1 Perspectives for a data assimilation system in Tagus Estuary

• Main Author: Ângela Canasa
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Estuarine dynamics; Tide gauges; Modelling; Kalman filters; Twin experiment; MOHID Water; Portugal; Northeast Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.543.8382; http://maretec.mohid.com/PublicData/products/Papers/TagusAssimilationINSEAPaper.pdf

In this work a simplified extended Kalman filter correcting state along pre-specified error variability modes is applied, in a twin experiment, to a 2D hydrodynamic model of a large shallow Northeast Atlantic tidal estuary- the Tagus Estuary (Portugal) – and adjacent coast to correct a forecast error derived from mean sea level perturbation with tide gauge measurements. Forecast error departures from normal probability distribution are assessed to verify optimality of the filter correction. Considering a system state comprised of water level and zonal and meridional horizontal velocity components, the error variability modes are derived from the EOF analysis of historical model forecast estimates. The filter performance is assessed in several coastal locations in the context of different number of measurement locations and use of different error variability modes. Important departures from normal probability distribution in the forecast error are detected in some of the locations, which are explained by bathymetry shallowness and circulation. The forecast state variability is very much dominated by astronomic tide, whose presence is evident in the first two EOFs which represent more than 70 % of total variability. Error variability, which is not related to tide, appears to be captured only on lower eigenvalue EOFs and very affected by local processes. The consideration of the