ClusterThemisGBO Workshop - PowerPoint PPT Presentation

Title: ClusterThemisGBO Workshop


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Cluster(Themis)-GBO Workshop

• V. Sergeev , M. Kubyshkina,
• S. Dubyagin, S. Apatenkov (SPbU)
• CONTENT
• THEMIS MIRACLE\Image conjunctions, recent
  events
• THEMIS SPbU efforts to get more accurate
  models (routine procession event
  oriented modeling)
• Importance of SW flow direction to get accurate
  mapping

2
THEMIS MIRACLE\Image conjunctions

• Major conjunctions over Canada, BUT
• Very interesting SC configurations conjugate to
  MIRACLE are possible
• A good example recent near-radial alignments of
  T1(B) and T2(C) near midnight - to study
  dipolarizations and plasma injections into the
  inner magnetosphere
• Recent injection event list
• Dec. 19, 2007 2120?
• Dec. 23, 2007 2115?
• Dec. 27, 2007 2132, 2220,
• Dec. 31, 2007 2010
• Jan. 04, 2008 2024, 2126 Q
• Jan. 08, 2008 2100, 2130,

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THEMIS MIRACLE conjunctions one example -
Dec.27, 2007 events

• th-B th-C
• 2132 UT
• -10.2, 0.2,-3.8 , -7.1, 0.9, -2.3
• 2220 UT
• -11.4, -.3, -4.4 , -8.5, 0.3, -3.0
• C - close to magn. equator
• Nice LANL injections (incl. DEH)

4
THEMIS MIRACLE conjunctions one example -
Dec.27, 2007 events (2)

• Ground magnetograms Pi2
• location
• timing, activations

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THEMIS MIRACLE conjunctions one example -
Dec.27, 2007 events (2)

• SW trigger?? Cluster
• Some auroral data exist (LYR)
• EISCAT ? CUTLASS ?

6
THEMIS MIRACLE\Image conjunctions

• Recent injection event list
• Dec. 19, 2007 2120?
• Dec. 23, 2007 2115?
• Dec. 27, 2007 2132, 2220, LYR
• Dec. 31, 2007 2010 MUO,LYR
• Jan. 04, 2008 2024, 2126 Q
• Jan. 08, 2008 2100, 2130,
• Mostly weak events (PBU-like), easier for
  studies with radars

7
Observation-based Tuning of
Magnetospheric Models for ????IS
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Mapping

• Mapping ionosphere ? magnetosphere -
  essential part of THEMIS
• ( THEMIS 5 SC dense conjugate ground
  network )
• How to do?
• Routine application of standard models
• Change/tune models to achieve best accuracy
  possible
• Standard tools available Empirical models
  (T96, T01, T03,TS05 ...) parametrized by solar
  wind/activity (Pd, By, Bz, Dst) input
• Problems?
• SW data are delayed
• SW data may not be accurate (inhomogeneous SW,
  wrong time shift, )
• Model often inadequate for unusual/extremal
  configurations which often
  are the most interesting to explore
• Which (of different!) models works best??
• General problem--What is the mapping accuracy?
  

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Adapted models for THEMIS , our approach

• THEMIS has a large potential for
  tuning/adapting the model using in
  situ magnetic observations
• 5SC , cover large distance range (10-30Re),
  allow to resolve amplitudes of different
  components (RC, tail modules, etc) in the model
• may include data of other magnetospheric SC
  (GOES, Geotail,..) and additional resources
  (Isotropic Boundaries, plasma pressure etc,
  e.g., Kubyshkina et al., JGR 2002)
• our approach - combine careful modeling of
  individual events (by expert) with
  routine processing (tuning)
• A simple approach selected for routine
  procession in THEMIS
• Main ideas
• Use standard models as a tool to interpolate B
  observed at 5() SC
• Treat SW parameters as input parameters of the
  model varying to obtain best fit to observations
• Restrain from changing internal parameters of
  models (to avoid unphysical effects, examples
  later..)
• Use SW flow deviation angle ? as additional
  free variable
• Output for users Pd, Bz, By, Dst, ?
  to use with GEOPACK-2007

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Testing the routine tuning algorithm

• Current state of activity
• Test on synthetic events
• Use THEMIS predicted orbits and past SW data
  (Feb.25-27, 2008/2001)
• Simulate observed B from T01 model,
  reconstruct using T96 model

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Testing the routine tuning algorithm (2)

• Tests on real events
• before Dec.15 bad X-coverage
• January 2008 data (in progress)
• An example of Jan.06,2008 (Qday)
• No Tilt ,
• Compare mapped footpoint latitudes for standard
  T96 and 2 tuned model codes
• Deviations up to gt5 degrees.
• Larger deviations if using tilts as free
  parameter /which part is real??/
• (pressure test/usage in tuning)
• Still in working stage

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Beta-version of the new release of the
Geopack-2007 fortran package /by
N.Tsyganenko/ New features(i)- includes
transformations to and from the GSW (solar-wind
magnetospheric) coordinate system. The new
version allows one to trace model field lines,
taking into account the observed deflections of
the solar wind from strictly radial
anti-sunward direction. (ii) - the s/r TRACE
was modified by adding 3 new input parameters, to
make it more 'tunable', (iii) - a new
subroutine GEODGEO was written and added to the
package,converting geodetic coordinates to
geocentric and back. Available at
http//geo.phys.spbu.ru/tsyganenko/
Updated Geopack-2007 fortran package
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• E N D

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?????????? (tail season) - ??????, ????? ??????,
?????

