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1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To) 

28-05-2003 Final Report 28 May 2002 - 28-May-03 


4. TITLE AND SUBTITLE 


Combined Svalbard Optical and Radar Observations for Polar Cusp/Cap 
research 


5a. CONTRACT NUMBER 

F61775-02-WE053 


5b. GRANT NUMBER 


5c. PROGRAM ELEMENT NUMBER 



5d. PROJECT NUMBER 


5d. TASK NUMBER 


5e. WORK UNIT NUMBER 


7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

University of Oslo 
Box 1048 Blindem 
N-0316 Oslo 
Norway 


8. PERFORMING ORGANIZATION 
REPORT NUMBER 


9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 


10. SPONSOR/MONITOR'S ACRONYM(S) 


EOARD 

PSC 802 BOX 14 
FPO 09499-0014 


11. SPONSOR/MONITOR’S REPORT NUMBER(S) 
SPC 02-4053 


12. DISTRIBUTION/AVAILABILITY STATEMENT 


Approved for public release; distribution is unlimited. 


13. SUPPLEMENTARY NOTES 


20040210 113 


14. ABSTRACT 


This report results from a contract tasking University of Oslo as follows: The contractor will investigate the ionosphere using meridian 
scanning photometers, all-sky imagers and the incoherent scatter radar on Svalbard. The main aim of this research proposal is to obtain a 
reliable understanding of disturbances in the polar ionosphere, which is important to current space research and its application in space 
weather activities. In particular, the contractor will focus on locating the boundary between open and closed magnetic field lines and then 
determine which processes occur on open and which one on closed field lines. 


15. SUBJECT TERMS 

EOARD, Ionosphere, Polar Cap/Cusp 


16. SECURITY CLASSIFICATION OF: 

a. REPORT 

UNCLAS 

b. ABSTRACT 
UNCLAS 

c. THIS PAGE 
UNCLAS 


17. LIMITATION OF 
ABSTRACT 
UL 


18, NUMBER 
OF PAGES 


19a. NAME OF RESPONSIBLE PERSON 

MICHAEL KJ MILLIGAN, Lt Col, USAF 


19b. TELEPHONE NUMBER (Include area code) 

+44 (0)20 7514 4955 


Standard Form 298 (Rev. 8/98) 
Prescribed by ANSI Std. Z39-18 





























SPC 02-4053 
Contract No: F61775-02-WE053 


FINAL REPORT 


on 

COMBINED SVALBARD OPTICAL AND RADAR 
OBSERVATIONS FOR POLAR CUSP/CAP RESEARCH 


by 

Professor Joran Moen, PI 
28 MAY, 2003 


Correspondence to: 

Prof. Joran Moen 
Department of Physics 
P.O. Box 1048, Blindem 
N-0316 Oslo, Norway 
e-mail: jmoen@fys.uio.no 


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distribution statement a 

Approved for Public Release 
Distribution Unlimited 




1. BACKGROUND INFORMATION 


The EISCAT incoherent radar facilities consist of 3 radar systems. The UHF (933 MHz) 
and the VHF (224 MHz) located in northern Scandinavia, and the EISCAT Svalbard 
Radar (ESR) located in Longyearbyen, Svalbard. The UHF is the only three static 
incoherent scatter radar system in the world, with a transmitting and receiving antenna 
(32 m parabolic dish) located at Tromso, and two additional receiving antennas in 
Sodankyla, Finland and Kiruna, Sweden. The Tromso VHF system has a 5000 m 2 
reflector with a meridional beam steering. ESR represents a new generation incoherent 
radar, located inside the polar cap most of the time. The system comprises two parabolic 
dish antennas sharing the same transmitter and receiver system, working at 500 MHz. 
ESR-1, is a 32-m diameter antenna, which can swing 540° in azimuth and from 0 to 180 
in elevation. ESR-2, 42 m in diameter, is a fixed beam oriented along the magnetic field 
line. The ESR radar facility is located on the mountain of Mine 7, within 6 km from the 
Longyearbyen Auroral Station. With the three EISCAT radar systems working together it 
is possible to provide a spatial radar coverage of up to ~20° in magnetic latitude, with 
high time and spatial resolution. 



