Smitha Thampi, Diwakar Tiwari, Ruigang Wang, Hui Zhang, Ling Qian Zhang, Yihua Zheng

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Smitha Thampi, Diwakar Tiwari, Ruigang Wang,Hui
Zhang, Ling Qian Zhang, Yihua Zheng Tutor Robert
L. McPherron
Presentation atCOSPAR Capacity Development
Workshop Beijing, China - May 13, 2004
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Introduction Scientific Background

• Geomagnetic storms, in which the global
  geomagnetic field intensity decreases some tens
  to hundreds nT, are a large scale manifestation
  of solar wind-magnetosphere-ionosphere coupling.
• Geomagnetic storms develop when solar
  wind-magnetosphere coupling is intensified by
  solar wind disturbances such as corotating
  interaction regions (CIR) or coronal mass
  ejections (CME).
• Types of Geomagnetic storms CME driven, CIR
  driven, Alfven wave driven (?), orbital geometry
  (dipole tilt angles)

Solar maximum (CMEs)
Solar minimum (CIRs)
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Introduction Scientific Background --- continued

• Characteristics (view of the present) the storms
  driven by the fast CMEs are usually very intense
  (Dst lt-100 nT) and of short duration.
• Storms diven by CIRs are usually weaker with
  irregular main phase and long recover phase
  lasting many days to weeks. They cause High
  Intensity Long Duration Continuous AE Activity
  (HILDCAAs). Since they are caused by recurrent
  high speed streams, they occur regularly and are
  ordered in time.
• Importance Although CIR storms are weak, they
  may be very important in generating relativitic
  electrons (semiannual variation of killer
  electrons and Dst in solar minimum), which are
  detremental to spacecraft, human in space and so
  on. gt
• Focus of the proposal Characteristics of CIR
  storms and the how they differ from other types
  of magnetic storms

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CIR storms killer e- fluxes
High flux of killer electrons appear in solar
minimum
Killer electrons' semiannual variation
Dst also has semiannual variations
gt solar min storms correlate with killer
electron fluxes
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Scientific Objectives

• Scientific objectives to understand the
  characteristics, and the differences and
  similarities of the solar origin (the driver) of
  the two types of magnetic storms and the
  differences and similarities of the ionosphere's
  responses to the two-type storms via auroral
  activities. Specifically, we will use 40 years of
  solar wind and IMF data along with other
  necessary parameters to study
• Difference (if any) between CME and CIR Storms
  (solar wind and IMF para.)
• Distribution of AE during CME and CIR storms
• Duration of AE disturbances in the recovery phase
  of two types of storms
• The role of Russell-McPherron effect on CIR
  storms
• Effects of the two storm types on relativistic
  electrons
• Other Ionospheric effects caused by the two
  types.

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Investigation of a Recent Conjecture

• Substorms in the recovery phase of CIR storms are
  driven by Alfven waves and may have properties
  different from substorms in other types of storms

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Significance of the proposal

• Scientifically this investigation will help in
  better understanding the following outstanding
  questions related to geomagnetic storms a) the
  role of solar wind density in storm growth? b)
  How do the properties of storms change with the
  solar cycle? c) Does storm development depend on
  season and universal time?
• Pratically with better understanding of the
  driver characteristics of two types of storms
  during solar minimum and solar maximum, it will
  help us in a better definition of forecasting
  procedure from the solar origin, which is crucial
  in space weather forecasting.
• Relativistic (killer) electrons are
  detremental to satellites, human in space and can
  also create great damage on the ground. They are
  known to have high fluxes during solar minimum
  and are possibly correlated to CIR driven storms.
  Understanding their relationship is very
  important for reducing or minimizing their
  damaging effects.

