|
ABSTRACT
At high-latitudes, the neutral atmosphere
above ~100 km is driven predominantly by upward propagating tides
and waves, solar ultraviolet heating, and momentum transferred
from convecting ions. These forces act over a range of spatial
and temporal scales. Our understanding of the slowly-time varying,
large scale (~1000 km or more) circulation is relatively complete.
In comparison, very little is known about the behavior of the real
neutral atmosphere on spatial scales of 500 km or less. Phenomena
in this category include vertical winds, gravity waves, horizontal
gradients, and the behavior of the wind field in an interface such
as the E-region. Small-scale processes such as these are difficult
to incorporate into first principles-based numerical models, however
they have the potential to significantly impact the global-scale
circulation. Vertical winds, for example, can locally perturb the
neutral and ion composition, and these perturbations can be transported
long distances by fast horizontal winds, or deformed in complex
ways by wind gradients. Understanding these processes is therefore
very important for accurately modeling the impacts of space-weather
events on Earth’s upper atmosphere. This talk will focus
on my research into observing neutral thermospheric dynamics on
spatial scales of 500 km or less. In particular, I will present
neutral wind measurements from a bistatic array of Scanning Doppler
Imager’s (SDI’s), an investigation into local-scale
ion-neutral coupling, and some new questions raised by recent climatological
E-region wind measurements.
|
|