A description of the 1981 and 1982 spring transitions over the Northern California Shelf

摘要: The spring transition between winter and summer conditions on the northern California continental shelf occurred suddenly, over a period of days, in late March 1981 mid-April 1982. marks onset upwelling season is response to an atmospheric associated with sudden seasonal change large-scale pressure field North Pacific. 1982 transitions are characterized by drop water temperature 2°–4°C reduction difference across column at midshelf from 2°C 0.5°C. Isotherms isopycnals, which were level prior transition, slope upward toward coast after transition. mass balance for event roughly two dimensional, offshore flow near surface balanced weaker subsurface onshore flow. alongshore momentum during not dimensional includes establishment gradient opposes wind apparently drives poleward observed weak following cross-shelf geostrophic, density fluctuations contributing gradient. heat budget due primarily exchange circulation.