Distinct Patterns of Tropical Pacific SST Anomaly and Their Impacts on North American Climate

Guo, Yuanyuan; Ting, Mingfang; Wen, Zhiping; Lee, Dong Eun

doi:10.1175/jcli-d-16-0488.1

Cited by 35 publications

(21 citation statements)

References 60 publications

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“…We additionally examine the effect of SST forcing on U.S. temperature trends using a 16-member ensemble of Global Ocean Global Atmosphere (GOGA) simulations (Guo et al 2016). The GOGA simulations were performed with the National Center for Atmospheric Research Community Atmosphere Model version 5 (NCAR CAM5), with an Eulerian spectral dy-core in T42 horizontal resolution and 30 vertical levels.…”

Section: Methodsmentioning

confidence: 99%

Timing and seasonality of the United States ‘warming hole’

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et al. 2017

Environ. Res. Lett.

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The United States 'warming hole' is a region in the southeast/central U.S. where observed long-term surface temperature trends are insignificant or negative. We investigate the roles of anthropogenic forcing and internal variability on these trends by systematically examining observed seasonal temperature trends over all time periods of at least 10 years during 1901-2015. Long-term summer cooling in the north central U.S. beginning in the 1930s reflects the recovery from the anomalously warm 'Dust Bowl' of that decade. In the northeast and southern U.S., significant summertime cooling occurs from the early 1950s to the mid 1970s, which we partially attribute to increasing anthropogenic aerosol emissions (median fraction of the observed temperature trends explained is 0.69 and 0.17, respectively). In winter, the northeast and southern U.S. cool significantly from the early 1950s to the early 1990s, but we do not find evidence for a significant aerosol influence. Instead, long-term phase changes in the North Atlantic Oscillation contribute significantly to this cooling in both regions, while the Pacific Decadal Oscillation also contributes significantly to southern U.S. cooling. Rather than stemming from a single cause, the U.S. warming hole reflects both anthropogenic aerosol forcing and internal climate variability, but the dominant drivers vary by season, region, and time period.

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Section: Methodsmentioning

confidence: 99%

Timing and seasonality of the United States ‘warming hole’

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Fiore

et al. 2017

Environ. Res. Lett.

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“…We use a field significance test (Johnson 2013;Guo et al 2017) that controls the ''false discovery rate'' (FDR) to determine how many distinct types of ARs can be classified on the basis of historical period as represented ERA-I. False discovery is an expected consequence of any statistical test since such tests operated by comparing values of a test statistic against values that would be considered, but not impossible, unusual under the null hypothesis.…”

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confidence: 99%

The Role of Circulation and Its Changes in Present and Future Atmospheric Rivers over Western North America

et al. 2020

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Performance in simulating atmospheric rivers (ARs) over western North America based on AR frequency and landfall latitude is evaluated for 10 models from phase 5 of the Coupled Model Intercomparison Project among which the CanESM2 model performs well. ARs are classified into southern, northern, and middle types using self-organizing maps in the ERA-Interim reanalysis and CanESM2. The southern type is associated with the development and eastward movement of anomalous lower pressure over the subtropical eastern Pacific, while the northern type is linked with the eastward movement of anomalous cyclonic circulation stimulated by warm sea surface temperatures over the subtropical western Pacific. The middle type is connected with the negative phase of North Pacific Oscillation–west Pacific teleconnection pattern. CanESM2 is further used to investigate projected AR changes at the end of the twenty-first century under the representative concentration pathway 8.5 scenario. AR definitions usually reference fixed integrated water vapor or integrated water vapor transport thresholds. AR changes under such definitions reflect both thermodynamic and dynamic influences. We therefore also use a modified AR definition that isolates change from dynamic influences only. The total AR frequency doubles compared to the historical period, with the middle AR type contributing the largest increases along the coasts of Vancouver Island and California. Atmospheric circulation (dynamic) changes decrease northern AR type frequency while increasing middle AR type frequency, indicating that future changes of circulation patterns modify the direct effect of warming on AR frequency, which would increase ARs (relative to fixed thresholds) almost everywhere along the North American coastline.

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“…There are several possible factors that cause variations in North American climate between El Niño events. These include random atmospheric internal variability and sensitivity to differences in the detailed structure and longitudinal location of the SST anomalies (SSTAs) (e.g., Hoerling and Kumar 1997;Guo et al 2017). The different longitudinal locations of the SSTAs can cause shifts in the forced stationary waves, leading to different teleconnection patterns and impacts on North American climate (e.g., Mo and Higgins 1998a,b;Barsugli and Sardeshmukh 2002;Hoerling and Kumar 2002).…”

Section: Introductionmentioning

confidence: 99%

Role of Equatorial Pacific SST Forecast Error in the Late Winter California Precipitation Forecast for the 2015/16 El Niño

et al. 2018

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During the strong 2015/16 El Niño, only normal to below-average precipitation fell across California in the late winter. This disagrees with both predictions by the ensemble mean of forecast models and expectations for strong El Niños. The authors examine one of the possible reasons why this event did not bring expected precipitation to California in the late winter. The maximum equatorial Pacific sea surface temperature anomalies (SSTAs) were located, compared to the 1982/83 and 1997/98 strong El Niños, farther to the west in the 2015/16 winter, which possibly caused less convection in the eastern tropical Pacific and shifted the teleconnection patterns westward in the North Pacific, thus weakening the influences on California. The SSTA and precipitation forecast for February–April 2016, based on the North American Multimodel Ensemble, showed large discrepancies from observations, with the ensemble mean of most of the models overestimating SSTAs in the eastern tropical Pacific and California precipitation. Atmospheric general circulation model (AGCM) experiments were conducted to test the hypothesis that the warmer eastern tropical Pacific SSTA forecast may have caused the wetter forecast in California in 2015/16 compared to observations. The AGCM experiments suggest it is difficult to assert that the eastern tropical Pacific SSTAs caused the too-wet California precipitation forecast, especially in Southern California, given that the models disagree. Results indicate forecast error can be influenced by atmosphere-model sensitivity to forecast SSTs, but they also indicate atmospheric internal variability may have been responsible for the combination of a strong El Niño and near-normal California precipitation.

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Distinct Patterns of Tropical Pacific SST Anomaly and Their Impacts on North American Climate

Cited by 35 publications

References 60 publications

Timing and seasonality of the United States ‘warming hole’

Timing and seasonality of the United States ‘warming hole’

The Role of Circulation and Its Changes in Present and Future Atmospheric Rivers over Western North America

Role of Equatorial Pacific SST Forecast Error in the Late Winter California Precipitation Forecast for the 2015/16 El Niño

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