Altimetry for coastal oceanography in Australia -an assessment of PISTACH David Griffin, Madeleine Cahill, Jim Mansbridge, Neil White

Insert presentation title Much of Australia has shelf-edge jets

Insert presentation title Australian Baseline Array of quality tidegauges

Insert presentation title Since 2004: altimetry + tidegauge -> shelf current

Insert presentation title First attempt at including PISTACH on-shelf FASL in a Jason-1, -2, Envisat, Tidegauges OI map FASL=Filtered (ie no tides) Adjusted (ie bottom-pressure equivalent) Sea Level. (anomaly understood)

Insert presentation title One-month animation of FASL maps

Insert presentation title Doesn’t look right. What are we doing wrong? SL = Orbit – range – iono – dry – wet – ssb – mss – solid Earth & pole tides. (correct either alt or TG for loading tide) FSL = SL – geocentric ocean tides (alt), Low-pass filter TG FASL = FSL – IB(isostatic) – HF corrections (MOG2d) Options tried: Orbit: IGDR MOE, GPS OGDR Range: IGDR, OCE3, RED3 Iono: GIM (J2 C band has problems) Dry: model Wet: radiometer, composite, decontaminated SSB: ssb_ku MSS: mss1(CLS01V1), mss3(DNSC08) Ocean tide: tide1 (Got 00), tide2(FES04), tide3(GOT 4.7)

Insert presentation title Study period: cycles 1-43 (July 2008 – Sep 2009) IGDR, PISTACH v0, v3, v4 v0: MOE, mss3(DNSC08), red3, decont_wet, tide3(GOT4.7) v3: oce3 v4: composite wet compute correlation, regression, mean and std dev of difference pointwise along track (1Hz averages) with Esperance (70km shelf) and Thevenard (200km shelf) for FASL, FSL, SL

Insert presentation title Esperance FASL corr with IGDR

Insert presentation title Esperance FASL corr with PISTACH v0. - much more data. (but why tracks different?)

Insert presentation title Esperance FASL corr with PISTACH v3 (oce3). - less correlation than red3

Insert presentation title Esperance FASL regress with PISTACH v0. - implausible(?) gain pattern with red3, suspect noise

Insert presentation title Esperance FASL bias with PISTACH v0. - small along track gradient, but big inter-track difference

Insert presentation title Esperance FASL cf PISTACH v0 (3 closest good 1Hz). Much within-day change. Peaks unsampled. OI no hope

Insert presentation title Esperance FSL cf PISTACH v0 (3 closest good 1Hz). - IB relatively small

Insert presentation title Esperance SL cf PISTACH v0 (3 closest good 1Hz). errors are the same with IB and tides not removed

Insert presentation title Esperance SL cf PISTACH v0 (pass 64) - hard to complain with r=0.96 r=0.96, G=0.84, std. dev 72mm, bias -111mm, 15km distance

Insert presentation title Esperance FASL cf PISTACH v0 (pass 64). r=0.67. sd 77mm. Residual tide + other HF?

Insert presentation title Esperance FASL cf PISTACH v0 (pass 227). - 3d offset: uncorrelated signal and errors cf pass 64

Insert presentation title Reminder: problems near Thevenard pass 114, cycle 33:

Insert presentation title Thevenard SL corr with PISTACH v0. at coast: 114, 201, 23

Insert presentation title Thevenard SL cf PISTACH v0 (pass 114) some big (400mm) errors, but 29 May OK: r=0.88 G=0.65, sd 190mm, 28 km from coast

Insert presentation title Thevenard FASL cf PISTACH v0 (pass 114). errors up to 400mm, eg 29 May r=0.56, G=0.54, sd=130mm. 9.8km from coast

Insert presentation title Thevenard SL cf PISTACH v0 - note 3 high tides daily 29 May – 5 June

Insert presentation title Thevenard FASL cf PISTACH v0. 400mm error on 29 May ruined OI map

Insert presentation title Burnie (pass 225) 500mm+ outliers otherwise good

Insert presentation title Burnie J1 CalVal. 40.5mm std dev using GDR-C

Insert presentation title Conclusions PISTACH data has much to offer compared with standard products. But please: more documentation of data products! These three example tidegauges highlight unresolved site- specific issues Esperance: SL has 70mm std dev noise. ~OK Big discrepancies at Thevenard not yet explained. For FASL, some of the error may be un-modelled M3 tide (cf R Ray) But SL errors are also large (up to 400mm,130mm sd) must also remember: 10-day sampling grossly inadequate to capture all shelf variability even daily-averages are inadequate, need 12h. To do: 1) better tide model, 2) check SSB

Insert presentation title Thankyou Pierre Thibaut, Franck Mercier, Claire Dufau

Insert presentation title Esperance FASL regress with IGDR. - question did not arise with IGDR

Insert presentation title Esperance FASL regress with PISTACH v3 (OCE3). - severe coastal trapping