The 22 June 2012 Technical News item listed some of the best MODIS Chlorophyll-a images for the initial 2011-2012 batch of MODIS imagery, and compared these with the recent re-processing using SeaDAS6.4. Here, we list some of the clearest or interesting images of the Leeuwin Current in south-west WA, for 2002-2011. The peculiar seasonality of the Leeuwin current and the associated cycle of surface chlorophyll, appearing where you might least expect it, is clear:
There is presently a satellite-tracked drifter apparently trapped in a cold-core eddy off NSW. On 2 May 2013 it was at 33S 155.5E, doing ~30km-diameter clockwise loops in a 120km-diameter cyclonic eddy. The 'parent' cold-core eddy of the present, smaller eddy has existed for a long time but between 13 March and 16 March it became elongated to the NNW. The drifter did its first cyclonic loop at the northern limit of this feature (32S 155E) on 20 March, then proceeded to do many more as the eddy meandered about (the images around 24 April are the clearest). The MODIS image for 10 April shows that the eddy had low (near-surface) chlorophyll-a, in contrast to the other cyclonic eddy positioned a similar distance offshore, off Jervis Bay at 35S. Stepping back through time reveals that the difference between the eddies' chlorophyll concentations is explained by their different origins; the southern one having been formed over the continental shelf near Sydney-NewCastle around 13 March. The tendency of drifters to remain in eddies has been noted before but we cannot recall an instance of a drifter doing so many loops in a cyclonic eddy in this region before. Does it matter? Yes, because it tells us something about the exchange of water between the eddy and its surroundings. It also suggests there may be some convergence at the surface and therefore downwelling at the centre of the eddy, and also that the eddy is certainly not a wavelike feature, with a sea level anomaly essentially un-coupled from any particular mass of water.
An IMOS Slocum glider sampling the Storm Bay line out from Hobart encountered extremely strong currents towards the NE recently, sweeping it up the Tasmanian coast towards Maria Island as shown at right. The glider's track also included a few unplanned loops. One of these was east of the southern tip of the Tasman Peninsula, over the mid-shelf between Tasman Island and the Hippolyte Rocks. A CSIRO experimental near-real-time model simulation has an anti-cyclonic eddy, at about the same location as the glider's loop, that appears to be a topographic lee eddy resulting from the strong (nearly 1m/s) alongshelf flow streaming past the SE tip of the Tasman Peninsula. [more about the model, and real-time output] [animation won't play?]
Tide gauges at Broome, Port Hedland and Cape Lambert have also recorded the impact on sea level but this does not appear to have been large, relative to the large tidal range of the Pilbara coast. The elevated sea level, however, is expected to travel southwards along the Australian continental margin as a Coastal Trapped Wave, raising sea level by about 0.4m above the tidal prediction at 
Perth on 1-3 March , according to the Bureau of Meteorology ocean model forecast, as shown at right.
The far eastern coast of Victoria has one of Australia's upwelling 'hotspots'. An example of intense localised upwelling occurred in the last few weeks, starting on
13 Feb. The signal is clear off Marlo (longitude 148.5°E) by 15 Feb. According to satellite imagery, SST reached a minimum of 16°C on 17 Feb and the cold plume extended 80 km to the south west. Observers at nearby Beware Reef measured surface temperatures as low as 15°C. The cold upwelling triggered a phytoplankton bloom that was clearly evident in a MODIS chl-a image for 21 Feb and even more evident to the Beware Reef diver pictured, who noted only a few m visual range down to 20m where it was quite dark, and only 12°C. The upwelling event appears to be due to the combined effect of 1) the local wind which was upwelling-favourable from 10 Feb, and 2) dynamic uplift from the along-shelf flows associated with a warm-core EAC eddy. The event has been simulated quite well in near-real time using the Bluelink-developed nested-model system but the dynamics have not yet been fully explored. [model estimates of SST and currents] Photo credit: Friends of Beware Reef.
