References of "Mende, S. B."
     in
Bookmark and Share    
See detailTwo types of localized auroral UV emission on the dayside
Frey, H. U.; Mende, S. B.; Immel, T. J. et al

Conference (2001, December 01)

The FUV instrument on IMAGE frequently observes localized ultraviolet emission on the high latitude dayside, poleward of the normal auroral oval. There are two different types of these localized emissions ... [more ▼]

The FUV instrument on IMAGE frequently observes localized ultraviolet emission on the high latitude dayside, poleward of the normal auroral oval. There are two different types of these localized emissions. One is especially distinct in the observations of Doppler shifted Lyman alpha emission from proton precipitation. This type occurs during northward IMF and high solar wind dynamic pressure. We interpret this emission as the optical signature of proton precipitation into the cusp after lobe reconnection at the magnetopause. The second type of localized emission is visible in the wide-band (WIC) and oxygen (SI13) imagers, but is absent in the proton imager. This emission occurs during northward IMF but very low solar wind density and dynamic pressure. We interpret this emission as the optical signature of electron acceleration after reconnection. [less ▲]

Detailed reference viewed: 31 (6 ULg)
Peer Reviewed
See detailAuroral Precipitation during the Bastille Day Storm Recovery
Immel, T. J.; Mende, S. B.; Frey, H. U. et al

Conference (2001, December 01)

The recovery period following the geomagnetic storm of July 15-16, 2000 is marked by rapid changes in auroral morphology and brightness in the sunlit hemisphere. These observations are made by the FUV and ... [more ▼]

The recovery period following the geomagnetic storm of July 15-16, 2000 is marked by rapid changes in auroral morphology and brightness in the sunlit hemisphere. These observations are made by the FUV and EUV imagers aboard the IMAGE satelite. Clear signatures of magnetospheric convection are observed in the motion of the auroral forms, indicating sunward convection of plasma in the polar cap under the strong northward component of the IMF. Precipitation is also observed equatorward of the auroral oval on the dayside in large diffuse arcs. Unlike previously observed detached proton arcs, this precipitation appears to have a significant electron component. Determination of the characteristic energies and fluxes of electrons and protons requires the proper removal of FUV airglow emissions, which in this case have been strongly affected by the recent magnetic activity. EUV images provide a very clear signature of these events, with practically no airglow contamination. With proper modeling, these EUV images could provide improvements to the characterization of the magnetospheric energy input to the thermosphere and ionosphere from space-based imaging. [less ▲]

Detailed reference viewed: 32 (4 ULg)
See detailDetermination of electron and proton auroral energy inputs from FUV-IMAGE
Gérard, Jean-Claude ULg; Hubert, Benoît ULg; Meurant, M. et al

Conference (2001, May 01)

The FUV experiment onboard the IMAGE spacecraft offers the unique possibility to obtain simultaneous snapshots of the global north aurora every 2 minutes in three different spectral channels. The WIC ... [more ▼]

The FUV experiment onboard the IMAGE spacecraft offers the unique possibility to obtain simultaneous snapshots of the global north aurora every 2 minutes in three different spectral channels. The WIC camera has a broadband channel covering the 135-190 nm interval including the N[SUB]2[/SUB] LBH bands, part of which may be absorbed by O[SUB]2[/SUB]. The SI13 channel is centered on the OI 135.6 nm line which is optically thin and includes a ~ 40% LBH contribution. Finally, the SI12 camera images the Doppler-shifted Ly-α emission excited by the proton aurora. This set of instrumentation is combined with auroral models to determine the electron and the proton energy fluxes from the magnetosphere. Examples will be presented and compared with the values deduced from the NOAA satellites. Simultaneous in-situ measurements of the particle characteristic energy have been combined with the data extracted from the FUV images to validate the models and derive empirical relationships between the particle flux measured by the detectors and the brightness observed by FUV-IMAGE at the footprint of the same magnetic field line. Finally, we will assess the ability to deduce the characteristic energy of the auroral particles from the ratio of co-registered images in the WIC and SI13 cameras. This method is based on the difference of vertical distribution of the LBH and the OI 135.6 nm emissions. It offers the potential to globally remotely sense not only the energy flux from the magnetosphere but also the main features of the electron characteristic energy. [less ▲]

