Skip to main content
Have a personal or library account? Click to login
Impact of the North Atlantic Oscillation on winter climate of Germany Cover

Impact of the North Atlantic Oscillation on winter climate of Germany

Open Access
|Jan 2017

Figures & Tables

Fig. 1.

Correlation map of DJFM precipitation with NAO at 5% significance level for the period from 1981 to 2014.

Fig. 2.

Time series comparison between (a) observed precipitation over north Germany and the regression model, (b) observed precipitation over south Germany and the regression model, (c) observed temperature over north Germany and the regression model and (d) observed temperature over south Germany and the regression model. In the regression models ILLN is taken as independent variable.

Table 1.

Data used, its sources and latitude/longitude resolution.

DataSourceResolutionTemperatureGlobal Historical Climatology Network (GHCN) v20.5° × 0.5°TemperatureNational Centre of Environmental Prediction (NCEP)2.5° × 2.5°PrecipitationClimate Research Unit (CRU), University of East Anglia0.5° × 0.5°PrecipitationNational Centre of Environmental Prediction (NCEP)1° × 1°Sea Level PressureNational Centre of Environmental Prediction (NCEP)2.5° × 2.5°700 mb windsNational Centre of Environmental Prediction (NCEP)2.5° × 2.5°
Table 2a.

Correlation coefficients between precipitation of Northern and Southern Germany and COA indices and NAO.

VariablesCRU observed dataNCEP/NCAR reanalysisNorth Germany precipitationSouth Germany precipitationNorth Germany precipitationSouth Germany precipitationAZPS_DJFM0.46*0.280.45*0.32AZLT_DJFM0.320.140.35*0.29AZLN_DJFM0.44*0.39*0.45*0.42*ILPS_DJFM−0.32−0.14−0.29−0.16ILLT_DJFM0.35*0.120.36*0.21ILLN_DJFM0.64*0.52*0.63*0.55*NAO_DJFM0.48*0.310.47*0.35*

* Significance level is 5%.

Table 2b.

Correlation coefficients between mean temperature of Northern and Southern Germany and COA indices and NAO.

VariablesGHCN observed dataNCEP/NCAR reanalysisNorth Germany temperatureSouth Germany temperatureNorth Germany temperatureSouth Germany temperatureAZPS_DJFM0.68*0.63*0.67*0.64*AZLT_DJFM0.48*0.310.48*0.26AZLN_DJFM0.37*0.280.39*0.25ILPS_DJFM−0.69*−0.71*−0.70*−0.74*ILLT_DJFM0.70*0.59*0.70*0.55*ILLN_DJFM0.58*0.59*0.57*0.59*NAO_DJFM0.68*0.65*0.68*0.64*

* Significance level is 5%.

Table 3.

Partial correlation between DJFM rainfall of northern Germany and the given variable by controlling all the other variables. The five independent variables considered here are AZH pressure, AZH longitude, IL latitude, IL longitude and NAO.

VariablesPartial correlationsAZPS0.37*AZLN0.49*ILLT−0.43*ILLN0.62*NAO−0.07

* Significance level is 5%.

Table 4.

Partial correlation between DJFM mean temperature of northern Germany and the given variable by controlling all the other variables. The seven independent variables considered here are AZH pressure, AZH latitude, IL pressure, IL latitude, IL longitude and NAO.

VariablesPartial correlationsAZPS0.19AZLT−0.12AZLN0.13ILPS−0.27ILLT0.31ILLN0.40*NAO−0.20

* Significance level is 5%

Table 5.

Partial correlation coefficients between mean DJFM temperature of Southern Germany with a given variable. The five independent variables considered here are AZH pressure, IL pressure, IL latitude, IL longitude and NAO.

VariablesPartial correlationsAZPS0.13ILPS−0.46*ILLT0.14ILLN0.45*NAO−0.14

* Correlation is significant at the 0.05 level (2-tailed).

Fig. 3.

Sea level distribution over north Atlantic (a) averaged for 1981–2014, (b) when Icelandic Low is situated to the east of its mean location by more than one standard deviation and (c) when Icelandic Low is situated to the west of its mean location by more than one standard deviation.

Fig. 4.

(a) Climatological mean of Germany precipitation (in mm) from 1981 to 2010 and (b) difference of mean precipitation between IL E and IL W winters.

Fig. 5.

(a) Climatological mean of DJFM air temperature (°C) from 1981 to 2010 and (b) difference of mean air temperature between IL E and IL W winters.

Fig. 6.

(a) Mean wind over western Europe at 700 mb height (1981–2010), (b) composite anomaly map for vector wind at 700 mb level when Icelandic Low longitude is east of its mean value by one standard deviation and (c) composite anomaly map for vector wind at 700 mb level when Icelandic Low longitude is west of its mean value by more than one standard deviation. Shading corresponds to the wind speed.

Fig. 7.

(a) Difference in wind speeds for IL E years and IL W years and (b) difference in angles at each grid point for IL E years and IL W years. Solid black line indicates the grid points where the angles are different at p < 0.05 level.

Fig. 8.

(a) Composite anomaly map for SLP in winters when the Icelandic Low is situated east of its mean longitude position by more than one standard deviation and (b) composite anomaly map for SLP in winters when the Icelandic Low is situated west of its mean longitude position by more than one standard deviation.

Fig. 9.

Student’s t-test for difference in SLP at each grid point for IL E years and IL W years. Solid black line indicates the grid points where the angles are different at p < 0.05 level.

Language: English
Page range: 1406263 - 1406263
Submitted on: Apr 6, 2017
Accepted on: Nov 13, 2017
Published on: Jan 1, 2017
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services

© 2017 Syed M. F. Riaz, M. J. Iqbal, Sultan Hameed, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.