Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Winter Precipitation Changes in California Under Global Warming: Contributions of CO 2 , Uniform SST Warming, and SST Change Patterns

TitleWinter Precipitation Changes in California Under Global Warming: Contributions of CO 2 , Uniform SST Warming, and SST Change Patterns
Publication TypeJournal Article
Year of Publication2021
JournalGeophysical Research Letters
Volume48
Number5
Abstract / Summary

Climate models project a wetting winter over California, distinct from the drying in all other Mediterranean climate regions under warming. Dynamic effect via an eastward extension of the westerly jet stream over the North Pacific is the root cause for the wetting California. Utilizing four sets of prescribed-SST (sea surface temperature) simulations, the relative effects of direct CO2 radiative forcing, uniform SST warming, and SST change patterns are investigated. The wetting winter is dominated by uniform SST warming mainly through its effect on the jet extension. As a fundamental response to the enhanced upper-tropospheric warming in the tropics, the jet extension in coupled simulations is well reproduced under uniform SST warming and robust among models. An El Niño-like SST warming pattern has a secondary contribution to the jet extension via atmospheric teleconnection, but with large intermodel spread. Relative to the SST forcing, the direct CO2 radiative effect is negligible.

URLhttp://dx.doi.org/10.1029/2020gl091736
DOI10.1029/2020gl091736
Journal: Geophysical Research Letters
Year of Publication: 2021
Volume: 48
Number: 5
Publication Date: 03/2021

Climate models project a wetting winter over California, distinct from the drying in all other Mediterranean climate regions under warming. Dynamic effect via an eastward extension of the westerly jet stream over the North Pacific is the root cause for the wetting California. Utilizing four sets of prescribed-SST (sea surface temperature) simulations, the relative effects of direct CO2 radiative forcing, uniform SST warming, and SST change patterns are investigated. The wetting winter is dominated by uniform SST warming mainly through its effect on the jet extension. As a fundamental response to the enhanced upper-tropospheric warming in the tropics, the jet extension in coupled simulations is well reproduced under uniform SST warming and robust among models. An El Niño-like SST warming pattern has a secondary contribution to the jet extension via atmospheric teleconnection, but with large intermodel spread. Relative to the SST forcing, the direct CO2 radiative effect is negligible.

DOI: 10.1029/2020gl091736
Citation:
Dong, L, and L Leung.  2021.  "Winter Precipitation Changes in California Under Global Warming: Contributions of CO 2 , Uniform SST Warming, and SST Change Patterns."  Geophysical Research Letters 48(5).  https://doi.org/10.1029/2020gl091736.