Figure 1: The EISCAT radar site on Svalbard with view down the valley towards Logyearbyen 

Svalbard provides a unique platform in the Northern Hemisphere for studies of dayside 
polar cap auroras as well as related phenomena within the cusp and polar cap boundary 
layers. Svalbard is nearly 12 hours separated in magnetic time from the Alaska sector and 
its conjugacy to stations in Antarctica makes Svalbard even more attractive. The Svalbard 
climate - due to the Gulf Stream is unusual mild. Thus, there is no other place at the same 
latitudes as our stations on Svalbard in which the comforts of modem living can be 
enjoyed, and is so accessible from the world’s largest metropolises. 

The Ny-Alesund (geogr. lat 78.9°N; geomagnetic lat. 76.07°) and Longyearbyen Auroral 
observatories (geogr. lat 78.2°N; geomagnetic lat. 75.12°) are the master stations in our 


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Svalbard network. The main optical instruments are meridian scanning photometers 
(MSP) and All-Sky CCD imagers at different wavelengths. 

The CUTLASS HF radar complements the EISCAT and optical ground-measurements 
with a 2-dimensional field of view above the Svalbard archipelago. The coherent 
scattered signals from the CUTLASS radar (part of SuperDARN) constitute a powerful 
tool for investigations of both temporal and spatial behaviour of the polar cap 
electrodynamics. 

Whenever possible, our ground observations have also been correlated with in-situ 
measurements from low-altitude polar orbiting satellites (NOAA, DMSP, Polar and 
Cluster) as well as space platform observations of the solar wind (ACE, Wind and IMP- 
8 ). 


2. OBSERVATIONS CARRIED OUT 

We carried out optical campaigns at Ny-Alesund in December 2002 and January 2003. 
Observation time is listed in the table below. During the December campaign we 
operated ESR, and provided diagnostics of launch conditions for NASA’s cusp rocket 
(PI. Dr. R. Pfaff). 


Date 

Time (UT) 

Instrument 

Quality 

2002-12-01 

16:50-20:00 

ASC, ESR 

Partly cloudy 

2002-12-02 

05:15-10:35 

ASC, ESR 

Partly cloudy 

2002-12-03 

07:00-11:00 

ESR 

Overcast 

2002-12-04 

07:00-11:00 

ESR 

Overcast 

2002-12-05 

07:00-11:00 

ESR 

Overcast 

2002-12-06 

06:00-10:04 

ASC, ESR 

Partly cloudy 

2002-12-07 

17:34-23:59 

ASC, ESR 

Partly cloudy 

2002-12-08 

00:00-09:03 

ASC, ESR 

Partly cloudy 

2002-12-09 

06:15-15:08 

ASC, ESR 

Partly cloudy 

2002-12-10 

06:13-19:05 

ASC, ESR 

Partly cloudy 

2002-12-11 

05:45-12:35 

ASC, ESR 

Partly cloudy 

2002-12-12 

09:08-14:07 

ASC, ESR 

Partly cloudy 

2002-12-13 

07:41-14:42 

ASC, ESR 

Partly cloudy 

2002-12-14 

10:04-12:11 

ASC, ESR 

Overcast 

2002-12-15 

06:30-12:25,12:30-15:45 

ASC, MSP, ESR 

Clear sky 

2002-12-16 

07:30-12:53 

MSP, ESR 

Clear sky 

2003-01-02 

12:00-23:59 

ASC, MSP 

Clear sky 

2003-01-03 

00:00-23:59 

ASC, MSP 

Clear sky 

2003-01-04 

00:00-23:59 

ASC, MSP 

Clear sky 

2003-01-05 

00:00-06:30 

ASC,MSP 

Overcast 

2003-01-06 

13:08-16:12 

ASC, MSP 

Overcast 

2003-01-07 

05:20-23:59 

ASC, MSP 

Clear sky (mostly) 

2003-01-08 

00:00-23:59 

ASC, MSP 

Clear sky 

2003-01-09 

00:00-10:30 

ASC, MSP 

Partly cloudy 

2003-01-10 

05:25-12:10,16:15-23:59 

ASC, MSP 

Clear sky 

2003-01-11 

00:00-14:04, 18:30-23:59 

ASC, MSP 

Partly cloudy 

2003-01-12 

00:00-12:00 

ASC, MSP 

Clear sky (mostly) 


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3. SCIENTIFIC RESULTS 

Cusp studies based on combined ground-space observations: 

The optical observations from Svalbard is the basic element in our program of describing 
and understanding the spatio-temporal structure of the dayside aurora in terms of solar 
wind-magnetosphere interaction processes. The emphasis has been placed on the 
establishment of the ionospheric response to magnetopause reconnection events. 

