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Junjie Liu

Photo of Junjie Liu


4800 Oak Grove Drive
M/S 233-200

Pasadena, CA 91109



Curriculum Vitae:

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Member of:

Carbon Cycle And Ecosystems

Principal Scientist


  • Ph. D, December 2007: University of Maryland-College Park.
  • M. S., Spring 2003: Nanjing Institute of Meteorology, China
  • B. S., 2000: Nanjing Institute of Meteorology, China.

Professional Experience

  • Principal Scientist, Aug 2022
  • Acting Science Team Lead for Orbiting Carbon Observatory -2/3, Jan 2022
  • Visiting Associate, Aug 2018-,  Caltech
  • Research Scientist, Feb 2011-: Jet Propulsion Laboratory, Caltech
  • Assistant Researcher, Feb 2010-Feb 2011: University of California, Berkeley
  • Research associate, Feb 2008-Feb 2010: University of California, Berkeley
  • Research associate, Dec 2007-Feb 2008: University of Maryland-College Park

Research Interests

  • Carbon-climate interactions and predictions
  • Top-down atmosphere flux inversions
  • Human impact on carbon cycle

Selected Awards

  • NASA Exceptional Achievement medal (2018)
  • JPL Ed Stone Award (2018)
  • JPL Voyager Award (2017)
  • NASA early career achievement award (2015)
  • NASA Group Achievement Award, Carbon Monitoring System Flux Pilot Project Team (2013)
  • Best Ph. D thesis award in Atmospheric and Oceanic Science department, University of Maryland, 2007
  • Second place student paper award for "Application of Local Ensemble Transform Kalman Filter: Perfect model experiments with NASA fvGCM" in AMS 86th annual meeting held in Atlanta, GA, Jan. 28-Feb. 3, 2006

