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JT Reager

Photo of JT Reager


4800 Oak Grove Drive
M/S 300-323

Pasadena, CA 91109



Curriculum Vitae:

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Member of:

Water & Ecosystems



Dr. JT Reager is an Earth Scientist specializing in the topic of freshwater. His research focuses on measuring changes in Earth's water cycle with a particular focus on hydrologic extremes, changing water resources, and implications for society.

The Earth is presently undergoing a dynamic evolution, due to the combined influences of natural variability and the direct/indirect impacts of human development. As the Earth changes in time, it is important to quantify and monitor the form and shape of this evolution, to better enable the prediction of potential future states, as well as to better understand the connected nature of natural and man-made processes on our home planet. Dr. Reager leverages innovative approaches in space-based observation to quantify changes in the cycling of water between the global ocean and global land, and to connect those changes to local and regional hydrologic hazards like extreme floods and droughts, or to measure the availability of water resources in snow, surface water and groundwater.

J.T. studied aerospace engineering as an undergraduate, and physical oceanography as a masters student. Upon realizing a predisposition to kinetosis (sea sickness), he switched fields to remote sensing hydrology and Earth System Science for his PhD. He joined JPL in 2014, and is a member of the NASA GRACE/GRACE-FO science team, the NASA Sea Level Change science team, and the NASA Applied Science Water Resources science team.


  • Postdoctoral Researcher, UC Center for Hydrological Modeling (2014)
  • PhD in Earth System Science, University of California, Irvine; Irvine, CA (2012)
  • M.S. in Physical Ocean Science and Engineering, University of Delaware, College of Marine Studies, Newark, DE (2004)
  • B.S. in Aerospace Engineering, B.S. in Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA (2001)

Professional Experience

  • Jet Propulsion Laboratory, Pasadena, CA
    • Scientist (2014-present)
  • University of California, Los Angeles, CA
    • Visiting Researcher, JIFRESSE (2014-present)

Research Interests

  • Water in the Earth System
  • New approaches in space-based and airborne observations
  • Uncertainty quantification
  • Identification of observational gaps
  • Ocean/land water cycling
  • Carbon/water interactions
  • Water/solid earth interactions
  • Human impacts on the Earth System
  • Natural resource sustainability

Selected Awards

  • JPL Voyager Award (2020) for leadership in the Surface Deformation and Change D.O. Study Hydrology Science and Applications Traceability Team.
  • JPL Voyager Award (2019) for advancements in the application of satellite data for the Hydrological Sciences and for student mentoring.
  • PECASE: Presidential Early Career Award for Science and Engineering (2019) for studies of the Terrestrial Water Cycle using GRACE.
  • NASA Early Career Achievement Medal (2017) for Contributions to understanding hydrologic extreme events.
  • NOAA David Johnson Early Career Award (2016) for Innovative application of Earth observation satellite data for operational purposes.
  • Newkirk Center for Science and Society Fellowship (2100-2012) for Estimating long-range global flood potential using GRACE terrestrial water storage and CMIP precipitation.
  • ARCS Foundation Scholar Achievement Award (2010-2012) for GRACE and the critical limits of the global water cycle.
  • NASA Earth and Space Science Fellowship (2009-2012) for Applications of a frequency-domain terrestrial water balance using GRACE.

Selected Publications

90+ publications; Citations: 6822; H-index: 36; i10-index: 70 (as of 04/2023)

