'Santa Ana' winds and upwelling filaments off Northern Baja California

An atmospheric condition known as a `Santa Ana' wind occurred from 9 to 11 February 2002. Its effect was felt over a large portion of southern California and the northern half of the Baja California Peninsula. Santa Ana winds are dry, strong northwesterly through easterly mountain downslope winds, most common in winter. Satellite data from Quickscat show two large wind jets crossing the mountains of the peninsula and extending 300 km offshore. Data from a coastal station reveal that the event lasted over 52 h with average speeds of 11 m s(-1) and gusts of 25 m s(-1). The southernmost jet crosses the mountains at the San Matias mountain pass and generates a cold filament off Point Colonel. Satellite imagery shows this feature lasting at least two inertial periods (T-i = 22h) and extending 100 km offshore during the observation period. Estimates of the stationary Ekman pumping produced vertical speeds of 20m per day, consistent in time and location with the observed structures. The ocean off Point Colonel is well known for the existence of upwelling episodes. They occur mostly in the spring or early summer when persistent winds blow towards the equator and parallel to the coast. The events described here present a different phenomenon: upwelling filaments induced by short-lived, offshore winter winds. (C) 2003 Elsevier Science B.V. All rights reserved.