Arctic Field Projects



Project Title: Towards an Operational System for Estimating Greenland Ice Sheet Thickness Change from Altimetry (Award# NNX14AH90G)

PI: Howat, Ian M (ihowat@gmail.com)
Phone: (614) 292.6641 
Institute/Department: Ohio State University, Byrd Polar Research Center 
IPY Project?
Funding Agency: US\Federal\NASA
Program Manager: Dr. Thomas Wagner (thomas.wagner@nasa.gov)
Discipline(s): | Cryosphere |

Project Web Site(s):

Science Summary:
NASA and other agencies are invested in obtaining measurements of Greenland Ice Sheet surface elevation with the objective of constraining the ice sheet’s contribution to present and future sea level rise. Air and space-based altimetry provides the only direct means for observing changes in ice thickness at high spatial resolution. A major limitation of repeat altimetry measurements, however, is that variations in the density of surface accumulation and the firn layer must be constrained in order to extract ice thickness and mass change. As thinning initiated at the margin of the ice sheet propagates inland this limitation is becoming more problematic for two reasons: first, as thinning propagates and diffuses, the rate of thinning decreases relative to variations in accumulation and compaction, becoming more difficult to observe. Second, substantial thinning is now occurring in the wet snow and percolation zones of the ice sheet where variations in density are particularly unconstrained and models perform poorly. Additionally, recent warming and historically extreme melt events may be substantially changing the density of the firn, effecting altimeter measurements. Researchers on this project aim to develop and test deploy in situ sensor packages that will aid the deconvolution of surface change observations. Each sensor package will consist of a device for measuring deep-firn compaction, a snow pillow for measuring accumulation mass, and an echo sounder for measuring accumulation thickness. The sensors will broadcast their data daily via iridium uplink and will be designed to withstand at least 2 years of accumulation, depending on location, reducing the revisit time. The sensor data will be used to calibrate meteorological reanalysis model output that will drive a surface accumulation and firn compaction model. The goal of this project will be to provide a foundation for a more extensive operational system in concert with the launch of ICESat-2 planned for 2018.

Logistics Summary:
Researchers involved in this project will perform ice thickness studies in Greenland. They will develop and test deploy an instrument suite as in situ sensor packages that will aid the deconvolution of surface change observations. Each sensor package will consist of a device for measuring deep-firn compaction, a snow pillow for measuring accumulation mass, and an echo sounder for measuring accumulation thickness. The sensor data will be used to calibrate meteorological reanalysis model output that will drive a surface accumulation and firn compaction model. In 2015 and 2016, a field team of 4 will conduct a test phase, deploying three sensors above Jakobshavn Isbrae via Twin Otters based out of Ilulissat. In 2016, two researchers will travel from Ilulissat to Summit for a half day's work making measurements of snow/firn density and grain size utilizing a microwave radiometer. They will travel via Twin Otter and return to Ilulissat on the same day. Additionally, the project will ship a snow water equivalency (SWE) instrument to Summit to be installed by CPS technicians near the 50-meter tower to run for an initial one year test period. In 2017 one team member will travel to Greenland via the Air National Guard for one day of field work, basing out of Kangerlussuaq. The team member will visit three established sites (CRAGS lower, mid, upper) on the Jakobshavn Glacier. Snow-Water equivalent measurements will continue to be taken at Summit Station. In 2018 a team of three will travel to Kangerlussuaq via the Air National Guard (ANG) and then on to Ilulissat in the Twin Otter that they will use for field work. The team will service the three existing sensor stations at CRAGS upper, CRAGS middle, and CRAGS lower on the catchment area of the Jacobshavn Glacier. The team will then install a sensor suite at a new station located at DYE-2. All of the stations aim to measure surface mass balance and related firn processes (compaction, melt, accumulation). This work will be conducted by day trips from Ilulissat via the Twin Otter. At the beginning of May upon completion of the field work, the team will return to Kangerlussuaq with the Twin Otter and then on to New York via the ANG. The Snow-Fox, a snow water equivalency instrument, continues to acquire data at Summit. The research group did not need to visit Summit in 2018. In 2019 a team of three will travel to Kangerlussuaq via the Air National Guard (ANG). The team will service three existing sensor stations at DYE-2, as well as CRAGS upper, and CRAGS lower on the catchment area of the Jakobshavn Glacier. They will also install firn compaction monitors at all three sites. All of the stations aim to measure surface mass balance and related firn processes (compaction, melt, accumulation). The team will also perform a brief radar survey via snowmachine on the ~45km route between CRAGS upper and CRAGS lower. This work will be conducted by day trips from either Kangerlussuaq or Ilulissat via the Twin Otter. At the beginning of May, upon completion of the field work, the team will return to Kangerlussuaq with the Twin Otter and then on to New York via the ANG. The Snow-Fox, a snow water equivalency instrument, continues to acquire data at Summit therefore, the research group will not visit Summit Station in 2019.