Selected Publications

  1. Friedlingstein, P., et al. (including J. Liu).: Global Carbon Budget 2021, Earth Syst. Sci. Data, 14, 1917–2005,, 2022.
  2. Laughner, Joshua L, Jessica L Neu, David Schimel, Paul O Wennberg, Kelley Barsanti, Kevin W Bowman, Abhishek Chatterjee, et al. 2021. “Societal Shifts Due to COVID-19 Reveal Large-Scale Complexities and Feedbacks between Atmospheric Chemistry and Climate Change.” Proceedings of the National Academy of Sciences 118 (46).
  3. Barkhordarian, Armineh, Kevin W Bowman, Noel Cressie, Jeffrey Jewell, and Junjie Liu. 2021. “Emergent Constraints on Tropical Atmospheric Aridity{\textendash}carbon Feedbacks and the Future of Carbon Sequestration," October.
  4. Byrne, B, J Liu, M Lee, Y Yin, K W Bowman, K Miyazaki, A J Norton, et al. 2021. “The Carbon Cycle of Southeast Australia During 2019–2020: Drought, Fires, and Subsequent Recovery.” AGU Advances 2 (4): e2021AV000469." ""
  5. He, Wei, Fei Jiang, Mousong Wu, Weimin Ju, Marko Scholze, Zhi Chen, Brendan Byrne, et al. n.d. “China’s Terrestrial Carbon Sink over 2010–2015 Constrained by Satellite Observations of Atmospheric CO2 and Land Surface Variables.” Journal of Geophysical Research: Biogeosciences n/a (n/a): e2021JG006644.
  6. Zhang, Li, Kenneth J Davis, Andrew E Schuh, Andrew R Jacobson, Sandip Pal, Yu Yan Cui, David Baker, et al. 2022. “Multi-Season Evaluation of CO2 Weather in OCO-2 MIP Models.” Journal of Geophysical Research: Atmospheres 127 (2): e2021JD035457.
  7. Xu, Liang, Sassan S Saatchi, Yan Yang, Yifan Yu, Julia Pongratz, A Anthony Bloom, Kevin Bowman, J. Worden, J. Liu, et al. 2021. “Changes in Global Terrestrial Live Biomass over the 21st Century.” Science Advances 7 (27): eabe9829.
  8. Chen, Z., Huntzinger, D. N., Liu, J., ...., and Miller, S. M.: Five years of variability in the global carbon cycle: comparing an estimate from the Orbiting Carbon Observatory-2 and process-based models, Environ. Res. Lett. 16 054041
  9. Worden, J., Saatchi, S., Keller, M., Bloom, A., Liu, J., Parazoo, N., et al. (2021). Satellite observations of the tropical terrestrial carbon balance and interactions with the water cycle during the 21st century. Reviews of Geophysics, 59, e2020RG000711.
  10. Liu, J., Baskaran, L., Bowman, K., Schimel, D., Bloom, A. A., Parazoo, N. C., Oda, T., Carroll, D., Menemenlis, D., Joiner, J., Commane, R., Daube, B., Gatti, L. V., McKain, K., Miller, J., Stephens, B. B., Sweeney, C., and Wofsy, S.: Carbon Monitoring System Flux Net Biosphere Exchange 2020 (CMS-Flux NBE 2020), Earth Syst. Sci. Data, 13, 299–330,, 2021.
  11. Liu, J., Wennberg, P. O., Parazoo, N. C., Yin, Y., & Frankenberg, C. (2020). Observational constraints on the response of high‐latitude northern forests to warming. AGU Advances, 1, e2020AV000228.
  12. Chen, Z., Liu, J., Henze, D. K., Huntzinger, D. N., Wells, K. C., and Miller, S. M.: Linking global terrestrial CO2 fluxes and environmental drivers using OCO-2 and a geostatistical inverse model, Atmos. Chem. Phys., 21, 6663–6680,, 2021.
  13. Carroll, D., Menemenlis, D., et al. (including J. Liu), (2020). The ECCO‐Darwin data‐assimilative global ocean biogeochemistry model: Estimates of seasonal to multidecadal surface ocean pCO2 and air‐sea CO2 flux. Journal of Advances in Modeling Earth Systems, 12, e2019MS001888.
  14. Liao, E., Resplandy, L., Liu, J., & Bowman, K. W. (2020). Amplification of the ocean carbon sink during El Niños: Role of poleward Ekman transport and influence on atmospheric CO2. Global Biogeochemical Cycles, 34, e2020GB006574.
  15. Yin, Y. et al. (including J. Liu), 2020, Fire decline in dry tropical ecosystems enhances decadal land carbon sink. Nat Commun 11, 1900 (2020).
  16. Yi, Y., Kimball, J. S., Watts, J. D., Natali, S. M., Zona, D., Liu, J., Ueyama, M., Kobayashi, H., Oechel, W., and Miller, C. E.: Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model, Biogeosciences, 17, 5861–5882,, 2020.
