Winter MODIS observations of West Greenland fjord ice activity

Recent observations suggest that calving of West Greenland’s outlet glaciers typically ceases during winter months. However, increasingly long iceberg calving seasons pose a risk for increased dynamic thinning of Greenland’s outlet glaciers. Recent publications suggest that Jakobshavn Isbrae is one example of an outlet glacier that has recently begun to experience winter calving episodes. Records of such events are limited to local field campaigns that deploy seismometers and time-lapse photography. We have compiled a MODIS-derived 1-km daily Sea Surface Temperature (SST) record of several West Greenland fjords. This thermal record, which captures surface “temperature” records of fjord ice cover even during winter darkness, demonstrates that sudden, brief periods of warming, related to increased mobility of ice cover, or even open water, have occurred in traditionally frozen fjords, and that these periods coincide with published seismic data indicating calving from Jakobshavn Isbrae. The record of changes in fjord ice cover is compared with glacier terminus positions from the Landsat archive. Observations of coincident change are investigated. This study examines the use of the MODIS thermal record for year-round, near daily observations of the fjords fed by outlet glaciers, and introduces a potential tool for: 1). Spatially and temporally verifying seismically detected calving events in the fjords, and 2) monitoring the connection between the fjord ice cover and outlet glacier calving events during the winter months when visible band data is not available.