The estimation of surface flow velocity for Indonesian flow (ITF) using Himawari-8 SST data

Abstract

The Indonesian Throughflow (ITF) is one of the key ocean current in considering global climate change because ITF transports substantial heat content from the Western Pacific tropical zone to the Eastern Indian Ocean tropical zone. However, the field observation system at the site is very few, and the detail of ITF is not clear. Meanwhile, Japanese geostationary weather satellite, "Himawari-8", which has been in full operation since July 2015, has the ability to observe the hemisphere including the ITF area from visible to infrared radiation at 10 minute intervals. In this research, techniques to estimate the flow distribution of ITF were discussed taking advantage of the features of such high frequency observation. Specifically, surface velocity was estimated by MCC (Maximum Cross Correlation) method using multiple SST (2 km spatial resolution, 1 hour average interval, Level 3) data of P-tree System provided by JAXA. As a result, the flow velocity of 0.5 m/s or more was estimated using the data of August 2017 in the Major Straits of the ITF such as the Lombok Strait. The estimate is consistent with the field observation value measured by ADCP. By using such high-frequency latest satellite data, the possibility of quantifying short-term coastal environment change was shown.