Intra-Annual Variation of Eddy Diffusion (k zz ) in the MLT, From SABER and SCIAMACHY Atomic Oxygen Climatologies.

Atomic oxygen (O) in the mesosphere and lower thermosphere (MLT) results from a balance between production via photo-dissociation in the lower thermosphere and chemical loss by recombination in the upper mesosphere. The transport of O downward from the lower thermosphere into the mesosphere is preferentially driven by the eddy diffusion process that results from dissipating gravity waves and instabilities. The motivation here is to probe the intra-annual variability of the eddy diffusion coefficient (k zz ) and eddy velocity in the MLT based on the climatology of the region, initially accomplished by Garcia and Solomon (1985, https://doi.org/10.1029/JD090iD02p03850). In the current study, the intra-annual cycle was divided into 26 two-week periods for each of three zones: the northern hemisphere (NH), southern hemisphere (SH), and equatorial (EQ). Both 16 years of SABER (2002-2018) and 10 years of SCIAMACHY (2002-2012) O density measurements, along with NRLMSIS® 2.0 were used for calculation of atomic oxygen eddy diffusion velocities and fluxes. Our prominent findings include a dominant annual oscillation below 87 km in the NH and SH zones, with a factor of 3-4 variation between winter and summer at 83 km, and a dominant semiannual oscillation at all altitudes in the EQ zone. The measured global average k zz at 96 km lacks the intra-annual variability of upper atmosphere density data deduced by Qian et al. (2009, https://doi.org/10.1029/2008JA013643). The very large seasonal (and hemispherical) variations in k zz and O densities are important to separate and isolate in satellite analysis and to incorporate in MLT models.

Exact wave functions in a noncommutative field theory.

We consider the nonrelativistic field theory with a quartic interaction on a noncommutative plane and compute the 2-->2 scattering amplitude within perturbative analysis to all orders. We regain the results of the perturbative analysis by finding the scattering and the bound state wave functions of the two particle Schrodinger equation. These wave functions unusually have two center positions in the relative coordinates, whose separation is transverse to the total momentum and scales linearly with its magnitude, exhibiting the stringy nature of the noncommutative field theory.

Image plane detector spectrophotometer: construction and nightglow observations.

Following the theoretical simulation of an image plane detector spectrophotometer (IPDS) presented in a previous paper, a ground-based IPDS for airglow measurements is constructed. This low resolution spectrometer can measure a molecular band spectrum at 12 wavelength positions simultaneously without mechanical scan. The band brightness and rotational temperature of the emitter can be obtained from the measurements. We describe the optical design and calibration of the instrument and present some results of mesospheric nightglow observations. The evaluation and analysis on the performances of the new instrument are also given. The result shows that, although the constructed instrument does not represent the optimized IPDS, the instrument performed reasonably well, and with some improvements the IPDS has great potential of being used to study small-scale oscillations in airglow layers.

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.

Image plane detector spectrophotometer: application to O(2)atmospheric band nightglow.

A new variety of low resolution spectrometer is described. This device, an image plane detector spectrophotometer, has high sensitivity and modest resolution sufficient to determine the rotational temperature and brightness of molecular band emissions. It uses an interference filter as a dispersive element and a multichannel image plane detector as the photon collecting device. The data analysis technique used to recover the temperature of the emitter and the emission brightness is presented. The atmospheric band of molecular oxygen is used to illustrate the use of the device.

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.