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Droughts

1000 year generated time series of monthly mean precipitation anomalies over Europe are analyzed in terms of consequtive wet/dry months.

Consucetive Month

Wet

1961-1990 1990-2019
Screenshot Screenshot

North-East Germany: The 100-year event of consequtive wet months has increased between 1961-1990 and 1990-2019 from 7.0 months to 7.5 months caused by dynamical changes.

Dry

1961-1990 1990-2019
Screenshot Screenshot

North-East Germany: The 100-year event of consequtive dry months has increased between 1961-1990 and 1990-2019 from 7.5 months to 8.0 months caused by dynamical changes.

Code

Importing

import matplotlib  
matplotlib.use('Agg')
import numpy as N
import matplotlib.pyplot as P
from scipy import stats as S
from netCDF4 import Dataset,num2date
from mpl_toolkits.basemap import Basemap,maskoceans
from matplotlib.offsetbox import AnchoredText

P.rcParams["font.family"] = "serif"

Processing

for j in ['1961-1990','1990-2019']:
    for k in ['dry','wet']:

        file = '../csv/gen_%s/dw/prc_%s_ja.nc'%(j,k)

        nc = Dataset(file,'r')
        lons = N.array(nc.variables['longitude'][:])
        lats = N.array(nc.variables['latitude'][:])
        dats = N.array(nc.variables['pr'][:])
        nc.close()

        dats = dats[0,:,:]

        P.figure(figsize=(6,8))
        ax = P.subplot(111)

        map = Basemap(projection='cyl',llcrnrlat=35.,urcrnrlat=70.,llcrnrlon=-15,urcrnrlon=30,resolution='l')

        map.drawcoastlines(color='k')
        map.drawcountries(linewidth=1,color='k')
        map.drawlsmask(land_color = "lightgray",ocean_color="lightblue",resolution = 'h')

        lon,lat = map(*N.meshgrid(lons,lats))

        dat = maskoceans(lon,lat,dats)

        lev = N.arange(1.2,2.6,0.2)

        if(k=='dry'): lev = N.arange(6.5,10.5,0.5); col = 'terrain'; lab = 'consecutive dry months'
        if(k=='wet'): lev = N.arange(5.5,9.5,0.5); col = 'terrain_r'; lab = 'consequtive wet months' 

        CM = map.contourf(lon,lat,dat,levels=lev,cmap=P.get_cmap(col),extend='both')

        cbar = map.colorbar(CM,location='right',extend='max',pad="1%",drawedges=True,ticks=lev)
        cbar.set_label(lab,fontsize=12,weight='bold')
        cbar.ax.tick_params(labelsize=8)

        at = AnchoredText(r"$\varnothing$ %.1f"%N.nanmean(dat),prop=dict(size=10),frameon=True,loc='upper left') 
        at.patch.set_boxstyle("round,pad=0.,rounding_size=0.2")
        ax.add_artist(at)

        at = AnchoredText(j,prop=dict(size=10),frameon=True,loc='lower left')
        at.patch.set_boxstyle("round,pad=0.,rounding_size=0.2")
        ax.add_artist(at)

        P.savefig('./img/risk_%s_%s.png'%(k,j),dpi=240,transparent=False,bbox_inches='tight',pad_inches=0.0)