The first session of the meeting was con-

vened by its host, Ian Mann (York). To

mark the successful deployment of the

four CLUSTER II spacecraft, the first 11 papers

were devoted to early scientific returns from the

mission. Andrew Fazakerley (Mullard Space

Science Laboratory) presented measurements of

electron velocity distributions from the Plasma

Electron And Current Experiment (PEACE). He

described the efforts to calibrate the four instru-

ments. The first simultaneous observations of

magnetic fields both at the magnetopause and in

the magnetosheath using the Cluster spacecraft

were presented by Elizabeth Lucek (Imperial

College). Variations between instruments was

marked normal to the magnetosheath boundary.

Malcolm Dunlop (IC) investigated the mag-

netopause dusk flank and boundary layer

using the fluxgate magnetometer. A magnetic

storm compressed the magnetopause which

permitted a detailed analysis of the magneto-

pause boundary layer. PEACE observations of

electrons in the dayside magnetopause region

were reported on by Chris Owen (MSSL). He

identified transient bursts of magnetosheath-

like plasma in the data suggestive of flux trans-

fer events with periods of order 4–8 minutes.

Jonathan Eastwood (IC) used the fluxgate

magnetometer to investigate the structures in

the solar wind and magnetosphere. In particu-

lar a sector boundary in the solar wind was

observed as the spacecraft entered and left the

magnetosheath.

Two papers from MSSL focused once more

on the PEACE instruments. Matthew Taylor

described observations of electrons in the

northern cusp region. He found an example of

two spacecraft entering the open–closed

boundary layer while the other two remained

outside. Ian Krauklis combined PEACE and

FGM measurements from two spacecraft to

observe the mid-altitude cusp. The open–

closed boundary was seen to erode due to low

latitude reconnection. Enhancements in densi-

ty may have been related to field aligned cur-

rents and flux transfer events.

Bowshock observations

After the interval, Chris Owen took the chair.

Tim Horbury (IC) presented observations of

the magnetic field at the bowshock. Detailed

observations of a number of parameters around

the bowshock could be estimated. Whistler

waves were observed that varied rapidly in

response to changing IMF conditions. Ian Bates

(Sheffield) used the wave field decomposition

method developed for the AMPTE pair of

spacecraft to determine the wave dispersion

relation for Cluster. The technique was well

suited to the study of magnetosheath waves.

Jim Wild (Leicester) studied flux transfer

events at the high-latitude magnetopause from

Cluster and ground-based instrumentation.

Bipolarizations of the magnetic field indicative

of FTEs were observed and the radars observed

pulsed poleward-moving flows. Co-coordinated

ground magnetometer and Cluster data were

also employed by Ian Mann to study

Kelvin–Helmholtz instabilities driven by solar

wind impulses. During intervals of fast solar

wind speed, the instability can bathe the flank

magnetosphere with low frequency wave power.

Moving away from Cluster, Iain Coleman

(British Antarctic Survey) presented a study of

magnetic field line draping in the dayside

magnetosheath using Geotail and Wind space-

craft data. The relationship between the solar

wind and the magnetopause became more

complex moving from the subsolar point to the

flanks. Bridget Cooling (Queen Mary and

Westfield) described results from a 3-D model

of open flux tubes along the magnetopause,

which was used to estimate the location of

reconnection and the asymmetries between the

Parker spiral direction and seasonal asymme-

tries of polar convection.

The last paper of the day was given by

Mervyn Freeman (BAS). He examined the

influence of the solar wind on the scaling prop-

erties of energy dissipation in the magneto-

sphere, using the AE index of ionospheric cur-

rents. The time series was found to have fractal

properties indicating turbulence. John Sherman

(Rutherford Appleton Laboratory) updated the

MIST community on Starlink services that are

now available and invited STP suggestions

towards forthcoming infrastructure plans.

A highlight of the meeting was the inaug-

uration of the MIST five-a-side football tour-

nament; a trophy was presented to the winning

team at the conference dinner.