The ultimate goal of these studies is to establish the magnetopause reconnection topology 
and the detailed evolution of magnetopause reconnection events as a function of IMF 
orientation. This is an important element in the process of understanding solar wind- 
magnetosphere coupling, which is a major task in magnetospheric physics. The focus is 
on multi-instrument and multi-point observations of spatio-temporal structure in the cusp 
region. Spacecraft observations (Cluster, Polar, and DMSP) have been combined with the 
continuous ground observations of the aurora and plasma convection. The latter 
observations represent a critical element in the continuous monitoring of solar wind- 
magnetosphere coupling processes. 


Auroral footprints of cusp boundary layers during magnetopause reconnection 
events: 

It has been found in recent studies that the auroral response to reconnection events 
involves a wide variety of different plasma sources and particle precipitation regimes 
which are typically manifest in the ~ 0900-1500 MLT/ 70-80° MLAT sector. We recently 
documented the coherent reconnection responses involving the different auroral 
forms/precipitations, such as the CPS, precipitation void, dayside BPS, and the 
LLBL/cusp/mantle (Papers 2, 3, 11, 13, 14). The phenomenon of poleward moving 
auroral forms (PMAFs), which has been established as a signature of pulsed 
magnetopause reconnection, also referred to as flux transfer events (Russell and Elphic, 
1978, Paschmann et al., 1982), occur within the regime of LLBL/cusp/mantle 
precipitation. PMAFs are often preceded by an auroral intensification at the 
cusp equatorward boundary, so-called equatorward boundary intensifications (EBIs), 
typically containing electron fluxes extending up to 1-2 keV energy. These auroral 
features (EBIs) are discussed in relation to specific sub-structures of cusp boundary 
layers, where strong field-aligned currents are generated, possibly due to the presence of 
viscous stresses (on open field lines), as envisaged by e.g. Sonnerup and Siebert (2003). 
The identification of the boundary layer substructure (Phan et al., 1996; Vaisberg et al., 
2001) and its auroral signature, may allow us to determine the spatio-temporal scales of 
the same boundary layer structure. The present discussion of auroral features (e.g., 
EBIs) within the context of the electron edge (Gosling et al., 1990) of LLBL precipitation 
and the dayside BPS regime (Papers 7, 14), represents one step forward towards this 
goal. 


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PMAFs in the context of plasma convection: 

In Paper 11 we combined optical auroral observations and plasma convection data 
obtained by the CUTLASS Finland radar and other radars in the SuperDARN network. 
We focused on intervals characterized by auroral events belonging to the category of 
PMAF activity. The aurora-convection events could be subdivided in two main phases. 
The initial, brightening phase, during IMF Bz < 0; By > 0 conditions, is characterized by 
enhanced westward convection and a westward-expanding auroral form in the 1200-1500 
MLT sector. In the later phase, when the auroral motion/expansion is mainly directed 
poleward, primarily in the 0900-1200 MLT sector, plasma convection in the same sector 
is also directed poleward. The latter convection events are often referred to as pulsed 
ionospheric flows (PIFs). Thus, we documented the coherent spatio-temporal evolution 
of auroral and plasma convection events that have been in previous work connected with 
a pulsed magnetopause reconnection process. 


The IMF regulation of magnetopause reconnection processes and their ionospheric 
signatures: Implications concerning reconnection topology: 