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Significance (Ionospheric)--continued

• Magnetic activity affects significantly to the
  EITS (Equatorial ionosphere thermosphere system
  i.e. equatorial electrojet (EEJ), equatorial
  ionization anamoly (EIA), Counter equatorial
  electrojet (CEEJ), equatorial spread F etc.)
  processes.
• Many of the unresolved problems i.e day-to-day
  variability of the occurence/non occurence of
  Equatorial spread F need to be understood from
  the magnetosphere-ionosphere coupling.
  Nowcasting/forecasting of the ESF is important
  for the navigation (i.e. GPS reciever).

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Approach Preliminary Work

• Acquire Data sets
• OMNI data
• AE, AL, Dst geomagnetic indices are from Kyota
  website
• Synchronous relativistic electron fluxes
  (Aerospace)
• Ionospheric data from equatorial or low, mid and
  high latitude stations, i.e. Ionospheric
  Coherent/incoherent scatter radar, ionosonde
  (EISCAT, SuperDarn and JULIA radar data)
• Perform Preprocessing
• Data editing and creation of Matlab binary files
• Develop Analysis tools
• Plot solar wind and IMF data along with AE and
  Dst indices to select events and then the
  significant times (CIR stream interface CME
  storm interface) for further analysis (done using
  an automated boundary selector)
• Use Matlab built-in functions and/or procedures
  (pdf, cdf) and also develop necessary software to
  perform superposed epoch and statistical analysis
  and display tools
• Data analyis tools on high resolution parameters
  (such as AE) will be needed for result
  interpretation.

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Data Analysis Summary

• Combine next four slides

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Approach Creation of Lists

• Creation of Event lists for entire history of
  solar wind
• Obtain existing lists of storms, CIR, sector
  boundaries, interplanetary shocks, magnetic
  clouds
• Define reference time to be used for each type of
  event
• Make lists consistent by interactive selection
  tool
• Define subsets of events for detailed analysis
• Solar max storms
• Solar min storms
• CME driven storms at max and min
• CIR driven storms at max and min
• IP shock driven storms
• Cloud driven storms
• Also equinox and solstice storms at these times

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Existing lists of different subsets
CME event list http//lasco-www.nrl.navy.mil/cmel
ist.html (1998-2003) Storm and solar events
http//data.engin.umich.edu/intl_space_weather/ sr
amp/SHINE_GEM_CEDAR.html
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Approach Variables to Study

• Solar wind and IMF parameters, Vsw, n, DP, Ey,
  IMF Bz, By, Mach number, plasma beta
• Auroral activity AE, AL, AU
• Ionospheric parameters Electric field, electron
  density, electron and ion temperature,
  composition

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Approach Analysis of Event Lists

• Illustrate general properties with examples
• Perform superposed epoch analysis on important
  variables in every list saving quantile traces
• Create aggregate cdfs for different lists and
  different intervals relative to reference times

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Details on analysis approachInteractive Tools
An example of how to find CIR recurrent high
speed stream interface

• Display solar wind parameters defining streams
• Set cross hair at zero crossing of azimuthal flow
  angle
• The interface is located on velocity gradient
  just after density decrease and B field maximum
• Magnetic activity begins before the interface and
  maximizes shortly after

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Clouds driven storm interface identification
When Bz has a northward crossing
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Superposed Epoch Analysis

• Fixed length segments of data are selected, time
  of stream interfaces at their center
• Data are stored in rows of an ensemble array
• Statistics of the distribution of values are
  taken at each epoch time
• The distributions are characterized by quartiles
• Velocity reaches a minimum about 6 hours before
  the interface and a maximum about 48 hours after
  the interface

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Comparison of Quantiles for CIR and Magnetic
Clouds
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An Example CDF Comparison
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Preliminary Results
Cumulative probability distribution function

• We have combined data from all epoch times before
  and after the boundary for both the solar min and
  solar max storms
• We then calculate cdfs for each subset and
  compare the distributions for different variables
• Solar max storms seem to have higher AE both
  before and after the stream interface, but the
  Dst distributions are almost identical

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Interpretation of Results

• We can look at the Cdf of AE, AL, or derivatives
  of them to determine if there are differences
  during two types of storms and identity the
  driving mechanism.

