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Weigel's research and teaching page

This page contains descriptions of things that I have worked on, research interests and notes, the courses I have taught, and a list of some of the projects that I am involved in. There are also links to the research pages of my graduate and undergraduate students.

Contents

  1. Research
    1. Geomagnetic
      1. Long time scale
      2. Medium time scale
      3. Short time scale
    2. Radiation belt
    3. Decision Theory
    4. Dynamical systems
    5. Forecasting
  2. Publications/Presentations
    1. Publications
    2. Presentations
  3. Projects
    1. SWx Contest
    2. Autoplot
    3. ViRBO
    4. VxOware
    5. CISM_DX
  4. Education/Outreach
    1. CDS Blog
    2. CDS 101
  5. Courses
    1. 2009, Fall
    2. 2009, Spring
    3. 2008, Fall
    4. 2008, Spring
    5. 2007, Fall
    6. 2007, Spring
    7. 2006, Fall
    8. 2006, Spring
  6. Students
    1. Graduate
      1. Current
      2. Former
    2. Undergraduate
      1. Current
      2. Former
    3. High School
      1. Former
  7. Notes
    1. PI Reports
    2. SVN Projects
      1. SWF
      2. MediaWiki
    3. Unix, Sysadmin, and Hardware Notes
    4. Presentation Notes
      1. Portability
      2. Creating Bitmap images
      3. Screencasts
    5. Unfinished Notes

[edit] 1 Research

My research interests include magnetospheric physics and geomagnetism, solar wind/magnetosphere/ionosphere coupling, inverse methods for magnetospheric modeling, nonlinear dynamics, decision theory applied to rare event forecasting, scientific visualization, and collaborative software development.

[edit] 1.1 Geomagnetic

The magnetic field on Earth's surface is approximately 30,000 nT. On top of this are fluctuations of the order of 1,000 nT. These fluctuations are caused by changes in the solar wind that are mediated by the magnetosphere and ionosphere. This system can be modeled as a dynamical system of varying orders of complexity.

[edit] 1.1.1 Long time scale

Day-of-year and semiannual variation in geomagnetic activity

When the IMF points southward for an extended period of time (say, greater than on hour or so), geomagnetic activity follows (Fairfield and Ness, 1967)[1] and so it makes sense that the fact that if this average amount of "southwardness" was larger near equinox, you should observe on average more geomagnetic activity (Russell and McPherron, 1973[2]). The Russell and McPherron explanation of the semiannual variation in geomagnetic activity makes a lot of sense. Until you look at it closely. Then you may notice that the explanation provides either a variation that is much smaller than the observed semiannual variation in geomagnetic activity as has been summarized by Cliver et al., (2000)[3]. Mayaud, 1974[4][5]) noted other inconsistencies.

In Figure 3, at MLT=22:00, of Weigel and Baker, 2003 [6] you will see a pronounced semiannual variation in geomagnetic activity. The first reaction by nearly everyone who commented on this was that the peaks are "simply due to the R-M effect". However, the R-M effect predicts the peak in fall to be larger than that in spring, which is opposite that observed. It was for this reason that I began to look more closely at what the R-M (1973) explanation for the semiannual variation in geomagnetic activity did and did not explain.

Many other have noted similar problems, and a number of explanations have been proposed.

Weigel 2007[7] showed that the inconsistencies of the data with the R-M (1973) hypothesis can be resolved by simply using a more sophisticated model. This explanation does not require one to invoke a new, previously unnoticed mechanism, such as a change in response efficiency with season. One just needs to generalize the model used by Russell and McPherron, 1973 to account for the fact that the magnetospheric response to the solar wind can last many hours.

Boller and Stolov (1970) [8] proposed that an increase in the likelihood of the excitation of Kelvin-Helmholtz waves on the magnetosphere boundary could explain the semiannual variation in geomagnetic activity.

