Altimeter Data Evaluation in the Coastal Gulf of Maine and Mid-Atlantic Bight Regions

Abstract

Satellite altimeter sea surface height anomaly (SSHA) data accuracy and applications are rapidly maturing over the open ocean, but more attention is required where continental shelves and marginal seas are concerned. Refined radar range measurement correction approaches are needed to enhance the quality of coastal altimeter SSHA data and to enhance the potential impact that altimeter data can play in improved ocean circulation modeling and prediction. This study provides a regional assessment of satellite altimeter SSHA data from the Jason-2, Jason-1, and TOPEX/Poseidon data sets collected over the Northwest Atlantic coastal region of the United States. The validation approach follows recent studies in numerous shelf regions to address changes from standard or default data quality flagging scheme that can enhance satellite altimeter SSHA data recovery, optimal choice of de-aliasing corrections in deriving subtidal sea level time series, and validation of altimeter data using in situ tide gauge and current measurement data sets. Spatial analyses show the impact of data filtering and corrections from the coastline out onto the slope. Revised handling of the data provides a 5–10% increase in availability (from about 70% up to 80% for waters beyond 50 km from shore). The RMS differences between tide gauge and surface layer current measurements at the 60 day time scale are 3–4 cm and 6 cm/s, respectively, and of magnitude consistent with several recent coastal altimeter data validation efforts.