Outlook - Wind Energy Meteorology: Atmospheric Physics for Wind Power Generation - page 152

gives an overview of the present abilities to probe the atmospheric boundary layer by
ground-based remote sensing. The substitution process from in situ to remote sensing
measurements is to be accompanied by scientific investigations which compare the
wind and turbulence data obtained from masts and remote sensing techniques. Such
investigations are presently under way and have to lead to rewritten standards for
measurement procedures. Most probably optical techniques such as wind lidars will be
the measurement tools for the future (see, e.g., Trujillo et al. 2011 ).
The abilities of numerical models must be enhanced as well. Simple analytical
models such as those presented in this publication (see, e.g., Sect. 4.2 ) and existing
mesoscale wind field models will no longer be sufficient for large turbines in very
complex terrain and for turbines in smaller wind parks. Work is under way to design
more sophisticated models which have a higher spatial resolution, both in the hori-
zontal and in the vertical close to the ground. This work includes the development of
suitable large-eddy simulation (LES) models for offshore wind parks (Cañadillas and
Neumann 2010 ; Steinfeld et al. 2010 ) and for smaller wind parks and complex terrain.
7.5 Wind Resources and Climate Change
Wind turbines and wind parks are usually planned for several decades of opera-
tion. Thus, estimations on future changes in wind resources in selected regions
may influence the economic prospects of these installations. Site assessment,
especially for regions with marginal wind resources, should take into account
future wind scenarios from global and regional climate models.
First of all, global warming is expected to generally weaken the west wind belts
around the globe, because the warming in the polar regions will be stronger than in
the tropics. This differential warming trend will decrease the global meridional
temperature gradient between the lower and the higher latitudes, which had been
identified as the main driver for the global westerlies in Sect. 2.1 . Due to non-
linearities in the atmospheric system, this relation is not straight-forward and needs
specific investigations (see, e.g., Geng and Sugi 2003 ). Additionally, the weak-
ening temperature gradient could also be accompanied by a poleward shift of the
climate zones and storm tracks on Earth (Yin 2005 ). These two effects can be
derived from simulations with global climate models.
Apart from the general impact on the global meridional temperature gradients,
climate change can also lead to regional atmospheric circulation changes. These
changes may alter regional weather patterns such as regional storm tracks and
main wind directions which can lead to considerable variations in the wind climate
of a selected site. The assessment of such possible regional circulation changes
should be made from regional climate model simulations. Regional climate models
have a much higher spatial resolution than global climate models. Regional models
are run for limited regions taking the output from global climate models as
boundary conditions. Many of such regional studies have been performed. For a
wind energy-related study, see, e.g., Nolan et al. ( 2011 ).