Why pay attention to Greenland? Greenland’s ice sheets are melting and contributing to global sea level rise. There is enough ice on Greenland that global sea level can rise by 6 meters if it were all to melt. Satellites can tell us how much ice mass loss is occurring, thanks to GRACE, but that does not provide a full picture of the processes that are causing the melt. To better understand this question the Oceans Melting Greenland (OMG) project will survey Greenland’s glaciers and ice sheets and study how the oceans and ice interact with each other and the physical parameters that effect melt that cannot be captured by satellites. The data and information gathered will help enhance ocean and ice sheet models and make sea level predictions more accurate.
OMG is a 5-year mission that started in 2015. Most satellites cannot see through ice so OMG will be using shipboard, airborne, and in situ measurements to tell us what the satellites cannot. These data will help our understanding of what fundamentally affects the melt rate of Greenland’s ice by providing information on how the ocean interacts with the ice sheets, including circulation in the fjords, movement of ice sheets and the physical properties of the ocean water. Bathymetric surveys were taken around Greenland’s coast to map the seafloor depth on the continental shelf and within the long narrow fjords that bring ocean water to ice sheets. To measure the depth of the ocean on the continental shelf OMG used airborne gravimetry, AirGrav for short, a highly sensitive instrument that “weighs” the amount of water beneath the aircraft. Ocean depths in fjords were measured using Singlebeam and Multibeam Echo Sounders (MBES), highly accurate instruments that can create3D maps of the seafloor. These sonar surveys revealed valuable information about exactly where the ice and ocean come into direct contact. A Conductivity-Temperature-Depth (CTD) instrument is also deployed from the sonar ship allowing scientists to better understand how ocean properties change through space. The CTD measures the salinity (via conductivity), temperature, and depth of the water column, all of which is used to determine the circulation patterns that can lead to ice melt.