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Alex Gardner

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Address:

4800 Oak Grove Drive
M/S 300-323

Pasadena, CA 91109

Curriculum Vitae:

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Website:

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Member of:

Sea Level And Ice

Group Supervisor

Employed By

Caltech/JPL

Biography

Alex is a Research Scientist in JPL’s Sea Level And Ice Group. He studies the Earth's cryosphere (frozen Earth) with a particular focus on glaciers and ice sheets and their impacts on sea level rise and water resources. He is most interested in how glaciers respond to natural and human induced forcing and the implications for our future. Alex is a member of NASA's ICESat-2, NISAR, GRACE, Surface Topography and Vegetation, Surface Deformation and Change, and Sea Level Change Science Teams. He is also involved with many novel initiatives to measure ice on Earth, and elsewhere, including the use of snake-like robots (EELS) to look for life under Enceladus’ icy shell. Alex is also PI of the ITS_LIVE NASA MEaSUREs initiative.

Education

  • Ph.D., Department of Earth and Atmospheric Sciences, University of Alberta, (August 2010)
  • B. Eng., Department of Civil Engineering, Great Distinction, University of Saskatchewan, (May 2005)

Professional Experience

  • Jet Propulsion Laboratory/California Institute of Technology (2014-present)
  • Assistant Professor, Graduate School of Geography Clark University (2012-2014)
  • NSERC Research Fellow, Department of Atmospheric, Oceanic and Space Sciences University of Michigan (2010-2012).

Research Interests

  • Remote Sensing of
    • Elevation change using radar/laser altimetry and photography
    • Surface deformation using optical and SAR data
    • Mass change using time variable gravity
    • Ice Thickness and bedrock elevation
  • Robotic exploration of Earth and planetary ice
  • Ice shelf melt rates and fracture processes
  • Ice sheet dynamics
  • Sea level change
  • Climate-cryosphere Interaction

Selected Awards

  • JPL Team Award for Deployable Antarctic Sheet Explorer Rovers (DASHER)
  • JPL Lew Allen Award for Excellence
  • NASA Early Career Achievement Medal
  • NSERC Postdoctoral Fellowship
  • A. Stewart Memorial Graduate Prize (Awarded to top 25 University of Alberta PhD candidates)
  • NSERC Alexander Graham Bell Canada Graduate Scholarship D
  • Alberta Ingenuity Student Scholarship
  • NSERC Canada Graduate Scholarship M
  • Civil Engineering Alumni Medal (Top Civil Engineering Graduate)

