Storm tracks associated with extreme storm surges, coastal currents and waves in Southern Australia Yasha Hetzel, Charitha Pattiaratchi, Simone Cosoli, Ivica Janekovic Oceans Graduate School The UWA Oceans Institute The University of Western Australia Southern Ocean extremes Global GFS winds 9-9-2015 Storm surge www.Ozsealevelx.org http://sealevelx.ems.uwa.edu.au Global GFS winds 9-9-2015 Southern Ocean winter storms • How does storm track influence the intensity of coastal currents, storm surges, and wave heights in Southern Australia? Global GFS winds 9-9-2015 Study site: South Australian Gulfs • Wide continental shelf across Bight • Directly exposed to Southern Ocean storms • Big waves, storm surges, strong shelf currents Thevenard Port Lincoln Adelaide + SAG Cape du Couedic Study site: South Australian Gulfs • Entrance to Spencer Gulf, fishing, shipping, ports • Remote! Cape Wiles, Cape Spencer Cape Wiles +Cape Catastrophe, Anxious Bay, Coffin GlobalBay… GFS winds 9-9-2015 Study site: South Australian Gulfs • Entrance to Spencer Gulf, fishing, shipping, ports • Remote! Cape Wiles, Cape Spencer • But… data are available! +Cape Catastrophe, Anxious Bay, Coffin GlobalBay… GFS winds 9-9-2015 Study site: South Australian Gulfs • Entrance to Spencer Gulf, fishing, shipping, ports • Remote! Cape Wiles, Cape Spencer • But… data are available! Global GFS winds 9-9-2015 Data Focus on 5 years 2012-2016 • HF Radar surface current velocity • Tide gauge data • Cape du Couedic wave buoy • Storm tracks ECMWF ERA-Interim Port Lincoln SAG + HF Radar Tide gauge + Wave buoy Currents, storm surges, waves Global GFS winds 9-9-2015 Top 10 storms (currents, surge, waves) Currents ? Extreme events often specific to Surge variable, except ? for the biggest storms Relative amplitude Relative Waves Global GFS2012 winds 9 - 9 -20132015 2014 2015 2016 Amplitudes of extremes Stronger east Currents velocities >0.5 m surges, higher at Storm surge Thevenard Waves ~60% of extreme wave heights > 7m Global GFS winds 9-9-2015 Time series - currents Time series of events 2012-2016 Seabreeze Winter storms 2016 % data available 120 ranked events (storms) Current velocities & sea level 09Day9--JulJul 2 - (123(12 (12 hrhr hrmean)mean)mean) west south Global GFS winds 9-9-2015 Current velocities & sea level 11-Jul (12 hr mean) west south Global GFS winds 9-9-2015 Current velocities & sea level 11-Jul (6 hr mean) west south Global GFS winds 9-9-2015 Storm tracks Global GFS winds 9-9-2015 Storm track clusters Track along coast Low pressure Strong winds Along coast wind gradients Track along coast Less low pressure Weak winds Uniform winds HIGH pressure or Far from coast Distant storms (often summer) Global GFS winds 9-9-2015 Storm track clusters Track along coast Low pressure Strong winds Along coast wind gradients Track along coast Less low pressure Weak winds Uniform winds HIGH pressure or Far from coast Distant storms (often summer) Global GFS winds 9-9-2015 Storm track clusters Track along coast Low pressure Strong winds Along coast wind gradients Track along coast Less low pressure Weak winds Uniform winds HIGH pressure or Far from coast Distant storms (often summer) Global GFS winds 9-9-2015 All storm tracks Slp (hPa) 1010 1000 990 980 970 960 Global GFS winds 9-9-2015 Storms causing strong currents 1010 1000 990 980 970 960 Global GFS winds 9-9-2015 Are these coastally trapped waves? 65 km 5-7 m s-1 Global GFS winds 9-9-2015 Are these coastally trapped waves? • Most storms travel faster than the surge (& CTW) 65 km 5-7 m s-1 Global GFS winds 9-9-2015 The Perfect Storm • Intense storm (Low pressure + strong winds) • Slow translational speed • Rotating structure (onshore/offshore flow) • High pressure to west is favorable • Track along coast → coastally trapped waves likely Global GFS winds 9-9-2015 The Perfect Storm • Intense storm (Low pressure + strong winds) • Slow translational speed • Rotating structure (onshore/offshore flow) • High pressure to west is favorable • Track along coast → coastally trapped waves likely Global GFS winds 9-9-2015 The Perfect Storm • Intense storm (Low pressure + strong winds) • Slow translational speed • Rotating structure (onshore/offshore flow) • High pressure to west is favorable • Track along coast → coastally trapped waves likely Global GFS winds 9-9-2015 The Perfect Storm • Intense storm (Low pressure + strong winds) • Slow translational speed • Rotating structure (onshore/offshore flow) • High pressure to west is favorable • Track along coast → coastal trapped waves likely Global GFS winds 9-9-2015 Composite maps of top 10 events currentGlobal GFS winds 9-9-2015 surge waves s Currents (top10) Global GFS winds 9-9-2015 Storm surge (top10) Global GFS winds 9-9-2015 Waves (top10) Global GFS winds 9-9-2015 Common storms – currents & surge Global GFS winds 9-9-2015 Common storms – waves & surge Global GFS winds 9-9-2015 Common storms – waves & currents Global GFS winds 9-9-2015 #1 ranked waves storm Global GFS winds 9-9-2015 Common storm (from all top 10) Global GFS winds 9-9-2015 Common storm (from all top 10) Global GFS winds 9-9-2015 Summary • S. Australia extreme currents and storm surges sensitive to Southern Ocean storm tracks • Coastally trapped waves likely important • Big wave events often have different storm signature • High pressure to west is common to all extreme events • “Perfect Storm” can still exist 1. Track along coast 2. Slow, intense Tropical vs. extra-tropical TC Olivia 408 km/hr wind Global GFS winds 9-9-2015 Tropical Cyclone Bianca Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 ROMS 2D vs. 3D Global GFS winds 9-9-2015 .