Many current studies are attempting to enhance the quality of altimetry data close to the coasts. New processing methods and applications can then be developed for littoral and shallow-water regions, some of the most fragile and important areas of the oceans.
The shortage of altimetry data near the coasts (or their inferior quality) is due to several factors:
- the technique itself, since the radar echoes reflected off water, and off a combination of water and land are not identical, and basically only the former undergo processing by the ground segments. Other altimetry satellite measurements also suffer from the same problem, such as those from the radiometer (at a distance of about 50 km from the coast),
- the fact that the basic distributed data (GDR) are mainly average over one second, thus covering about 7 km on the ground (data averaged over 1/20 s do exist, however),
- the computation of some corrections. Tides, in particular, are much more complex near the shores than in the open sea, and require a highly precise knowledge of the coastal geography to be accurately computed. Moreover, rapid variations ("high frequency") must be taken into account in those areas (for the tides as well as for the atmospheric pressure). Wet tropospheric corrections, computed from radiometer measurements are also less precise, or even missing, near the coasts.
Such studies are leading to advances that will soon make it possible to use altimetry data close to the coasts. With new possibilities such as the use of individual altimetry echoes (as opposed to averaged ones today), we can at last hope for real coastal data.
- Coastal Altimetry community and workshop
- Data : Experimental Coastal and Hydrology products (Pistach) and experimental Coastal Along-Track SLA Jason-2 products
- Data Use Cases with the Basic Radar Altimetry Toolbox dedicated to the coastal studies:
- The North Western Mediterranean Sea
- The Agulhas current by using coastal dedicated products
- The Florida Keys currents by using coastal dedicated products
- OSTST 2013 (oral presentations): see the Joint CAW/OSTST SARM Splinter (Part II) on the dedicated page
- OSTST 2013 (posters):
- Coastal altimetry with the Ka-band, F.Niño et al.
- Comparison and validation of mult-mission coastal altimetry around Venice, P.Cipollini
- Multi-sensor observations towards coastal and mesoscale characterization: SARAL/AltiKa, HF radar, glider and drifters, A.Pascual et al.
- Using CTOH tidal constants for coastal studies, C.Delebecque et al.
- Coastal and Inland water SAR altimetry at 80 Hz , R.Dinardo et al.
- SARAL/AltiKa altimeter data over open ocean, coastal zones and inland waters: the PEACHI project, G.Valladeau
- OSTST 2009: Coastal and inland altimetry, posters and oral presentations in pdf.
- OSTST 2008: Operational applications, coastal and inland waters, wind/waves and associated Cal/Val studies, posters and oral presentations in pdf