Stellar alignment of the High Resolution Doppler Imager

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77037/1/AIAA-26727-328.pd

SMLTM simulations of the diurnal tide: comparison with UARS observations

Wind and temperature observations in the mesosphere and lower thermosphere (MLT) from the Upper Atmosphere Research Satellite (UARS) reveal strong seasonal variations of tides, a dominant component of the MLT dynamics. Simulations with the Spectral mesosphere/lower thermosphere model (SMLTM) for equinox and solstice conditions are presented and compared with the observations. The diurnal tide is generated by forcing specified at the model lower boundary and by in situ absorption of solar radiation. The model incorporates realistic parameter-izations of physical processes including various dissipation processes important for propagation of tidal waves in the MLT. A discrete multi-component gravity-wave parameterization has been modified to account for seasonal variations of the background temperature. Eddy diffusion is calculated depending on the gravitywave energy deposition rate and stability of the background flow. It is shown that seasonal variations of the diurnal-tide amplitudes are consistent with observed variations of gravity-wave sources in the lower atmosphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47861/1/585_1997_Article_70151187.pd

High Resolution Doppler Imager observations of ozone in the mesosphere and lower thermosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95237/1/jgrd9497.pd

The High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76425/1/AIAA-1993-123-305.pd

Atmospheric wind measurements with the high-resolution Doppler imager

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76745/1/AIAA-26590-119.pd

TMTM simulations of tides: Comparison with UARS observations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95593/1/grl10703.pd

Continuous Middle-Atmospheric Wind Profile Observations by Doppler Microwave Radiometry

Observations of wind profiles in the upper stratosphere /lower mesosphere are challenging as the established measurement techniques based on in situ methods, radars or airglow spectrometers cannot cover this altitude range. Nevertheless, wind information from these altitudes is important for the assessment of middle-atmospheric dynamics in general and as basis for planetary wave or infrasound propagation estimates. Benefitting from recent developments in spectrometers and low-noise amplifiers, microwave radiometry now offers the opportunity to directly and continuously measure horizontal wind profiles at altitudes between 35 and 70 km. This is achieved by retrieving the wind-induced Doppler shifts from pressure broadened atmospheric emission spectra. The typical measurement uncertainties and vertical resolutions of daily average wind profiles lie between 10–20 m/s and 10–16 km, respectively. In this chapter, comparisons of the measured wind profiles to different ECMWF model versions and MERRA re-analysis data are shown. Moreover, the oscillatory behaviour of ECMWF winds is investigated. It appears that the longer period wave activities agree well with the observations, but that the model shows less variability on timescales shorter than 10 days

Two-day wave structure and mean flow interactions observed by radar and High Resolution Doppler Imager

Data obtained with four MF and meteor radars at equatorial and subtropical sites and with the High Resolution Doppler Imager (HRDI) instrument aboard the UARS satellite were used to examine the structure, wave-mean flow interactions, and potential sources of the 2-day wave in the middle atmosphere during three southern hemisphere summers. The three wave events were highly transient, having typical durations of 20 to 30 days and exhibiting modulation at shorter periods. Temporal variations were found to exhibit good correlations between radar and HRDI data. Radar and HRDI data were used to estimate those components of the Eliassen-Palm flux that could be assessed with these data. Meridional fluxes of momentum and heat were computed using HRDI data and agree reasonably with the momentum fluxes computed from radar data at discrete locations. These fluxes were found to exhibit consistent latitudinal structures each year, suggesting systematic wave excitation and wave-mean flow interactions. Meridional momentum flux gradients were seen to be anticorrelated with zonal wind accelerations in a manner consistent with wave forcing of the large-scale circulation. The apparent wave-mean flow interactions suggest that the 2-day wave could be a transient response to baroclinic instability of the summer hemisphere mesospheric jet. A calculation of the meridional gradient of quasi-geostrophic potential vorticity using HRDI winds and the COSPAR International Reference Atmosphere (CIRA 1986) temperatures exhibits a region of instability in the lower and middle mesosphere extending into subtropical latitudes and provides additional evidence of a possible source of this motion via baroclinic instability of the summer hemisphere jet structure. Copyright 1999 by the American Geophysical Union