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This is an excerpt from
Applying the science and technology of data assimilation
by Brian Bevirt 07/11/2017
as part of a CISL News series describing the many ways CISL improves
modeling beyond providing supercomputing systems and facilities.
These plots show measured and modeled zonal mean temperatures between
70N and 90N during the January 2009 sudden warming of the stratosphere.
The bottom plot shows the observed temperatures (in degrees Kelvin,
see legend at right), the center plot shows how this state of the
atmosphere was simulated by the specified-dynamics version of the
WACCM model, and the top plot shows WACCM's improved result after
using DART to assimilate middle atmosphere observations.
The key point in this figure is that WACCM+DART captures both the
stratosphere warming and mesosphere cooling that are seen in the
observations. Also seen in the specified-dynamics version of WACCM,
the elevated stratopause that forms at high altitudes around day 30
descends too fast compared to the observations. The elevated stratopause
is maintained at a high altitude in the WACCM+DART simulation.
This has implications for the descent of species from the mesosphere
into the stratosphere. Accurate representation of the mesosphere
dynamics is important for the ionosphere variability during sudden
stratosphere warming events. (Figure courtesy of Nick Pedatella, HAO)
[link to more information]
Nick Pedatella, nickp@ucar.edu
Hanli Liu, liuh@ucar.edu
Jing Liu, jingliu@ucar.edu
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