A number of recent papers have attempted to explain the semiannual variation that is not explained by the R-M [1973] hypothesis in geomagnetic activity by changes in geomagnetic response efficiency for constant solar wind input conditions (this is in contrast to the R-M (1973) hypothesis, which uses the fact that the average input solar wind conditions change) Crooker and Siscoe, 1987[9] developed a merging model which predicted a change in magnetospheric response efficiency with season. Cliver et al. (2000)[10] noted that one of the possible resolutions was a change in response efficiency. Russell et al. (2003) [11] used a MHD simulation to show the reconnection line length had a DOY variation that was similar to the DOY variation in geomagnetic activity. However, no check was made to see if the simulation actually produced a DOY geomagnetic variation consistent with the data. O'Brien et al. (2003) [12] found that the parameters of a Dst model that were related to response efficiency were consistent with the response efficiency explanation.

Newell (1998)[13] proposed that a “UV insulation” mechanism may provide a significant contribution to the semiannual variation in geomagnetic activity. (see also Lyatsky et al., (2002)[14] and Newell et al., (2002) [15].

Scurry and Russell, (1990),[16] (see also Orlando et al., (1990)[17]) who sorted the data by the direction of the IMF and claimed a confirmation of the R-M (1973) hypothesis. In fact these papers simply confirm that southward IMF drives geomagnetic activity, which is was already well established[18]

  1. ↑ http://adsabs.harvard.edu/abs/1967JGR....72.2379F
  2. ↑ http://adsabs.harvard.edu/abs/1973JGR....78...92R
  3. ↑ http://adsabs.harvard.edu/abs/2000JGR...105.2413C
  4. ↑ http://adsabs.harvard.edu/abs/1974JGR....79.1131M
  5. ↑ http://adsabs.harvard.edu/abs/1974JGR....79.1132R
  6. ↑ http://adsabs.harvard.edu/abs/2003GeoRL..30wSSC4W
  7. ↑ http://adsabs.harvard.edu/abs/2007JGRA..11210207W
  8. ↑ http://adsabs.harvard.edu/abs/1970JGR....75.6073B
  9. ↑ http://adsabs.harvard.edu/abs/1986JGR....9113393C
  10. ↑ http://adsabs.harvard.edu/abs/2000JGR...105.2413C
  11. ↑ http://adsabs.harvard.edu/abs/2003GeoRL..30rSSC5R
  12. ↑ http://adsabs.harvard.edu/abs/2002JGRA..107.1341O
  13. ↑ http://adsabs.harvard.edu/abs/1998EOSTr..79..625N
  14. ↑ http://adsabs.harvard.edu/abs/2001GeoRL..28.2353L
  15. ↑ http://adsabs.harvard.edu/abs/2002JGRA..107.1305N
  16. ↑ http://adsabs.harvard.edu/abs/1990GeoRL..17.1065S
  17. ↑ http://adsabs.harvard.edu/abs/1995JGR...10019565O
  18. ↑ http://adsabs.harvard.edu/abs/1990GeoRL..17..307B

[edit] 1.1.2 Medium time scale

One way to probe a system’s internal dynamical properties is to look at it while it relaxes. The advantage of this is that the input driver is eliminated, allowing one to look at “relaxation events”, time intervals when the input is near zero after an enhancement in activity. Given enough events, one can test various hypotheses about amplitude-dependent processes that are predicted to affect decay time scales. Previous studies of magnetospheric time scales derived decay parameters from looking at epoch averages. The problem with this is the decay time is a function of the solar wind driver amplitude, whose epoch average is non-zero. Preliminary results indicate that the relaxation time scale following a substorm is strongly dependent on the amplitude of the geomagnetic storm (Weigel and Wiltberger, 2006).

[edit] 1.1.3 Short time scale

A remarkable fact about geomagnetic fluctionations involves its statistics. To first order, the magnetosphere acts like a low-pass filter of the solar wind. This explains about 50% of the geomagnetic fluctuations observed on Earth's surface. The part not explained by the solar wind has some very interesting statistical properties that give hints into the physical processes that drive them, for example, rapid variations in ionospheric conductance. The next thing I want to look at is coupling these results to data from Polar's UVI instrument.

[edit] 1.2 Radiation belt

[edit] 1.3 Decision Theory

To date, most algorithms developed to predict a magnetospheric space weather time series involve the filtering of data measured by a satellite upstream of Earth. The filters are optimized to have the minimum mean of the square prediction errors (MSE). This is in contrast to what the users of a prediction a user wants to know: will something happen? A filter optimized to give a small MSE will not generally give the best answer to the user-relevant question. These ideas have been developed in the paper Decision theory and the analysis of rare event space weather forecast pdf.

