Altimetry for coastal oceanography in Australia -an assessment of PISTACH

Since 2004 we have been routinely combining multi-mission altimetric observations of off-shelf sea level with tide gauge observations of coastal sealevel in order to infer the along-shelf geostrophic current. This approach certainly has value under certain conditions, but can never, of course, reveal any detail of the across-shelf structure of the along-shore flow. That extra information is in the altimetry data but the question is whether it is separable from erroneous signals of various origin. The southern shelf of Australia is a good location for addressing this question, because 1) it is a long zonal coast with many altimeter tracks normal to the shelf, and 2) the shelf-edge current is a dominant feature with a strong annual signal, overlain with wind-driven fluctuations. Results of including PISTACH data in the CSIRO routinely-generated analysis (http://www.marine.csiro.au/remotesensing/oceancurrents/) will be discussed.