Examining the Consistency of Sea Surface Temperature and Sea Ice Concentration in Arctic Satellite Products

• Published in: Remote Sensing
• Main Authors: Castro, Sandra L., Wick, Gary A., Eastwood, Steinar, Steele, Michael A., Tonboe, Rasmus T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: SST/SIC consistency for modeling; Freezing–melting balance; Near-ice mixed pixel; SIC post-processing filter; Arctic L4 SST performance; Arctic; Sea ice
• Online Access: https://orbit.dtu.dk/en/publications/ef1fe2c7-cc59-4373-ab87-72828a240b06; https://doi.org/10.3390/rs15112908; https://backend.orbit.dtu.dk/ws/files/326113686/remotesensing_15_02908_v2.pdf

Available observations and a theoretical simulation are used to explore the consistency and relationship between sea surface temperature (SST) and sea ice concentration (SIC) within open-ocean-sea ice mixed satellite pixels as a function of grid resolution. The maximum limiting SST value for a specified SIC and spatial resolution is first examined within collocated satellite-derived products contained within existing Level 4 SST analyses distributed using the data specification from the Group for High Resolution Sea Surface Temperature. The shape of the interdependence is further validated with manually quality-controlled buoy SST and SIC collocations. A parametric equation for the limiting SST value is derived from simulations of a mixed ocean/ice pixel with specified ice fraction and a linear SST gradient extending away from the ice edge. The exponential curve matching the observed interdependence suggests a maximum 5 km pixel-averaged SST at SIC values approaching zero between 6 and 8 °C. This maximum value is significantly greater than the previously assumed limiting values of ~3 °C and the corresponding SST gradient is larger than those typically observed with satellite SST products, but agrees well with recent Saildrone SST observations near ice. The curve provides a conservative limit with which inconsistent SST/SIC pairings can be identified, not only near the ice edge but at intermediate ice concentrations. Application of the filter improves the agreement between the SST/SIC relationship in satellite products and available Saildrone observations as well as the internal consistency of the different satellite products.