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Ann. Geophys., 23, 2785-2801, 2005
www.ann-geophys.net/23/2785/2005/
© European Geosciences Union 2005
The STAFF-DWP wave instrument on the DSP equatorial spacecraft: description and first results
N. Cornilleau-Wehrlin1, H. St. Alleyne2, K. H. Yearby2, B. de la Porte de Vaux1, A. Meyer1, O. Santolík3, M. Parrot4, G. Belmont1, L. Rezeau5, O. Le Contel1, A. Roux1, D. Attié1, P. Robert1, V. Bouzid1, D. Herment1, and J. Cao6
1CETP/IPSL, 10-12 Ave de l’Europe, 78140 Vélizy, France
2University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
3Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 PRAHA 8, Czech Republic
4LPCE, 3A Av. de la Recherche Scientifique, 45071 Orléans Cedex 2, France
5CETP/IPSL/UPMC, 10-12 Av. de l’Europe, 78140 Vélizy, France
6CSSAR, Chinese Academy of Sciences, No 1, Nan Er Tiao, Zhong Guan Cun, Haidian District 100080, Beijing, People’s Republic of China
Abstract. The STAFF-DWP wave instrument on board the equatorial spacecraft (TC1) of the
Double Star Project consists of a combination of 2 instruments which are a
heritage of the Cluster mission: the Spatio-Temporal Analysis of Field
Fluctuations (STAFF) experiment and the Digital Wave-Processing experiment
(DWP). On DSP-TC1 STAFF consists of a three-axis search coil magnetometer, used to
measure magnetic fluctuations at frequencies up to 4 kHz and a waveform
unit, up to 10 Hz, plus snapshots up to 180 Hz. DWP provides several onboard
analysis tools: a complex FFT to fully characterise electromagnetic waves in
the frequency range 10 Hz-4 kHz, a particle correlator linked to the PEACE
electron experiment, and compression of the STAFF waveform data. The
complementary Cluster and TC1 orbits, together with the similarity of the
instruments, permits new multi-point studies. The first results show the
capabilities of the experiment, with examples in the different regions of
the magnetosphere-solar wind system that have been encountered by DSP-TC1 at
the beginning of its operational phase. An overview of the different kinds
of electromagnetic waves observed on the dayside from perigee to apogee is
given, including the different whistler mode waves (hiss, chorus, lion
roars) and broad-band ULF emissions. The polarisation and propagation
characteristics of intense waves in the vicinity of a bow shock crossing are
analysed using the dedicated PRASSADCO tool, giving results compatible with
previous studies: the broad-band ULF waves consist of a superimposition of
different wave modes, whereas the magnetosheath lion roars are right-handed
and propagate close to the magnetic field. An example of a combined Cluster
DSP-TC1 magnetopause crossing is given. This first case study shows that the
ULF wave power intensity is higher at low latitude (DSP) than at high
latitude (Cluster). On the nightside in the tail, a first wave event
comparison - in a rather quiet time interval - is shown. It opens the doors
to future studies, such as event timing during substorms, to possibly
determine their onset location.
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