Monthly mean sea ice draft from the Fram Strait Arctic Outflow Observatory since 1990.
We acknowledge scientists that previously had leading roles with ULS NPI data, Torgny Vinje, Terje Brink Løyning, Edmond Hansen, and Gunnar Spreen. Structure of the data file is described in README.txt in the zip file.
Quality
The sea ice draft is obtained from Upward Looking Sonars (ULS) and Ice Profiling Sonars (IPS) deployed on an east-west oriented mooring array in the western Fram Strait. The section longitude varies from 78.8°N to 79.2°N (except for 1990), depending on year and location of each mooring. Zonal positions of the moorings are approximately 3° W (F11), 4° W (F12), 5° W (F13), and 6.5 / 7.0° W (F14), whereas the exact longitude slightly changes year to year. The exact position of each mooring in each year can be found in each data file as an attribute of the data object. The original data gained from ULS/IPSs are travel times of sound reflected at the bottom of floating sea ice. The raw data are processed to sea ice draft data by ASL Environmental Science Inc., following standard procedures described in Melling et al. (1995) and Fissel et al. (2008). A screening of erroneous data records and sound speed correction was done by ASL Environmental Science Inc. The original ice drift data are averaged over each daily period and then monthly mean ice draft is calculated. Temporal coverage of the daily data are taken into account when calculating the monthly mean draft.
Reference: Melling, H., Johnston, P. H. and Riedel, D. D. Measurements of the Underside Topography of Sea Ice by Moored Subsea Sonar, J. Atmos. Oceanic Technol., 12 (3), 589 – 602, https://doi.org/10.1175/1520-0426(1995)012<0589:MOTUTO>2.0.CO;2 (1995) . Fissel, D.B., Marko, J.R. and Melling, H. Advances in upward looking sonar technology for studying the processes of change in Arctic Ocean ice climate, Journal of Operational Oceanography, 1(1), 9-18, DOI: 10.1080/1755876X.2008.11081884 (2008). ASL Environmental Sciences Inc., Data Processing and analysis of ice keel depths, Fram Strait, 2006-2007. Report for Norsk Polarinstitutt, Tromsø, Norway by ASL Environmental Sciences Inc., Victoria, B.C. Canada (2009).