KLIWAS 
Seite 9 
1 Ab stia c t 
KLIWAS 
Climatology 
of North Sea 
Fronts 
The KLIWAS climatology of sea surface temperature (SST) and ocean colour (OC) 
fronts in the North Sea was established by a co-operation of the Federal Maritime and 
Hydrographic Agency (BSH) and Brockmann Consult (BC) in order to generate a 
reliable reference data set for the assessment of changes in frontal position, gradients, 
and seasonal variability due to climate change on the basis satellite data. 
Frontal zones are relative sharp boundaries between different water masses and can 
be identified by feature extraction and classification of satellite data from different 
sensors providing information about the SST and OC i.e. chlorophyll or suspended 
matter concentration. While frontal zones of thermal fronts can be identified directly 
from SST, water quality parameters such as chlorophyll concentration can be a proxy 
for a frontal zone, but not every strong OC gradient is mandatory an oceanic front. 
More than two decades of satellite data have been analysed for this climatology 
referring to type and location of frontal zones, horizontal scales (e.g. gradients 
perpendicular to the front), and sensor characteristics like spatial resolution and noise. 
This report consists of three parts: 
Part A (this document) describes background, methods, data, the algorithms, and the 
data access via ftp. The data are freely available for everyone. 
Part B presents a selection of SST products, and 
Part C presents a selection of OC products.