*See CV for full list

  1. Rodell, M., & Reager, J. T. (2023). Water cycle science enabled by the GRACE and GRACE-FO satellite missions. Nature Water, 1(1), 47-59.
  2. Liu, P. W., Famiglietti, J. S., Purdy, A. J., Adams, K. H., McEvoy, A. L., Reager, J. T., ... & Rodell, M. (2022). Groundwater depletion in California’s Central Valley accelerates during megadrought. Nature Communications, 13(1), 7825.
  3. Adams, K. H., Reager, J. T., Rosen, P., Wiese, D. N., Farr, T. G., Rao, S., ... & Rodell, M. (2022). Remote sensing of groundwater: current capabilities and future directions. Water Resources Research, 58(10), e2022WR032219.
  4. Wiese, D. N., Bienstock, B., Blackwood, C., Chrone, J., Loomis, B. D., … Reager, J. T., Sauber, J. & Zlotnicki, V. (2022). The mass change designated observable study: overview and results. Earth and Space Science, 9(8), e2022EA002311.
  5. Farahmand, A., Reager, J. T., & Madani, N. (2021). Drought Cascade in the Terrestrial Water Cycle: Evidence from Remote Sensing. Geophysical Research Letters, e2021GL093482.
  6. Chandanpurkar, H. A., Reager, J. T., Famiglietti, J. S., Nerem, R. S., Chambers, D. P., Lo, M. H., ... & Syed, T. H. (2021). The seasonality of global land and ocean mass and the changing water cycle. Geophysical Research Letters, 48(7), e2020GL091248.
  7. Pascolini‐Campbell, M., Fisher, J. B., & Reager, J. T. (2021). GRACE‐FO and ECOSTRESS Synergies Constrain Fine‐Scale Impacts on the Water Balance. Geophysical Research Letters, 48(15).
  8. Pascolini‐Campbell, M. A., Reager, J. T., & Fisher, J. B. (2020). GRACE‐based mass conservation as a validation target for basin‐scale evapotranspiration in the contiguous United States. Water Resources Research, 56.
  9. Morris, M., Chew, C., Reager, J. T., Shah, R., & Zuffada, C. (2019). A novel approach to monitoring wetland dynamics using CYGNSS: Everglades case study. Remote Sensing of Environment, 233, 111417.
  10. Fournier, S., Reager, J. T., Dzwonkowski, B., & Vazquez‐Cuervo, J. (2019). Statistical Mapping of Freshwater Origin and Fate Signatures as Land/Ocean “Regions of Influence” in the Gulf of Mexico. Journal of Geophysical Research: Oceans, 124(7), 4954-4973.
  11. Stampoulis, D., Reager, J. T., David, C. H., Andreadis, K. M., Famiglietti, J. S., Farr, T. G., ... & Lundgren, P. R. (2019). Model-data fusion of hydrologic simulations and GRACE terrestrial water storage observations to estimate changes in water table depth. Advances in Water Resources, 128, 13-27.
  12. Tapley, B. D., Watkins, M. M., Flechtner, F., Reigber, C., Bettadpur, S., Rodell, M., ... & Reager, J. T. (2019). Contributions of GRACE to understanding climate change. Nature Climate Change, 1.
  13. Wang, J., Song, C., Reager, J. T., Yao, F., Famiglietti, J. S., Sheng, Y., ... & Wada, Y. (2018). Recent global decline in endorheic basin water storages. Nature geoscience, 11(12), 926.
  14. Chew, C., Reager, J. T., & Small, E. (2018). CYGNSS data map flood inundation during the 2017 Atlantic hurricane season. Scientific Reports (Nature Publisher Group), 8, 1-8.
  15. Rodell, M., Famiglietti, J. S., Wiese, D. N., Reager, J. T., Beaudoing, H. K., Landerer, F. W., & Lo, M. H. (2018). Emerging trends in global freshwater availability. NATURE, 1.
  16. Tourian, M. J., Reager, J. T., & Sneeuw, N. (2018). The Total Drainable Water Storage of the Amazon River Basin: A First Estimate Using GRACE. Water Resources Research, 54(5), 3290-3312.
  17. Fournier, S., J.T. Reager, T. Lee, C.H. David, J. Vazquez and M. Gierach (2016) A Texas flood from land to ocean observed by SMAP, Geophysical Research Letters.
