The auroral 6300 Å emission: Observations and modeling

Solomon, Stanley C.; Hays, P. B.; Abreu, Vincent J.

doi:10.1029/ja093ia09p09867

Cited by 275 publications

(275 citation statements)

References 148 publications

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“…This procedure requires hypothesis on the particle mean energy. The method to extract the precipitating electron energy flux is based on simulations with the GLOW model (Solomon et al, 1988) extended to higher energies for auroral calculations . This model, based on a two-stream approximation, calculates the auroral electron energy degradation and excitation by electron-induced process.…”

Section: The Fuv Imagers and The Auroral Precipitationmentioning

confidence: 99%

Global auroral conductance distribution due to electron and proton precipitation from IMAGE-FUV observations

et al. 2004

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Abstract. The Far Ultraviolet (FUV) imaging system on board the IMAGE satellite provides a global view of the north auroral region in three spectral channels, including the SI12 camera sensitive to Doppler shifted Lyman-α emission. FUV images are used to produce instantaneous maps of electron mean energy and energy fluxes for precipitated protons and electrons. We describe a method to calculate ionospheric Hall and Pedersen conductivities induced by auroral proton and electron ionization based on a model of interaction of auroral particles with the atmosphere. Different assumptions on the energy spectral distribution for electrons and protons are compared. Global maps of ionospheric conductances due to instantaneous observation of precipitating protons are calculated. The contribution of auroral protons in the total conductance induced by both types of auroral particles is also evaluated and the importance of proton precipitation is evaluated. This method is well adapted to analyze the time evolution of ionospheric conductances due to precipitating particles over the auroral region or in particular sectors. Results are illustrated with conductance maps of the north polar region obtained during four periods with different activity levels. It is found that the proton contribution to conductance is relatively higher during quiet periods than during substorms. The proton contribution is higher in the period before the onset and strongly decreases during the expansion phase of substorms. During a substorm which occurred on 28 April 2001, a region of strong proton precipitation is observed with SI12 around 14:00 MLT at ∼75 • MLAT. Calculation of conductances in this sector shows that neglecting the protons contribution would produce a large error. We discuss possible effects of the proton precipitation on electron precipitation in auroral arcs. The increase in the ionospheric conductivity, induced by a former proton precipitation can reduce the potential drop along field lines in the upward field-aligned currents by creating an opposite polarization electric field. This feedback mechanism possibly reduces the electron acceleration.

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Section: The Fuv Imagers and The Auroral Precipitationmentioning

confidence: 99%

Global auroral conductance distribution due to electron and proton precipitation from IMAGE-FUV observations

et al. 2004

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“…We calculate O 1 D from the continuity equation using the chemical reactions of formation and loss of O 1 D presented in Table 3 (Solomon et al, 1988), t is determined by Eq. (A.18), ph is the rate of the O 1 D formation in collision of O 3 P with photoelectrons, the value of ph is calculated by using the semi-empirical formula (Pavlov, 1990;Konikov and Pavlov, 1991), u i i 1±6 are the rate coe cients of the chemical reactions of Table 3.…”

Section: Continuity Equation For Y 1 Hmentioning

confidence: 99%

Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

Павлов

1997

Ann. Geophys.

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Abstract. This study compares the OV1-10 satellite measurements of the integral airglow intensities at 630 nm in the SAR arc regions observed in the northern and southern hemisphere as a conjugate phenomenon, with the model results obtained using the time-dependent one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the IZMIRAN model) during the geomagnetic storm of the period 15±17 February 1967. The major enhancements to the IZ-MIRAN model developed in this study are the inclusion of He ions (three major ions: O , H , and He , and three ion temperatures), the updated photochemistry and energy balance equations for ions and electrons, the di usion of NO and O 2 ions and O 1 D and the revised electron cooling rates arising from their collisions with unexcited N 2 Y O 2 molecules and N 2 molecules at the ®rst vibrational level. The updated model includes the option to use the models of the Boltzmann or nonBoltzmann distributions of vibrationally excited molecular nitrogen. Deviations from the Boltzmann distribution for the ®rst ®ve vibrational levels of N 2 were calculated. The calculated distribution is highly nonBoltzmann at vibrational levels v b 2 and leads to a decrease in the calculated electron density and integral intensity at 630 nm in the northern and southern hemispheres in comparison with the electron density and integral intensity calculated using the Boltzmann vibrational distribution of N 2 . It is found that the intensity at 630 nm is very sensitive to the oxygen number densities. Good agreement between the modeled and measured intensities is obtained provided that at all altitudes of the southern hemisphere a reduction of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the IZMIRAN model with the non-Boltzmann vibrational distribution of N 2 . The e ect of using of the O 1 D di usion results in the decrease of 4±6% in the calculated integral intensity of the northern hemisphere and 7±13% in the calculated integral intensity of the southern hemisphere. It is found that the modeled intensities of the southern hemisphere are more sensitive to the assumed values of the rate coe cients of O 4 S ions with the vibrationally excited nitrogen molecules and quenching of O 2 D by atomic oxygen than the modeled intensities of the northern hemisphere.

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“…In the ®eld of airglow, tomographic research has been made using the airglow experiment on board the Atmospheric Explorer satellites (Solomon et al, 1988;Abreu and Yee, 1989). These studies, however, are aimed at investigating the vertical airglow pro®le up in the thermosphere, not the airglow structures lower down around the mesopause altitude.…”

Section: Introductionmentioning

confidence: 99%

Application of tomographic inversion in studying airglow in the mesopause region

Nygrén

Taylor

Lehtinen³

et al. 1998

Ann. Geophys.

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Abstract. It is pointed out that observations of periodic nightglow structures give excellent information on atmospheric gravity waves in the mesosphere and lower thermosphere. The periods, the horizontal wavelengths and the phase speeds of the waves can be determined from airglow images and, using several cameras, the approximate altitude of the luminous layer can also be determined by triangulation. In this paper the possibility of applying tomographic methods for reconstructing the airglow structures is investigated using numerical simulations. A ground-based chain of cameras is assumed, two-dimensional airglow models in the vertical plane above the chain are constructed, and simulated data are calculated by integrating the models along a great number of rays with di erent elevation angles for each camera. After addition of random noise, these data are then inverted to obtain reconstructions of the models. A tomographic analysis package originally designed for satellite radiotomography is used in the inversion. The package is based on a formulation of stochastic inversion which allows the input of a priori information to the solver in terms of regularization variances. The reconstruction is carried out in two stages. In the ®rst inversion, constant regularization variances are used within a wide altitude range. The results are used in determining the approximate altitude range of the airglow structures. Then, in the second inversion, constant non-zero regularization variances are used inside this region and zero variances outside it. With this method reliable reconstructions of the models are obtained. The number of cameras as well as their separations are varied in order to ®nd out the limitations of the method.

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The auroral 6300 Å emission: Observations and modeling

Cited by 275 publications

References 148 publications

Global auroral conductance distribution due to electron and proton precipitation from IMAGE-FUV observations

Global auroral conductance distribution due to electron and proton precipitation from IMAGE-FUV observations

Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

Application of tomographic inversion in studying airglow in the mesopause region

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