Climatology of diablo winds in Northern California and their relationships with large-scale climate variabilities
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Climatology of diablo winds in Northern California and their relationships with large‑scale climate variabilities Yi‑Chin Liu1 · Pingkuan Di1 · Shu‑Hua Chen2 · XueMeng Chen1 · Jiwen Fan3 · John DaMassa1 · Jeremy Avise1,4 Received: 1 May 2020 / Accepted: 10 November 2020 © The Author(s) 2020
Abstract The most destructive wildfires recently in Northern California have been linked to the occurrences of Diablo Winds (DWs). This study investigates the climatology of DWs during September–December 1979–2018, and their relationships with various climate modes using observations and two high-resolution reanalysis datasets. Our finding shows that DWs do not have a long-term trend in terms of the annual total number, total duration, and associated maximum wind speeds of DWs over the past 4 decades. However, their associated minimum relative humidity (RH) has decreased significantly, especially in October, which suggests that the dryness during DWs has become more severe with time, possibly leading to an increased chance of fires, and their destructive potential. We also find that the annual total number and duration of DWs have exhibited an quasi-periodic variation, with intervals ranging from 2 to 4 years. The periodic variability of DWs might be attributed to the teleconnections between DWs and climate oscillations, specifically the El Niño–Southern Oscillation (ENSO) and the quasi-biennial oscillation (QBO), through their modulation of pressure systems near California and the location of the Pacific jet stream. It is suggested that when La Niña and the QBO westerly phases co-occur in the spring, DWs in the following fall and winter tend to occur more frequently, and are associated with more intense high winds and dryness as compared to other springtime QBO and ENSO phases. This relationship may be used to predict the seasonal outlook of DWs.
1 Introduction California with its Mediterranean climate is a fire-prone state. As the population grows and wildland and urban interface areas continue to increase (Williams et al. 2019), wildfires are becoming an ongoing threat to many of these communities as they adversely affect regional air quality and lead to loss of life and property. Wildfires are defined here as unpredicted and uncontrolled fires, which are different from prescribed fires that are planned and/or managed to reduce excess fuel buildup in forested areas. Among the Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00382-020-05535-5) contains supplementary material, which is available to authorized users. * Yi‑Chin Liu [email protected] 1
California Air Resources Board, Sacramento, CA, USA
2
Department of Land, Air, and Water Resources, University of California, Davis, CA, USA
3
Pacific Northwest National Laboratory, Richland, WA, USA
4
Washington State University, Pullman, WA, USA
top 20 most destructive wildfires in California history, six of them—the Camp Fire (2018), the Tubbs Fire (2017), the Tunnel Fire (1991), the Nuns Fire (2017), the A
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