TU Bergakademie Freiberg , Brennhausgasse 14, 09596 Freiberg, GermanyPhone: 0 37 31/39-3533, www.tu-freiberg.de

Spatial response and temporal development (1901 – 2010) of two manual atmospheric

circulation classifications in Europe

Andreas Hoy, Mait Sepp, Jörg Matschullatandreas.hoy@ioez.tu-freiberg.de

ClassificationsGrosswetterlagen (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)

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W

C

E

Average Frequencies: 1901 – 2010 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)

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Spatial Response – Westerlies WHY

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GWLc

VGc

Spatial Response – Westerlies SHY

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GWLc

VGc

Spatial Response – Conceptual Maps

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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

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

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Time Series – GWLc Westerlies

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Time Series – VGc Westerlies

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Annual Cycle – GWLc Westerlies

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Annual Cycle – VGc Westerlies

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Annual Cycle – VGc Westerlies

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Annual Cycle – GWLc Westerlies

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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

behaviourEMS, 15.09.2011 andreas.hoy@ioez.tu-freiberg.de 14

Spare slides

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Classifications Manually classified Automated classified

Assignment of daily synoptic conditions to one specific circulation form

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• 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 (!) qualityDisadvantages• Shorter time series (most input data

not available before the 1950s)• Missing flexibility through fixed

input parameters

Manual classifications: useful complement to automated classificationsEMS, 15.09.2011 andreas.hoy@ioez.tu-freiberg.de

EMS, 15.09.2011 17andreas.hoy@ioez.tu-freiberg.deGWLc: Westerlies (monthly)

EMS, 15.09.2011 18andreas.hoy@ioez.tu-freiberg.deVGc: Westerlies (monthly)

GWLc Westerlies: moving trend analysis

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