  18. Behrangi, A., Gardner, A. S., Reager, J. T., & Fisher, J. B. (2017). Using GRACE to constrain precipitation amount over cold mountainous basins. Geophysical Research Letters, 44(1), 219-227.
  19. Jensen, D., Reager, J. T., Zajic, B., Rousseau, N., Rodell, M., & Hinkley, E. (2018). The sensitivity of US wildfire occurrence to pre-season soil moisture conditions across ecosystems. Environmental research letters, 13(1), 014021.
  20. Taeb, A., J.T. Reager, V. Chandrasekaran and M. Turmon (2017) California reservoir drought sensitivity and exhaustion risk using statistical graphical models, Water Resources Research.
  21. Chandanpurkar, H.A., J.T. Reager, J.S. Famiglietti and TH. Syed (2017) Satellite- and reanalysis-based mass balance estimates of global continental discharge (1993-2015), Journal of Climate.
  22. Solander, K. C., Reager, J. T., Wada, Y., Famiglietti, J. S., & Middleton, R. S. (2017). GRACE satellite observations reveal the severity of recent water over-consumption in the United States. Nature Scientific Reports, 7.
  23. Wada, Y., M.-H. Lo, J.T. Reager et al. (2016) Fate of water pumped from underground and contributions to sea level rise, Nature Climate Change.
  24. Castle, S. S., Reager, J. T., Thomas, B. F., Purdy, A. J., Lo, M. H., Famiglietti, J. S., & Tang, Q. (2016). Remote detection of water management impacts on evapotranspiration in the Colorado River Basin. Geophysical Research Letters, 43(10), 5089-5097.
  25. Richey, A.S., B.F. Thomas, M.-H. Lo, J.S. Famiglietti, J.T. Reager, K.S. Voss, S.C. Swenson and M. Rodell (2015) Uncertainty in Global Groundwater Storage Estimates in a Total Groundwater Stress Framework. Water Resources Research.
  26. Singh, R.S., J.T. Reager and N.L. Miller, J.S. Famiglietti (2015) Towards hyper-resolution land surface modeling: The effects of fine-scale model grid resolution on CLM4.0 simulations in the Southwestern US. Water Resources Research, 50.
  27. Bierkens, M.F.P., V.A. Bell, P. Burek, N. Chaney, L. Condon, C.H. David, A. de Roo, P. Döll, N. Drost, J.S. Famiglietti, M. Flörke, D.J. Gochis, P. Houser, R. Hut, J. Keune, S. Kollet, R. Maxwell, J.T. Reager, L. Samaniego, E. Sudicky, E.H. Sutanudjaja, N. van de Giesen, H. Winsemius and E.F. Wood (2015) Hyper-resolution global hydrological modeling: what’s next? Hydrological Processes, 29 (2), 310-320.
  28. Reager, J.T., A.C. Thomas, E.A. Sproles, M. Rodell, H.K. Beaudoing, B.-L. Li, J.S. Famiglietti (2015) Assimilation of GRACE terrestrial water storage observations into a land surface model for the assessment of regional flood potential. Remote Sensing 7 (11), 14663-14679.
  29. Castle, S.S., B.F. Thomas, J.T. Reager, M. Rodell, S.C. Swenson and J.S. Famiglietti (2014) Groundwater Depletion During Drought Threatens Future Water Security of the Colorado River Basin. Geophysical Research Letters, 41, 5904–5911.
  30. ^Highlighted in Science, Editors’ choice, “Looking beneath the drying surface”, August 2014.
  31. Thomas, A.C., J.T. Reager, J.S. Famiglietti and M. Rodell (2014) GRACE-observed water storage deficits for hydrological drought characterization. Geophysical Research Letters, 41, 1537–1545.
  32. Reager, J.T., B.F. Thomas and J.S. Famiglietti (2014) River basin flood potential inferred using GRACE gravity observations at several months lead-time. Nature Geoscience, 7, 588-592.
  33. ^Highlighted in Science, “Gravity measurements can predict river flooding”, July, 2014.
  34. Reager, J.T. and J.S. Famiglietti (2013), Characteristic mega-basin water storage behavior from GRACE. Water Resources Research, 49, 3314–3329.
  35. Reager, J.T. and J.S. Famiglietti (2009), Global terrestrial water storage capacity and flood potential using GRACE. Geophysical Research Letters, 36, L23402.