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Alexandra Christensen

Signal Analysis Engineer

About

Bio

Alex Christensen grew up in Tempe, Arizona and became interested in wetland ecosystems while studying at the University of California, Berkeley. She went on to study coastal hydrology and nutrient cycling at Louisiana State University. She joined JPL as a NPP fellow with Marc Simard in May 2020. She transitioned to a Signal Analysis Engineer in 334F in 2022. Her research focuses on hydrodynamics of coastal deltas using numerical modeling and satellite remote sensing to study the interaction of vegetation and surface water hydrology.

Alex is a passionate, multi-disciplinary coastal engineer and scientist with 8 years of experience leading and coordinating wetland field campaigns, processing large and diverse remote sensing datasets, and developing hydrodynamic models. Detail-oriented, thorough, and well organized as demonstrated through management of field teams, tutorials, and large datasets for the Delta-X and NISAR missions. Recent work involves building open-source hydrodynamic models, validating SWOT data in coastal deltas, and monitoring wetland vulnerability. Also, part of the NISAR Project Science Team, preparing workflows to generate L3 ecosystem science products.

Competences include Python and Matlab programming, ANUGA and Delft3D hydrodynamic and water quality modeling, SNAP and ISCE3 to process TerraSAR-X, Sentinel-1, UAVSAR, and ALOS/PALSAR-2 in backscatter and interferometric mode for scientific applications, and SPDLIB to process Lidar data. Field experience includes installing pressure transducers, surveying GNSS elevations and ADCP channel discharge, and sampling vegetation and soil biogeochemistry.

Education

  • Ph.D. Oceanography and Coastal Sciences, Louisiana State University, 2020
  • M.S. Coastal and Ecological Engineering, Louisiana State University, 2017
  • B.S. Conservation and Resource Studies, Minor in Forestry, University of California, Berkeley, 2011

Research Interests

  • Surface water hydrology
  • Ecology
  • Water Quality
  • Vegetation dynamics

Experience

Professional Experience

  • Signal Analysis Engineer 2022 - present
  • JPL Post-doc, 2022
  • NASA Postdoctoral Fellow, 2020 - 2022
  • Graduate Research Assistant 2013 - 2020

Research Community Service

  • JPL New Researcher Support Group (NRSG) President 2025
  • JPL New Researcher Support Group (NRSG) Vice President 2024
  • AGU Thriving Earth Exchange Community Science Fellow 2021-2023

Achievements

Awards & Recognitions

Publications

Peer-Reviewed Publications:

Biswas, P., Twilley, R. R., Rovai, A. S., Christensen, A., Shribman, Z. I., & Kameshwar, S. (2025). Incorporating Uncertainty in a Wetland Soil Accretion Model (NUMAN 2.0) to Test Generality Across Coastal Environmental Settings of South Florida. Estuarine, Coastal and Shelf Science, 109407.

Christensen, A., Siqueira, P., Chapman, B., Kellndorfer, J., McDonald, K., Saatchi, S., ... & Ramachandran, N. (2024, July). Preparing an on-Demand Cloud Processing Workflow for NISAR Ecosystems Science Products. In IGARSS 2024-2024 IEEE International Geoscience and Remote Sensing Symposium (pp. 6635-6637). IEEE.

Belhadj-aissa S., Simard M., Jones C. E., Oliver-Cabrera T., Christensen A. (2024). Separation of Water Level Change from Atmospheric Artifacts Through Application of Independent Component Analysis to InSAR Time Series. AGU Space and Earth Sciences Journal.

Rovai, A.S., Twilley, R., Christensen, A., et al. (2022). Biomass allocation of tidal freshwater marsh species in response to natural and manipulated hydroperiod in coastal deltaic floodplains. Estuarine, Coastal and Shelf Science.

Jensen, D., Cavanaugh, K. C., Simard, M., Christensen, A., Rovai, A., & Twilley, R. (2021). Aboveground biomass distributions and vegetation composition changes in Louisiana's Wax Lake Delta. Estuarine, Coastal and Shelf Science, 250, 107139.

Christensen, A., Twilley, R. R., Willson, C. S., & Castañeda-Moya, E. (2020). Simulating hydrological connectivity and water age within a coastal deltaic floodplain of the Mississippi River Delta. Estuarine, Coastal and Shelf Science, 245, 106995. https://doi.org/https://doi.org/10.1016/j.ecss.2020.106995

Li, S., Christensen, A., & Twilley, R. R. (2020). Benthic fluxes of dissolved oxygen and nutrients across hydrogeomorphic zones in a coastal deltaic floodplain within the Mississippi River delta plain. Biogeochemistry, 149(2), 115-140.

Twilley R. R., Day J. W., Bevington A. E., Castañeda-Moya E., Christensen A., Holm G., Heffner L. R., Lane R, McCall A, Aarons A, Li S, Freeman A, Rovai AS (2019). Ecogeomorphology of coastal deltaic floodplains and estuaries in an active delta: Insights from the Atchafalaya Coastal Basin. Estuarine Coastal and Shelf Science 227: 106341.

Dataset Publications:

Twilley, R., P. Biswas, A. Rovai, A.L. Christensen, A.F. Cassaway, and I.A. Vargas-lopez. 2024. Delta-X: NUMAR Soil Accretion Modeled to 2100, MRD, Louisiana, USA. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2368

Christensen, A., M.W. Denbina, and M. Simard. 2023. Delta-X: Digital Elevation Model, MRD, LA, USA, 2021. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2181

Christensen, A., J.M. Mallard, J. Nghiem, J. Harringmeyer, M. Simard, T.M. Pavelsky, M.P. Lamb, and C.G. Fichot. 2022. Delta-X: Sonar Bathymetry Survey of Channels, MRD, LA. 2021. ORNL DAAC, Oak Ridge, Tennessee, USAhttps://doi.org/10.3334/ORNLDAAC/2085

Christensen, A., J.M. Mallard, and J. Nghiem. 2021. Delta-X: Acoustic Doppler Current Profiler Channel Surveys, Coastal Louisiana, 2021. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1939

Christensen, A., J.M. Mallard, M. Simard, T.M. Pavelsky, and A. Rovai. 2023. Delta-X: In-situ Water Surface Elevation, MRD, Louisiana, USA, 2021. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2086

Castaneda, E., A. Christensen, M. Simard, A. Bevington, R. Twilley, and A. Mccall. 2020. Pre-Delta-X: Vegetation Species, Structure, Aboveground Biomass, MRD, LA, USA, 2015. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1805

Simard, M., M.W. Denbina, E. Rodriguez, A. Christensen, K.A. Wright, and A. Rovai. 2022. Delta-X: Ecogeomorphic Cell Products across the MRD, LA, USA, 2021. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2108

Christensen, A., T.M. Pavelsky, D.J. Jensen, and K. Liu. 2020. Pre-Delta-X: River Discharge Channel Surveys across Atchafalaya Basin, LA, USA, 2016. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1806

Castaneda, E., A. Christensen, M. Simard, D.J. Jensen, R. Twilley, and R. Lane. 2020. Pre-Delta-X: Total Suspended Solids of Surface Water, MRD, LA. 2015-2016. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1802

Open-Science Software and Tutorial Publications:

Christensen A. BAM: Building ANUGA Models Repository. https://github.com/achri19/BAM

Christensen A. Delta-X Field Data Overview, Access, and Application. May 4-5, 2022. https://daac.ornl.gov/resources/tutorials/2022_deltax_workshop/