One of the big issues in magnetospheric physics today is the question of antiparallel 
versus component (subsolar) reconnection at the dayside magnetopause.These are two 
different hypothesies concerning the requirements of the amount of magnetic shear across 
the magnetopause current sheet which is necessary for reconnection to occur. According 
to one wiew (component reconnection) there is no strong restriction on the magnetic 
shear, i. e., the reconnection rate approaches zero only when the angle between the 
reconnecting fields goes to zero (Gonzales and Mozer, 1974; Hill, 1975; Cowley, 1976; 
Moore et al., 2002). The antiparallel hypothesis limits the process to regions of large field 
shear (Crooker, 1979; Luhmann, et al., 1984). Thus, very different reconnection 
geometries are predicted in the two cases during conditions of By-dominant (east-west) 
IMF orientation. In this case reconnection in the subsolar region is either present 
(component reconnection along tilted X-line) or absent (the antiparallel case). The 
different reconnection modes are expected to give rise to differences in ionospheric 
footprints in the form of plasma convection (Coleman et al., 2001; Rodger et al., 2003) 
and auroral precipitation (Papers 5, 6, 11). In a recent study (Paper 14) we pointed out 
that the ocurrence of poleward moving auroral forms (PMAFs) is restricted to a more 
limited range of IMF orientations (as parametrized by the clock angle) than previously 
thought. For example, PMAFs are found to be absent for the state of strongly south IMF 
orientation (clock angles >150 deg). A possible explanation for this behaviour, as 
suggested in Paper 14, is that PMAFs constitute an auroral signature which is uniquely 
related to antiparallel reconnection, taking place at high magnetopause latitudes. This 
interpretation is supported by a recent study (Paper 15) of isolated PMAF events 
occurring during a long interval of steady south-east directed IMF (clock angle =135 
deg.) In this case auroral brightenings in the pre- and postnoon sectors are bracketed by a 
500 km wide longitudinal gap in the auroral emission. This is taken to be a signature of 
the absence of open LLBL flux in the subsolar region. The latter is one of the predictions 
of the antiparallel merging model. Thus, we conclude that the aurora provides evidence 
complementary to that found in plasma convection data, which is in favour of the 
importance of antiparallel merging in solar wind-magnetosphere-ionosphere coupling. 


5 




Figure 1: Images from the Ny Alesund and Heiss Island imagers projected to 250 km altitude and merged 
in a common geographic frame. Notice the north-south motion of the dayside aurora and the formation of 
auroral forms from the main trace. 


In collaboration Dr. Cesar Valladares we have carried out multisite-site observations of 
the association between cusp aurora and plasma convection in the cusp polar cap (Paper 
16). Figure 1 shows six pairs of 630.0 ran images from the Heiss Island and the Ny- 
Alesund imagers that have been merged and projected into a common geographic frame 
(software developed by the University of Oslo). The top left frame (0708 UT) shows the 
cusp aurora divided longitudinally in two broad regions. This configuration persists for 
few minutes until 0710 UT when the western aurora dims and the eastern side brighten. 
There are also three forms re-brightening near the eastern end of the aurora, which are 
seen to drift poleward and increase their extension toward the west. At 0714 UT the 
main auroral trace starts retreating poleward. However, this motion is not uniform along 
the east-west extension of the aurora; the westward part seems to leap poleward first. 
This is followed by a brightening of the red and green (data not shown) line emissions 
propagating westward along the newly formed aurora. The images of 0717 and 0720 UT 
show that the intensity at the poleward boundary of the aurora decreases sharply, and the 
equatorward edge presents smaller auroral features emanating from the main band. The 
images in the bottom panels, corresponding to 0721 and 0724 UT, show that the 
equatorward auroral forms continue moving equatorward and westward. These two 
auroral forms grow from two regions that are separated in the east-west direction by 


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-1000 km, one of them located near Ny-Alesund and the other over Heiss Island. At 
0724 UT the western form, seen equatorward of the main band, continues moving 
westward and the eastern region displays a rayed structure. After 0726 UT (images not 
shown) a more stable and typical type 1 cusp auroral forms (attributed to magnetopause 
merging) at the equatorward side of the arcs described above. The cusp aurora, seen with 
both imagers, may map to an extended reconnection line located solely in the northern 
hemisphere. Future research based on data from our pair of imagers should enable us to 
test the component versus the anti-parallel merging hypothesis. 


4 . PERSONNEL 

The key persons on this project are: 

Dr. Joran Moen, Professor, University of Oslo (also at UNIS, Svalbard) 

Dr. P.E. Sandholt, Professor, University of Oslo 

Dr. Alv Egeland, Professor, University of Oslo 

Dr. Bjorn Lybekk, Senior Engineer, University of Oslo 

Mr. Espen Trondsen, Senior Engineer, University of Oslo 

and graduate students at University of Oslo. 


5. LIST OF PUBLICATIONS 

1. Sandholt, P. E., C. J. Farrugia, S. W. H. Cowley, M. Lester, S. Milan, W. F. Denig, B. 
Lybekk, and E. Trondsen, Multi-stage substorm expansion: Auroral dynamics in relation 
to plasma sheet particle injection, precipitation, and plasma convection, J. Geophys. Res., 
107(A11), 1342, doi: 10.1029/2001JA900116,2002. 

2. Sandholt, P. E., and C. J. Farrugia, Monitoring the magnetosheath-magnetosphere 
interconnection topology from the aurora, Ann. Geophys., 20,629, 2002. 

