Vorticity and geopotential height extreme values in ERA-Interim data during boreal winters

Blender, R.; Raible, C. C.; Franzke, C. L. E. (2017). Vorticity and geopotential height extreme values in ERA-Interim data during boreal winters. Quarterly Journal of the Royal Meteorological Society, 143(703), pp. 634-640. Royal Meteorological Society 10.1002/qj.2944

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The properties and dependences of lower tropospheric geopotential height (GPH) and relative vorticity extreme values are investigated in high spatial resolution ERA-Interim reanalysis data during the boreal winters from 1980–2014. A peak-over-threshold (POT) analysis is applied to determine the local generalized Pareto distribution (GPD) parameters with a 90th percentile threshold. In Northern Hemispheric storm tracks, the scale parameter decreases along the storm track axis for vorticity, whereas it increases for GPH. The shape parameters are weakly negative for both fields in the northern midlatitudes and over land, suggesting upper bounds for the extremes. The blackassociation of GPD parameters blackwith the large-scale flow is assessed using monthly mean indices for the North Atlantic Oscillation (NAO), Pacific–North American (PNA) pattern and El Niño Southern Oscillation (Nino3.4 index) as covariates. blackWhile the GPH parameters are related to the covariates in the regions associated with the covariate loadings, the vorticity parameters are weakly related to all covariates. It is noteworthy that the NAO dominates all covariates in the central tropical Pacific. The probability for concurrent extreme events of vorticity and GPH is highest in storm tracks with values of about 0.3–0.5.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Physics Institute > Climate and Environmental Physics

UniBE Contributor:

Raible, Christoph

Subjects:

500 Science > 530 Physics
500 Science > 550 Earth sciences & geology

ISSN:

0035-9009

Publisher:

Royal Meteorological Society

Language:

English

Submitter:

Doris Rätz

Date Deposited:

15 Mar 2017 13:39

Last Modified:

15 Mar 2017 13:39

Publisher DOI:

10.1002/qj.2944

BORIS DOI:

10.7892/boris.92592

URI:

https://boris.unibe.ch/id/eprint/92592

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