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S4: Altimetry for Regional and Coastal Models - part II
16:40 - 17:20
Session Chair: Claire Dufau Session Chair: Ole Roggenbuck Session Chair: John Wilkin
16:40 - 17:00
Integration of Coastal Altimetry Data in the Tuscan Coastal Observing System
Carlo Brandini1,2, Bartolomeo Doronzo1,2, Maria Fattorini1,2, Chiara Lapucci1,2, Stefano Taddei1, Alberto Ortolani1,2, Paolo Cipollini3
1Consorzio LaMMA, Italy; 2CNR Ibimet, Italy; 3NOC, UK
Ocean circulation modelling at regional/coastal scales provides information that is crucial not only to many socioeconomic activities (including safety at sea) but also to support improved sea monitoring procedures (as required in Europe by the Marine Strategy Framework Directive 2008/56/EC).
A major limitation of models, either used for forecasting and long retrospective analysis, is their reliability. This can only be improved by a proper use of observations for the validation and calibration of the models and, if possible, for data assimilation. A number of recently established Coastal Observing systems attempt to make the best possible use of in-situ and satellite data, and to integrate this information in coastal circulation models.
In Tuscany, a coastal observing system was recently established under the SICOMAR project It includes, in addition to traditional in-situ data (buoys and tide gauges), automatic samplers onboard ships, autonomous marine vehicles, and most of all HF radars. The information obtained is used by a coastal circulation model to allow for a better description of the hydrodynamic circulation at short time and spatial scales. The area under investigation, between the Thyrrenian and Ligurian seas, is characterized by significant exchange of water masses through the Corsica Channel and, further north, by the well-known convergence zone of the eastern and western Corsica currents which form of the North Mediterranean current. This dynamics has been repeatedly studied using Coastal Altimetry data, which allowed a better understanding of the processes and their seasonal variability (Vignudelli et al., 2000, 2002, 2005; Bouffard et al., 2014).
Coastal Altimetry data can be integrated in hybrid monitoring systems (Wilkin and Hunter, 2013) alongside HF radars and hydrodynamic models, even to describe sub-seasonal circulation scales. In this contribution we show how a combination of different data, including reprocessed Jason-1 and Jason-2 data from the ALES processor run at NOC, can improve the description of circulation features that are still scarcely known and that are considered responsible for phenomena of accumulation of floating debris (such as, for example surface microplastic). Such circulation features are in turn confirmed by a number of independent observations in this area.
17:00 - 17:20
High-Resolution Altimetry for the Eastern Canadian Shelf Regional Model
Claire Dufau1, Greg Smith2, Fraser Davidson3
1CLS, France; 2Environment and Climate Change Canada, Canada; 3Fisheries and Oceans Canada, Canada
A multi-mission high-resolution altimetry chain has been set up over the Canadian Eastern Seas, from the US border to the Baffin Bay [95°W-43°W; 42°N-82°N]. A regional tuning has been done in terms of corrections and reference surface. Issued from the most recent research activity in altimetry field, a new estimation of the satellite-sea distance based on the waveform classification has been proposed for the satellite mission Jason-2 and SARAL/Altika missions. For the satellite mission Cryosat-2, data measured by its Synthetic Aperture Radar (SAR) mode have locally been used when available. A dedicated data selection strategy has been developed for this regional production in order to take more precisely into account the seasonal ice coverage. It provides a good compromise between the quantity of observations and their variance reduction. A dedicated spatial filtering has been applied on native 20Hz/40Hz observations to remove their noise level. The choice of the cut-off length has been done on the basis of a regional spectral analysis. Each mission has been considered separately.
This paper will present a quality assessment of the high-resolution altimetry data set optimized for the observation of small scale oceanic structures near the Eastern Canadian coasts and in sea ice areas, with a particular attention on to the Gulf of St Lawrence area and the Grand Banks area. This paper will also present the use of this dataset in the Canadian Regional Ice-Ocean Prediction circulation regional modeling System (RIOPS).