Scientific Theme: Advanced Modeling and Observing Systems

Theme report: Climate System Variability
ACCOMPLISHMENTS FOR GMD05.2:
Measurements of atmospheric concentrations of ozone-depleting gases continued during the July 2006-June 2007
period. Several accomplishments and products derived from these measurements:
In late 2006, the Ozone Depleting Gas Index was first introduced and posted on the NOAA website. This index
allows a summary of progress being made in the global effort to reduce the atmospheric burden of ozone-depleting
gases. Subsequently, measurement data were updated in early 2007 that extended the index through the end of 2006.
MILESTONE GMD05.3:
Utilize aircraft and stratospheric balloon platforms to measure several ODSs (N2O, CFC-11,
CFC-12) in the troposphere and stratosphere. These data will be used to validate measurements
by space-borne instrumentation aboard the Aura satellite.
ACCOMPLISHMENTS FOR GMD05.3:
Nitrous oxide (N2O) was measured in situ aboard the Unmanned Aircraft System (UAS) Altair by an automated gas
chromatograph during the October 2006 NASA-USDA Forest Service Fire Mission. Vertical profiles of N2O were
obtained between the middle troposphere and lower stratosphere during numerous spiral ascent/descent maneuvers
of the aircraft. These (and other) vertical profile data obtained during the mission have been compared to the vertical
profiles retrieved from near-coincident soundings of the Microwave Limb Sounder (MLS) and Tropospheric
Emission Spectrometer (TES) aboard the NASA Aura satellite. A stratospheric balloon platform was not available
for CIRES/NOAA instruments during this report period.
CSD06 : Turbulent Meteorological Motions
CSV-04: Climate Dynamics
GOAL:
Understand the mechanisms and effects by which turbulence influences atmospheric chemistry, composition,
radiation, and transport on all scales, from that of molecular diffusion to that of the globe, some nine orders of
magnitude.
MILESTONE CSD06.1:
Continue efforts to link, via high-resolution observations, the macroscopic theory of scale
invariance with molecular-scale non-equilibrium statistical mechanics; examine the implications
for the definition of atmospheric temperature in the horizontal with aircraft data and in the vertical
with dropsonde data.
ACCOMPLISHMENTS FOR CSD06.1:
The work has reached the stage of presentable syntheses, which either have been published this year, are in press or
have been submitted. The case has been established that the molecular dynamics of the population of air molecules
in an anisotropic environment leads to the emergence of vorticity on very short time and space scales, picoseconds
and nanometers. In turn, this generation of vorticity on very small scales has implications for radiative transfer and
for atmospheric chemistry; turbulent dynamics, radiation and chemistry are coupled at the molecular level, in a way
that is not compatible with the widely used assumption of local thermodynamic equilibrium. Atmospheric
temperature is not proportional to the width of a Maxwell-Boltzmann distribution of molecular speeds – there is an
overpopulation of translationally hot air molecules, largely but not wholly maintained by photo-fragments from
ozone photo-dissociation.
PSD03: Empirical and Process Studies
GOAL:
Improve understanding of basic physical processes that contribute to climate variability across a broad spectrum of
scales, with emphasis on (i) moist atmospheric convection, (ii) radiative transfer in cloudy areas, and (iii) air-sea
interaction.
57