||These images compare the scale
growth of a dynamic scalar (top, potential temperature) with a passive
top-down scalar (bottom) in classical, horizontally homogeneous, dry
convection after more than 50 large eddy turnover times, in a large
eddy simulation in a domain whose size is comparable to that of a
field campaign. While it is clear that the dominant horizontal scale
for the passive tracer is about four times larger than for its dynamic
counterpart, this rather surprising result is not well understood.
These results highlight the importance of turbulence in the atmospheric
and oceanic boundary layers, and they hint at the critical role these
regions play in earth's weather and climate. (Images courtesy of Peter
Geophysical Turbulence Program
The Geophysical Turbulence Program (GTP) has been in existence since
almost the beginning of NCAR. It is by construction an interdisciplinary
group that spans many divisions and laboratories at NCAR, with a few
external affiliates. It encompasses research at NCAR on multi-scale
nonlinear processes, with an array of applications in broad areas;
it is also the outreach arm of this research. It supports NCAR's
strategic priority of "Conducting research in computer science,
applied mathematics, statistics, and numerical methods," "Creating
a conceptual framework for integrating research across time and space
scales to aid decision makers and enrich understanding of processes
across scales," and "Engaging a broader and more diverse community."
In FY 2006, GTP has held 11 seminars and has hosted 7 long-term
visitors (with an average stay of 4 weeks each). The topics covered
in collaboration with NCAR staff range from wind-wave interactions,
intermittency and modeling of turbulent flows, fast dynamos,
convection, and entrainment in the Planetary Boundary Layer using
Large Eddy Simulations, to the effect of air turbulence on rain
development in warm clouds. Details are provided on the
GTP web site.
Three workshops were held by GTP in FY 2006. One was in conjunction
with the IMAGe's 2006
other two dealt with modeling turbulent flows. The first one had 36
flows in the presence of
magnetic fields and applications to the geo-dynamo. The second
GTP workshop had 61 participants and dealt with
turbulence and scalar transport
in roughness sublayers e.g., near air-land and air-water interfaces.
Represented at these two workshops were 34 universities, 9 national
laboratories, and 38 countries.
In FY 2007, more visitors will be hosted, and more workshops will
be held. The agenda will be decided at the GTP annual meeting in
GTP research is sponsored by the NSF cooperative agreement through
UCAR, and partially by a variety of grants.