State-of-the-Art Mean Sea Surface and Geoid Model assessment in the Arctic and implications for Sea Ice Freeboard Retrieval
Event: 2017 Ocean Surface Topography Science Team Meeting
Session: The Geoid, Mean Sea Surfaces and Mean Dynamic Topography
Presentation type: Type Poster
Contribution: PDF file
State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors in a given model in the high frequency domain, primarily due to7 unresolved gravity features, can result in errors in the estimated along-track freeboard. These8 errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multi-sensor oceanographic time-series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL04/13, DTU15/13/10) and a commonly used GGM (EGM2008). We describe errors due to unresolved gravity features, inter- satellite biases, and remaining satellite orbit errors, and their impact on the derivation of sea ice freeboard. The latest MSS models, incorporating CryoSat-2 sea surface height measurements, show improved definition of gravity features, such as the Gakkel Ridge. The standard deviation between models ranges 0.03-0.25 m. The impact of remaining MSS/GGM errors on freeboard retrieval can reach several decimetres in parts of the Arctic.