[edit] 1.4 Dynamical systems

  • An implementation of the open-plus-closed-loop chaos control method.
  • The WINDMI model which is a more complex system that models the magnetosphere-solar wind system using a set of six ordinary differential equations. In the same way that the Lorentz model shows that a high-degree of freedom system of fluid equations reduced to a set of ODE's can exhibit nonlinear dynamics, the WINMI model shows that the same is true for a plasma system modeled with both magnetofluid and kintetic equations.

[edit] 1.5 Forecasting

[edit] 2 Publications/Presentations

[edit] 2.1 Publications

[edit] 2.2 Presentations

[edit] 3 Projects

[edit] 3.1 SWx Contest

The Space Weather Forecasting Contest is a competition to predict a few space weather environment parameters. The goal of this contest is to allow students and professionals from around the world to learn and experience about space weather by actively trying to predict it.

[edit] 3.2 Autoplot

In the VxO world, searches often return a long list of "granules" (in the form of files). The next step in usability and scientific value is to present the user a way of quickly visualizing the granules. With Jeremy Faden, we designed the program Autoplot to automatically make sense of data files, in the same way that your web browser makes sense of many file formats (png, gif, htm, xml, etc.). Underneath, Autoplot uses the das2 framework. See http://autoplot.org.




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[edit] 3.3 ViRBO

ViRBO is one of the Virtual Observatories as part of NASA's Heliophysics Data Environment program. See http://virbo.org








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[edit] 3.4 VxOware

A metadata search, discovery, accesss, version control, and edit tool. See http://vxoware.org and http://virbo.org/meta
A metadata search, discovery, accesss, version control, and edit tool. See http://vxoware.org and http://virbo.org/meta

In space physics, there is a very large effort to create standard metadata for data products [1]. The most important reason for this is to enable search; the number of data products is increasing, and with the advent of small satellites http://adsabs.harvard.edu/abs/2008SpWea...605007M, we will likely double the number of available data products in a very short amount of time (I talk more about this here [link]). In our proposal for the ViRBO project, we laid out a plan to build on an existing code base that had metadata search, discovery, access, version control, and edit functions. The developers of this code base are from GC RAS and NGDC, and as part of the ViRBO project, we have significantly extended its capabilities.




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[edit] 3.5 CISM_DX

http://bu.edu/cism/cismdx
http://bu.edu/cism/cismdx

The project goal is to coordinate the diverse contributions of analysis software, data, and visualization tools used by CISM scientists into a package of software with parts that could be built upon by researchers and used by forecasters, students, and teachers. The CISM_DX software package was initially based entirely on the extensive OpenDX module package (SPDX) by Wiltberger, Lyon, and Guild. To it we added and coordinated contributions from many other researchers and students, including tutorials, forecast models, documentation, cross-platform installs, computer labs and exercises, and time series data.






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[edit] 4 Education/Outreach

[edit] 4.1 CDS Blog

http://computationalanddatascience.blogspot.com

[edit] 4.2 CDS 101

Developing labs for CDS 101 course: http://cds101.org.

[edit] 5 Courses

[edit] 5.1 2009, Fall

[edit] 5.2 2009, Spring

Sabbatical

[edit] 5.3 2008, Fall

[edit] 5.4 2008, Spring

[edit] 5.5 2007, Fall

[edit] 5.6 2007, Spring

[edit] 5.7 2006, Fall

  • Astronomy 111 Lecture Tuesday and Thursday 9:00-10:15 am Enterprise Hall Room 80. The textbook is "The Universe, 7th Edition" by Freedman and Kaufmann.

[edit] 5.8 2006, Spring

[edit] 6 Students

[edit] 6.1 Graduate

[edit] 6.1.1 Current

  • Brian Curtis works on problems in space weather forecasting, model analysis, and general science software tools. He developed and runs the Space Weather Forecasting Contest [2] and is working on validating MHD-based magnetosphere and solar wind simulations.
  • Andrew Kercher
  • Christy Henderson is analyzing the periodicities in the solar wind observed by the Ulysses satellite in an attempt to distinguish between the different mechanisms that have been proposed to cause them, such as current sheet crossings or non-radial expansion effects near the poles of the sun.
  • Randy Bell is investigating wave particle interactions using kinetic and hybrid plasma models and comparison to observations to characterize magnetosphere transient activity.