Selected Publications

  1. Buzzanga, B., Heijkoop, E., Hamlington, B. D., Nerem, R. S., & Gardner, A. (2021). An Assessment of Regional ICESat-2 Sea-Level Trends. Geophysical Research Letters, 48(9), e2020GL092327. https://doi.org/https://doi.org/10.1029/2020GL092327
  2. Lei, Y., Gardner, A., & Agram, P. (2021). Autonomous Repeat Image Feature Tracking (autoRIFT) and Its Application for Tracking Ice Displacement. In Remote Sensing (Vol. 13, Issue 4). https://doi.org/10.3390/rs13040749
  3. Luthcke, S. B., Thomas, T. C., Pennington, T. A., Rebold, T. W., Nicholas, J. B., Rowlands, D. D., Gardner, A. S., & Bae, S. (2021). ICESat-2 Pointing Calibration and Geolocation Performance. Earth and Space Science, 8(e2020EA001494). https://doi.org/https://doi.org/10.1029/2020EA001494
  4. Greene, C. A.*, Gardner, A. S., & Andrews, L. C. (2020). Detecting seasonal ice dynamics in satellite images. The Cryosphere Discuss., 2020, 1–21. https://doi.org/10.5194/tc-2020-122
  5. Fair, Z., Flanner, M., Brunt, K., Fricker, H. A., & Gardner, A. (2020). ICESat-2 and Operation IceBridge altimetry for supraglacial lake depth retrievals. The Cryosphere.
  6. Moon, T. A., Gardner, A. S., Csatho, B. M., Parmuzin, I., & Fahnestock, M. A. (2020). Rapid reconfiguration of the Greenland Ice Sheet coastal margin. Journal of Geophysical Research: Earth Surface, 125(e2020JF005585). https://doi.org/10.1029/2020JF005585
  7. Dehecq, A.*, Gardner, A. S., Alexandrov, O., McMichael, S., Hugonnet, R., Shean, D., & Marty, M. (2020). Automated Processing of Declassified KH-9 Hexagon Satellite Images for Global Elevation Change Analysis Since the 1970s. In Frontiers in Earth Science (Vol. 8, p. 516). https://www.frontiersin.org/article/10.3389/feart.2020.566802
  8. Sasgen, I., Wouters, B., Gardner, A. S., King, M. D., Tedesco, M., Landerer, F. W., et al. (2020). Return to rapid ice loss in Greenland and record loss in 2019 detected by the GRACE-FO satellites. Communications Earth & Environment, 1(1), 8. https://doi.org/10.1038/s43247-020-0010-1
  9. Fricker, H. A., Gardner, A. S. (2020): Recent Changes in the Antarctic Ice Sheet [in “State of the Climate in 2019"]. Bull. Amer. Meteor. Soc.,101 (8), S 304–S306, https://doi.org/10.1175/BAMS-D-20-0090.1.
  10. Behrangi, A., Gardner, A. S., & Wiese, D. N. (2020). Comparative Analysis of Snowfall Accumulation over Antarctica in Light of Ice Discharge and Gravity Observations from Space. Environmental Research Letters, 15. https://doi.org/10.1088/1748-9326/ab9926
  11. B. D. Hamlington, A. S. Gardner, 49 Others, Understanding of contemporary regional sea-level change and the implications for the future. Rev. Geophys. (2020), doi:10.1029/2019RG000672.
  12. A. Shepherd, E. Ivins, E. Rignot, B. Smith, M. van den Broeke, I. Velicogna, P. Whitehouse, K. Briggs, I. Joughin, G. Krinner, S. Nowicki, T. Payne, T. Scambos, N. Schlegel, G. A, C. Agosta, A. Ahlstrøm, G. Babonis, V. R. Barletta, A. A. Bjørk, A. Blazquez, J. Bonin, W. Colgan, B. Csatho, R. Cullather, M. E. Engdahl, D. Felikson, X. Fettweis, R. Forsberg, A. E. Hogg, H. Gallee, A. Gardner, L. Gilbert, N. Gourmelen, A. Groh, B. Gunter, E. Hanna, C. Harig, V. Helm, A. Horvath, M. Horwath, S. Khan, K. K. Kjeldsen, H. Konrad, P. L. Langen, B. Lecavalier, B. Loomis, S. Luthcke, M. McMillan, D. Melini, S. Mernild, Y. Mohajerani, P. Moore, R. Mottram, J. Mouginot, G. Moyano, A. Muir, T. Nagler, G. Nield, J. Nilsson*, B. Noël, I. Otosaka, M. E. Pattle, W. R. Peltier, N. Pie, R. Rietbroek, H. Rott, L. Sandberg Sørensen, I. Sasgen, H. Save, B. Scheuchl, E. Schrama, L. Schröder, K.-W. Seo, S. B. Simonsen, T. Slater, G. Spada, T. Sutterley, M. Talpe, L. Tarasov, W. J. van de Berg, W. van der Wal, M. van Wessem, B. D. Vishwakarma, D. Wiese, D. Wilton, T. Wagner, B. Wouters, J. Wuite, T. I. Team, Mass balance of the Greenland Ice Sheet from 1992 to 2018. Nature. 579, 233–239 (2020).