3. Sandholt, P. E., and C. J. Farrugia, Tha aurora as monitor of solar wind-magnetosphere 
interactions, in P. T. Newell and T. Onsager (editors), pp. 335-349, Earth's Low-Latitude 
Boundary Layer, Proceedings of Chapman Conference on LLBL dynamics, New 
Orleans, April 2001, Geophysical Monograph 133, AGU, Washington DC, 2003. 

4. Farrugia, C. J., and P. E. Sandholt, Magnetosphere-ionosphere coupling at midmorning 
local times: Dependence on IMF parameters, in P. T. Newell and T. Onsager (editors), 
pp.351-359, Earth's Low-Latitude Boundary Layer, Proceedings of Chapman Conference 
on LLBL dynamics, New Orleans, April 2001, Geophysical Monograph 133, AGU, 
Washington DC, 2003. 


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5. Maynard, N. C., W. J. Burke, P. E. Sandholt, J. Moen, D. M. Ober, D. R. Weimer, A. 
Egeland, and M. Lester, Observations of simultaneous effects of merging in both 
hemispheres, J. Geophys. Res., 106,24551,2001. 


6. Maynard, N. C., W. J. Burke, J. Moen, P. E. Sandholt, M. Lester, D. M. Ober, D. R. 
Weimer, and W. W. White, Bifurcation of the cusp: Implications for understanding 
boundary layers, in P. T. Newell and T. Onsager (editors), Proceedings of Chapman 
Conference on LLBL dynamics, New Orleans, April 2001, Geophysical Monograph 133, 
AGU, Washington DC, 2003. 

7. Sandholt, P. E., W. F. Denig, C. J. Farrugia, B. Lybekk, and E. Trondsen, The electron 
edge in low-latitude boundary layer precipitation in relation to auroral forms and 
activities in the 1100-1300 MLT sector, J. Geophys. Res., 107(A9), 1235, 

doi: 10.1029/2001JA005081,2002. 

8. Sandholt, P. E., A. Egeland and H. Carlson, Dayside and Polar Cap Aurora, 
Astrophysics and Space Science Library, Vol. 270 (pp. 1 -287), Kluwer Academic 
Publishers, Dordrecht, Holland, 2002 (ISBN 1-4020-0447-8). 

9. Sandholt, P. E., C. J. Farrugia, J. Moen, and W. F. Denig, The cusp in rapid transition, 
J. Geophys. Res., 107(A12), 1235, doi:10.1029/2001JA009214, 2002. 

10. Cowley, S. W. H., J. A. Davies, A. Grocott, H. Khan, M. Lester, K. A. McWilliams, 
S. E. Milan, G. Provan, P. E. Sandholt, J. A. Wild, and T. K. Yeoman, Solar wind- 
magnetosphere-ionosphere interactions in the Earth's plasma environment, 

Roy. Astron. Soc. (Phil. Trans A), in press 2002. 

11. Sandholt, P. E., J. Moen, C. J. Farrugia, S. W. H. Cowley, M. Lester, S. E. Milan, C. 
Valladares, W. F. Denig, and S. Eriksson, Multi-site ground-based observations of the 
association between aurora and plasma convection in the cusp/polar cap during 
south-eastward IMF orientation, Ann. Geophys., 21, 539, 2003. 

12. Khan, H., M. Lester, J. A. Davies, S. E. Milan, and P. E. Sandholt, Multi-instrument 
study of the dynamic cusp during dominant IMF By conditions, Ann. Geophys., in press 
2002. 

13. Sandholt, P. E., C. J. Farrugia, W. F. Denig,S. W. H. Cowley, and M. Lester, 
Spontaneous and driven cusp dynamics: Optical aurora, particle precipitation, and plasma 
convection, Planet. Space Sci., in press 2003. 

14. Sandholt, P. E., C. J. Farrugia, and W. F. Denig, Dayside aurora and the role of IMF 
|By/Bz|: detailed morphology and response to magnetopause reconnection, 

Ann. Geophys. in press, 2003. 


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15. Sandholt, P. E., and C. J. Farrugia, Does the aurora provide evidence for the 
occurrence of antiparallel magnetopause reconnection?, J. Geophys. Res., submitted 
2003. 

16. Valladares, C. E., J. Moen, P. E. Sandholt, W. F. Denig, and O. Troshichev, 
Simultaneous observations of dayside aurora from Heiss Island and Ny-Alesund, 
Geophys. Res. Lett., 29(24), 2202,10.1029/2002GL016001,2002. 


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