Detailed reference viewed: 17 (5 ULg)
See detailDerivation of Auroral Conductances from IMAGE FUV
Immel, T. J.; Mende, S. B.; Frey, H. U. et al

Conference (2001, May 01)

Auroral emissions are observed in 3 separate Far-Ultraviolet (FUV) wavelength regimes by IMAGE. The Wideband Imaging Camera (WIC) is sensitive mainly to N[SUB]2[/SUB] LBH and N I emissions in the 140-190 ... [more ▼]

Auroral emissions are observed in 3 separate Far-Ultraviolet (FUV) wavelength regimes by IMAGE. The Wideband Imaging Camera (WIC) is sensitive mainly to N[SUB]2[/SUB] LBH and N I emissions in the 140-190-nm range, while the Spectrographic Imager (SI) spectrally separates the OI 135.6-nm emission and Doppler shifted hydrogen emissions of the proton aurora at 121.8 nm. The brightness of the N[SUB]2[/SUB] LBH and OI 135.6-nm emissions depend in part on the spectrum and total energy flux of incoming electrons, and on the height-density profile of the respective species, and O[SUB]2[/SUB]. Due mainly to these atmospheric factors, the ratio of the N[SUB]2[/SUB] and OI emissions depends strongly on the characteristic energy of precipitating electrons which, once estimated, can in turn be used to calculate the total energy flux. The proton aurora generates secondary electrons, which excite additional emissions of N[SUB]2[/SUB] and OI. It is not possible to absolutely determine either the total proton energy flux or the characteristic proton energy (<E[SUB]p[/SUB]>) with a single proton imaging channel. However, the proton-induced N[SUB]2[/SUB] and OI emissions depend mainly on the total proton energy flux, so reasonable estimates of <E[SUB]p[/SUB]> can be used in the calculation of proton energy input. Ground-based or in-situ observations of proton energies can help in this determination. With accurate corrections for N[SUB]2[/SUB] and OI airglow emissions, and formulae such as those provided by Robinson et al. [1987], IMAGE FUV can provide global maps of height-integrated conductivity (conductance) in the auroral oval. It is also possible to examine the degree to which the proton aurora contributes to enhanced conductance on a global scale. The promise of providing these conductances using IMAGE's real-time capabilities will be discussed. Robinson, R. M., R. R. Vondrak, K. Miller, T. Dabbs, and D. Hardy, On Calculating Ionospheric Conductances from the Flux and Energy of Precipitating Electrons, J. Geophys. Res., 92, 2566, 1987. [less ▲]

Detailed reference viewed: 16 (2 ULg)
See detailElectron and Proton Auroral Dynamics
Mende, S. B.; Frey, H. U.; Carlson, C. et al

Conference (2001, May 01)

Data from the IMAGE Wide-band Imaging Camera (WIC),sensitive to far ultraviolet auroras and from the Spectrographic Imager (SI) channel SI12, sensitive to proton precipitation induced Lyman alpha, were ... [more ▼]

Data from the IMAGE Wide-band Imaging Camera (WIC),sensitive to far ultraviolet auroras and from the Spectrographic Imager (SI) channel SI12, sensitive to proton precipitation induced Lyman alpha, were analyzed during a high altitude orbit segment of the IMAGE spacecraft. This segment began during the expansive phase of a substorm. The aurora developed into a double oval configuration, consisting of a set of discrete poleward forms and a separate diffuse auroral oval equatorwards. Although IMF Bz was negative, considerable activity could be seen poleward of the high latitude arcs in the polar cap region. The optical signature of precipitating protons showed that the proton aurora was on the equatorward side of the diffuse aurora and there was a lack of intense energetic proton fluxes in the poleward arcs. A simultaneous FAST pass provided a diagnostic of the particle types in the various regions. These data showed that lower intensity protons were present throughout the entire double oval configuration but with insufficient intensity to produce aurora that could be observed by IMAGE. The FAST data also showed that the bright poleward discrete arcs were accelerated by electrostatic processes, and the wave accelerated electrons were located on the poleward edge of these features. [less ▲]

Detailed reference viewed: 11 (1 ULg)
See detailCusp studies with IMAGE-FUV
Frey, H. U.; Mende, S. B.; Fuselier, S. A. et al

Conference (2001, May 01)