Now, the state of the East Australian current and its eddies: The 'speed hump' in Bass Strait that presented navigators with a difficult decision last year is not there this year. Instead, the rhumbline appears to be fairly free of any strong currents as far as we can tell from the latest satellite information. To the east of the rhumbline there is some favourable current clearly evident in the latest images so the warm, anticlockwise-rotating eddy is a feature worth watching in the next few days. There appears to have been a northward flow on the continental shelf of north-east Tasmania (as evidenced by the plume of cold water streaming north from Eddystone Pt) in the last few days but this feature is unlikely to persist until race day. The situation between Sydney and Cape Howe is very complex this year. There are two small cyclonic (clockwise rotating) eddies off the continental shelf, so the flow is adverse in places seaward of the 200m isobath. Over the shelf, however, there was evidently a favourable flow of about 1kt on 15 Dec, as can be seen from the southward drift of a satellite-tracked buoy. The thermal imagery for 19 Dec suggests there was a narrow warm stream flowing south past Jervis Bay over the outer continental shelf. It is unclear from the altimetry what the speed of the flow was. Navigators should watch the imagery for any evidence of this flow persisting til race time, which is quite possible but certainly not guaranteed. As usual, we wish all competitors an exciting but safe race and apologize in advance if the imagery on our website stops updating at any point due to a computer failure while our IT staff enjoy their holidays.
[8 Aug 2012], now you don't: 
[14 Aug 2012]. What made the thin streak of warm EAC water south of Coffs Harbour suddenly disappear? Two things happened between 8 and 14 Aug, as shown in the larger-scale map for 11 Aug 2012. One is that the cold core eddy at 30S 155E, over the continental slope off Coffs Harbour, was restricting the southward flow of the East Australian Current at that point, so most of the flow went offshore around a big warm core eddy centered off Byron Bay. The consequence of this is that the thin streak of warm water south of Coffs was probably quite shallow. The other thing happening was that an atmospheric low pressure system was off NSW, centered at 34S 159E on 11 Aug. Strong southerly winds drive coastal currents northward and raise coastal sea level, as shown in the tidegauge data, but that would not change the surface temperature away from the coast. The cold southerlies cool the warm surface layer by extracting heat, but possibly more importantly, also by increasing the surface turbulence, mixing warm shallow layers with the water beneath. In summary, we think that the winds being so strong, and the flow volume so reduced, are what made the surface exression of the EAC off NSW disappear so fast. 22 August update: a fresh nose of warm surface waters can now be seen flowing south again between Coffs and the eddy offshore. April 2013 update: The CH070 and CH100 ADCPs certainly recorded the northward current pulse but no temperature rise at the bottom due to vertical mixing is evident.
On 10, 11 and 13 June 2012, the Bureau of Meteorology National Tidal Facility tide gauge at Hillarys, Perth, recorded non-tidal sea level anomalies of up to 0.8m above mean sea level. The WA Department of Transport tide gauge at Fremantle Boat Harbour recorded a similar surge but also a ~3h-period oscillation that contributed to the highest sea level ever recorded at Fremantle: 1.35m above mean sea level. Fortunately, these surges came at neap tide (click images to expand - Hillarys data courtesy of BoM, Fremantle data and image courtesy of WA DoT). The total sea level might have been an additional 0.3m otherwise (e.g., if it had occurred during the high spring tide a few days earlier). Low atmospheric pressure was a contributor to the high sea level but strong onshore (westerly) winds associated with the low pressure systems passing south of the mainland was the main cause. A consequence of these strong winds being onshore rather than alongshore is that they would not (in contrast to the geostrophic sea level-based estimates shown on our map) have generated particularly strong along-shore currents. This will be confirmed when the radar data processing resumes. Along the southern coast of Australia, where the winds blew along the shelf rather than across it, they generated a 0.75m non-tidal sea level anomaly on 14 June 2012 at Thevenard, where such events are more common. The surge has now passed through Portland, Vic (non-tidal anomaly 0.3m) and will possibly also be measurable soon east of Bass Strait.