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Spatial response and temporal development (1901 – 2010) of two manual atmospheric circulation classifications in Europe. TU Bergakademie Freiberg , Brennhausgasse 14, 09596 Freiberg, Germany Phone: 0 37 31/39-3533, www.tu-freiberg.de. Andreas Hoy , Mait Sepp, Jörg Matschullat
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Spatial response and temporal development (1901 – 2010) of two manual atmospheric circulation classifications in Europe TU Bergakademie Freiberg , Brennhausgasse 14, 09596 Freiberg, Germany Phone: 0 37 31/39-3533, www.tu-freiberg.de Andreas Hoy, Mait Sepp, Jörg Matschullat andreas.hoy@ioez.tu-freiberg.de
E W C Classifications Grosswetterlagen (GWLc) Vangengeim-Girs (VGc) Werner/ Gerstengarbe 2010, updated Bolotinskaya/ Ryzhakov 1964, updated - Central Europe/ Germany - NE Europe/ NW Russia - Continental focus (Europe) - Hemispheric focus (Eurasia, Polar) - 29 subtypes; e.g., 10 major types - 3 circulation forms - Minimum persistence of 3 days - No minimum persistence - Here: Westerlies (GWT W, ½ SW, ½ NW) - Here: Westerlies (circ. form W) Average Frequencies: 1901 – 2010 andreas.hoy@ioez.tu-freiberg.de Anissimov et al. 2010
Spatial Response – Methods • Correlation mapping of montly sea level pressure averages/ circulation type frequency (via SURFER 9.2.397) • Goal: visualisation of average distribution of pressure centres (location of cyclones/ anticyclones: negative/ positive correlations) • Global illustrations (80°N to 80°S) for full spatial response • Sea level pressure: gridded set of monthly averages in 5 x 5° worldwide resolution (Allan/ Ansell 2006) • Focus on highly significant correlations with r≥0.3/ r≤‑0.3, α=0.001 • Linear detrending of time series to reduce „artificial“ correlations (! subperiodical, polynomial, … trends) andreas.hoy@ioez.tu-freiberg.de
Spatial Response – Westerlies WHY GWLc VGc andreas.hoy@ioez.tu-freiberg.de
Spatial Response – Westerlies SHY GWLc VGc andreas.hoy@ioez.tu-freiberg.de
Spatial Response – Conceptual Maps Westerlies (W) Easterlies (E) Northerlies (C) • GWLc: dark filling - VGc: light filling • borders: if dashed, system is nonexisting in specific months • arrows: direction of inflow in classifications focus region andreas.hoy@ioez.tu-freiberg.de
Temporal Development - Methods • Relative frequency (%) of circulation types • Time series and linear trends for 1901 – 2010 (yearly, half yearly) • Annual cycle: 31 day smoothing, 1901 – 2010 vs. climate normals 1951-1980, 1981-2010 • Goal: evaluation of annual/ inner-annual changes in frequency of atmospheric circulation patterns andreas.hoy@ioez.tu-freiberg.de
Time Series – GWLc Westerlies andreas.hoy@ioez.tu-freiberg.de
Time Series – VGc Westerlies andreas.hoy@ioez.tu-freiberg.de
Annual Cycle – GWLc Westerlies andreas.hoy@ioez.tu-freiberg.de
Annual Cycle – VGc Westerlies andreas.hoy@ioez.tu-freiberg.de
Annual Cycle – VGc Westerlies EMS, 15.09.2011 andreas.hoy@ioez.tu-freiberg.de 12
Annual Cycle – GWLc Westerlies EMS, 15.09.2011 andreas.hoy@ioez.tu-freiberg.de 13
Summary (Westerlies) Spatial response: • Correlation maps illustrate average spatial impact and magnitude of analysed circulation patterns • Spatial response WHY > SHY in both classifications • Spatial response VGc > GWLc (only WHY), confirming different conceptual focus • „Teleconnections“ subject of further research Temporal development: • Trends GWLc: low annually, but inner-annually pronounced • Trends VGc: large fluctuations (circulation epochs?), no use of linear trends • Time series hardly comparable, but similarities in inner-annual behaviour andreas.hoy@ioez.tu-freiberg.de
Spare slides andreas.hoy@ioez.tu-freiberg.de
Classifications • by experienced meteorologists • Disadvantages • No reproducibility • Inhomogeneities (subjectivity of/ and change of executing scientists) • Advantages • Availability of long data series (>100 years) more robust conclusions • Better generalisation of dynamic processes & adjustment of missing data by human eye • via numerical methods • Advantages • Limitless reproducibility • No inhomogeneities, if incoming data are of the same (!) quality • Disadvantages • Shorter time series (most input data not available before the 1950s) • Missingflexibilitythroughfixedinputparameters Manual classifications: useful complement to automated classifications Manually classified Automated classified Assignment of daily synoptic conditions to one specific circulation form EMS, 15.09.2011 andreas.hoy@ioez.tu-freiberg.de 16
andreas.hoy@ioez.tu-freiberg.de GWLc: Westerlies (monthly)
andreas.hoy@ioez.tu-freiberg.de VGc: Westerlies (monthly)
GWLc Westerlies: moving trend analysis andreas.hoy@ioez.tu-freiberg.de