The FUV instrument on IMAGE frequently observes localized ultraviolet emission on the high latitude dayside, poleward of the normal auroral oval location. This emission is especially distinct in the ... [more ▼]

The FUV instrument on IMAGE frequently observes localized ultraviolet emission on the high latitude dayside, poleward of the normal auroral oval location. This emission is especially distinct in the observations of Doppler shifted Lyman alpha emission from precipitating protons. We interpret this emission as the optical signature of precipitation into the cusp after lobe reconnection at the magnetopause. Several cusp crossings by the FAST satellite are used to establish an estimate of the energy input and the characteristics of the precipitating protons. Multivariate cluster analysis and other statistical tools are used to determine the dependence of this precipitation on solar wind parameters. This shows that under northward IMF and high solar wind dynamic pressure, proton precipitation can be the dominating energy input into the cusp region. [less ▲]

Detailed reference viewed: 3 (0 ULg)
See detailCusp studies with IMAGE-FUV
Frey, H. U.; Mende, S. B.; Fuselier, S. A. et al

Conference (2001, May 01)

The FUV instrument on IMAGE frequently observes localized ultraviolet emission on the high latitude dayside, poleward of the normal auroral oval location. This emission is especially distinct in the ... [more ▼]

The FUV instrument on IMAGE frequently observes localized ultraviolet emission on the high latitude dayside, poleward of the normal auroral oval location. This emission is especially distinct in the observations of Doppler shifted Lyman alpha emission from precipitating protons. We interpret this emission as the optical signature of precipitation into the cusp after lobe reconnection at the magnetopause. Several cusp crossings by the FAST satellite are used to establish an estimate of the energy input and the characteristics of the precipitating protons. Multivariate cluster analysis and other statistical tools are used to determine the dependence of this precipitation on solar wind parameters. This shows that under northward IMF and high solar wind dynamic pressure, proton precipitation can be the dominating energy input into the cusp region. [less ▲]

Detailed reference viewed: 9 (1 ULg)
See detailElectron and Proton Auroral Dynamics
Mende, S. B.; Frey, H. U.; Carlson, C. et al

Conference (2001, May 01)

Data from the IMAGE Wide-band Imaging Camera (WIC),sensitive to far ultraviolet auroras and from the Spectrographic Imager (SI) channel SI12, sensitive to proton precipitation induced Lyman alpha, were ... [more ▼]

Data from the IMAGE Wide-band Imaging Camera (WIC),sensitive to far ultraviolet auroras and from the Spectrographic Imager (SI) channel SI12, sensitive to proton precipitation induced Lyman alpha, were analyzed during a high altitude orbit segment of the IMAGE spacecraft. This segment began during the expansive phase of a substorm. The aurora developed into a double oval configuration, consisting of a set of discrete poleward forms and a separate diffuse auroral oval equatorwards. Although IMF Bz was negative, considerable activity could be seen poleward of the high latitude arcs in the polar cap region. The optical signature of precipitating protons showed that the proton aurora was on the equatorward side of the diffuse aurora and there was a lack of intense energetic proton fluxes in the poleward arcs. A simultaneous FAST pass provided a diagnostic of the particle types in the various regions. These data showed that lower intensity protons were present throughout the entire double oval configuration but with insufficient intensity to produce aurora that could be observed by IMAGE. The FAST data also showed that the bright poleward discrete arcs were accelerated by electrostatic processes, and the wave accelerated electrons were located on the poleward edge of these features. [less ▲]

Detailed reference viewed: 7 (1 ULg)
Peer Reviewed
See detailThe electron and proton aurora as seen by IMAGE-FUV and FAST
Frey, H. U.; Mende, S. B.; Carlson, C. W. et al

in Geophysical Research Letters (2001), 28

The Far Ultraviolet Instrument (FUV) on the IMAGE spacecraft observes the aurora in three different channels. One of them (SI12) is sensitive to the signal from precipitating protons, while the other two ... [more ▼]

The Far Ultraviolet Instrument (FUV) on the IMAGE spacecraft observes the aurora in three different channels. One of them (SI12) is sensitive to the signal from precipitating protons, while the other two (WIC and SI13) observe auroral emissions which are not only excited by precipitating electrons, but also by protons. We examine a period when in-situ particle measurements by the FAST spacecraft were available simultaneously with global imaging with FUV. The measured electron and proton energy spectra are used to calculate the auroral brightness along the FAST orbit. The comparison with the FUV/IMAGE observations shows good quantitative agreement and demonstrates that under certain circumstances high proton fluxes may produce significant amounts of auroral FUV emission. [less ▲]

