MIST meeting
22 November 2002

Geological Society Lecture Room, Burlington House, London (enter from Piccadilly)

[Report published in Astronomy & Geophysics 44, 1.30-1.31 (February 2003)]

A. Programme B. Report C. Abstracts

MIST meeting, London, Autumn 2002

Coffee (served in the Library)

First session - Chairman: Ingo Mueller-Wodarg (UCL)

J Eastwood, A Balogh, E Lucek (IC), I Dandouras and C Mazelle (CESR), Cluster observations of waves and particles in the terrestrial foreshock
G A Abel, A J Smith (BAS), N P Meredith (MSSL) and R R Anderson (Iowa), The evolution of substorm enhanced whistler mode waves: Why is electron energy dispersion not reflected in the waves?
N P Meredith (MSSL), R M Thorne (UCLA), R B Horne (BAS), D Summers (MUN), B J Fraser (Newcastle) and R R Anderson (Iowa), Statistical analysis of relativistic electron energies for cyclotron resonance with EMIC waves observed on CRRES
Y Taroyan and R Erdelyi (Sheffield), Steady state excitation of field line resonances by global waveguide modes in the magnetosphere
A Dobbin and A Aylward (UCL), Revisiting the basics of middle atmosphere flow using CMAT
N Balan, H Alleyne (Sheffield), S Kawamura and S Fukao (Kyoto), Mean wind velocity and tidal parameters in the mid latitude thermosphere
S England and N Arnold (Leicester), The impact of gravity waves on the dynamics of the mesosphere-lower thermosphere region - recent model results
J A Wild, S E Milan, S W H Cowley (Leicester), C J Owen (MSSL) and H Frey (Berkeley), Space- and ground-based observations of the structure and dynamics of the auroral ionosphere during an interval of BY dominated interplanetary magnetic field
A J Smith (BAS), MIST announcements
Lunch (available in the Library)

Second session - Chairman: Nigel Meredith (MSSL)

R W Sims and S E Pryse (Aberystwyth), ESR line-of-sight velocities and the open/closed boundary during northward IMF in summer
J P Dewhurst, C J Owen and A N Fazakerley (MSSL), Cluster PEACE observations of thinnings and expansions of the substorm plasma sheet
B Hnat, S C Chapman and G Rowlands (Warwick), Intermittency, scaling and the Fokker-Planck approach to fluctuations of the solar wind bulk plasma parameters as seen by WIND
S C Chapman, B Hnat, G Rowlands (Warwick), N W Watkins and M P Freeman (BAS), Scaling of solar wind epsilon and the AU, AL and AE indices as seen by WIND
S W Ellacott and W P Wilkinson (Brighton), The heating of directly transmitted ions at perpendicular shocks: a new approach based on Lagrangian dynamics
K Nykyri (IC) and A Otto (Alaska), Influence of Hall effects on the Kelvin-Helmholtz instability
A N Fazakerley, C J Owen and J P Dewhurst (MSSL), Cluster PEACE observations of X-line Hall current electrons in the Earth's magnetotail?
Tea (served in the Library)

Third session - Chairman: Gary Abel (BAS)

J Scuffham, A Balogh and G Giampieri (IC), Modelling Mercury's magnetosphere
J D Nichols, S W H Cowley and E J Bunce (Leicester), Magnetosphere-ionosphere coupling currents in Jupiterís middle magnetosphere: Dependence on ionospheric Pedersen conductivity and Iogenic plasma mass outflow rate
P Hanlon, M Dougherty and G Giampieri (IC), Jovian plasma sheet dynamics
G Giampieri and M K Dougherty (IC), Modelling of the ring current in Saturn's magnetosphere
I C F Mueller-Wodarg (UCL), R V Yelle (Arizona), M Mendillo (Boston) and A D Aylward (UCL), Eclipses on Titan: Effects on its upper atmosphere
T Moffat, A Aylward and I Mueller-Wodarg (UCL), Battles with the god of war: Taming the UCL Mars model

Affiliation abbreviations:

Aberystwyth: University of Wales, Aberystwyth
Alaska: University of Alaska, Fairbanks, USA
Arizona: University of Arizona, USA
BAS: British Antarctic Survey
Berkeley: University of California at Berkeley, USA
Boston: Boston University, USA
Brighton: University of Brighton
CESR: Centre d'Etude Spatiale des Rayonnements, Toulouse, France
IC: Imperial College, London; Space & Atmospheric Physics Group
Iowa: University of Iowa, USA
Kyoto: Kyoto University, Kyoto, Japan
Leicester: University of Leicester, Radio and Space Plasma Physics
MSSL: Mullard Space Science Laboratory
MUN: Memorial University of Newfoundland, Canada
Newcastle: University of Newcastle, Australia
Sheffield: University of Sheffield
UCL: University College, London; Atmospheric Physics Laboratory
UCLA: University of California at Los Angeles, USA
Warwick: University of Warwick; Space and Astrophysics Group

