Science: About SASSIE

APL-UW = Applied Physics Laboratory, University of Washington | BEC = SMOS Barcelona Expert Center | ESR = Earth & Space Research | JPL = NASA Jet Propulsion Laboratory| LOCEAN = Laboratoire d'Oceanographie et de Climat Experimentations et Approches Numeriques | UNCW = University of North Carolina Wilmington | WHOI = Woods Hole Oceanographic Institution

Sea ice extent in the Arctic Ocean has declined dramatically over the past decades. Autumn ice advance is slower and occurs later, while summer ice retreat is faster and occurs earlier. The result is a lengthening open-water period each year, leading to changes in air-sea heat and momentum fluxes, the freshwater cycle, surface albedo feedbacks, primary production, and regional and global climate as well as human and ecological health.

We hypothesize that sea surface salinity anomalies generated by summer sea ice melt are an important predictor for autumn ice advance.
Our experiment will examine how summer ice melt evolves into and is inexorably linked with autumn sea ice advance, focusing on:
  1. Quantifying the salinity anomalies generated by melting ice, how they evolve in time, and how they affect stratification, sea surface temperature (SST), and subsequent ice advance;
  2. Exploring these processes using a series of model experiments; and
  3. Collecting data to enable improved satellite sea surface salinity (SSS) retrievals in polar oceans, and linking the in situ salinity signals with those observed from satellites.
Earth showing the north pole
Located in the Beaufort Sea, the SASSIE study site will be determined based on local conditions, approximately within the region outlined in red. Video shows Arctic sea ice age (grayscale) from Jan. 1984 to Sep. 2019. [Credit: Scientific Visualization Studio]
SASSIE will address its science themes in a multi-scale in situ, airborne, satellite, and modeling experiment. The primary aim of the field campaign is to capture the upper ocean structure during the transition from summer sea ice retreat to autumn sea ice advance. We will quantify the strength, size, and depth of fresh near-surface anomalies resulting from melting ice; the horizontal and vertical structure of those fresh anomalies as they evolve due to air-sea fluxes and waves, ocean currents and mixing; and the ocean conditions and the presence of sea ice as it begins to form.
2022 Field Campaign
August September: Intensive Observing Period (IOP) October and Beyond
Expected conditions Summer ice retreat, Melting ice Transition from sea ice retreat to advance, Meltwater layers Growing ice, Freeze-up
Platforms Small vessels and ships of opportunity will deploy instruments ahead of the IOP Large vessel (Norseman II), Unmanned Aerial Systems, Aircraft with salinity and other sensors Some instruments will remain behind to measure freeze-up conditions
Key instruments
[tools page]
Autonomous Assets – Wave Gliders, Ice Mass Balance buoys
Ship – Underway CTD, Salinity Snake, Air-sea flux sensors
Piloted and Drifting Assets – Wave Gliders, SWIFT, UIF, Surface Velocity Program Drifters, UpTempO buoys, Jet Surface Salinity Profiler
UpTempO buoys, UIF, SWIFT and Surface Velocity Program Drifters
Satellite & other data
Salinity – Soil Moisture Active Passive (SMAP), Soil Moisture Ocean Salinity (SMOS)
Temperature – NOAA Optimum Interpolation Sea Surface Temperature (OISST)
Sea Ice Properties, Motion, and Melt – National Snow and Ice Data Center, ICESat-2, Synthetic Aperture Radar
Air-sea Fluxes – NASA Modern-Era Retrospective analysis for Research and Applications (MERRA), European Centre for Medium-Range Weather Forecast (ECMWF), and others
Icebergs
Click to view a StoryMap that provides background on SASSIE.
Science Themes
Quantifying the horizontal and vertical structure of near-surface stratification anomalies generated by melting sea ice in summer.
Understanding the extent to which salinity anomalies generated due to summer sea ice melt precondition the upper ocean for autumn ice advance.
Linking the in situ salinity signals in open Arctic waters to those measured by satellites.
SASSIE team members
SASSIE team members during August 2021 field campaign planning meeting.
Example data slides
Example data slides discussed during the SASSIE planning meeting.