Extreme oceanic events David Griffin CSIRO Marine and Atmospheric Research

Special thanks to Madeleine Cahill George Cresswell and Jason Middleton John Wilkin and Alan Pearce Peter Campbell, Jason Waring, Kim Badcock (and the whole remote sensing group) Jim Mansbridge The Bluelink and IMOS communities (many great people) Peter Thompson, referees and the panel

1995 Mass Mortality of Pilchard – due to an extreme ocean event? ?

Event was extreme but not unprecedented Shift focus to the virus Exposed ill-preparedness for addressing urgent questions Assembling data took too long Available data were too few Too hard to know ‘how anomalous’ various observations were Nevertheless, I think we got it right BTW, the next comparable upwelling was not til 2010:

2010 upwelling event, similar to 1995:

The cause: occasional summer wind pattern Sea Surface Temperature Sea level anomaly High wind

Next, two Qld events. Ocean impact unnoticed?

beautiful one day….(9 Feb 1997) Sea level anomaly Sea Surface Temperature

TC Andrew (25 March 1997) the next. Sea level anomaly Sea Surface Temperature

Month later: cold along NGBR Sea level anomaly

16 March 2010: TC ULUI Sea level anomaly L

25 May (TC ULUI + 40d)

30 June 2010 (TC ULUI + 110d) Fast current, Possible upwelling

Tropical cyclones on NWS: hazard to oil and gas. TC Phil 31 Dec 1996, cat 3 but slow moving

More recently (15 March 2012) TC Lua

20 March 2012 (TC Lua + 5d)

Chlor-a for same day (new on IMOS OceanCurrent): 100km.100km.30m =60t chl-a

Highest-ever sea level at Fremantle, 2pm WST: 3h period seiche (Molloy, 2001) MSL surge tide Leeuwin

Two weeks before storm: Cold core eddy Leeuwin 0.4m

ROAM sea level, June Sea level anomaly N E Rottnest Is Cockburn Sound Leeuwin 180km

CSIRO Bluelink Relocatable Ocean Atmosphere Model sea level, 10 June m 1000m

2pm WST 10 June 2012

Cockburn Sound. Highest sea level: 2pm WST 10 June 2012: Photo Credit: Steve Brooks, PerthWeatherLive Photo: Steve Brooks, Perth Weather Live

A few days later Photo: Steve Brooks, Perth Weather Live

Insert presentation title Median energy flux of ocean currents 0 Median non-tidal current speed 0.8 (m/s)

Insert presentation title Median energy flux of ocean currents 0 Median non-tidal current speed 0.8 (m/s)

Cyclonic Eddy (Low sealevel) Is it real? Yes, see drifter. Is it extraordinary? Lets look at some history

Maximum (in ) gridded altimetric (+ filtered tidegauge) sea level anomaly: +1m SLA -1m wide range: 0.3m to 1.1m

99 th percentile anomaly (exceeded 1% of time) - the max is 30% higher than this +1m SLA -1m 0.2m 0.7m

1 st percentile anomaly (exceeded 99% of time) +1m SLA -1m -0.7m

Insert presentation title Lowest sea level is 30% lower than 1 st %-ile -1m

Maximum anomaly map again. highest highs are south of the lowest lows +1m SLA -1m Lowest low was here Highest high Is here

Median elevation (50 th percentile) near zero – i.e. distribution is fairly symmetric +1m SSHA -1m

Cyclonic Eddy (Low sealevel) Is it real? Yes, see drifter. Is it extraordinary? Lets use that history

Insert presentation title 16 Jan 2011: Many extreme highs and lows 1.5m/s

Insert presentation title Back 4 days (to 12 Jan) flood

Insert presentation title Back 4 days (to 8 Jan) Pre flood: Sea level extreme

Insert presentation title Back 4 days (to 4 Jan)

Insert presentation title Back 4 days (to 31 Dec)

Insert presentation title Back 4 days (to 27 Dec)

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That high sea level all along the Qld-NSW coast was not a ‘storm surge’ Coastal sea level was very high. Anomaly of nearshore current was zero. Odd situation – still needs investigation. Lets now go back to 16 Jan then step forward.

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vanishing growing

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Discussion Marine science has tended to focus on the ‘normal’ behaviour of the ocean But observing systems are now adequate for us to also focus on the rare occasions when something extreme happens Some events have obvious societal impacts, e.g. beach erosion, coastal flooding, coral bleaching, fish kills, oil rig failures Many do not – but may – e.g. chlor-a blooms and deserts Extreme events pose a challenge to observing system design, quality control of data, and data interpretation I think the effort is warranted

Insert presentation title Thank you