Search Publications
Comparison between theory and observation of the frequency sweep rates of equatorial rising tone chorus
Li, W.; Tao, X.; Bortnik, J. +2 more
Theoretical predictions for chorus frequency sweep rates by Helliwell and Trakhtengerts are compared with observations from the THEMIS satellites and a previously published dataset from the Cluster satellites. We first extend the theories to use a general magnetic field model to include the effects of magnetic local time and geomagnetic activity, …
Dynamic Martian magnetosphere: Transient twist induced by a rotation of the IMF
Dubinin, E.; Modolo, R.; Chanteur, G. M.
Simulation studies of the Martian environment are usually restricted to stationary situations under various steady conditions of the solar wind and solar radiation. Dynamic transients and their implications have so far attracted little attention although global simulation models can provide valuable insights to understand disagreements between sim…
Pc2 EMIC waves generated high off the equator in the dayside outer magnetosphere
Liu, Y. H.; Fraser, B. J.; Menk, F. W.
It is generally accepted that electromagnetic ion cyclotron (EMIC) waves are generated around the equatorial regions and propagate toward the high latitude ionospheres in both hemispheres. Here we describe a prolonged EMIC wave event in the Pc2 (0.1-0.2 Hz) frequency band above the He+ cyclotron frequency detected by the four Cluster sa…
How the inclination of Earth's orbit affects incoming solar irradiance
Cheung, M. C. M.; Kretzschmar, M.; Dudok de Wit, T. +3 more
The variability in solar irradiance, the main external energy source of the Earth's system, must be critically studied in order to place the effects of human-driven climate change into perspective and allow plausible predictions of the evolution of climate. Accurate measurements of total solar irradiance (TSI) variability by instruments onboard sp…
Peak emission altitude of Saturn's H3+ aurora
Baines, Kevin H.; Brown, Robert H.; Melin, Henrik +3 more
Here we present the first detailed measurement of the altitudinal profile of H3+ emission within Saturn's ionosphere, made using images taken by the VIMS instrument on Cassini on 11-12 October 2006, during a chance alignment between the visible limb of the planet and the position of the main auroral emission. Using this, we s…
Asymmetric magnetosphere deformation driven by hot flow anomaly(ies)
Němeček, Z.; Šafránková, J.; Přech, L. +2 more
We present a case study of a large deformation of the magnetopause on November 26, 2008. The investigation is based on observations of five THEMIS spacecraft located at the dawn flank in the magnetosphere and magnetosheath, on Cluster measurements at the dusk magnetosheath, and is supported by ACE solar wind monitoring. The main revelation of our …
The influence of spectral solar irradiance data on stratospheric heating rates during the 11 year solar cycle
Weber, M.; Solanki, S. K.; Krivova, N. A. +7 more
Heating rate calculations with the FUBRad shortwave (SW) radiation parameterization have been performed to examine the effect of prescribed spectral solar fluxes from the NRLSSI, MPS and IUP data sets on SW heating rates over the 11 year solar cycle 22. The corresponding temperature response is derived from perpetual January General Circulation Mo…
Giant flux ropes observed in the magnetized ionosphere at Venus
Luhmann, J. G.; Russell, C. T.; Wei, H. Y. +10 more
The Venus ionospheric response to solar and solar wind variations is most evident in its magnetic field properties. Early Pioneer Venus observations during the solar maximum revealed that the Venus ionosphere exhibits two magnetic states depending on the solar wind dynamic pressure conditions: magnetized ionosphere with large-scale horizontal magn…
On the Edgeworth-Kuiper Belt dust flux to Saturn
Horányi, Mihály; Poppe, Andrew R.
Dust grains originating from the Edgeworth-Kuiper Belt (EKB) are believed to be the dominant species of dust in the outer solar system. These grains, evolving inward from the EKB under the influence of a variety of forces, will encounter the giant planets or their ring and moon systems. At Saturn, this influx drives several physical processes incl…
Titan airglow during eclipse
Strobel, D. F.; West, R. A.; Gladstone, G. R. +4 more
Solar XUV photons can provide enough energy to account for the observed nitrogen UV dayglow emissions above 800 km, but a small or sporadic contribution from energetic particles cannot be ruled out. Furthermore, ion production at altitudes deeper than 800 km as inferred from radio occultation cannot be produced by solar XUV stimulation and implies…