Himawari-8 is Japan’s advanced geostationary weather satellite that provides a ‘full disc’ scan of Earth every 10 minutes. Fortunately for us, the centre of this view (at longitude 140.7°) is close to us.
The result is an SST product spanning 80°E to 200°E with a resolution (2–4 km at the equator) that is nearly as good as the low-earth orbit NOAA satellites. Cloud is, of course, the bane of observers of satellite SST and Himawari-8 cannot see through cloud, but with so many looks there is a much better chance to piece together a clear view.
The image (right) is from an animated gif of 48 hours of the 4-hour composites offshore from Perth, WA. It shows tiny eddies, about 10 km in diameter, being swirled around the large cyclonic eddy in the centre of the image. There are also a couple of tiny eddies just to the southeast of the central eddy.
Eddies of this size have certainly been seen before but the presence of so many suggests they are much more prevalent than we thought and that they play an important part in mixing between two water masses. Also, the movement of these tiny eddies demonstrates not just the complexity of the SST but also of the surface velocity field.
* All available satellite SST (including NOAA15, NOAA18, NOAA19, VIIRS and MODIS) is used in the composites to get the best coverage to the coast.
This article, by Madeleine Cahill, originally appeared in IMOS OceanCurrent News.