  13. Smith, B., Fricker, H. A., Holschuh, N., Gardner, A. S., Adusumilli, S., Brunt, K. M., et al. (2019). Land ice height-retrieval algorithm for NASA's ICESat-2 photon-counting laser altimeter. Remote Sensing of Environment, 111352. https://doi.org/10.1016/j.rse.2019.111352.
  14. Walker, C. C.*, & Gardner, A. S. (2019). Evolution of ice shelf rifts: Implications for formation mechanics and morphological controls. Earth and Planetary Science Letters, 526, 115764. https://doi.org/10.1016/j.epsl.2019.115764.
  15. St. Pierre, K. A., St. Louis, V. L., Schiff, S. L., Lehnherr, I., Dainard, P. G., Gardner, A. S., Aukes, P. J. K., Sharp, M. J. (2019). Proglacial freshwaters are significant and previously unrecognized sinks of atmospheric CO2; Proceedings of the National Academy of Sciences, 201904241. https://doi.org/10.1073/pnas.1904241116.
  16. Greene, C.A.*, K. Thirumalai, K.A. Kearney, J.M. Delgado, W. Schwanghart, N.S. Wolfenbarger, K.M. Thyng, D.E. Gwyther, A.S. Gardner, and D.D. Blankenship. The Climate Data Toolbox for MATLAB. Geochemistry, G, and D. D. B. (2019). The Climate Data Toolbox for MATLAB. Geochemistry, Geophysics, Geosystems. https://doi.org/doi:0.1029/2019GC008392.
  17. Wouters, B., A. S. Gardner and G. Moholdt (2019). Status of the global glaciers from GRACE (2002-2016). Frontiers in Earth Science 7: 75.
  18. Tapley, B., M. M. Warkins, F. Flechtner, C. Reigber, S. Bettadpur, M. Rodell, I. Sasgen, J. Famiglietti, F. Landerer, D. Chambers, J. Reager, A. S. Gardner, H. Save, imanshu , E. Ivins, S. Swenson, C. Boening, C. Dahle, D. Wiese, H. Dobslaw, M. Tamisiea and I. Velicogna (accepted). Contributions of GRACE to understanding climate change. Nature Climate Change.
  19. Khazendar, A., I. G. Fenty, D. Carroll, A. S. Gardner, C. M. Lee, I. Fukumori, O. Wang, H. Zhang, H. Seroussi, D. Moller, B. P. Y. Noël, M. R. van den Broeke, S. Dinardo and J. Willis (2019). Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools. Nature Geoscience.
  20. St. Pierre, K. A., V. L. St. Louis, I. Lehnherr, A. S. Gardner, J. A. Serbu, C. A. Mortimer, D. C. G. Muir, J. A. Wiklund, D. Lemire, L. Szostek and C. Talbot (2019), Drivers of Mercury Cycling in the Rapidly Changing Glacierized Watershed of the High Arctic's Largest Lake by Volume (Lake Hazen, Nunavut, Canada), Environmental Science & Technology, 53(3), 1175-1185, doi:10.1021/acs.est.8b05926.
  21. Menounos, B., R. Hugonnet, D. Shean, A. Gardner, I. Howat, E. Berthier, B. Pelto, C. Tennant, J. Shea, M.-J. Noh, F. Brun and A. Dehecq (2019). Heterogeneous Changes in Western North American Glaciers Linked to Decadal Variability in Zonal Wind Strength. Geophysical Research Letters 46(1): 200-209.
  22. Dehecq, A.*, N. Gourmelen, A. S. Gardner, F. Brun, D. Goldberg, P. W. Nienow, E. Berthier, C. Vincent, P. Wagnon, and E. Trouvé (2018), Twenty-first century glacier slowdown driven by mass loss in High Mountain Asia, Nature Geosci., doi:10.1038/s41561-018-0271-9.
