Western Pacific ITCZ changes from 24 July to 2 August 2023
Hourly estimates of Total Precipitable Water (TPW) from MIMIC, shown above in an mp4 animation (click here for an animated gif), show the Intertropical Convergence Zone (ITCZ, as measured by TPW) over the western Pacific evolving from a linear feature at the start of the animation to one with a significant break near 140oE – 150oE longitude. This has occurred as Typhoons Doksuri (moving between the Philippines and Taiwan at the start of the animation) and Khanun (moving south of Japan at the end of the animation) have developed (here is a blog post on the formation of Khanun). Formation of tropical cyclones during the breakdown of the ITCZ is not uncommon (as noted, for example, here, and here). The mp4 animation below (click here for an animated gif) tracks the Upper- and Lower-level water vapor infrared imagery (Himawari-9 Bands 8 and 10 at 6.24 µm and 7.3 µm, respectively) over the same time period.
Himawari-9 Clean Window imagery, below, at 0000 UTC on 24 July (left) and 2 August (right) show little in the way of ITCZ convection between the Equator and 20oN on 2 August, especially compared to 24 July, over the western Pacific. ITCZ convection does persist to the east of 160oE longitude. MIMIC TPW fields at those two times (here) also show a similar rearrangement of convective centers.