Detailed reference viewed: 11 (0 ULg)
Peer Reviewed
See detailGlobal observations of proton and electron auroras in a substorm
Mende, S. B.; Frey, H. U.; Lampton, M. et al

in Geophysical Research Letters (2001), 28

This is the first report of a substorm observed by the IMAGE FUV instruments permitting global observations of electron and proton produced auroras. On the 28th of June 2000 at 1956 UT in the pre-substorm ... [more ▼]

This is the first report of a substorm observed by the IMAGE FUV instruments permitting global observations of electron and proton produced auroras. On the 28th of June 2000 at 1956 UT in the pre-substorm phase at early evening local time the proton aurora was equatorward of the electron precipitation and near midnight they were collocated. There was bright electron and proton aurora in the post midday afternoon side. The sudden brightening of the aurora at substorm onset near midnight is seen in the electrons only although there are protons present at this location. During the expansive phase both the electrons and protons expand poleward. The electron aurora forms a bright surge at the poleward boundary while the protons just show diffuse spreading. The peak intensity of the protons did not change substantially during the entire event. The proton aurora is brighter on the dusk while the electron aurora on the dawn side. As the electron surge expands poleward it leaves the protons behind. The electrons form a discrete auroral feature near the aurora-polar cap boundary, which is devoid of substantial energetic (>1 keV) proton precipitation. The presence of precipitating protons at the point where the initial brightening is seen shows that substorms are initiated on closed field lines. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Peer Reviewed
See detailIon outflow observed by IMAGE: Implications for source regions and heating mechanisms
Fuselier, S. A.; Ghielmetti, A. G.; Moore, T. E. et al

in Geophysical Research Letters (2001), 28

Images of the Earth's proton aurora from the IMAGE spacecraft on 8 June 2000 indicate a temporally and spatially isolated ionospheric response to a shock that impinged on the Earth's magnetopause ... [more ▼]

Images of the Earth's proton aurora from the IMAGE spacecraft on 8 June 2000 indicate a temporally and spatially isolated ionospheric response to a shock that impinged on the Earth's magnetopause. Sometime after this ionospheric response, the Low Energy Neutral Atom imager on IMAGE detected enhanced ionospheric outflow. The time delay between the ionospheric response and the enhanced outflow is consistent with the travel time of ~30 eV neutral Oxygen (created by charge exchange of outflowing O[SUP]+[/SUP] with the exosphere) from the low altitude ionosphere to the spacecraft. The prompt ionospheric outflow implies that the shock deposited sufficient energy in the topside ionosphere near or above the O[SUP]+[/SUP] exobase to initiate the outflow. [less ▲]

Detailed reference viewed: 5 (0 ULg)
Full Text
Peer Reviewed
See detailFar ultraviolet imaging from the IMAGE spacecraft. 1. System design
Mende, S. B.; Heetderks, H.; Frey, H. U. et al

in Space Science Reviews (2000), 91

Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora, the footprint of magnetospheric regions. To assure the simultaneity of these ... [more ▼]

Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora, the footprint of magnetospheric regions. To assure the simultaneity of these observations and the measurement of the magnetospheric background neutral gas density, the IMAGE satellite instrument complement includes three Far Ultraviolet (FUV) instruments. In the wavelength region 120-190 nm, a downward-viewing auroral imager is only minimally contaminated by sunlight, scattered from clouds and ground, and radiance of the aurora observed in a nadir viewing geometry can be observed in the presence of the high-latitude dayglow. The Wideband Imaging Camera (WIC) will provide broad band ultraviolet images of the aurora for maximum spatial and temporal resolution by imaging the LBH N_2 bands of the aurora. The Spectrographic Imager (SI), a monochromatic imager, will image different types of aurora, filtered by wavelength. By measuring the Doppler-shifted Ly-alpha, the proton-induced component of the aurora will be imaged separately. Finally, the GEO instrument will observe the distribution of the geocoronal emission, which is a measure of the neutral background density source for charge exchange in the magnetosphere. The FUV instrument complement looks radially outward from the rotating IMAGE satellite and, therefore, it spends only a short time observing the aurora and the Earth during each spin. Detailed descriptions of the WIC, SI, GEO, and their individual performance validations are discussed in companion papers. This paper summarizes the system requirements and system design approach taken to satisfy the science requirements. One primary requirement is to maximize photon collection efficiency and use efficiently the short time available for exposures. The FUV auroral imagers WIC and SI both have wide fields of view and take data continuously as the auroral region proceeds through the field of view. To minimize data volume, multiple images are taken and electronically co-added by suitably shifting each image to compensate for the spacecraft rotation. In order to minimize resolution loss, the images have to be distortion-corrected in real time for both WIC and SI prior to co-adding. The distortion correction is accomplished using high speed look up tables that are pre-generated by least square fitting to polynomial functions by the on-orbit processor. The instruments were calibrated individually while on stationery platforms, mostly in vacuum chambers as described in the companion papers. Extensive ground-based testing was performed with visible and near UV simulators mounted on a rotating platform to estimate their on-orbit performance. The predicted instrument system performance is summarized and some of the preliminary data formats are shown. [less ▲]

Detailed reference viewed: 33 (8 ULg)
Full Text
Peer Reviewed
See detailFar ultraviolet imaging from the IMAGE spacecraft. 3. Spectral imaging of Lyman-alpha and OI 135.6 nm
Mende, S. B.; Heetderks, H.; Frey, H. U. et al

in Space Science Reviews (2000), 91

Two FUV Spectral imaging instruments, the Spectrographic Imager (SI) and the Geocorona Photometer (GEO) provide IMAGE with simultaneous global maps of the hydrogen (121.8 nm) and oxygen 135.6 nm ... [more ▼]

Two FUV Spectral imaging instruments, the Spectrographic Imager (SI) and the Geocorona Photometer (GEO) provide IMAGE with simultaneous global maps of the hydrogen (121.8 nm) and oxygen 135.6 nm components of the terrestrial aurora and with observations of the three dimensional distribution of neutral hydrogen in the magnetosphere (121.6 nm). The SI is a novel instrument type, in which spectral separation and imaging functions are independent of each other. In this instrument, two-dimensional images are produced on two detectors, and the images are spectrally filtered by a spectrograph part of the instrument. One of the two detectors images the Doppler-shifted Lyman-alpha while rejecting the geocoronal `cold' Ly-alpha, and another detector images the OI 135.6 nm emission. The spectrograph is an all-reflective Wadsworth configuration in which a grill arrangement is used to block most of the cold, un-Doppler-shifted geocoronal emission at 121.567 nm. The SI calibration established that the upper limit of transmission at cold geocoronal Ly-alpha is less than 2%. The measured light collecting efficiency was 0.01 and 0.008 cm^2 at 121.8 and at 135.6 nm, respectively. This is consistent with the size of the input aperture, the optical transmission, and the photocathode efficiency. The expected sensitivity is 1.8x10^-2 and 1.3x10^-2 counts per Rayleigh per pixel for each 5 s viewing exposure per satellite revolution (120 s). The measured spatial resolution is better than the 128x128 pixel matrix over the 15 degx15 deg field of view in both wavelength channels. The SI detectors are photon counting devices using the cross delay line principle. In each detector a triple stack microchannel plate (MCP) amplifies the photo-electronic charge which is then deposited on a specially configured anode array. The position of the photon event is measured by digitizing the time delay between the pulses detected at each end of the anode structures. This scheme is intrinsically faster than systems that use charge division and it has a further advantage that it saturates more gradually at high count rates. The geocoronal Ly-alpha is measured by a three-channel photometer system (GEO) which is a separate instrument. Each photometer has a built in MgF_2 lens to restrict the field of view to one degree and a ceramic electron multiplier with a KBr photocathode. One of the tubes is pointing radially outward perpendicular to the axis of satellite rotation. The optic of the other two subtend 60 deg with the rotation axis. These instruments take data continuously at 3 samples per second and rely on the combination of satellite rotation and orbital motion to scan the hydrogen cloud surrounding the earth. The detective efficiencies (effective quantum efficiency including windows) of the three tubes at Ly-alpha are between 6 and 10%. [less ▲]

Detailed reference viewed: 25 (5 ULg)