MIST meeting, 22 November 2002
Meeting Report

by J A Wild (University of Leicester)

Published in Astronomy & Geophysics 44, 1.30-1.31 (February 2003)

This year's one-day autumn meeting of the MIST (Magnetosphere, Ionosphere and Solar-Terrestrial) community was held on 22 November 2002 at the Geological Society, Burlington House. Jim Wild reports.

The morning session of the meeting began under the chairmanship of Ingo Mueller-Wodarg (University College London). Jonathan Eastwood (Imperial College) presented observations of Ultra Low-Frequency (ULF) waves in the foreshock standing upstream of the Earth's magnetosphere. Employing plasma and magnetic field data from the four-spacecraft Cluster mission he was able to compare the properties of the observed waves using single and multi-spacecraft analysis techniques. Transferring the discussion to the interior of the magnetospheric cavity, Gary Abel (British Antarctic Survey) discussed why it is that the energy dispersion observed in substorm-injected electrons is not reflected in substorm-enhanced whistler waves. He demonstrated that the evolution of whistler mode waves would be controlled by a number of factors such as the electron energy distribution function, as well as diffusion and propagation effects. By studying over 800 electromagnetic ion cyclotron wave events observed by the CRRES spacecraft Nigel Meredith (Mullard Space Science Laboratory) was able to demonstrate that pitch-angle scattering due to wave-particle interactions with electrons of less than 2 MeV are found within the local time range 13-18 MLT for L > 4.5. He went on to show that these electrons are only subject to strong scattering over a small fraction of their drift orbits, resulting in drift averaged scattering lifetimes in the range several hours to a day. Youra Taroyan (Sheffield) addressed the shortcomings of many descriptions of long-period magnetic pulsations. By adopting a unified approach, rather than the separate treatment of the problems of wave excitation and resonant coupling, a new field line resonance excitation mechanism was presented that goes some way to reconciling some of the discrepancies between waveguide/cavity mode theories and observations.

In the first of three talks on the neutral atmosphere, Alison Dobbin (UCL) discussed recent developments in the Coupled Middle Atmosphere and Thermosphere (CMAT) model. The consequences of removing gravity wave drag and auroral momentum and energy inputs from the model were presented and compared with a staged turn-on of each individual process. It was suggested that during periods of low solar and geomagnetic activity, the dynamics of the middle atmosphere are influenced by the ionosphere above 100 km. Balan Nanan (Sheffield) presented incoherent scatter radar observations of variations in the diurnal mean wind velocity, and the amplitude and phase of tidal effects in the mid-latitude thermosphere. He reported that mean wind velocity and tidal amplitudes decrease with increasing solar activity and that the rate of decrease is notably faster for stronger tides. Scott England (Leicester) went on to discuss results from the newly developed Stratosphere to Thermosphere Energy Variability Experiment (STEVE). After outlining the model, the results of an investigation into the impact of gravity waves on the dynamics of the mesosphere and lower thermosphere using various gravity wave parameterisations in the model were presented. Moving on to issues of magnetosphere-ionosphere coupling, Jim Wild (Leicester) employed ground- and space-based observations of the auroral ionosphere to investigate the motion and size of the polar cap during BY dominant (BZ positive) Interplanetary Magnetic Field (IMF) conditions. He reported that the poleward boundary of the ultraviolet aurora, as observed from space, was displaced significantly equatorward from the open/closed field line boundary measured by the plasma instruments on the Cluster, DMSP, and FAST spacecraft and suggested caution in the use of UV auroral images in defining such boundaries.

Following lunch, Nigel Meredith (MSSL) took the chair. Ricky Sims (Aberystwyth) continued the discussion of the location of the open/closed boundary during IMF BZ positive conditions. Using EISCAT Svalbard radar observations of ion temperature and flow velocity in the dayside summer ionosphere, he demonstrated the existence of open flux tubes convecting rapidly away from a high latitude reconnection site and made comparisons with the Tsyganenko magnetic field model configuration in that region. Crossing to the magnetotail, Jason Dewhurst (MSSL) presented a statistical investigation into the thinning and expansion of the plasma sheet during magnetospheric substorms using data from the Cluster PEACE instrument. In addition to the expected Z-component motion, he reported a significant Y-component motion during substorms when observed in the dusk sector and, on average, differences (~ 10%) between the average plasma sheet thinning and expansion velocities.