The second day of the meeting was brought to

order by Alan Aylward (University College

London). David Rees (Utah/Hovemere)

described a double etalon Fabry–Perot interfer-

ometer for studying the dayside aurora using

the oxygen green line. He presented results

from several aurora in addition to day-glow in

a two-dimensional full sky image. Proton auro-

ra observations from Svalbard using several

ground and space based instrumentation were

described by Stuart Robertson (Southampton).

A shock event was monitored and the first mea-

surements of the backscatter Doppler shift of

the hydrogen-β line in the cusp were reported.

Cosmic noise intensity

Steve Maple gave the first of three talks from

Lancaster. He used the sky map of the

38.2 MHz Imaging Riometer for Ionospheric

Studies (IRIS) to determine the distribution of

cosmic noise intensity. The map is used to gen-

erate the quiet day curves. Carlos del Pozo

used IRIS and EISCAT radar observations over

three years to assess the correspondence

between absorption, electric field strength and

conductivity during substorm activity and

E-region instability conditions. John Har-

greaves examined the fine structure in auroral

absorption “spike” events, where there is a

peak lasting only for a minute or two at a sub-

storm onset. Pi2 periodicities of 15–60 seconds

were seen using wavelet analysis.

An adaptive model of the ionosphere using

radio tomography was described by R Dabas

(National Physical Laboratory, India). The

technique demonstrated a role for tomography

in near-real-time ionospheric mapping for

radio broadcasting applications. Henry Rish-

beth (Southampton) explained how the season-

al asymmetry in the F2 layer could not be

explained by the eccentricity of the Earth’s

orbit around the Sun. Tides may well account

for this phenomenon. Simulations of integrat-

ed oxygen emissions from the Coupled Middle

Atmosphere and Thermosphere general circu-

lation model were presented by Alan Aylward

(UCL) and compared with Fabry–Perot inter-

ferometer results from Sweden and Norway.

Mark Lester (Leicester) took over the chair

till lunch time. A report of progress on a major

upgrade to the CUTLASS HF radar system was

made by Tim Yeoman (Leicester). Very good

correspondence between the new, independent

operating modes was obtained, but some data

contamination needed to be resolved. Mervyn

Freeman (BAS) presented a unified model of

Meeting report

4.18 August 2001 Vol 42

Jorvik MIST

– 2001The magnetosphere, ionosphere and solar–terrestrial physics

community gathered at the Department of Chemistry, University of

York from 9–11 April 2001. Neil Arnold and Ian Mann report.

the response of ionospheric convection to

changes in the interplanetary magnetic field.

He used the model to test two conflicting the-

ories of magnetic reconnection.

Four talks were devoted to the scientific

exploitation of SuperDARN HF radar data.

Kathryn McWilliams (Leicester) presented the

first two-dimensional electric field measure-

ments of anti-sunward ionospheric flow bursts

within the footprint of newly reconnected mag-

netic flux. She used the twin CUTLASS radars

in conjunction with Defense Meteorological

Satellite Programme data. Gareth Chisham

(BAS) tested competing hypotheses of reconnec-

tion during large IMF By conditions as observed

by SuperDARN HF radar measurements of the

ionosphere. It was found that the anti-parallel

merging hypothesis matched the data far better

than the subsolar merging hypothesis. Adrian

Grocott (Leicester) presented observations of

substorm excited flows in the high-latitude

ionosphere using the radar network, magne-

tometer and spacecraft data. He provided evi-

dence that convection flows could be driven by

nightside reconnection. Finally, Emma Wood-

field (Leicester) carried out an inter-hemispher-

ic statistical study of night-time spectral width

distributions observed by two of the radars.

There were many similarities but dawn–dusk

asymmetries and seasonal variations observed

at Iceland were not seen at Syowa.

