Santa Ana Winds of Southern California: Their climatology, extremes, and behavior spanning six and a half decades

Abstract

Santa Ana Winds (SAWs) are an integral feature of the regional climate of Southern California/Northern Baja California region, but their climate‐scale behavior is poorly understood. In the present work, we identify SAWs in mesoscale dynamical downscaling of a global reanalysis from 1948 to 2012. Model winds are validated with anemometer observations. SAWs exhibit an organized pattern with strongest easterly winds on westward facing downwind slopes and muted magnitudes at sea and over desert lowlands. We construct hourly local and regional SAW indices and analyze elements of their behavior on daily, annual, and multidecadal timescales. SAWs occurrences peak in winter, but some of the strongest winds have occurred in fall. Finally, we observe that SAW intensity is influenced by prominent large‐scale low‐frequency modes of climate variability rooted in the tropical and north Pacific ocean‐atmosphere system.

Atmospheric Inputs of Iron and Manganese to Coastal Waters of the Southern California Current System: Seasonality, Santa Ana Winds, and Biogeochemical Implications

“…We answered this question by estimating the number of days (t SAW ) with SAW conditions per year during the 2010–2014 period; then, based on equation , we estimated the annual contribution of dust input of all SAW events (%SAW dust ), which was then compared with the annual and seasonal dust budgets. Our analysis indicates that the average t SAW for our 5 year time series was 28 ± 3 days (Figure f), which compares favorably with the range of 30–64 SAW days per year recently reported for the Southern California region (Guzman‐Morales et al, ; Jones et al, ). Over the period of 2010–2014, 86% of SAW days occurred during the cool season and the input of dust associated with SAW events was (10.6 ± 1.4) × 10 2 mg m −2 .…”

Brief Communication: Synoptic-scale differences between Sundowner and Santa Ana wind regimes in the Santa Ynez Mountains, California

“…The hourly SAW index used for comparison with our Sundowner climatology was developed for southern California by Guzman-Morales et al (2016) using output from a dynamically downscaled regional climate model at 10 km horizontal resolution. Guzman-Morales et al (2016) defined SAWs at each grid cell by first identifying winds with a negative u-component (between 0 and 180 • ) that exceeded the upper quartile of wind velocities in this cell.…”

“…Guzman-Morales et al (2016) defined SAWs at each grid cell by first identifying winds with a negative u-component (between 0 and 180 • ) that exceeded the upper quartile of wind velocities in this cell. To be categorized as a SAW event, they required a 12 h period of continuous winds that had at least 1 h of velocity exceeding the grid cell velocity threshold.…”

“…Extensive study on extreme fire weather in southern California has focused on Santa Ana winds (hereafter SAWs) that have contributed to many massive conflagrations (Raphael, 2003;Hughes and Hall, 2010;Moritz et al, 2010;Abatzoglou et al, 2013;Guzman-Morales et al, 2016). SAW conditions result from the development of a strong pressure gradient produced in response to a thermal gradient between the cold, inland deserts and warmer maritime air mass (Hughes and Hall, 2010).…”

A Surface Observation Based Climatology of Diablo-Like Winds in California’s Wine Country and Western Sierra Nevada

“…Despite the massive destruction wrought by the Diablo winds, associated with the Northern California firestorm of October 2017 and the Oakland Hills firestorm of 1991, very little is known quantitatively about them, especially relative to the Southern California downslope winds that favor wildfires, such as Santa Ana [1][2][3][4][5][6][7][8][9][10] and Sundowner [11][12][13][14][15] winds. A prescient preliminary analysis of 'Santa Ana-like' winds in the Oakland Hills was performed in 1973 [16], some 18 years prior to the Oakland Hills fire of 1991, and analyses [17][18][19] subsequent to that fire confirmed their localization at the eastern San Francisco Bay Area.…”