Bogdan Hnat (Warwick) presented the first of two talks to address the multi-fractal nature of variations in geophysical time-series. A model-independent technique of differencing and rescaling was described that identifies self-similarity in the Probability Density Fluctuations (PDF) in the solar wind plasma parameters observed by the WIND spacecraft. The discussion was continued by Sandra Chapman (Warwick) who applied the finite size scaling technique to quantify the statistical properties of the fluctuations in the AU, AL and AE indices and the epsilon parameter that quantifies energy input from the solar wind to the magnetosphere. She reported that the exponents required to rescale the PDF of the fluctuations are the same for all of these quantities, that self-similarity was evident in each, and suggested that this placed important constraints on current models of the coupled solar wind/magnetosphere system. In the next presentation, Steve Ellacott (Brighton) discussed the results of a theoretical study in which the evolution of a Maxwellian ion velocity distribution transmitted through a stationary 1-D perpendicular model shock profile was investigated. By using a Lagrangian/Hamiltonian formulation of the ion equations, he demonstrated that it is possible to reproduce the stretching and rotation effects observed in such ion velocity distributions. Whilst the resultant velocity distribution remains Gaussian in the low-temperature limit, this was found not to be the case for higher temperature. In the final talk to report on recent developments in modelling and simulation, Katariina Nykyrib (IC) presented the results of MHD simulations of magnetic reconnection inside small-scale filamentary field and current structures that develop at the flank magnetopause due to the Kelvin-Helmholtz instability. She explained that due to the small scale of these current structures the MHD approximation is invalid, and that the Hall term of Ohm's law must be included. The subsequent results of 2-D Hall-MHD simulations were presented and compared with those from plain 2-D MHD models. Chris Owen (MSSL) presented electron and magnetic field observations from a different reconnection region, this time in the Earth's magnetotail. Using multi-spacecraft data from the Cluster mission, the possible signatures of Hall currents in the vicinity of a reconnection X-line were reported and compared with previous single spacecraft studies. Whilst similarities with these earlier studies were demonstrated, is was not clear whether or not subtle differences observed during this event could be reconciled in the framework of the model inspired by previous observations.

The final session of the meeting, with Gary Abel (BAS) in the chair, was devoted to planetary science. James Scuffham (IC) reported on the development of a magnetic field model of Mercury, beginning with an overview of the limited observations of the planet's magnetic field. He went on to discuss the applicability and modifications required of existing Terrestrial magnetospheric models in order to describe realistically the Hermean magnetic field, and what differences are expected between the two systems. Switching attention to Jupiter, Jon Nichols (Leicester) presented a study of magnetosphere-ionosphere coupling in the Jovian magnetosphere. By considering the breakdown in corotation of plasma originating from the moon Io, he demonstrated that magnetosphere-ionosphere coupling currents are generated and presented a realistic model of the system. Paul Hanlon (IC) used magnetic field observations from the Galileo mission to Jupiter to investigate the structure of the current carrying plasma sheet that dominates the Jovian magnetosphere. By studying many plasma sheet encounters with the spacecraft, he concluded that at distances of less than ~ 30 Jupiter Radii (RJ) from the planet the plasma sheet is ~ 4-6 RJ thick, whilst the motion of the plasma sheet due to the rotation of the planet introduced large uncertainties in this estimate at greater distances. Continuing the discussion of planetary magnetospheres, Giacomo Giampieri (IC) exploited magnetic field data from the Voyager 1 and 2, and Pioneer 11 encounters with Saturn in order to formulate a mathematical description of the Kronian ring current system. By comparing the resulting model's parameters for the three spacecraft flybys, he suggested a possible deviation from the axial and planar symmetries assumed in the model. Ingo Mueller-Wodarg (UCL) presented the expected thermospheric effects at Titan when the moon is eclipsed as it passes behind Saturn. This event, which occurs every 15 years, was simulated using a general circulation model that indicated a drop in the thermospheric temperature of ~ 20 K and the stimulation of globally propagating waves. Finally, Tracy Moffat (UCL) presented the results of recent updates to the UCL 3-D numerical model of the Martian thermosphere. The developments allow for increased flexibility and more realistic descriptions of the physical processes involved. She went on to demonstrate that the model results compare favourable with existing models whilst offering a variety of potential advantages in the future. The meeting concluded with thanks to all the contributors and chairmen.

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