  17. Byrne, B.*, Liu, J., Bloom, A. A., Bowman, K. W., Butterfield, Z., Joiner, J., et al. (2020). Contrasting regional carbon cycle responses to seasonal climate anomalies across the east‐west divide of temperate North America. Global Biogeochemical Cycles, 34, e2020GB006598.
  18. Byrne, B. *, Liu, J., Lee, M., Baker, I., Bowman, K. W., Deutscher, N. M., et al. (2020). Improved constraints on northern extratropical CO2 fluxes obtained by combining surface‐based and space‐based atmospheric CO2 measurements. Journal of Geophysical Research: Atmospheres, 125, e2019JD032029.
  19. Butler, M. P., Lauvaux, T., Feng, S., Liu, J., Bowman, K. W., & Davis, K. J. (2020). Atmospheric simulations of total column CO2 mole fractions from global to mesoscale within the carbon monitoring system flux inversion framework. Atmosphere, 11(8), 787.
  20. Bloom, A. A., Bowman, K. W., Liu, J., Konings, A. G., Worden, J. R., Parazoo, N. C., Meyer, V., Reager, J. T., Worden, H. M., Jiang, Z., Quetin, G. R., Smallman, T. L., Exbrayat, J.-F., Yin, Y., Saatchi, S. S., Williams, M., and Schimel, D. S.: Lagged effects regulate the inter-annual variability of the tropical carbon balance, Biogeosciences, 17, 6393–6422,, 2020.
  21. Jones, S., Rowland, L., Cox, P., Hemming, D., Wiltshire, A., Williams, K., Parazoo, N. C., Liu, J., da Costa, A. C. L., Meir, P., Mencuccini, M., and Harper, A. B.: The impact of a simple representation of non-structural carbohydrates on the simulated response of tropical forests to drought, Biogeosciences, 17, 3589–3612,, 2020.
  22. Yun et al., (including Liu, J), Enhanced regional terrestrial carbon uptake over Korea revealed by atmospheric CO 2 measurements from 1999 to 2017, Global Change, Biology, 2020, DOI: 10.1111/gcb.15.061
  23. Yin, Y., Byrne, B., Liu, J., Wennberg, P., Davis, K. J., Magney, T., et al. ( 2020). Cropland carbon uptake delayed and reduced by 2019 Midwest floods. AGU Advances, 1, e2019AV000140.
  24. Feng, S., T. Lauvaux, K. Davis, K. Keller, Y. Zhou, C. Williams, A. Schuh, J. Liu, I. Baker, 2019: Seasonal characteristics of model uncertainties from biogenic fluxes, transport, and large-scale boundary inflow in atmospheric CO2 simulations over North America. J. Geophys. Res.-Atmos.,
  25. Shi, M., Liu, J., Worden, J. R., Bloom, A. A., Wong, S., & Fu, R. ( 2019). The 2005 Amazon drought legacy effect delayed the 2006 wet season onset. Geophysical Research Letters, 46, 9082– 9090.
  26. Crowell, S., Baker, D., Schuh, A., Basu, S., Jacobson, A. R., Chevallier, F., Liu, J., Deng, F., Feng, L., McKain, K., Chatterjee, A., Miller, J. B., Stephens, B. B., Eldering, A., Crisp, D., Schimel, D., Nassar, R., O'Dell, C. W., Oda, T., Sweeney, C., Palmer, P. I., and Jones, D. B. A.: The 2015–2016 carbon cycle as seen from OCO-2 and the global in situ network, Atmos. Chem. Phys., 19, 9797–9831,, 2019.
  27. Philip, S., Johnson, M. S., Potter, C., Genovesse, V., Baker, D. F., Haynes, K. D., Henze, D. K., Liu, J., and Poulter, B.: Prior biosphere model impact on global terrestrial CO2 fluxes estimated from OCO-2 retrievals, Atmos. Chem. Phys., 19, 13267–13287,, 2019.
  28. Konings, A. G., Bloom, A. A., Liu, J., Parazoo, N. C., Schimel, D. S., and Bowman, K. W.: Global satellite-driven estimates of heterotrophic respiration, Biogeosciences, 16, 2269–2284,, 2019.
  29. Schuh, A., A. R. Jacobson, S. Basu, B. Weir, D. Baker, K. Bowman, F. Chevallier, S. Crowell, K. Davis, F. Deng, S. Denning, L. Feng, D. Jones, J. Liu, and P. Palmer, 2019, Quantifying the impact of atmospheric transport uncertainty on CO2 surface flux estimates. Global Biogeochemical Cycles, 33, 484– 500.
  30. Basu, S., Baker, D. F., Chevallier, F., Patra, P. K., Liu, J., and Miller, J. B.: The impact of transport model differences on CO2 surface flux estimates from OCO-2 retrievals of column average CO2, Atmos. Chem. Phys., 18, 7189–7215,, 2018.
  31. Hedelius, J. K., Liu, J., Oda, T., Maksyutov, S., Roehl, C. M., Iraci, L. T., Podolske, J. R., Hillyard, P. W., Liang, J., Gurney, K. R., Wunch, D., and Wennberg, P. O.: Southern California megacity CO2, CH4, and CO flux estimates using ground- and space-based remote sensing and a Lagrangian model, Atmos. Chem. Phys., 18, 16271-16291,, 2018.
  32. Liu, J., et al., 2018, Detecting drought impact on terrestrial biosphere carbon fluxes over contiguous US with satellite observations, Environmental Research Letters, vol 13, 095003.
  33. Liu J., et al., 2018, Response to Comment on “Contrasting carbon cycle responses of tropical continents to 2015-2016 El Nino”, Vol. 362, Issue 6418, eaat1211. DOI: 10.1126/science.aat1211
  34. Souri, A. H., Choi, Y., Pan, S., Curci, G., Nowlan, C. R., Janz, S. J., M. K. Kowalewski, J. Liu et al.(2018). First Top‐Down Estimates of Anthropogenic NOx Emissions Using High‐Resolution Airborne Remote Sensing Observations. Journal of Geophysical Research: Atmospheres, 123.
  35. Sellers, P. J., D. S. Schimel, B. Moore, J. Liu, and A. Eldering, Observing Carbon Cycle-climate feedbacks from space, Proceedings of the National Academy of Sciences Jul 2018, 115 (31) 7860-7868; DOI: 10.1073/pnas.1716613115
  36. Parazoo NC, Arneth A, Pugh TAM, et al (including Liu, J.). 2018, Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing. Glob Change Biol. 2018;24:3416–3435.
  37. Liu, J. et al 2017 Contrasting carbon cycle responses of the tropical continents to the 2015–2016 El Nino Science 358 eaam5690
  38. Eldering, A., Wennberg, P. O., Crisp, D., Schimel, D. S., Gunson, M. R., Chatterjee, A.,J. Liu, et al.(2017). The Orbiting Carbon Observatory‐2 early science investigations of regional carbon dioxide fluxes. Science, 358, eaam5745.
  39. Shi, M., Liu, J., Zhao, M., Yu, Y., & Saatchi, S. (2017). Mechanistic processes controlling persistent changes of forest canopy structure after 2005 Amazon drought. Journal of Geophysical Research: Biogeosciences, 122, 3378–3390.
  40. Mueller, K.J., J. Liu, W. McCarty, and R. Gelaro, 2017: An Adjoint-Based Forecast Impact from Assimilating MISR Winds into the GEOS-5 Data Assimilation and Forecasting System. Mon. Wea. Rev., 145, 4937–4947,
  41. Bowman, K. W., Liu, J., Bloom, A. A., Parazoo, N. C., Lee, M., Jiang, Z., … Wunch, D. (2017). Global and Brazilian carbon response to El Niño Modoki 2011–2010. Earth and Space Science, 4, 637–660.
  42. Byrne, B., D. B. A. Jones, K. Strong, Z.‐C. Zeng, F. Deng, and J. Liu,(2017), Sensitivity of CO2 surface flux constraints to observational coverage, J. Geophys. Res. Atmos., 122, 6672–6694, doi:10.1002/2016JD026164.
  43. Liu, J., K. W. Bowman, and M. Lee (2016), Comparison between the Local Ensemble Transform Kalman Filter (LETKF) and 4D-Var in atmospheric CO2 flux inversion with the Goddard Earth Observing System-Chem model and the observation impact diagnostics from the LETKF, J. Geophys. Res. Atmos., 121, 13,066–13,087, doi:10.1002/2016JD025100.
  44. Liu, J., and K. Bowman (2016), A method for independent validation of surface fluxes from atmospheric inversion: Application to CO2, Geophys. Res. Lett., 43, doi:10.1002/2016GL067828.
  45. Liu, J., K. W. Bowman, and D. K. Henze (2015), Source-receptor relationships of column-average CO2 and implications for the impact of observations on flux inversions. J. Geophys. Res. Atmos., 120, 5214–5236. doi: 10.1002/2014JD022914.
  46. Worden, J. R., Turner, A. J., Bloom, A., Kulawik, S. S., Liu, J., Lee, M., Weidner, R.,
  47. Bowman, K., Frankenberg, C., Parker, R., and Payne, V. H.: Quantifying lower tropospheric methane concentrations using GOSAT near-IR and TES thermal IR measurements, Atmos. Meas. Tech., 8, 3433-3445, doi:10.5194/amt-8-3433-2015, 2015.