  23. Smith, B. E., A. S. Gardner, A. Schneider, and M. Flanner (2018), Modeling biases in laser-altimetry measurements caused by scattering of green light in snow, Remote Sensing of the Environment, 215, 398-410, doi:https://doi.org/10.1016/j.rse.2018.06.012.
  24. Behrangi, A., A. Gardner, J. T. Reager, J. B. Fisher, D. Yang, G. J. Huffman, and R. F. Adler Using GRACE to estimate snowfall accumulation and assess gauge undercatch corrections in high latitudes, Journal of Climate, doi:10.1175/jcli-d-18-0163.1.
  25. WCRP Global Sea Level Budget Group (2018). Global sea-level budget 1993-present. Earth System Science Data 10(3): 1551-1590.
  26. Minchew, B. M., G. H. Gudmundsson, A. S. Gardner, F. S. Paolo, and H. A. Fricker (2018), Modeling the dynamic response of outlet glaciers to observed ice-shelf thinning in the Bellingshausen Sea Sector, West Antarctica, J. Glaciol., 1-10, doi:10.1017/jog.2018.24.
  27. Lehnherr, I., V. L. St. Louis, M. Sharp, A. S. Gardner, J. P. Smol, S. L. Schiff, D. C. G. Muir, C. A. Mortimer, N. Michelutti, C. Tarnocai, K. A. St. Pierre, C. A. Emmerton, J. A. Wiklund, G. Köck, S. F. Lamoureux and C. H. Talbot (2018), The world's largest High Arctic lake responds rapidly to climate warming, Nature Communications, 9(1), 1290, doi:10.1038/s41467-018-03685-z.
  28. Gardner, A. S., G. Moholdt, T. Scambos, M. Fahnstock, S. Ligtenberg, M. van den Broeke, and J. Nilsson (2018), Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years, The Cryosphere, 12(2), 521-547, doi:10.5194/tc-12-521-2018.
  29. Walker*, C. C., and A. S. Gardner (2017), Rapid drawdown of Antarctica's Wordie Ice Shelf glaciers in response to ENSO/Southern Annular Mode-driven warming in the Southern Ocean, Earth and Planetary Science Letters, 476, 100-110, doi:https://doi.org/10.1016/j.epsl.2017.08.005
  30. Cook, J. M., A. J. Hodson, A. S. Gardner, M. Flanner, A. J. Tedstone, C. Williamson, T. D. L. Irvine-Fynn, J. Nilsson, R. Bryant, and M. Tranter (2017), Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo, The Cryosphere, 11(6), 2611-2632, doi:10.5194/tc-11-2611-2017.
  31. Markus, T., T. Neumann, A. Martino, W. Abdalati, K. Brunt, B. Csatho, S. Farrell, H. Fricker, A. Gardner, D. Harding, M. Jasinski, R. Kwok, L. Magruder, D. Lubin, S. Luthcke, J. Morison, R. Nelson, A. Neuenschwander, S. Palm, S. Popescu, C. K. Shum, B. E. Schutz, B. Smith, Y. Yang and J. Zwally (2017), The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2): Science requirements, concept, and implementation, Remote Sens. Environ., 190, 260-273, doi:http://dx.doi.org/10.1016/j.rse.2016.12.029.
  32. Behrangi, A., A. Gardner, J. T. Reager, and J. B. Fisher (2016), Using GRACE to constrain precipitation amount over cold mountainous basins, Geophys. Res. Lett., n/a-n/a, doi:10.1002/2016GL071832.
  33. Wada, Y., J. T. Reager, B. F. Chao, J. Wang, M.-H. Lo, C. Song, Y. Li, and A. S. Gardner (2016), Recent Changes in Land Water Storage and its Contribution to Sea Level Variations, Surveys in Geophysics, 1-22, doi:10.1007/s10712-016-9399-6.
  34. Nilsson, J., A. S. Gardner, L. Sørensen, and R. Forsberg (2016), Improved retrieval of land ice topography from CryoSat-2 data and its impact for volume change estimation of the Greenland Ice Sheet. The Cryosphere.
