Heatwaves of Southern California
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Authors
Zubar, Eric
Issue Date
2023
Type
Thesis
Language
Keywords
Alternative Title
Abstract
Improving forecasting accuracy for the heavily populated Southern California coastal regions, such as in Los Angeles (LAX) and San Diego (SDI), is an important undertaking. Research was conducted to find the different components and lifecycles of Santa Ana Wind heatwaves (SAWs) and non-Santa Ana Wind heatwaves (NSAWs), and how each type impact this region. Station data from LAX and SDI showed that NSAWs are hotter and SAWs are drier on average, and station data from intermountain cities such as Salt Lake City (SLC) showed the opposite in terms of relative humidity. Station data also showed surprisingly little difference in wind behavior at LAX and SDI, especially with wind speed. ERA5 composite images showed that SAWs planetary wave breaks (PWBs) that are more westward longitudinally than NSAWs, as well as possessing flow that is more northeasterly at many pressure levels of the atmosphere, and NSAWs showed a propensity for higher land surface temperatures throughout the West. These images also showed that SAWs have less clouds at various levels, in particular at the 1000 hPa level, which represents the marine layer. HYSPLIT backwards trajectories that run back 48 hours from the time of the event (TOE) showed the most compelling evidence: SAWs tend to have non-reflective, long, smooth, and simple PWBs, and NSAWs tend to have reflective, short, rough, and complex downscale PWBs. Skew-T graphs taken near LAX and SDI using ERA5 showed solid confirmation of the ERA5 composite images’ conditions, while also demonstrating significant differences in lifting condensation level between SAWs (higher) and NSAWs (lower). Finally, mean sea level pressure (MSLP) images were run that expectedly revealed that NSAWs typically have maximum pressure values more eastbound (Utah) while SAWs’ max values are more westbound (Western Nevada).