Interactions Between the Quasi 2-Day Wave and Background
Recent observations from the Upper Atmosphere Research Satellite.
Atmospheric Science Space Physics UARS Mesospheric↗
Engineering topics
Hays, P. B.
Publications and source records attributed to Hays, P. B..
Observations of the 5-day wave in the mesosphere and lower thermosphere
The 5-day planetary wave has been detected in the winds measured by the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) in the mesosphere and lower thermosphere (50-110 km). The appearances of the 5-day wave are transient, with a lifetime of 10-20 days in the two-year data set. The structures of selected 5-day wave events are in generally good agreement with the (1,1) Rossby normal mode for both zonal and meridional components. A climatology of the 5-day wave is presented for an altitude of 95 km and latitudes mainly between 40 deg S and 40 deg N.
Wu, D. L.↗
Observations of the O2 atmospheric band nightglow by the High Resolution Doppler Imager
During nighttime operation the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) measures both the horizontal wind field at about 94 km altitude and the limb brightness of the O2(b(sup 1) Sigma(sup +)(sub g) - Chi(cubed)Sigma(sup +)(sub g)) (0,0) atmospheric band airglow. The dominant feature of the observed emission is a latitudinal and local time dependence which is consistent with the (1,1) diurnal tidal mode. A survey of the available data set from November 1991 to July 1993 reveals a semiannual variation in the peak brightness observed at the equator, with maxima observed at the equinoxes and minima at the solstices. These results are consistent with the long-term variations in the diurnal tidal amplitudes detected in HRDI wind measurements.
Burrage, M. D.↗
Comparison of NOAA/NMC stratospheric wind analyses with UARS high resolution Doppler Imager wind measurements
The NOAA National Weather Service currently derives global stratospheric wind analyses via several procedures. The first is the operational data assimilation system that extends from the surface up to about 50 mb and is in process of being tested to about 10 mb. In addition, a balanced wind is determined from the available Climate Analysis Center stratospheric height analyses that encompass the 70-0.4 mb region. The High Resolution Doppler Imager (HRDI) recently launched as a member of the Upper Atmosphere Research Satellite (UARS) is the first satellite instrument designed to measure winds in this stratospheric region and, thus, provide a basic evaluation of the NMC derived products. The HRDI accomplishes this by utilizing a triple-etalon Fabry-Perot interferometer that allows one to measure the Doppler shift of O2 absorption and emission features of the atmosphere, from which the wind field can be determined.
Miller, A. J.↗
Zonal mean winds in the equatorial mesosphere and lower thermosphere observed by the High Resolution Doppler Imager
This paper presents analyses of mesospheric and lower thermospheric zonal mean winds observed by the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS). Monthly averages of the equatorial zonal mean zonal winds are presented for January 1992 through June 1993. Equatorial zonal winds in the 70-90 km region are dominated by a semiannual oscillation (SAO), ranging from 30 m/s (westerly) to -100 m/s (easterly). At high latitudes the zonal wind variations are predominantly annual. Above 90 km, the low-latitude flow is easterly at all times, punctuated by a small semiannual variation. This behavior may be related to the deposition of momentum by the diurnal tides.
Lieberman, R. S.↗
Observations of the quasi 2-day wave from the High Resolution Doppler Imager on UARS
A strong westward traveling oscillation, with a period of 2 days and zonal wave number 3, is observed in the mesospheric and lower thermospheric winds from the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS). The important events happen in January, July, and September/October, of which the occurrence in January is the strongest with an amplitude over 60 m/s. Detailed analyses for the periods of January 1992 and January 1993 reveal a cause-and-effect relationship in the wave developing process at 95 km. The global structures of the wave amplitude and phase are also presented.
Wu, D. L.↗
Comparison of HRDI wind measurements with radar and rocket observations
Wind fields in the mesosphere and lower thermosphere are obtained with the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) by observing the Doppler shifts of emission lines in the O2 Atmospheric band. The validity of the measured winds depends on an accurate knowledge of the positions on the detector of the observed lines in the absence of a wind-induced Doppler shift. These positions have been determined to an accuracy of approximately 5 m/s from the comparison of winds measured by HRDI with those obtained by MF radars. Excellent agreement is found between HRDI measured winds and winds observed with radars and rockets. In addition, the sensitivity of HRDI to migrating tides and other large scale waves is demonstrated.
Burrage, M. D.↗
Absorption line profiles in a moving atmosphere - A single scattering linear perturbation theory
An integral equation is derived which linearly relates Doppler perturbations in the spectrum of atmospheric absorption features to the wind system which creates them. The perturbation theory is developed using a single scattering model, which is validated against a multiple scattering calculation. The nature and basic properties of the kernels in the integral equation are examined. It is concluded that the kernels are well behaved and that wind velocity profiles can be recovered using standard inversion techniques.
Hays, P. B.↗
Absorption and emission line shapes in the O2 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 O2 1Sigma(+)g - 3Sigma(-)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.
Abreu, Vincent J.↗
Joule heating in the mesosphere and thermosphere during the July 13, 1982, solar proton event
The solar proton event of July 13, 1982 produced considerable ionization in the polar-cap mesosphere. Energetic solar proton fluxes were measured by the NOAA-6 satellite. The DE-2 satellite measured the low-energy electrons, the ion drift velocity, and other atmospheric and ionospheric properties during the event in the region of the measured maximum electric field (189 mV/m at 2215 UT near 60 deg N), a Joule heating rate of 1-3 K/day is calculated between 70 and 80 km, exceeding the heating due to ozone absorption at noon in the summer hemisphere in that altitude range. The Joule heating rate above 90 km greatly exceeded 20 K/day. The calculated height-integrated Joule heating rate above 100 km in the same region exceeded 400 ergs/sq cm sec, and DE-2 near 350 km measured neutral winds of nearly 1000 m/s and neutral gas temperatures of over 2000 K. The overall ionospheric structure calculated below the DE-2 satellite is described.