  35. Gilbert, A., G. E. Flowers, G. H. Miller, B. T. Rabus, W. Van Wychen, A. S. Gardner, and L. Copland, 2016. Sensitivity of Barnes Ice Cap, Baffin Island, Canada, to climate state and internal dynamics, Journal of Geophysical Research: Earth Surface, n/a-n/a, doi:10.1002/2016JF003839.
  36. Behrangi, A., M. Christensen, M. Richardson, M. Lebsock, G. Stephens, G. J. Huffman, D. Bolvin, R. F. Adler, A. Gardner, B. Lambrigtsen and E. Fetzer, 2016. Status of High latitude precipitation estimates from observations and reanalysis. Journal of Geophysical Research.
  37. Reager, J. T., A. S. Gardner, J. S. Famiglietti, D. N. Wiese, A. Eicker, and M.-H. Lo, 2016, A decade of sea level rise slowed by climate-driven hydrology, Science, 351(6274), 699-703, doi:10.1126/science.aad8386.
  38. Earl*, L., A. S. Gardner, 2016: A Satellite Derived Glacier Inventory for North Asia. Annals of Glaciology, 57(71). 50-60.
  39. Fahnestock, M., T. Scambos, T. Moon, A. Gardner, T. Haran, and M. Klinger, 2015. Rapid large-area mapping of ice flow using Landsat 8, Remote Sensing of the Environment, doi:http://dx.doi.org/10.1016/j.rse.2015.11.023.
  40. Flanner, M. G., A. S. Gardner, S. Eckhardt, A. Stohl, and J. Perket, 2014: Aerosol radiative forcing from the 2010 Eyjafjallajökull volcanic eruptions. Journal of Geophysical Research: Atmospheres, 119, 9481-9491.
  41. Pfeffer, W.T., Arendt, A.A., Bliss, A., Bolch,T., Cogley, J.G., Gardner, A.S., Hagen, J-O., Hock, R., Kaser, G., Kienholz, C., Miles, E.S., Moholdt, G., Moelg, N., Paul, F., Radic, V., Rastner, P., Raup, B., Rich, J., Sharp, M.J. and the Randolph Consortium, 2014. The Randolph Glacier Inventory: a globally complete inventory of glaciers. Journal of Glaciology, 60, 537-552.
  42. Donnellan, A., B. Bills, J.J. Green, R. Goullioud, S. Jones, R. Knight, M. Underhill, J. Goguen, E. M. De Jong, A. Ansar, T. Scambos, P. Morin, B. Hallet, L. Thompson, A.S. Gardner, J. Ekholm, 2014. Studying mountain glacier processes using a staring instrument. Aerospace Conference, 2014 IEEE, 1-17.
  43. Gardner, A.S., G. Moholdt, J.G. Cogley, B. Wouters, A.A. Arendt, J. Wahr, E. Berthier, R. Hock, W.T. Pfeffer, G. Kaser, S.R.M. Ligtenberg, T.Bolch, M.J. Sharp, J.O. Hagen, M.R. van den Broeke, and F. Paul, 2013: A reconciled estimate of glacier contributions to sea level rise: 2003 to 2009. Science, 340, 852-857. (Featured Article)
  44. IPCC. 2013. Working Group 1 Contribution to the IPCC Fifth Assessment Report (AR5), Climate Change 2013: The Physical Science Basis. Chapter 4: Observations: Cryosphere. Co-ordinating Lead Authors: D.G. Vaughan, J.C. Comiso; Lead Authors: I.Allison, J.Carrasco, G.Kaser, R.Kwok, P.Mote, T.Murray, F.Paul, J.Ren, E.Rignot, O.Solomina, K.Steffen, T.Zhang; Contributing Authors: A.A.Arendt, D.B.Bahr, M.van den Broeke, R.Brown, J.G.Cogley, A.S. Gardner, S.Gerland, S.Gruber, C.Haas, J-O. Hagen, R.Hock, D.Holland, M.Huss, T.Markus, B.Marzeion, R.Massom, G.Moholdt, P.P. Overduin, A.Payne, W.T.Pfeffer, T.Prowse, V.Radic, D.Robinson, M.Sharp, K.Shiklomanov, S.Smith, S.Stammerjohn, I.Velicogna, P.Wadhams, A.Worby, L.Zhao. 102pp.
