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Previous WG2 results have shown that different models exhibit a wide range of predictions of IWP for idealised cirrus cases (Starr et al., 2000). In the last ICMC (Idealised Cirrus Model Comparison), some degree of grouping was noted depending on the type of microphysical scheme (bin or bulk), but there was still wide variability even within each of these approaches. The past study identified and documented the differences, it is now appropriate that we evaluate the models relative to observations. Our next proposed WG2 study will be to address the question: how well can our current cirrus models reproduce the characteristics of a set of well-observed cirrus cloud cases? Basing this study in well observed cases will allow modellers to evaluate how well their models reproduce the observations and will provide a basis for identifying if any of our models are consistently performing well and why. This collective approach to assessing our models with observations will provide an ideal environment in which to progress our cirrus understanding and model development. This study will involve not only high resolution modelling but also NWP and climate models simulating at the 1km resolution and upwards. A marriage of the analysis of the various models and observations will allow this working group to make important steps towards addressing what model resolution and degree of complexity is necessary for representing cirrus in large scale models?
We are seeking the involvement of cloud-scale modelling participants using various models such as SCMs, LEMs, CRMs, as well as NWP and GCM models. At present, we have a commitment from all of these groups, but we are encouraging more NWP and GCM modellers to become involved in this study. Comparison to observations is a major theme in this study and so the involvement of observationalists is encouraged. The next case study involving the ARM SGP IOP 2000 has now been released (Feb 26, 2007) for member participation To participate visit March 9, 2000 inter-comparison study . If you would like to
get involved in this study then please contact: |
The GCSS
working group on cirrus clouds (WG2) provides an environment which addresses
cirrus research, fosters collaboration and inter-comparisons, and provides a
framework to evaluate and improve our cirrus models. Our aims are to enable
the cirrus community to collectively identify and address key problems in
cirrus research.
This next
study will use observational data from the ARM Southern Great Plains site
during the spring 2000 IOP campaign. The Atmospheric Radiation Measurement
(ARM) Program conducted a cloud Intensive Operational Period (IOP) in March
2000 that was the first-ever effort to document the 3-dimensional cloud field
from observational data. Three-dimensional representations of actual clouds
and their microphysical properties, such as the distribution of ice will be
very useful for this current study, as will the mm Doppler radar to constrain
fall-velocities. There is an intention for the future to develop cases of
cirrus anvils (e.g. Crystal-Face or TWP) in addition to further mid-latitude
cases (e.g. ARM, Chilbolton).