Detecting Greenland Melt with the SMAP L-band Radiometer
- 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States of America (andreas.colliander@jpl.nasa.gov)
- 2University of Colorado Boulder, Boulder, CO, USA (jzmiller.research@gmail.com)
- 3Massachusetts Institute of Technology, Cambridge, MA, USA (darae@mit.edu)
- 4The Ohio State University, Columbus, OH, USA (johnson@ece.osu.edu)
- 5University of Maryland, Baltimore County at NASA Goddard Space Flight Center, Baltimore, MD, USA (cshuman@umbc.edu)
- 6Cold Regions Research and Engineering Laboratory, Hanover, NH, USA (zoe.r.courville@usace.army.mil)
- 7University of Montana, Missoula, MT, USA (John.Kimball@mso.umt.edu)
Complex processes within the ice govern and record the evolution of the Greenland Ice Sheet. Low frequency microwave measurements have been used to gain insight into what happens deep inside the ice for some time now. NASA’s SMAP mission offers a valuable additional set of observations. SMAP covers virtually the entire ice sheet twice a day with its L-band radiometer. The overpasses center on morning and evening hours as the satellite is on a 6 AM/6PM equator-crossing orbit, and the spatial resolution of the instrument is about 40 km.
In this study, we investigated the response of L-band (1.4 GHz) measurements to surface melting of the ice sheet from the 2015 through 2019 melt seasons. The changes in brightness temperature caused by surface melt differs in the ablation zone, the active melt areas, and the interior’s dry snow zone. The melt area can be tracked with SMAP when accounting for these differences. SMAP’s frequent revisit time enables tracking of the melt events with comparatively high temporal fidelity. The evolution of the seasonal melt area derived from SMAP is consistent with other methods used for tracking ice sheet melt area.
Most notably, Greenland experienced an unusually strong melt event at the end of July 2019, which extended the melt area to the dry snow zone of the ice sheet over a period of two days. In-situ temperatures measured at Greenland’s Summit station show above-freezing temperatures during this event, and subsequent in-situ ice analyses have revealed ice structure changes associated with melt on these dates and subsequent refreezing. SMAP was able to record the extent of this unusual melt event on both days, and to show the anomalous extent of the melt event compared to the past 4 years of operational measurements.
This presentation will discuss the SMAP signal sensitivity to ice structure changes, the seasonal melt extent evolution and its inter-annual variation, and the comparison of the results to other data sources.
How to cite: Colliander, A., Mousavi, M., Miller, J., Entekhabi, D., Johnson, J., Shuman, C., Courville, Z., and Kimball, J.: Detecting Greenland Melt with the SMAP L-band Radiometer, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11508, https://doi.org/10.5194/egusphere-egu2020-11508, 2020.