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Work Plan (1 year)

• Data Downloading Ruigang Wang and Hui Zhang
  (1month)
• Software development Diwakar Tiwari, Smitha
  Thampi (1 month)
• Literature search and knowledge enhancement
  Yihua Zheng and Ling Qian Zhang (1 month)
• These are done simultaneously.
• Event selection and data analysis divide and
  conquer, each of
• the team members perform the investigation for
  several years (10 month)
• Interpretation of the results all (1 month)

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References
1. Gonzalez, W. D., B. T. Tsurutani and A. L. C.
Gonzalez, Interplanetary origin of geomagnetic
storms, Space Sci. Rev. 88, 529-562,1999 2.
Kamide, Y., R.L. McPherron, W.D. Gonzalez, D.C.
Hamilton, H.S. Hudson, J.A. Joselyn, S.W. Kahler,
L.R. Lyons, H. Lundstedt, and E. Szuszczewicz,
Magnetic storms Current understanding and
outstanding questions, in Proceedings of the
Chapman Conference on Magnetic Storms, pp. 1-19,
American Geophysical Union, Jet Propulsion
Laboratory, Pasadena, CA, 1997. 3. McPherron,
R.L., Physical processes producing magnetospheric
substorms and magnetic storms, in Geomagnetism,
Vol 4, edited by J. Jacobs, pp. 593-739, Academic
Press Ltd., London, England, 1991. 4. O'Brien,
T.P., Empirical Analysis of Storm-Time Energetic
Electron Enhancements, Unviersity of California
Los Angeles, Los Angeles, 2001. 5. O'Brien,
T.P., R.L. McPherron, D. Sornette, G.D. Reeves,
R. Friedel, and H.J. Singer, Which magnetic
storms produce relativistic electrons at
geosynchronous orbit?, Journal of Geophysical
Research, 106 (A8), 15533-44, 2001. 6.
Tsurutani, B. T., and W. D. Gonzalez, The cause
of high-intensity long-duration continuous AE
activity (HILDCAAS) Interplanetary Alfven wave
trains, Planet. Space Sci., 35, 405-412,
1987. 7. Tsurutani, B.T., and W.D. Gonzalez, The
causes of geomagnetic storms during solar
maximum, presented at Eos Trans. AGU, 1994. 8.
Tsurutani, B.T., W.D. Gonzalez, and Y. Kamide,
Magnetic storms, Surveys in Geophysics, 18,
363-383, 1997.
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Extras
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Preliminary results
Solar maximum
Solar minimum

• Note we used stream interfaces at both minimum
  and maximum and that this may not be correct
• Less change in velocity at interfaces near solar
  maximum
• Much less density change at maximum
• Dynamic pressure peak is broader for max storms
  this may be a phasing problem resulting from
  difficulty in picking a reference time
• Time variations of AE is more sharply peaked in
  CIR storms
• Dst decrease is larger in solar max storms

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Preliminary results

• Comparison between CIR (1995) and CME (2000)
  driven storms
• Parameters shown (Vsw, IMF Bz, Mach number,
  plasma beta, AE, Dst)

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Superposed Epoch analysis for Clouds driven
storms (1995-2001)
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Motivation---some open questions in Solar Cycle
Variations in Storms

• Is there a difference between storms at solar
  minimum and maximum?
• Do solar minimum storms develop differently from
  solar-max storms?
• Do these storms last longer?
• Does the occurrence rate of substorms, SMC,
  Sawtooths in different phases of a storm change
  with solar cycle?
• Why are there more killer electrons at solar
  minimum?
• Why is there a strong semiannual and universal
  time variation in occurrence and size of storms
  at solar minimum?
• What physical effects are the cause of the
  semiannual variation in Dst?
• What effects do Alfen waves in high speed streams
  have on storms?

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