RUSSIAN JOURNAL OF EARTH SCIENCES VOL. 10, ES1002, doi:10.2205/2007ES000262, 2008
[2] A number of studies [e.g., Crout, 1997] have provided a general understanding of the difficulties and challenges in interpreting altimeter-derived measurements in marginal seas such as those surrounding Europe; these studies have confirmed the great value of the altimetric products for large- and meso-scale applications. For instance, in the Mediterranean Sea, altimetry has been successfully applied at basin scale [e.g., Ayoub et al., 1998; Larnicol et al., 1995; Vignudelli, 1997] and in specific open sea regions [e.g., Buongiorno Nardelli et al., 1999; Vignudelli et al., 2000, 2003]. Comparison of satellite altimetry data with tide gauge data and hydrodynamic simulation results for the Barents and White Seas [e.g., Lebedev and Tikhonova, 2002; Lebedev et al., 2003] has shown that the remotely sensed data satisfactorily describe the hydrodynamic regime of these seas, including tides. Satellite altimetry data have allowed investigation of both mesoscale dynamics and water balances of the Black Sea [e.g., Eremeev et al., 2004; Ginzburg et al., 2003]. They are indispensable for investigation of significant seasonal and interannual variability of Caspian Sea level, including Kara Bogaz Gol Bay [e.g., Lebedev and Kostianoy, 2005]. The usefulness of standard altimetric products, however, is greatly reduced in coastal areas due to sampling issues, inaccurate corrections and other data quality problems [Anzenhofer et al., 1999]. This has motivated recent investigations into ad-hoc data screening and processing to recover valuable information near the coast, which have yielded partial but encouraging results at a specific Mediterranean site [Vignudelli et al., 2005].
[3] The coastal environment varies from the open sea in many ways. It is a region where sea conditions can vary quickly, both in time and space. Altimeter processing over these areas requires accurate knowledge of tides and of the hi-frequency atmospheric (wind and pressure) effects at the sea surface. Working next to land also poses the challenge of retrieving data flagged as unreliable but potentially recoverable after more careful, specific screening. There is clear scope for investigating the limitations of the current 1 Hz data stream and assessing the advantages and feasibility of the adoption of higher data stream rates (typically 10 Hz or 20 Hz). The standard data treatment also needs to be remodelled, minimizing the inclusion of spurious values and gaps and monitoring the processing chain from beginning to end. This need for better screening or interpolation/extrapolation of missing values does not only apply to the raw altimetric measurements, but also to the necessary corrections, that may suffer from similar (or worse) problems of land contamination and inadequate models. From a calibration and validation point of view, there is also the question of evaluating how improved averages over satellite footprints may be compared to point-wise values (in situ data) normally collected at different temporal scales; this involves non-trivial sampling and averaging issues, as well as assumptions on the local scales of variability of the altimeter-derived products.
Citation: 2008), Exploiting satellite altimetry in coastal ocean through the ALTICORE project, Russ. J. Earth Sci., 10, ES1002, doi:10.2205/2007ES000262.
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