Gary Abel (BAS) compared the statistical

occurrence of pulsed ionospheric flows seen in

the ground to flux transfer events observed by

spacecraft. Power spectra indicate the former

have a turbulent “pink noise” distribution

indicative of self-organized criticality. Hina

Khan (Leicester) presented a study of the

dynamic cusp during strong IMF By conditions

using multiple ground and space based instru-

ments. Poleward-moving ionospheric flows

coincided with enhanced density and ion tem-

peratures, associated with pulsed dayside

reconnection. The morning session was con-

cluded by Steve Morley (Southampton) who

discussed the different origins of “sawtooth”

cusp features in the ion dispersions observed

by DMSP as it crossed the northern cusp

region. Changes in the signatures were likely to

be due to a change in the reconnection rates

encountered at different satellite passes.

Poloidal Alfvén waves

Proceedings for the first session of the after-

noon were directed by Tim Yeoman (Leices-

ter). Lewis Ozeke (York) described how asym-

metric ionospheric conductivities could

influence the generation of poloidal Alfvén

waves and generate modes that are not permit-

ted in the symmetric case. The so-called “drift-

bounce” mechanism may be an important fac-

tor in ring current decay processes. An

extensive survey of POLAR satellite ion distri-

bution data had been carried out by Lisa Bad-

deley (Leicester) to identify the energy sources

for particle-driven ultra-low-frequency waves.

Signatures on the spacecraft were then com-

pared with ground-based magnetometer and

radar observations of the waves.

Magnetometer data featured prominently in

the next three talks. Joe Mathews (York) was

interested in large-scale ionospheric pulsation

events. Observations indicated that the pertur-

bation was probably caused by the fundamen-

tal mode of oscillation of drifting ring current

ions. Zoe Dent (York) employed the cross-

phase technique to obtain the eigenfrequency of

the magnetic field line from two meridionally

spaced magnetometers. From this it was possi-

ble to estimate the plasma density in the equa-

torial plane and then compare the results with

in situ spacecraft data. Julia Rees (Sheffield)

analysed magnetic field data using the wavelet

transform technique. From this it was possible

to monitor the erosion of the plasmasphere fol-

lowing a magnetic storm. A simple convection

model was not sufficient to explain the results.

Antarctic studies

Andy Smith (BAS) described a campaign in the

Antarctic to study the bursts of whistler-mode

chorus waves that propagate to the ground fol-

lowing the injection of clouds of energetic elec-

trons around midnight during the substorm

expansion phase. Clare Watt (BAS) investigat-

ed the breakdown of idealized magneto-

hydrodynamics within space plasmas when

resistivity becomes important. The inclusion of

electrostatic ion acoustic waves indicated that

simple models significantly under-estimated

the true extent of the process.

Tuesday afternoon continued with a poster

session. In the first of two Cluster papers, Andy

Buckley (Sussex) highlighted the first results

from the Digital Wave Processing experiment

(DWP) particle correlator and showed electron

time structuring during both natural and plasma

sounding events. Then Malcolm Dunlop (IC)

presented first results from Cluster FGM show-

casing how to use four-point magnetic field data

to analyse the 3-D structure and motion of dis-

continuities (discontinuity analyser) and electric

current densities (curlometer).

Simon Foster (Southampton) showed that

there was a strong correlation between the lat-

itudinal spread in sunspot groups and the flux

emergence rate. The increase in coronal source

flux inferred from sunspot group observations

matched the century timescale increases in

solar flux. Continuing on the theme of the dri-

vers of geomagnetic activity, Abigail Rymer

(MSSL) presented multipoint measurements of

the evolution of a CME propagation speed

from 0–5 AU, using SOHO, Cassini, ACE

spacecraft and Earth-orbiting satellites. Youra

Taroyan (Sheffield) then examined the energy

injection into the magnetosphere resulting

from a resonant flow instability. He showed

that these surface wave resonant flow instabil-

ities could occur for shear flows below the

Kelvin–Helmholtz threshold.

