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Toward a systematic evaluation of warm conveyor belts in numerical weather prediction and climate models. Part II: Verification of operational reforecasts

Wandel, Jan; Quinting, Julian F. ORCID iD icon; Grams, Christian M.

Abstract:

Warm conveyor belts (WCBs) associated with extratropical cyclones transport air from the lower troposphere into the tropopause region and contribute to upper-level ridge building and the formation of blocking anticyclones. Recent studies indicate that this constitutes an important source and magnifier of forecast uncertainty and errors in numerical weather prediction (NWP) models. However, a systematic evaluation of the representation of WCBs in NWP models has yet to be determined. Here, we employ the logistic regression models developed in Part I to identify the inflow, ascent, and outflow stages of WCBs in the European Centre for Medium-Range Weather Forecasts (ECMWF) subseasonal reforecasts for Northern Hemisphere winter in the period January 1997 to December 2017. We verify the representation of these WCB stages in terms of systematic occurrence frequency biases, forecast reliability, and forecast skill. Systematic WCB frequency biases emerge already at early lead times of around 3 days with an underestimation for the WCB outflow over the North Atlantic and eastern North Pacific of around 40% relative to climatology. Biases in the predictor variables of the logistic regression models can partially explain these biases in WCB inflow, ascent, or outflow. ... mehr


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Originalveröffentlichung
DOI: 10.1175/JAS-D-20-0385.1
Scopus
Zitationen: 8
Dimensions
Zitationen: 9
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung Troposphärenforschung (IMKTRO)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 10.2021
Sprache Englisch
Identifikator ISSN: 0022-4928, 1520-0469
KITopen-ID: 1000138909
HGF-Programm 12.11.34 (POF IV, LK 01) Improved predictions from weather to climate scales
Erschienen in Journal of the atmospheric sciences
Verlag American Meteorological Society
Band 78
Heft 12
Seiten 3965–3982
Projektinformation SPREADOUT (HGF, HGF IVF2016 TALENT, VH-NG-1243)
Vorab online veröffentlicht am 01.10.2021
Schlagwörter Extratropical cyclones; Trajectories; Forecast verification/skill
Nachgewiesen in Dimensions
Web of Science
Scopus
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