1. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology Synergy of altimetry with other data and models - Australian Coastal Applications David Griffin & Madeleine Cahill November 7, 2008, Pisa www.cawcr.gov.au

2. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology Paolo said to make your point quickly: Specially-processed altimetry is not widely used in Australia. The following comes from using (I)GDRs. If you are interested in the continental shelf, you are crazy if you don’t use tidegauges (interpolated along-coast) as well as altimetry when making a sea level analysis (eg, by OI), You are just as crazy if you do not use high-res SST to help interpret a sealevel map (and/or geostrophic currents). You need a high-resolution estimate of the mean if you have a boundary current. We use one from the Bluelink global model that is 10km x 10km in Australasia To have confidence that you’re doing well: check drifter velocities. They also remind you that there’s still a way to go. To IB or not to IB? Coastal applications often want total sea level, so de-aliasing is counter-productive.

3. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

13. These examples demonstrate well-known facts: coastal sea level and deep ocean sea level are not tightly connected at all the sea level gradient across the shelf is very different to the gradient just off shelf (shelf currents are largely independent of deep-ocean currents) shelf currents are strongly wind-driven (so energetic at short time- scales), and have long along-shore length-scales off-shelf currents, where energetic, are independent of local wind and associated with baroclinic structures like WBCs and eddies therefore: both OI mapping of sea-level, and assimilation into models, must use very different covariance functions on- vs. off-shelf So far I’ve talked about synoptic maps and short time-scales, what about longer time scales?

14. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology

15. But how do I obtain tidegauge data? University of Hawaii Sea Level Center http://ilikai.soest.hawaii.edu/uhslc/data.html

16. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology I assume someone has already talked about MCC

17. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology OI using MCC and drifters works better

18. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology than the OI with just sea level

19. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology Conclusions Coastal altimetry has the potential to measure cross-shelf gradients of sea level. This could fill detail not resolved using just deep ocean altimetry and coastal tidegauges. but we need many altimeters to adequately sample the rapid changes of on-shelf sea level tidegauges record continously. Interpolate along-shore. we should be including the global network of tidegauges in gridded altimetry products SST is an essential accompaniment to altimetry – MCC can yield good velocity estimates

20. The Centre for Australian Weather and Climate Research A partnership between CSIRO and the Bureau of Meteorology THANK YOU