Abstract
Gravity waves (GWs) play an important role in the dynamics of
the mesosphere and lower thermosphere (MLT). Therefore, global observations of
GWs in the MLT region are of particular interest. The small scales of GWs,
however, pose a major problem for the observation of GWs from space. We
propose a new observation strategy for GWs in the mesopause region by
combining limb and sub-limb satellite-borne remote sensing measurements for
improving the spatial resolution of temperatures that are retrieved from
atmospheric soundings. In our study, we simulate satellite observations of
the rotational structure of the O2 A-band nightglow. A key element of the
new method is the ability of the instrument or the satellite to operate in so-called target mode
, i.e. to point at a particular point in the atmosphere
and collect radiances at different viewing angles. These multi-angle
measurements of a selected region allow for tomographic 2-D
reconstruction of the atmospheric state, in particular of GW
structures. The feasibility of this tomographic retrieval approach is
assessed using simulated measurements. It shows that one major advantage of
this observation strategy is that GWs can be observed on a much smaller scale
than conventional observations. We derive a GW sensitivity function, and it
is shown that target mode
observations are able to capture GWs with
horizontal wavelengths as short as ∼ 50 km for a large range of
vertical wavelengths. This is far better than the horizontal wavelength limit
of 100–200 km obtained from conventional limb sounding.
Citation
ID:
156814
Ref Key:
song2017atmospherictomographic