A Later Onset of the Rainy Season in California

Californian hydroclimate is strongly seasonal and prone to severe water shortages. Recent changes in climate trends have induced shifts in seasonality, thus exacerbating droughts, wildfires, and adverse water shortage effects on the environment and economy. Previous studies have examined the timing...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Luković, Jelena, Chiang, John C. H., Blagojević, Dragan, Sekulić, Aleksandar
Format: Article in Journal/Newspaper
Language:English
Published: American Geophysical Union, John Wiley & Sons 2021
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Online Access:https://grafar.grf.bg.ac.rs/handle/123456789/2356
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL090350
https://doi.org/10.1029/2020GL090350
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Summary:Californian hydroclimate is strongly seasonal and prone to severe water shortages. Recent changes in climate trends have induced shifts in seasonality, thus exacerbating droughts, wildfires, and adverse water shortage effects on the environment and economy. Previous studies have examined the timing of the seasonal cycle shifts mainly as temperature driven earlier onset of the spring season. In this paper, we address quantitative changes in the onset, amounts, and termination of the precipitation season over the past 6 decades, as well as the large‐scale atmospheric circulation underpinning the seasonal cycle changes. We discover that the onset of the rainy season has been progressively delayed since the 1960s, and as a result the precipitation season has become shorter and sharper in California. The progressively later onset of the rainy season is shown to be related to the summer circulation pattern extending into autumn across the North Pacific, in particular, a delay in the strengthening of the Aleutian Low and later southward displacement of the North Pacific westerlies.