Turning attention inside the magnetosphere,

Dave Milling (York) showed how the magneto-

meter cross-phase technique can be used to

infer the position of the plasmapause and track

its motion through the day. Moving lower into

the atmosphere, Mick Denton (Aberystwyth)

Meeting report

4.19August 2001 Vol 42

An artist’s impression of thefour Cluster satellites in flightover Earth, courtesy of ESA.

demonstrated an excellent agreement between

the results from the Coupled-Thermosphere-

Ionosphere-Plasmasphere (CTIP) model and

tomographic measurements of the high-

latitude ionosphere. Chris Wilford (Sheffield)

outlined the recent extension to the CTIP

model with the inclusion of He+ ions. The

revised CTIP code was validated by compari-

son with data from DMSP.

Ionospheric heating at Tromsö

Mervyn Freeman (BAS) was the chair for the

concluding series of talks for the day. FAST

satellite data had been employed by Sophie

Cash (Leicester) to characterize the effects of

3 Hz modulated ionospheric heating of the

E-region at Tromsö and the subsequent launch

of ULF waves. Variations in the electric field

measurements and a downward electron flux

from a height of 3500 km were observed. The

Tromsö heater was also used by Farideh Honary

(Lancaster) to examine artificially induced air-

glow emissions in the oxygen red and green

lines. Several theories had been proposed to

account for these emissions. Significant levels of

electron temperature enhancement were detect-

ed at the same time. Richard Horne (BAS) pre-

sented a paper on behalf of Nigel Meridith

(MSSL). They had examined the link between

enhanced substorm activity and electrons accel-

erated to relativistic energies. Using CRRES

satellite data, they showed that wave–particle

interactions were responsible for the accelera-

tion within the storm time convection electric

field. Richard Horne had also looked at the

pitch-angle distribution of energetic electrons

from CRRES during an acceleration event in the

outer radiation belt. Pitch-angle scattering

appeared to be consistent with the data.

A new auroral signature of solar wind pres-

sure pulses from the South Pole was described

by Mike Pinnock (BAS). Dynamic pressure vari-

ations in the dayside magnetopause generated

an equatorial spur in the green atomic oxygen

emission line. Alan Rodger (BAS) continued on

the theme of ionospheric signatures of pressure

pulses with a consideration of travelling convec-

tion vortices. The hemispheric asymmetry in the

magnetometer and riometer data may be

ascribed to the propagation of Alfvenic waves

from the subsolar point. The IRIS riometer was

used by Andrew Kavanagh (Lancaster) to inves-

tigate a solar wind pressure pulse. In addition to

high absorption readings at the riometer, the

STARE radar observed flow decreases and a loss

of backscattered power, while magnetometers

suggested Kelvin–Helmholtz instabilities.

The chair of the first session of the final day

was Farideh Honary (Lancaster). An overview

of the new BAS Geospace-Atmosphere Transfer

Functions programme was given by Martin

Jarvis, whereby the Antarctic between

60–200 km was to be studied to determine

long-term trends and contrast it with the Arctic.

The region is special because it is dynamically

isolated from the rest of the atmosphere in win-

ter. Owen Jones (BAS) described how the Imag-

ing Doppler Interferometer could be used to

measure winds in the upper mesosphere and

lower thermosphere. There was good agree-

ment between this instrument and a dedicated

meteor radar. In particular, confidence in the

results above 90 km was increased by the study.

Mark Clilverd (BAS) described how an MF

radar at Rothera, Antarctica was used to inves-

tigate whether the echoes in the upper meso-

sphere were consistent with Polar Mesospheric

Summer Echoes. Many of the measurements

were more consistent with turbulent diffusion

from gravity waves. Patrick Espy (BAS) used a

CCD all-sky imaging camera at Halley, Antarc-

tica, to observe optical airglow emissions.

Under good viewing conditions, atmospheric

gravity waves were found to be common in the

winter with fewer waves observed in the sum-

mer. Robert Hibbins (BAS) described in more

detail how the all-sky camera was able to

extract the airglow data from the background

signal that included stars. It was then possible

to obtain the relevant gravity wave parameters.