Roble, R. G.↗
The dayglow of the O2 atmospheric band system
The dayglow of the O2 atmospheric O2(1Sigma) band system has been simulated by taking into account the three main production mechanisms of the O2(1Sigma) state resonance fluorescence, a photochemical term due to quenching of O(1D), and a pure chemical process. Values of the emission rate, which are involved in the resonant scattering of the O2 atmospheric bands (A, B, and gamma), have been obtained as a function of altitude (0-120 km) and solar zenith angle using a line-by-line calculation. The values of the emission rate, along with updated rate coefficients, have been used in the calculation of the production rate of O2(1Sigma) and the volume emission rate of the (O2 1Sigma, v prime = 0)-(O2 3Sigma, v double prime = 0) transition. The results of these calculations are compared to observational measurements and are found to be in excellent agreement.
Bucholtz, A.↗
Tomographic inversion of satellite photometry. II
A method for combining nadir observations of emission features in the upper atmosphere with the result of a tomographic inversion of limb brightness measurements is presented. Simulated and actual results are provided, and error sensitivity is investigated.
Solomon, S. C.↗
The composition, structure, temperature and dynamics of the upper thermosphere in the polar regions during October to December 1981
Observational data obtained by the Dynamics Explorer-2 (DE-2) spacecraft were compared with global model simulations in order to study the composition, structure, temperature, and dynamics of the upper thermosphere in polar regions during the period October-December 1981. A UCL three-dimensional model was used to simulate the seasonal, diurnal, and geomagnetic response of the neutral thermosphere and to follow the major features of the solar and geomagnetic inputs during the late 1981 period. Overall agreement was obtained between the simulations and the DE-2 data for thermospheric wind structure at high latitudes, and for the combined thermal and compositional structure in both hemispheres. Computer-generated line drawings of the variations in thermospheric structure are given, as well as a series of color graphic illustrations of the DE-2 data.
Rees, D.↗
Optical effects of spacecraft-environment interaction Spectrometric observations of the DE-2 satellite
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Abreu, V. J.↗
Configuration of the high-latitude thermosphere neutral circulation for IMF B(y) negative and positive
Asymmetries in the Northern Hemisphere neutral circulation that are dependent on the sign of the east-west 'B(y)' component of the IMF are presently illustrated by measurements of the neutral wind in the polar F-region which were conducted by the DE-2 spacecraft. The data thus obtained are categorized according to the sign of the hourly averaged IMF B(y) component measured by ISEE-3 for the hour preceding the DE-2 measurements. It is noted that there is (1) an asymmetry in the polar cap neutral flow velocity, with the region of most rapid antisunward flow shifting from the dawn side to the dusk side of the polar cap as B(y) changes from positive to negative; (2) a shift occurs in the magnetic local time of the region of entry of neutral gas into the polar cap, from a location on the dawn side of the moon-midnight meridian for B(y) positive to one more biased, for B(y) negative; and (3) there is an enhancement of velocities associated with the dawn anticlockwise neutral vortex for B(y) negative relative to those observed for B(y) positive.
Mccormac, F. G.↗
Neutral motions in the polar thermosphere for northward Interplanetary Magnetic Field
During the rare occurrence of November 24, 1982, when the north-south B(z) component of the IMF became positive for a period of about 11 hours and reached a steady value of about 25 nT, the DE-2 spacecraft simultaneously measured the ionic and neutral species of the high latitude F-region along the track of the polar-orbiting satellite. Data from two northern winter polar passes of DE-2 illustrate the response of the neutral F-region to ion drag forcing that arises from a configuration of ion convection characteristics of strongly northward IMF. The multicellular ion drift pattern associated with positive B(z) is observed to drive a similar, but less structured and weaker, neutral wind configuration in the winter polar cap. While major features of the ion drift pattern are mimicked by the neutral circulation, smaller scale ion flow structures are not. These results demonstrate that the sunward flow of neutral gas can be established and maintained by ion drag in the central polar cap, for positive B(z).
Killeen, T. L.↗
The westward thermospheric jet-stream of the evening auroral oval
Ground-based and satellite measurements of the thermospheric wind in jet-streams during the evening auroral oval are analyzed, in order to study the geophysical mechanisms of thermospheric wind generation. Numerical simulations using a global, three-dimensional, time-dependent model of thermospheric dynamics were compared with the satellite data, and the results are discussed in detail. The wind distribution during the storm is shown in a series of color plates.
Rees, D.↗
Escape of suprathermal O(+) ions in the polar cap
Instruments on board the Dynamics Explorer (DE) 1 and 2 spacecraft have been used to investigate the characteristics of a very low-energy (less than 10 eV) outflow of O(+) ions at high altitudes over the polar cap. The measured O(+) outflow has a relatively high Mach number (2-6) and a flux of about 2 x 10 to the 8th/(sq cm s). A statistical study using 50 orbits of retarding ion mass spectrometer data indicates that the outflows occur during active magnetic conditions, lasting for several hours over large areas of the polar cap. The observations are then discussed and analyzed in a framework based on polar wind models with particular attention paid to the new information obtained by the DE 2 Fabry-Perot interferometer, and the impact these flows have on the composition of the magnetosphere. The observed suprathermal outflow of O(+) suggests a scenario requiring both significant compositional changes in the high latitude thermosphere and significant heating of the ions and electrons in the topside ionoshpere.
Waite, J. H., Jr.↗