  45. IPCC. 2013. Working Group 1 Contribution to the IPCC Fifth Assessment Report (AR5), Climate Change 2013: The Physical Science Basis. Chapter 13: Sea Level Rise. Co-ordinating Lead Authors: J. A. Church, P.U. Clark; Lead Authors: A. Cazenave, J.M. Gregory, S. Jevrejeva, A. Levermann, M.A. Merrifield, G.A. Milne, R.S. Nerem, P.D. Nunn, A.J. Payne, W.T. Pfeffer, D. Stammer, A.S. Unnikrishnan; Contributing Authors: D. Bahr, J.E. Box, D.H. Bromwich, M. Carson, W. Collins, X. Fettweis, P. Forster, A.S. Gardner, W.R. Gehrels, R. Giesen, P.J. Gleckler, P. Good, R.G. Graversen, R. Greve, S. Griffies, E. Hanna, M. Hemer, R. Hock, S.J. Holgate, J. Hunter, P. Huybrechts, G. Johnson, I. Joughin, G. Kaser, C. Katsman, L. Konikow, G. Krinner, A. Le Brocq, J. Lenaerts, S. Ligtenberg, C.M. Little, B. Marzeion, K.L. McInnes, S.H. Mernild, D. Monselesan, R. Mottram, T. Murray, G. Myhre, J.P. Nicholas, F. Nick, M. Perrette, D. Pollard, V. Radić, J. Rae, M. Rummukainen, C. Schoof, A. Slangen, J.H. van Angelen, W.J. van de Berg, M. van den Broeke, M. Vizcaíno, Y. Wada, N.J. White, R.Winkelmann, J. Yin, M. Yoshimori, K. Zickfeld. 124pp.
  46. Arendt, A., Luthcke, S., Gardner, A.S., O'neel, S., Hill, D., Moholdt, G., and Abdalati, W., 2013: Analysis of a GRACE global mascon Solution for Gulf of Alaska Glaciers, Journal of Glaciology, 59, 913-924.
  47. Lenaerts, J.T.M., J.H. van Angelen, M.R. van den Broeke, A.S. Gardner, B. Wouters, and E. van Meijgaard, 2013: Irreversible mass loss of Canadian Arctic Archipelago glaciers. Geophysical Research Letters, 40, 1-5.
  48. Gardner, A.S., G. Moholdt, A. Arendt, and B. Wouters, 2012: Accelerated contributions of Canada's Baffin and Bylot Island glaciers to sea level rise over the past half century, The Cryosphere, 6, 1103-1125, 10.5194/tc-6-1103-2012.
  49. Moholdt, G., B. Wouters, and A.S. Gardner, 2012: Recent mass changes of glaciers in the Russian High Arctic. Geophysical Research Letters, 39, L10502.
  50. Gardner, A.S., G. Moholdt, B. Wouters, G.J. Wolken, D.O. Burgess, M.J. Sharp, J.G. Cogley, C. Braun, and C. Labine, 2011: Sharply increased mass loss from glaciers and ice caps in the Canadian Arctic Archipelago, Nature, 473(7347), 357-360. (Cover Feature)
  51. Kuipers Munneke, P., M.R. van den Broeke, J.T.M. Lenaerts, M. G. Flanner, A.S. Gardner, and W.J. van de Berg, 2011: A new albedo parameterization for use in climate models over the Antarctic ice sheet. Journal of Geophysical Research, 116, D05114.
  52. Sharp, M., Burgess, D.O., Cawkwell, F., Copland, L., Davis, J.A., Dowdeswell, E.K., Dowdeswell, J.A., Gardner, A.S., Mair, D., Wang, L., Williamson, S.N., Wolken, G.J. and Wyatt, F. (2014), Remote sensing of recent glacier changes in the Canadian Arctic, in Global Land Ice Measurements from Space, edited by J. S. Kargel, G. J. Leonard, M. P. Bishop, A. Kääb and B. H. Raup, pp. 205-228, Springer Berlin Heidelberg, Berlin, Heidelberg, doi:10.1007/978-3-540-79818-7_9.
  53. Gardner, A.S. and M.J. Sharp, 2010: A review of snow and ice albedo and the development of a new physically based broadband albedo parameterization. Journal of Geophysical Research, 115, F01009.
  54. Gardner, A.S., M.J. Sharp, R. M. Koerner, C. Labine, S. Boon, S. J. Marshall, D. O. Burgess, and D. Lewis, 2009: Near-surface temperature lapse rates over Arctic glaciers and their implications for temperature downscaling. Journal of Climate, 22, 4281-4298.
  55. Gardner, A.S. and M.J. Sharp, 2009: Sensitivity of net mass balance estimates to near-surface temperature lapse rates when employing the degree-day method to estimate glacier melt. Annals of Glaciology, 50, 80-86.
  56. Gardner, A.S. and M. Sharp, 2007: Influence of the Arctic Circumpolar Vortex on the mass balance of Canadian High Arctic glaciers. Journal of Climate, 20, 4586–4598.

Projects

NASA Sea Level Change Team