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JT Reager

Photo of JT Reager

Address:

4800 Oak Grove Drive
M/S 300-323

Pasadena, CA 91109

Phone:

818.354.0552

Curriculum Vitae:

Click here

Member of:

Water & Ecosystems

Group Supervisor

Biography

J.T. Reager leads the Water and Ecosystems Group at NASA’s Jet Propulsion Laboratory, where he studies global freshwater dynamics and hydrologic extremes using space-based observations. His research spans the interactions between the terrestrial water cycle and broader Earth system processes, including land-ocean exchanges, climate variability, groundwater sustainability, and human impacts on water resources.

He also currently serves as Deputy Project Scientist for the GRACE Follow-On mission and leads Decadal Survey planning for the freshwater science community. He provides science advising to external agencies and organizations including the California Department of Water Resources.

Dr. Reager has authored over 100 peer-reviewed publications, received the Presidential Early Career Award for Scientists and Engineers (PECASE), and regularly represents NASA Earth Science at public events, science workshops, and international forums.

Education

  • 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

  • Scientist, Jet Propulsion Laboratory, California Institute of Technology (2014–Present)
    • Member of the Water and Ecosystems Group in the Earth Sciences Section. Conducts research on global freshwater dynamics, hydrologic extremes, and terrestrial water storage using satellite observations. Contributed over 100 peer-reviewed publications and received multiple national honors for scientific leadership and innovation.
  • Deputy Project Scientist – GRACE-FO Mission, JPL (2024–Present)
    • Supports science direction and stakeholder engagement for NASA’s gravity satellite mission monitoring mass change across the Earth system.

Community Service

  • Lead Author, NASA Mass Change Designated Observable Community Assessment Report (2022)
  • Organizer and Convener, annual GRACE/GRACE-FO AGU sessions (2018–present)
  • Co-Lead, Water Focus Area for NASA Decadal Survey Preparatory Activities at JPL (2024–present)
  • Science Advisor, Caltech Data to Discovery Summer Program (2022)
  • Organizer, Workshops on satellite hydrology with CUAHSI, UNESCO, and NASA DEVELOP (2015–2020)
  • Science Advisor, California Department of Water Resources – Satellite-Based Groundwater Updates (2021–present)

Research Interests

  • Global freshwater monitoring and mass change
  • Hydrologic extremes and drought/flood risk
  • Strategic Earth mission formulation
  • Integration of NASA observations into decision-making
  • Groundwater sustainability and human-Earth interactions

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

106+ publications; Citations: 13,000; H-index: 48;

*See CV for full list

  1. Jarugula, S., Fournier, S., Reager, J., & Pascolini‐Campbell, M. (2026). Land–ocean pathways linking Indo‐Pacific sea surface temperature variability to tropical Atlantic coastal salinity. Journal of Geophysical Research: Oceans, 131(5), e2025JC023816.
  2. Lee, C. M., Downs, B., Shah, R., Hestir, E. L., Owen, S., Schimel, D., Reager, J.T. et al. (2026). Advancing water security and national preparedness through Earth science observations and the Earth science workforce. Earth and Space Science, 13(4), e2025EA004804.
  3. Pierrat, Z. A., Gustine, R. N., Boser, A., Ruehr, S., Lee, C. M., Reager, J. T., & Cawse-Nicholson, K. (2026). Human contributions to evapotranspiration mitigate swings in dry-to-wet year transitions. Communications Sustainability, 1(1), 8.
  4. Blank, D., Eicker, A., Reager, J. T., & Güntner, A. (2025). Revisiting sub‐surface drought cascades with daily satellite observations of soil moisture and terrestrial water storage. Water Resources Research, 61(8), e2024WR039321.
  5. Chandanpurkar, H. A., Famiglietti, J. S., Gopalan, K., Wiese, D. N., Wada, Y., Kakinuma, K., Reager, J.T. & Zhang, F. (2025). Unprecedented continental drying, shrinking freshwater availability, and increasing land contributions to sea level rise. Science Advances, 11(30), eadx0298.
  6. Lambert, F. H., Allan, R. P., Behrangi, A., Byrne, M. P., Ceppi, P., Chadwick, R., ...Reager, J.T. & Stephens, G. L. (2025). Changes in the regional water cycle and their impact on societies. Wiley Interdisciplinary Reviews: Climate Change, 16(2), e70005.
  7. Wade, J., David, C. H., Collins, E. L., Denbina, M., Cerbelaud, A., Tom, M., Reager, J.T., ... & Gierach, M. M. (2025). Intrinsic Spatial Scales of River Stores and Fluxes and Their Relative Contributions to the Global Water Cycle. Geophysical Research Letters, 52(4), e2024GL113052.
  8. Adams, K. H., Reager, J. T., Buzzanga, B. A., David, C. H., Sawyer, A. H., & Hamlington, B. D. (2024). Climate‐induced saltwater intrusion in 2100: Recharge‐driven severity, sea level‐driven prevalence. Geophysical Research Letters, 51(22).
  9. Jaramillo, F., Aminjafari, S., Castellazzi, P., Fleischmann, A., Fluet‐Chouinard, E., Hashemi, H., Reager, J.T.,... & Salazar, J. F. (2024). The potential of hydrogeodesy to address water‐related and sustainability challenges. Water resources research, 60(11), e2023WR037020.
  10. Pradhan, A., Adams, K. H., Chandrasekaran, V., Liu, Z., Reager, J. T., Stuart, A. M., & Turmon, M. J. (2024). Modeling groundwater levels in California's Central Valley by hierarchical Gaussian process and neural network regression. Journal of Geophysical Research: Machine Learning and Computation, 1(4).
  11. Boser, A., Caylor, K., Larsen, A., Pascolini-Campbell, M., Reager, J. T., & Carleton, T. (2024). Field-scale crop water consumption estimates reveal potential water savings in California agriculture. Nature Communications, 15(1), 2366. https://doi.org/10.1038/s41467-024-42050-3
  12. Rodell, M., & Reager, J. T. (2023). Water cycle science enabled by the GRACE and GRACE-FO satellite missions. Nature Water, 1(1), 47-59.
  13. 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.
  14. 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.
  15. 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.
  16. Farahmand, A., Reager, J. T., & Madani, N. (2021). Drought Cascade in the Terrestrial Water Cycle: Evidence from Remote Sensing. Geophysical Research Letters, e2021GL093482.
  17. 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.
  18. 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).
  19. 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.
  20. 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.
  21. 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.
  22. 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.
  23. 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.

Projects

GRACE Follow-On
NASA Sea Level Change Team
SMAP - Soil Moisture Active Passive