Simulating gravity waves

Andy Lawrence (Cambridge) presented a grav-

ity wave ray-tracing model that was used to

simulate the horizontal and vertical propaga-

tion from the surface up to mesospheric alti-

tudes. The ray paths and momentum fluxes

provided an estimate of their source and ener-

gy distributions. George Millward (UCL) pre-

sented model simulations of the thermosphere,

ionosphere, plasmasphere and electrosphere

during a geomagnetic storm. More detailed

electrodynamics compared with earlier models

resulted in a more rapid response in the atmo-

sphere to the perturbation.

Richard Balthazor (Sheffield) described how

high-speed ion flows could be sustained in the

upper atmosphere using the CTIP model. Super-

sonic shock fronts could generate heating com-

parable to that associated with particle precipi-

tation. Yuanzhi Zu (Sheffield) used the Sheffield

University Plasmasphere Ionosphere Model to

examine the subauroral topside ionosphere dur-

ing a severe geomagnetic storm. The plasma-

pause was found to move to a very low L shell.

The final session of the meeting was chaired

by Tim Horbury (IC). Mai Lam (BAS)

analysed the impact of Forbush decreases in

galactic cosmic rays on the atmosphere over

the South Pole. No observable effects were

found, contradicting the results of an earlier

study at Vostok 1000 km to the north. Mike

Kosch (Lancaster) provided a critical evalua-

tion of the horizontal thermospheric winds

measured by the Fabry–Perot interferometer

located at Skibotn, Norway. During geomag-

netic storms, the vertical wind becomes an

important factor.

Michael Mendillo (Boston University) com-

pared the ionospheric variability of Mars and

the Earth. Mars Global Surveyor provided a

number of radio occultation opportunities to

measure the ionosphere while the spacecraft was

aerobraking into orbit. Andrew Coates (MSSL)

described the first results from the CAPS elec-

tron spectrometer on board the Cassini space-

craft as it passed Jupiter on the way to Saturn.

The planet’s bow shock was greatly expanded

compared with the Voyager encounters due to

changes in the solar wind. Stan Cowley (Leices-

ter) outlined his predictions for the behaviour of

Jupiter’s magnetosphere and its influence on the

ionosphere, as Cassini passed by the planet. The

position of the auroral oval should be affected

by the strength of the solar wind.

Predicting magnetic perturbations

Matthew Owens (IC) examined the relation-

ship between the peak magnetic field intensity

and peak ion velocity of the solar wind as seen

by the ACE spacecraft. Knowing the velocity

of solar emissions, it becomes possible to pre-

dict the magnitude of the subsequent magnetic

field perturbations as experienced by the

Earth. Andy Breen (Aberystwyth) compared

the large-scale structure of the solar-maximum

solar wind determined by the interplanetary

scintillation technique and in situ spacecraft

measurements. Results were particularly good

at slow velocities.

Three talks from Imperial College brought

the meeting to a close. Alan Rees reported on a

preliminary survey of magnetic clouds

observed by the Ulysses spacecraft as it passed

from high solar latitudes to the south pole of

the Sun. There were 32 clouds observed where

smooth magnetic-field rotations with a dura-

tion of several days occurred. Jonathan Gloag

discussed the limitations of shock parameter

calculations in describing heliospheric shock

waves. Over 100 shocks were observed by

Ulysses; more than half appeared to indicate a

breakdown in the MHD approximation. Mur-

taza Gulamali observed MHD turbulence at

the Ulysses spacecraft. A numerical simulation

was used to test several wave generation mech-

anisms, including solar coronal convection

outwards into the solar wind and localized

instabilities causing a turbulent energy cascade.

The meeting concluded with thanks to all

participants, particularly the local organizer

Ian Mann. �

Neil Arnold, University of Leicester; Ian Mann,University of York. Note: much of the workreported on above is collaborative. Full programmedetails, including titles, authors, abstracts andaffiliations, may be found on the MIST Web pagesat www.nerc-bas.ac.uk/public/uasd/mist.html.

Meeting report

4.20 August 2001 Vol 42