Surface currents and some surface temperatures in the Somali Basin have been plotted for May and June of each year from 1900 to 1973 when any data were available. A current pattern containing two clockwise gyres, one situated south of 5N, the other between 5N and 10N, was usually present in June. It is similar to the one observed in a detailed survey of the Somali Current in 1979. Some evidence is presented suggesting that the timing of the development of the gyres, in relation to changes in winds, was similar in other years to the sequence observed in May and June 1979.
Swallow, J. C., and M. Fieux. 1982. "Historical evidence for two gyres in the Somali Current." Journal of Marine Research 40, (S). https://elischolar.library.yale.edu/journal_of_marine_research/1665