HR: 14:00h
AN: A33B-01 INVITED     [Abstracts]
TI: The Low-Level Flow Along the Gulf of California During the North American Monsoon.
AU: * Bordoni, S
EM: bordoni@atmos.ucla.edu
AF: UCLA, Dept of Atmospheric and Oceanic Sciences, 7127 Math Sciences Bldg., Box 951565, Los Angeles, CA 90095-1565, United States
AU: Stevens, B
EM: bstevens@atmos.ucla.edu
AF: UCLA, Dept of Atmospheric and Oceanic Sciences, 7127 Math Sciences Bldg., Box 951565, Los Angeles, CA 90095-1565, United States
AB: Six-years (1999-2004) of QuikSCAT near-surface ocean winds are used to study the flow over the northeast Pacific and the Gulf of California (GoC) during the North American Monsoon season. The wind data show that the onset of the summer season is accompanied by a reversal of the flow along the GoC, with the establishment of a mean southerly wind throughout the gulf. This reversal occurs in late spring and precedes the onset of the monsoonal rains. In the heart of the monsoon season, the time-mean flow is found to be composed of periods of enhanced southerly winds associated with gulf surges. The role that gulf surges play in modulating the GoC mean southerly flow is further explored by performing an EOF analysis of the summertime daily wind anomalies. A gulf surge mode emerges from this analysis as the leading EOF, with the corresponding principal component time series interpretable as an objective index for gulf surge occurrence. This index is used as a reference time series for regression analysis, to explore the relationship between gulf surges and precipitation over the core and marginal regions of the monsoon, as well as the manifestation of these transient events in the large-scale circulation. It is found that, although seemingly mesoscale features confined over the GoC, gulf surges are intimately linked to patterns of large-scale variability of the eastern Pacific ITCZ and greatly contribute to the definition of the northward extent of the monsoonal rains.
DE: 3329 Mesoscale meteorology
DE: 3360 Remote sensing
DE: 3374 Tropical meteorology
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly