Sunglint-enabled views of internal waves in the Celebes Sea
As has been noted before, sunglint can occasionally show the parallel lines of internal waves within the ocean. On 4 September, this occurred again north of Sulawesi in the Celebes Sea, as shown in the animation above (created using geo2grid software and Himawari-9 HSD — Himawari Standard Data — files). Different sets of internal waves are apparent, propagating mostly to the southeast towards Sulawesi. However, intersecting sets of internal waves moving in different directions are also visible, especially at 0540 UTC on the 4th, as highlighted below.
Note that there are regions where the glint region is darker than its surroundings. This occurs north of Sulawesi where gap winds from the south are perturbing the ocean surface, reducing the amount of solar reflection. That is shown in the annotated image below, courtesy of Brandon Aydlett and Michael Ziobro, WFO Guam.
Advanced Scatterometer (ASCAT) data from Metop-C early on 4 September 2023, below, (source) show very strong south winds to the east of Sulawesi.
Many thanks to Brandon Aydlett and Michael Ziobro, WFO Guam, for alerting us to this very interesting event. Note also: there is a long history of using sunglint in MODIS imagery to view internal waves: Link 1; Link 2.