reference : Causes of the 2011–14 California drought

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/reference/4ca5a43c-5fbe-4cb0-8a7d-7ee3acafd7c0
Bibliographic fields
reftype Journal Article
Abstract The causes of the California drought during November–April winters of 2011/12–2013/14 are analyzed using observations and ensemble simulations with seven atmosphere models forced by observed SSTs. Historically, dry California winters are most commonly associated with a ridge off the west coast but no obvious SST forcing. Wet winters are most commonly associated with a trough off the west coast and an El Niño event. These attributes of dry and wet winters are captured by many of the seven models. According to the models, SST forcing can explain up to a third of California winter precipitation variance. SST forcing was key to sustaining a high pressure ridge over the west coast and suppressing precipitation during the three winters. In 2011/12 this was a response to a La Niña event, whereas in 2012/13 and 2013/14 it appears related to a warm west–cool east tropical Pacific SST pattern. All models contain a mode of variability linking such tropical Pacific SST anomalies to a wave train with a ridge off the North American west coast. This mode explains less variance than ENSO and Pacific decadal variability, and its importance in 2012/13 and 2013/14 was unusual. The models from phase 5 of CMIP (CMIP5) project rising greenhouse gases to cause changes in California all-winter precipitation that are very small compared to recent drought anomalies. However, a long-term warming trend likely contributed to surface moisture deficits during the drought. As such, the precipitation deficit during the drought was dominated by natural variability, a conclusion framed by discussion of differences between observed and modeled tropical SST trends.
Author Richard Seager; Martin Hoerling; Siegfried Schubert; Hailan Wang; Bradfield Lyon; Arun Kumar; Jennifer Nakamura; Naomi Henderson
DOI 10.1175/JCLI-D-14-00860.1
Issue 18
Journal Journal of Climate
Keywords North America,Drought,Interannual variability
Pages 6997-7024
Title Causes of the 2011–14 California drought
Volume 28
Year 2015
Bibliographic identifiers
.reference_type 0
_record_number 20258
_uuid 4ca5a43c-5fbe-4cb0-8a7d-7ee3acafd7c0