Santa Ana Winds
Santa Ana Winds are recurrent winds that are mostly experienced in Southern California in autumn, winter and spring characterized by relatively low humidity and moderately strong offshore winds (Lynn and Svejkovsky, 1984). The winds reach their peak in the month of December with and underlying effect of causing the exceptionally hard to contain wildfires known to cause irrevocable losses whenever they occur. These winds, which exhibit some similarity to the winds normally observed in the lee of the famous Front Ranges of Colorado, warm adiabatically as they move downwards due to compressional heating. According to Raphael (2003) the winds have a low frequency in the month of September though they hit a peak in December. Raphael (2003) further documents that the Santa Ana Winds’ frequency decrease during winter and even further during early spring. Apart from being characterized by a difference in topographic features, the winds also show temporal variations, all of which are time dependent.
Formation of the Santa Ana Winds
Just like any other wind, the Santa Ana Winds are created, as a result, in the difference in pressure; a pressure gradient that results from the difference in temperature of the cold desert surface and the temperature of the warm ocean air, both occurring in the same altitude. The Santa Ana Winds formation is associated with an intense high pressure system often common in the Great Basin region. The summing effect is that an off show flow, similar to a katabatic flow, is created from the pressure gradient built in the altitude in which these two bodies exist. These winds that are converse to the onshore sea breeze are, however, formed when the high pressure strengthens inland with a further influence of other average synoptic conditions like a large temperature gradient, which force the onshore winds strongly. The effect of the synoptic conditions together with the local thermodynamic mechanisms can be quantified empirically.
Researchers have constantly tried to design theoretical models that can be used to demonstrate how synoptic conditions create conducive environments for the development of these phenomenal winds. Fosberg, O’Dell and Schroeder (1966), provide us with such proven models. According to the trio, Synoptic aspects of the Santa Ana winds include low pressure on the offshore of South California and the anticyclone in Nevada (The Great Basin). Sommers (1978) is yet another scholar who has tried to explain the synoptic conditions that prompt the Santa Ana Winds using a model that he called the Limited Fine Mesh Model. His research, apart from explaining the synoptic conditions surrounding the occurrence of the Santa Ana Winds, was aimed at improving the winds’ forecasting techniques. His findings revealed that the orientation of the southern California Mountains serves as a well ‘meridional’ component in relation to the occurrence of the Santa Ana Winds. With the ongoing research on the role that synoptic conditions play in the formation of winds like the Santa Ana winds, understanding the formation of the Santa Ana Winds will be bettered; findings that will occupy the central focus in the study if these intriguing Southern California winds.
Effects of the Santa Ana Winds
When the Santa conditions set in, the results a typically hotter weather condition along the coast which it sweeps through. This wind that has a characteristically high energy channels itself along the Nevada region and the Rocky Mountains. There underlying benefits that that accrue as a result of the flow of these winds is that fish thrive well after it has blown. Santa Ana winds cause the cold water to rise from the bottom of water bodies bringing with them nutrients to the surface of the water. As a result, fishing is bettered.
The frequent wild fires out brakes in Southern California are normally caused by the Santa Ana Winds. The southern California is covered majorly foliage that is shrub-like in nature. When this foliage dry, the area is put on wild fire alert and, unfortunately, the Santa Ana Winds normally flow at a time when the foliage is relatively dry normally resulting into a fire outbreak; a fire that according to Phillips (1971), can consume over 30000 ha to rubble in a single day (as cited in Sugihara, 2006). This wind that is of much meteorological importance flows at a speed that can exceed 100 Km/hr. Worth noting is the fact the fire phenomenon is a relatively complex phenomenon that depends on the speed of the wind and the humidity. Allegedly, Santa Ana Winds were the cause of the infamous Southern California wild fire of October 2003.
Predicting the Santa Ana Winds
Though there has been limited research on the effect of the Santa Ana winds, there has been, however, some research that has revealed that there is a considerable relationship between the El Nino and the Santa Ana Winds. Finley & Raphael (2003) are among the first researchers to carryout pioneering research on the supposed relationship between the Santa Ana Winds duration and frequency and the El Nino Southern Oscillation (ENOS). The two researchers in an article, they which they called, ‘The Relationship between El Nino and the Duration and Frequency of the Santa Ana Winds of Southern California’ reveal that, indeed there is a relationship between the Santa Ana winds and the ENOS. According to Finley & Raphael (2003), the mean number of days of the Santa Ana Winds is fewer as compared to the mean number of days in non El Nino days. These results, which are consistent with the assertion by Raphael (2003), can go a long way in predicting the occurrence of these winds.
References
Finley, J. and Raphael M. (2007). ‘The Relationship between El Nin˜ o and the Duration and
Frequency of the Santa Ana Winds of Southern California.’ University of California,
59:2. 184-192.
Fosberg, M. A., C. A. O’Dell, and M. J. Schroeder. (1966). ‘Some characteristics of the three
dimensional structure of Santa Ana winds.’ U.S. Forest Service Research Paper PSW,
30:1, 26
Lynn, R.J., Svejkovsky, J. (1984). ‘Remotely sensed sea surface temperature variability of California during a "Santa Ana” clearing.’ J. Geophys. Res., 89, 8151-8162,.
Raphael, M. N. (2003). The Santa Ana Winds of California. Earth Interactions, 7, 1–13.
Sommers,W. T. (1978). LFM forecast variables related to Santa Ana wind occurrences. Monthly
Weather Review 106, 1307–16.
Sugihara, N. G. (2006). Fire in California's ecosystems. London: University of California Press.
