Observations of winds with an incoherent lidar detector.

We have developed a Fabry-Perot interferometer and image-plane detector system to be used as a receiver for a Doppler lidar. This system incorporates the latest technology in multichannel detectors, and it is an important step toward the development of operational wind profiler systems for the atmosphere (troposphere, stratosphere, and lower mesosphere). The instrumentation includes a stable highresolution optically contacted plane talon and a multiring anode detector to scan the image plane of the Fabry-Perot interferometer spatially. The high wavelength resolution provided by the interferometer permits the aerosol and molecular components of the backscattered signal to be distinguished, and the Doppler shift of either component can then be used to determine the wind altitude profile. The receiverperformance has been tested by measuring the wind profile in the boundary layer. The Fabry-Perot interferometer and image-plane detector characteristics are described and sample measurements are presented. The potential of the system as a wind profiler in the troposphere, the stratosphere, and the mesosphere is also considered.

Absorption and emission line shapes in the O(2) atmospheric bands: Theoretical model and limb viewing simulations.

A multiple scattering radiative transfer model has been developed to carry out a line by line calculation of the absorption and emission limb measurements that will be made by the High Resolution Doppler Imager to be flown on the Upper Atmosphere Research Satellite. The multiple scattering model uses the doubling and adding methods to solve the radiative transfer equation, modified to take into account a spherical inhomogeneous atmosphere. Representative absorption and emission line shapes in the O(2)((1)Sigma(+)(g)-(3)Sigma(-)(g)) atmospheric bands (A, B, and gamma) and their variation with altitude are presented. The effects of solar zenith angle, aerosol loading, surface albedo, and cloud height on the line shapes are also discussed.

Inversion of Fabry-Perot CCD images: use in Doppler shift measurements.

We consider how to use a charge-coupled device (CCD) as an imaging device for a Fabry-Perot interferometer. When the CCD is used in a conventional manner (pixel by pixel readout), the read noise limits its usefulness. Instead, we propose using the CCD in an operational mode so that the 2-D circular symmetric Fabry-Perot interference pattern is read as a 1-D array. The recovery of the signal is effected by carrying out an Abel inversion of the 1-D array. We show how by carrying out this operation it is possible to reduce greatly the effect of read noise. Finally, we consider how this image technique reflects on the accuracy of a Doppler shift measurement.

Optimization of a triple etalon interferometer.

The High Resolution Doppler Imager (HRDI) is a triple etalon Fabry-Perot interferometer designed to measure Doppler shifts of rotational lines in the O(2) atmospheric system from the Upper Atmosphere Research Satellite. These shifts are used to determine wind vectors in the stratosphere and mesosphere. This paper presents the techniques used to determine the gap thicknesses and reflectivities of the three etalons of the HRDI instrument. The spacings are found to be 1.000, 0.186, and 0.025 cm. These spacings are independent of the reflectivity of the etalons. The reflectivities of the three etalons should be nearly equal to minimize the errors in the wind measurement caused by mistuning of the etalons. The choice of the reflectivity does not strongly influence the statistical error in the wind error when the values are less than ~0.90.

Galactic and zodiacal light surface brightness measurements with the Atmosphere Explorer Satellites.

Galactic and zodiacal light surface maps are presented at 7320, 6300, 5577, 5200, and 4278 A. These were prepared from measurements made with the Visible Airglow Experiment on board the Atmosphere Explorer-C, -D, and -E satellites.

Tristatic high resolution Doppler lidar to study winds and turbulence in the troposphere.

The implementation of a high resolution Doppler lidar (HRDL) to measure tropospheric winds and turbulence using a high resolution Fabry-Perot optical interferometer is considered. The Fabry-Perot detector system we have chosen is based on the one developed for passive wind measurements on board the Dynamics Explorer satellite. This is a stable high resolution system consisting of an optically contacted plane étalon and a multiring anode detector to scan spatially the image plane of the Fabry-Perot. The Doppler lidar proposed here consists of two transmitters and a receiver in a collinear arrangement. This system enables measurement of a horizontal and the vertical components of the wind in a common volume in space. The volume is determined by the intersection of the field of view of the receiver and the divergence of the laser beam.

Parallax and atmospheric scattering effects on the inversion of satellite auroral observations.

A technique for the inversion of satellite auroral brightness observations is developed, which takes into account the backscattering of light from the snow-covered ground and atmospheric scattering. The theory includes parallax effects. Parallax arises when a point in the aurora is observed from different angles against a background with a variable brightness. It is shown that observations from a spinning satellite at any given angle from nadir are sufficient to recover the auroral form.

Wind measurements from an orbital platform using a lidar system with incoherent detection: an analysis.

A lidar system from an orbital platform is used to simulate the measurement of winds in the atmosphere using different scattering regimes. A high-resolution Fabry-Perot interferometer with a multiple-ring anode detector is used in the simulations. The main factors that limit the accuracy and spatial resolution of the measurement, such as laser bandwidth, detector resolution, and pointing accuracy, have been considered. It is shown that winds in the troposphere and stratosphere can be measured with an accuracy of 2 m/sec using the backscattered signal from aerosols and from cloud tops. In the mesosphere a wind accuracy of 5 m/sec can be achieved using the backscattered signal from the resonance fluorescence of sodium.

Influence of atmospheric absorption on satellite auroral observations.

A technique for the inversion of satellite auroral brightness observations is developed, which takes into account the backscattering of light from the snow-covered ground and the effects of atmospheric absorption.It is shown that the effects of atmospheric absorption are of importance in the inversion of satellite auroralobservations to obtain auroral brightness.