 These dates conventionally delimit the period of each year when most tropical cyclones form in the northern Indian Ocean.The scope of this article is limited to the Indian Ocean in the Northern Hemisphere, east of the Horn of Africa and west of the Malay Peninsula.There are two main seas in the North Indian Ocean – the Arabian Sea to the west of the Indian subcontinent, abbreviated "ARB" by the India Meteorological Department (IMD); and the Bay of Bengal to the east, abbreviated "BOB" by the IMD.