Via an interagency funds transfer NASA>NSF, CPS will provide Air National Guard coordination for cargo and passengers, KISS user days, Twin Otter support, a snowmachine, communications/safety gear as well as lodging and a rental vehicle in Ilulissat. At Summit Station CPS will support an existing experiment with a technician providing maintenance/weekly measurements with the Snow Water Equivalency (SWE) instrument, and space/power for the data acquisition/transmission system in the Mobile Science Facility. All other logistics and support will be paid by the PI.
SeasonField SiteDate InDate Out#People
2015Greenland - CRAGS 1 Howat04 / 28 / 2015 04 / 28 / 20153
2015Greenland - Ilulissat04 / 25 / 2015 05 / 02 / 20153
2015Greenland - J1 Howat04 / 26 / 2015 04 / 26 / 20152
2015Greenland - J1S Howat04 / 27 / 2015 04 / 27 / 20153
2015Greenland - J3 Howat04 / 29 / 2015 04 / 29 / 20153
2015Greenland - J4 Howat04 / 30 / 2015 04 / 30 / 20153
2015Greenland - Kangerlussuaq04 / 24 / 2015 05 / 05 / 20153
2016Greenland - Ilulissat04 / 26 / 2016 05 / 03 / 20164
2016Greenland - J1 Howat04 / 27 / 2016 04 / 27 / 20164
2016Greenland - J1S Howat04 / 30 / 2016 04 / 30 / 20164
2016Greenland - J3 Howat04 / 28 / 2016 04 / 28 / 20164
2016Greenland - J4 Howat04 / 29 / 2016 04 / 29 / 20164
2016Greenland - Kangerlussuaq04 / 25 / 2016 05 / 05 / 20164
2016Greenland - Summit05 / 01 / 2015 05 / 01 / 20164
2017Greenland - CRAGSL05 / 02 / 2017 05 / 02 / 20171
2017Greenland - CRAGSM05 / 02 / 2017 05 / 02 / 20171
2017Greenland - CRAGSU05 / 02 / 2017 05 / 02 / 20171
2017Greenland - Kangerlussuaq05 / 01 / 2017 05 / 05 / 20171
2017Greenland - Summit0
2018Greenland - CRAGSL04 / 26 / 2018 04 / 29 / 20183
2018Greenland - CRAGSM04 / 26 / 2018 04 / 29 / 20183
2018Greenland - CRAGSU04 / 26 / 2018 04 / 29 / 20183
2018Greenland - DYE-204 / 25 / 2018 04 / 25 / 20183
2018Greenland - Kangerlussuaq04 / 24 / 2018 05 / 03 / 20183
2018Greenland - Summit0
2019Greenland - CRAGSL05 / 05 / 2019 05 / 05 / 20193
2019Greenland - CRAGSU05 / 06 / 2019 05 / 06 / 20193
2019Greenland - DYE-205 / 04 / 2019 05 / 04 / 20193
2019Greenland - Ilulissat05 / 04 / 2019 05 / 06 / 20193
2019Greenland - Kangerlussuaq05 / 02 / 2019 05 / 08 / 20193
2019Greenland - Summit0
 


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