Search Publications
Nighttime sensitivity of ionospheric VLF measurements to X-ray bursts from a remote cosmic source
Giménez de Castro, C. Guillermo; Raulin, Jean-Pierre; Correia, Emilia +2 more
On 22 January 2009, a series of X-ray bursts were emitted by the soft gamma ray repeater SGR J1550-5418. Some of these bursts produced enhanced ionization in the nighttime lower ionosphere. These ionospheric disturbances were studied using X-ray measurements from the Anti-Coincidence Shield of the Spectrometer for Integral onboard the Internationa…
Cassini nightside observations of the oscillatory motion of Saturn's northern auroral oval
Coates, A. J.; Dougherty, M. K.; Kurth, W. S. +8 more
In recent years we have benefitted greatly from the first in-orbit multi-wavelength images of Saturn's polar atmosphere from the Cassini spacecraft. Specifically, images obtained from the Cassini UltraViolet Imaging Spectrograph (UVIS) provide an excellent view of the planet's auroral emissions, which in turn give an account of the large-scale mag…
In situ observation of magnetic reconnection in the front of bursty bulk flow
Huang, Can; Nakamura, Rumi; Lu, Quanming +5 more
Using the Cluster observation in the magnetotail, we investigate the dynamic processes associated with a bursty bulk flow (BBF) event. The BBF is inferred to be caused by magnetic reconnection proceeding to the lobe region in its tail, called "primary reconnection." On the BBF front, another reconnection was directly encountered by one of the four…
A tailward moving current sheet normal magnetic field front followed by an earthward moving dipolarization front
Goldstein, M. L.; Walsh, B. M.; Moore, T. E. +5 more
A case study is presented using measurements from the Cluster spacecraft and ground-based magnetometers that show a substorm onset propagating from the inner to outer plasma sheet. On 3 October 2005, Cluster, traversing an ion-scale current sheet at the near-Earth plasma sheet, detected a sudden enhancement of Bz, which was immediately …
Survey of Saturn auroral storms observed by the Hubble Space Telescope: Implications for storm time scales
Nichols, J. D.; Cowley, S. W. H.; Meredith, C. J.
We examine the ultraviolet images of Saturn obtained by the Hubble Space Telescope (HST) between 1997 and 2013 for the presence of auroral storm signatures, consisting of 2060 individual images over 74.4 h of exposure time. We find 12 storm intervals in these data, identified by bright high-latitude auroras spanning the dawn sector, which previous…
Observed decline in Titan's thermospheric methane due to solar cycle drivers
Waite, J. H.; Perryman, R.; Bell, J. M. +1 more
We present Cassini Ion and Neutral Mass Spectrometer observations of Titan's N2 and CH4 from Cassini flybys of Titan spanning the time period from 2004 to 2013 representing 9 years of in situ neutral density observations. This data reveal an upward trend in CH4 mixing ratios during the extended solar minimum encoun…
Variations of the 3-D coronal magnetic field associated with the X3.4-class solar flare event of AR 10930
Chen, P. F.; Yan, Yihua; Wang, Huaning +2 more
The variations of the 3-D coronal magnetic fields associated with the X3.4-class flare of active region 10930 are studied in this paper. The coronal magnetic field data are reconstructed from the photospheric vector magnetograms obtained by the Hinode satellite and using the nonlinear force-free field extrapolation method developed in our previous…
What flare and CME parameters control the occurrence of solar proton events?
Moon, Y. -J.; Park, Jinhye
In this study we examine the occurrence probabilities of solar proton events (SPEs) and their peak fluxes depending on both flare and coronal mass ejection (CME) parameters: flare peak flux, longitude, impulsive time, CME linear speed, and angular width. For this we use the NOAA SPEs, their associated X-ray flares, and CME from 1997 to 2011. We di…
Temporal and spatial scales of a high-flux electron disturbance in the cusp region: Cluster observations
Dunlop, Malcolm; Fazakerley, Andrew; Torkar, Klaus +4 more
Using the Cluster multispacecraft observations, we analyze a long-duration field-aligned high-flux electron disturbance in the cusp region on 30 September 2001. All four Cluster spacecraft observed the same disturbance in which both the upward and downward electrons are observed and the electron flux was 1 order of magnitude higher than usual in t…
Transient small-scale structure in the main auroral emission at Jupiter
Bonfond, B.; Palmaerts, B.; Grodent, D. +2 more
The main auroral emission at Jupiter results from the ionosphere-magnetosphere coupling current system associated with the corotation breakdown of iogenic plasma in the current sheet. The morphology and brightness of the main auroral emission are generally suggested to be stable during time intervals of the order of an hour. Here we reveal a trans…