of Geophysical Research: Atmospheres, 121 (22), 13753. https://doi.org/10.1002/2016JD025157


Lin M, Horowitz L W, Cooper O R, Tarasick D, Conley S, Iraci L T, Johnson B, Leblanc T, Petropavlovskikh I and Yates E L (2015). Revisiting the evidence of increasing springtime ozone mixing ratios in the free troposphere over western North America. Geophysical Research Letters, 42 (20), 8719. https://doi.org/10.1002/2015GL065311