On the Existence of Atmospheric Vortices Downwind of Hawaii during the HAMEC Project

Abstract

Aircraft observations west of the island of Hawaii in June 1980 during the Hawaii Mesoscale Energy and Climate (HAMEC) Project have provided the first in situ measurements of airflow within atmospheric vortices downwind of a tall island. A band of low-level westerly winds was observed to extend more than 150 km west of the island along the axis line separating cyclonic vortices to the north of that line from anticyclonic vortices to the south. The theoretical downstream propagation speed of those vortices is obtained from the solution to a quadratic equation, and while previous satellite studies of atmospheric vortices used the larger root (i.e., ?80% of the ambient flow), the present data are consistent with the smaller root ?20%). The turbulent Reynolds number for the flow is 140, and the corresponding vortex shedding time is 32 h.