Atmospheric response to tropical thermal forcing in real data integrations

Evidence is presented for a highly regular seasonal rearrangement of the long-wave pattern over North America from the winter to the spring. The change involves a reversal of the trough-ridge pattern between the two seasons wherein the anticyclone observed in the winter climatology over and west of the Rocky Mountains reverses to a spring trough, and the winter lee cyclone changes to a spring ridge over the eastern United States. These changes, which represent a westward shift of the long-wave pattern from winter to spring, are accompanied by westward shifts of the subtropical jet core from the east to west coast, and of the tropical rain maxima from the Amazon Basin to the tropical Pacific Ocean. -from Authors