• 1/ ??????????? ?????? ?96 (?!) ? ????? 5??? (?!),
  ????????
• ?) ? ??????? ?????? (1??? \ 4?????)
  ?????? / ?????
• ? T96-00? (?????? ? THEMIS, ??0)
  1 \ 0
• ? T96-01? (?????? ? THEMIS, ???0)
  1? \ 0
• ?) ?? ????????? ???. ?????? (GOES, Polar??,
  GT??,)
• ? T96-02? (?????? ? , ???0)
  1 \ 0
• \?????? ?????? ?????????\
• ?) ?? ????????? ??????. ???????? (1??????)
  
• ? T96-03? (? ? , ???0)
  0? \ 0
• ?) ?? ????????? ?????? ?? ?? ????????? (1??????)
  
• ? T96-04SW (??? ??????????, ??? ??????. ? )
  1? \ 0
• ?) ??? ?????? ??????? ()
• ? T96-05?? (?????? ??????????, ??? ??????.
  ???) 1? \ 0

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?????????? (tail season) - ??????, ????? ??????
(2)

• ?????
• 5 (x,y,z)
• 5(Bx,By,Bz)OBS ( 5 SC?n SC)
• ????????? ?????? ?96 (Pd,Dst,Bz,By, ??)
• ? ??????????? N ?? (-6.6, 0, NS), (-10, 0,
  NS)?, (-15, 0, NS),
• ???? ??????. ?????????,
• ? ???
• ???????????
• ?) ?????? ??? Rgt4Re ???? ? ??????? ?????? (???
  ?????? ????.???????)
• ?)
• ????? ???????????? ?????? ????????? ???????????
  ?????? ? ????????? ??

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?????????? (tail season) - ?????? (3)

• 1/ ??????????? ?????? ?96 (?!) ? ????? 5??? (?!),
  ????????
• 2/ ? T96-05?? - ?????? ??????????, ???
  ???.????????
• - ????. ??????????????? ????? ?????.????????
• ????. ??????????? ???????? ??????? ??????????????
  ????? ??????? ?????? ,
• ??????????? ???????????? ??? ? ???????
• 3/ ???????????? ? ??????? ???????????? ???????
• ???????? ??????????? ??????? (? ?.?. ?? ??????
  ??) ?????? ???????? ????????
• ????????????? ?????? ???????????? ??? ? ???????
• ???????? ?????????? ?????????? (BL, FT,
  ????????) ? ????????
• ???????????? SCW ?????? ?????????????? ??????

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Testing a simple tool Mapping latitudes

• Compare performance of T96 and T01 models, and
  accuracy of reconstruction/mapping by using T01
  model as input and reconstructing parameters of
  T96
• Reasonable quality of mapping (lt1deg CGLat),
  incl. stormy time (t60) for T2..T5
• Systematic deviations for T1 (T01 domain is
  rlt15Re)
• Large mapping error (t70) when many SC stay in
  near-Earth region

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A simple tool for mapping Conclusion

• Usage of T01/T96 models as interpolation/extrapol
  ation tool
• provides reasonable reproduction of
  magnetospheric B-field and satisfactory (lt1deg
  CGLat) mapping accuracy for large part of THEMIS
  observation time in the central tail (February)
• Usage of different models simultaneously allows a
  rough accuracy estimate
• Routine output of THEMIS-based B-fields
  procedure at
  (5-10min? Step)
• Input parameters of T96 (T01..) model (e.g.
  Pd, By, Bz, Dst, recommended for use in any
  kind of mapping
• Quality indicators to characterize potential
  problems (in case of clustering near perigee or
  near the neutral sheet, magnetopause etc)
  still in work
• Applicability domain during tail THEMIS orbits
  (others-??)

19
Advanced tool assimilative data-tuned model
Choice of a model to modify (any model with
free parameters) A Pulkkinen T.I., A Study
of magnetic field and current configurations in
the magnetotail at the time of the substorm
onset, Planet.Space Sci., 1991. Kubyshkina
M.V. et al., Hibrid Input AlgorithmAn event
oriented magnetospheric model, JGR, 1999.
Used T89 with modifications inserted
-         Additional tilt of the neutral sheet
(1 free parameter) -         Ring current
enhancement (1 free parameter) -         Surface
currents enhancement (1 free parameter) -        
Tail current enhancement (1 free
parameter) -         Tail current thinning (5
free parameters) -         Including an
additional thin current sheet of the similar
geometry (5 free parameters)

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Input data for modelling
Main sourceB-field measured at spacecraft -
Usual problem - lack of data too few spacecraft
in occasional positions  Possible
solutions   A use time-varying models with
predetermined behaviour of free parameters
(linear) T. Pulkkinen, G. Lu et al.   B add to
magnetic field data all the possible measurements
that may be reproduced from the adjusted model
(Kubyshkina et al, Ganushkina et al.)  This may
be 1) Isotropic boundaries for ions and
electrons of different energies
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Input data for modelling
2) ?B angle measured by LANL spacecraft
determines the B-direction as a symmetry axis of
temperaure matrix T (angle between symmetry axis
and spin axis of the spacecraft). Available if
Tpar/Tperp not close to 1
3) Pressure value measured at magnetospheric
spacecraft. Needed pressure balance across the
magnetotail Blobe observed 2µ0(PplasmaspcPmagn
spc)1/2 Blobe modeled Bmod(xspc, yspc,zspc5Re)
4) Pressure measured at low altitude in the
region of isotropic presssure
needed isotropy of Pressure so that gradPJ?B
and pressure is conserved along the B-line
5) Dst value but difficult to take in account
all the sources of measured Dst