[edit] 6.1.2 Former

  • Nathaniel Stickley implemented the Rice Convection Model algorithm in MATLAB. Eventually we will validate and test this code in a course on simulation and then use it in course magnetospheric physics for studying the role of different aspects of the system (ionospheric conductance, magnetic field model, etc.). The project left off with the code running and preliminary plots that looked as expected, but much more validation and testing is needed. Nathaniel finished his MS in Physics at GMU and now studies Astrophysics at the University of California at Riverside.
  • Juan Luna
  • Sandya Bandaru

[edit] 6.2 Undergraduate

[edit] 6.2.1 Current

[edit] 6.2.2 Former

[edit] 6.3 High School

[edit] 6.3.1 Former

[edit] 7 Notes

[edit] 7.1 PI Reports

  • http://discoverer.gmu.edu/pireports/
  • By month range
  • Use default DB, end user layer, etc.
  • Use pin for patriot web and login for patriot web
  • Commitments go thru June 9th (State Fiscal year) but last pay period is 16th
  • Do not include May 24th-June 9th as that is scheduled later
  • Faculty special payments = summer salary
  • Fringe =~ all salaries, complicated formula, 7% GRA, 7.65% Faculty summer, 36% Faculty other (clamps at a $ amount).
  • Use File->Export (not Export to File)
  • Put all items in text fields in single quotes
  • Click on arrow buttons to drill down
  • Pooled budget level is a 5-digit number which shows up in a column for Pooled Budget Summary.
  • Data refreshed daily
  • Discoverer guides https://docushare.gmu.edu/dsweb/View/Collection-2951
  • Grant with multiple funds can occur.
  • Click on fund arrow.
  • Equipment is everything > 2000
  • Use IE, Java 1.4
  • Lose value when you move from tuition to something other than equipment or subs > 25 (because of indirect).
  • New rate is 45.0% Indirect
  • Offsite is 24% Indirect
  • Grad assistants -> Select Labor
  • If pooled budget (starts with 6) -> Labor
  • Suffix is 00 means first contract -> 01 second contract under that grant
  • If you move grad student to a different grant, you need to fill out a form. Suffix starts at 00 for new grant.
  • Right click on arrow
    • Direct expenses by pooled budget means to look at all expenses with that full pooled number
    • Direct expenses "All" shows all with same pooled budget number
    • Labor summary only works on labor stuff.
  • Indirect do File->Open FIN_Labor and DE Drill -> Initial view


[edit] 7.2 SVN Projects

All projects http://aurora.gmu.edu/websvn

[edit] 7.2.1 SWF

Convert directory of eps files to a swf movie

http://aurora.gmu.edu/websvn/listing.php?repname=swf&path=%2F&sc=0

[edit] 7.2.2 MediaWiki

http://virbo.org/svn/mw

The Imgc.php extension allows
<imgc>url=http://upload.wikimedia.org/wikipedia/mediawiki/b/bc/Wiki.png</imgc>

Image from http://upload.wikimedia.org/wikipedia/mediawiki/b/bc on Nov 06 2009 20:10:02 UT

[edit] 7.3 Unix, Sysadmin, and Hardware Notes

System, Sysadmin, Unix tips, and Hardware Notes

http://aurora.gmu.edu/projects/index.php/Hardware_Software

[edit] 7.4 Presentation Notes

Things a student should know before giving a a presentation.

[edit] 7.4.1 Portability

  • If you have any equations in your document, make it more portable by embedding fonts (In powerpoint Tools-Options-Save and check Embed TrueType/Embed All)
  • If you have Powerpoint 2007, save in 2003 format.
  • Embedding Quicktime movies in PowerPoint on a Mac: http://www.pptfaq.com/FAQ00534.htm

[edit] 7.4.2 Creating Bitmap images

  • Know the difference between a bitmap and vector file format. Always create a .ps or a .eps first. Then convert it to png. See Hardware_Software#Ghostscript for information on how to make the image clear. Do not use JPEG (text will not be clear when defaults are used).

[edit] 7.4.3 Screencasts

[edit] 7.5 Unfinished Notes

http://aurora.gmu.edu/projects/index.php/Notes

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