  48. Bousserez, N., D. K. Henze, A. Perkins, K. W. Bowman, M.Lee, J.Liu, D.B.A. Jones, F. Deng (2015), Improved analysis error covariance matrix estimates for variational inverse problems, Q. J. R. Meteorol. Soc., 141: 1906--1921, do:10.1002/qj.2495,
  49. Miller, S. M., Hayek, M. N., Andrews, A. E., Fung, I., and Liu, J.: Biases in atmospheric CO2 estimates from correlated meteorology modeling errors, Atmos. Chem. Phys., 15, 2903-2914, doi:10.5194/acp-15-2903-2015, 2015.
  50. Ott, L. E., Steven Pawson, George J. Collatz, Watson W. Gregg, Dimitris Menemenlis, Holger Brix, Cecile S. Rousseaux, Kevin W. Bowman, Junjie Liu, Annmarie Eldering, Michael R. Gunson, and Stephan R. Kawa, 2015, Assessing the magnitude of CO2 flux uncertainty in atmospheric CO2 records using products from NASA’s Carbon Monitoring Flux Pilot Project, J. Geophys. Res. Atmos., 120, doi:10.1002/2014JD022411.
  51. Liu, J., Bowman, K., Lee, M., Henze, D., Bousserez, N., Brix, H., Collatz, G., Menemenlis, D., Ott, L., Pawson, S., Jones, D., Nassar, R.. Carbon monitoring system flux estimation and attribution: impact of ACOS-GOSAT XCO2 sampling on the inference of terrestrial biospheric sources and sinks. Tellus B, North America, 66, may. 2014. Available at: <>
  52. Parazoo, N. C., et al. (including Liu, J.) (2013), Interpreting seasonal changes in the carbon balance of southern Amazonia using measurements of XCO2 and chlorophyll fluorescence from GOSAT, Geophys. Res. Lett., 40, 2829–2833, doi:10.1002/grl.50452.
  53. Worden, J., et al. (including Liu, J.) (2013), El Niño, the 2006 Indonesian peat fires, and the distribution of atmospheric methane, Geophys. Res. Lett., 40, 4938–4943, doi:10.1002/grl.50937
  54. Liu, J., I. Fung, E. Kalnay, J.-S. Kang, E. T. Olsen, and L. Chen (2012), Simultaneous assimilation of AIRS Xco2 and meteorological observations in a carbon climate model with an ensemble Kalman filter, J. Geophys. Res., 117, D05309, doi:10.1029/2011JD016642.
  55. Kalnay, E., Y. Ota, T. Miyoshi, J. Liu (2012), A simpler formulation of forecast sensitivity to observations: application to ensemble Kalman filters. Tellus A.
  56. Kang, J.-S., E. Kalnay, T. Miyoshi, J. Liu, and I. Fung (2012), Estimation of surface carbon fluxes with an advanced data assimilation methodology, J. Geophys. Res., 117, D24101, doi:10.1029/2012JD018259.
  57. Liu, J., I. Fung, E. Kalnay, and J.-S. Kang (2011), CO2 transport uncertainties from the uncertainties in meteorological fields, Geophys. Res. Lett., 38, L12808, doi:10.1029/2011GL047213.
  58. Kang, J.-S., E. Kalnay, J. Liu, I. Fung, T. Miyoshi, and K. Ide (2011), “Variable localization” in an ensemble Kalman filter: Application to the carbon cycle data assimilation, J. Geophys. Res., 116, D09110, doi:10.1029/2010JD014673.
  59. Liu, J., E. Kalnay, T. Miyoshi, and C. Cardinali, 2009: Analysis sensitivity calculation within an ensemble Kalman filter. Quart. J. Roy. Meteor. Soc. 135, 1842-1851
  60. Liu, J., H. Li, E. Kalnay, E.J. Kostelich, and I. Szunyogh, 2009: Univariate and Multivariate Assimilation of AIRS Humidity Retrievals with the Local Ensemble Transform Kalman Filter. Mon. Wea. Rev., 137, 3918–3932.
  61. Fertig, E. J., S.-J. Baek, B. R. Hunt, E. Ott, I. Szunyogh, J. A. Aravequia, E. Kalnay, H. Li, and J. Liu, 2009: Observation bias correction with an ensemble Kalman filter. Tellus A, 61, 210-226.
  62. Liu, J. and E. Kalnay, 2008: Estimating observation impact study without adjoint model in an ensemble Kalman filter. Quart. J. Roy. Meteor. Soc, 134, 1327-1335.
  63. Liu, J., E. J. Fertig, H. Li, I. Szunyogh, B. Hunt, E. Kalnay, E. J. Kostelich, and R. Todling, 2008: Comparison between Local Ensemble Transform Kalman Filter and PSAS in the NASA finite volume GCM: perfect model experiments. Nonlin. Processes in Geophys., 15, 645-659.