Atmospheric sciences have dealt with
the special features of urban climate for
about 200 years, starting with the seminb
nal book of Howard. It therefore has been
long understood that urban areas govern
the dynamics and air chemistry of the atmb
mospheric boundary layer, they are key
drivers for the development of local circb
culation patterns and can modify local
and regional weather and climate. On the
other hand, local meteorological conditb
tions and large-scale weather patterns
drive the formation of the urban heat islb
land, can modify microclimate conditions
and affect air quality regionally and locb
cally. As such, holistic models have to be
developed in order to properly represent
interactions along both time and spatial
scales and preferably have to incorporate
both dynamics and air chemistry. A large
amount of studies exist already, which
highlight the importance of properly reprb
resenting urban areas within mesoscale
models via urban canopy parametrizations. Current
coordinated model activities try to assess these parb
rametrizations to be included e.g. in regional climate
models as being considered within Cordex FPS URBRCC
