Anhang C: Mishmash Climate 
196 
Nordseezustand 2003 
2003). The years 2002 and 2003, so far, are the warmest and 2 nd warmest, respec 
tively, on the North Sea record dating to 1968. 
C.2 Hybrid Wind Climate 
The distinguished geographic situation of the North Sea on the continental shelf of 
northwest Europe - and thus on the border of the vast Atlantic ocean and the earth's 
greatest landmass - makes it a region of competition for all major air masses that took 
on the surface characteristics of their maritime or continental source regions. As to 
temperature these characteristics result from the exceedingly large heat capacity of 
water as compared to rock and soil. Hence maritime climates are characterized by 
mild winters, cool summers and a flat seasonal temperature cycle, whereas continen 
tal climates experience cold winters, hot summers and an enhanced annual tempera 
ture range {Fig. 3-17, p. 71). 
If Wladimir Koppen had cared to classify ocean climates, the North Sea had probably 
been assigned type >Cfb< standing for a moderately warm (maritime), permanently wet 
climate. This type would reflect the fact that the redistribution of heat in temperate lat 
itudes is generally brought about by east-travelling waves and eddies such that winds 
from northwesterly to southwesterly directions predominate. Even so, one should not 
loose sight of the fact that atmospheric circulation in mid-latitudes is very changeable 
on all time scales such that large departures from mean wind conditions (and other 
wise) are nothing particular. 
It is a widely supported idea that the primary cause of climatic fluctuations are changes 
in the frequency of atmospheric circulation patterns. To gain further insight into the bi 
stability phenomenon of North Sea SST dynamics a circulation typing scheme origi 
nally devised by Jenkinson and Collinson (1977) is currently being employed to an 
alyze a North Sea subset of UK Met Office northern hemisphere daily mean sea level 
pressure fields. The data set was kindly placed at our disposal through the British At 
mospheric Data Centre (badc.nerc.ac.uk/data/mslp). 
An intermediate step in the typing scheme is the calculation of a single geostrophic 
wind vector representative of the entire North Sea domain on a particular day. As wind 
is the motor of air mass advection it appeared natural for a first step to analyze sea 
sonal wind distributions as to differences during the cold and warm SST regime. Re 
sults of this preliminary analysis are presented in Fig. 3-19, p. 75. 
For obvious geographical reasons winds from northeasterly to southerly directions 
(i. e. NE - S or 22.5° - 202.5°) are qualified »continental«, while those from the com 
plementary hemisphere are termed »maritime«. Since all modes of the set of 4 wind 
distributions are located in the maritime wind sector, the overall generalized wind cli 
mate indeed is maritime (>Cfb<). However, intensity and position of these modes in the 
velocity/direction plane exhibit substantial differences, not only among different sea 
sons of the same SST regime, but also among the same seasons of different regimes. 
If, on the other hand, one had to choose 2 pairs from the set that best resemble one 
another, one would »espouse« the winter (summer) distribution of the warm regime 
and the summer (winter) distribution of the cold regime (to obtain »pedigree maritime 
(continental) offspring«). The maritime couple is characterized by intense modes 
about W and reduced densities about E. Conversely, attributes of the continental cou 
ple are E-shifted weaker modes and increased densities about E. Instead of selecting