Satellite Altimetry in the Coastal Zone: Past, Present and Future Seminar
For more information regarding this seminar, please email Barend Van Maanen at B.Van-Maanen@soton.ac.uk .
Event details
Satellite altimetry over the oceans is regarded as one of the most successful remote sensing techniques, as it has allowed an unprecedented mapping of the ocean surface dynamics at the large- and meso-scale. With the improvements in orbit models, radar processing, atmospheric and geophysical effect corrections that have emerged over the years, altimetry gives today also a very accurate estimation of the rate of sea level rise and its geographical variability. However, altimetric data in the near-land strip (0 to 50 km from the coastline) are often flagged as bad and left unused, essentially owing to 1) difficulties with the corrections; and/or 2) the modification of the radar returns due to the presence of land in the footprint, which makes the fitting of the altimetric echoes with a waveform model (the so-called ‘retracking’ of the waveforms) problematic. This has prevented the applications of altimetry to be extended to the very oceanic domain where the impacts of changing climate and rising sea levels are most severely felt by society: the coastal zone.
In the last few years a vibrant international community of researchers has started developing the new field of coastal altimetry: i.e. techniques to recover meaningful estimates of the altimeter-derived parameters (height, significant wave height and wind) in the coastal zone, by improving the corrections and developing specialized retracking techniques; this has opened the way to a number of new applications, that are showcased at the annual Coastal Altimetry Workshops (see http://www.coastalt.eu/community).
In this talk I will summarize the main achievements of coastal altimetry so far, for the benefit of the oceanographic community at large. I will show examples of the improvements in retracking and corrections that have been developed in the last few years. I will then describe the currently available data archives, and show some applications of the reprocessed data to coastal currents, gravity field, storm surges, lake levels. I will discuss the need for integration with models (and the related problems on how best to assimilate the reprocessed data) and other in situ observations, and the continuing efforts for calibration and validation of the coastal altimetry data. Finally, I will discuss the future of this relatively new discipline, that looks bright not only for the continuing improvements in reprocessing, but also thanks to the advent of SAR (delay-Doppler) altimetry, the technology adopted for ESA’s Cryosat-2 and Sentinel-3 missions, which has inherently better coastal capabilities.
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Speaker information
Dr Paolo Cipollini,My research interests are in the field of remote sensing and satellite oceanography, by means of both active and passive instruments, and in the exploitation of the synergy and integration of data coming from different space-borne instruments with traditional in situ measurements. Within this broader range of interests, one particular topic of research is multisatellite observations of planetary waves in the oceans. This work has focused on the observation of extra-equatorial baroclinic planetary (Rossby) waves and the study of their characteristics with altimetry, infrared radiometry and ocean colour. In particular, I have contributed to the first simultaneous observation of Rossby waves in sea surface height and sea surface temperature (SST) and to the first global studies of Rossby waves in SST and in ocean colour. A theme which underpins my research is the development and application of advanced statistical and signal processing techniques to the retrieval of oceanographic information from satellites (also the topic of the a SOES course in which I lectured in the recent past). This includes the development and implementation of novel techniques for the analysis of satellite data, as well as the study of new sensors and new applications of existing sensors, as in the case of coastal altimetry. This is a new exciting frontier for satellite altimetry, one of the most successful techniques ever to look at the ocean, and I am involved in the coordination of the international community of coastal altimetrists through the moderation of the COASTALT-SWT group and the organization of the Coastal Altimetry Workshops. And it has important application, from capturing currents which flow very close to the coastline like the Agulhas Current, to helping with the monitoring and forecasting of extreme events like storm surges, which we do in the eSurge Project. Last but not least, I am interested in teleworking and collaborative work in distributed environments - which means, using the net to work better and travel less.