Ers-2 Altimetry In Operational Noaa Forecast Models

• Main Authors: John Lillibridge David, David Behringer, Jean Thiebaux, Michelle Mainelli, Remko Scharroo
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.20.5535; http://earth.esa.int/pub/ESA_DOC/gothenburg/206lilli.pdf

NOAA's Laboratory for Satellite Altimetry has been producing real-time altimetry products from ERS-1 and ERS-2 since 1995. Significant enhancements are made to ESA's fast-delivery data sets, most notably the addition of orbit information provided by the Delft University of Technology. In late 1998, several enhancements were made to the NOAA/Delft altimetry products: ESA's fast-delivery data now include measured wet troposphere corrections from the on-board radiometer; the Delft DGM-E04 gravity model (specifically tuned for ERS) is used in the orbit determination system; and an iterative feedback scheme is now performed to refine the real-time orbits by incorporating altimetric heights and crossovers. Within NOAA, several collaborative efforts are utilizing real-time ERS-2 data in their operational forecast models. At the largest scales, the Climate Modeling Branch at the National Centers for Environmental Prediction (NCEP) is assimilating TOPEX/Poseidon and ERS-2 altimetry into a coupled model for El Nio / Southern Oscillation prediction. Timeliness is not as critical as absolute accuracy in this modeling effort. Thus, we are combining the ERS-2 data with the more accurate TOPEX/Poseidon altimetry to further reduce orbit and environmental correction errors before assimilation in the ENSO model. At finer resolution, the NCEP Ocean Modeling Branch is assimilating TOPEX/Poseidon and ERS-2 altimetry into the Coastal Ocean Forecast System, which produces nowcast and 24-hour forecast fields for the Gulf Stream/western North Atlantic region. Evaluations carried out during a recent demonstration project established that addition of sea surface height anomalies derived from TOPEX/Poseidon added significant detail to the real-time products: sea surface heights, 1-meter currents,.