Table of Contents ====================================================================== 1. 2012 GEM Tutorials Are Available at GemWiki 2. 2012 WORKSHOP REPORT: Metrics and Validation Focus Group ====================================================================== *************************** ** THE GEM MESSENGER ** *************************** Volume 22, Number 23 September 5, 2012 ---------------------------------------------------------------------- 1. 2012 GEM Tutorials Are Available at GemWiki ---------------------------------------------------------------------- From: Peter Chi All the tutorial talks presented at the 2012 Summer Workshop are now available online on the Tutorials page on GemWiki at http://aten.igpp.ucla.edu/gemwiki/index.php/GEM_Tutorials. Below is the list of the 2012 GEM Tutorials: 1. Harry Warren - Supra Arcade Downflows and Evidence for Magnetic Reconnection in Solar Flares 2. Harlan Spence - Radiation Belt Reflections: Peering Back and Looking Forward to the Radiation Belt Storm Probes Mission 3. Bob Strangeway - The Magnetospheric Cusp: Solar Wind-Magnetosphere- Ionosphere-Thermosphere Coupling 4. Mona Kessel - Science of NASA's Radiation Belt Storm Probes 5. Misha Sitnov - Empirical geomagnetic field modeling 6. Paul Cassak - Theory of Magnetic Reconnection for Magnetospheric Applications 7. Dick Wolf - Transport From the Tail to the Inner Magnetosphere We are grateful to these tutorial speakers for providing their presentation materials. ---------------------------------------------------------------------- 2. 2012 WORKSHOP REPORT: Metrics and Validation Focus Group ---------------------------------------------------------------------- From: Lutz Rastaetter , Tim Guild, Masha Kuznetsova, and Howard Singer The Metrics and Validation Focus Group held two sessions at the summer workshop focusing on recent progress in the GGCM Modeling Challenge (session 1) and "Measuring Models Climatologically" (session 2). Both sessions were held on Wednesday, June 20th, were well attended and included lively audience participation. The first session, titled "GGCM Modeling Challenge" focused on scientific geospace models under evaluation for use in space weather operations. This activity aids the transition of models from research to operations, but is also effective for validating models, discovering where new physics needs to be included, and accelerating the installation of new model versions at CCMC for use by the scientific community. Lutz Rastaetter opened the session by introducing the project. This geospace model validation project is built upon the ground magnetic perturbations (delta-B) community-wide metrics study initiated in the summer of 2008. Phase I of the project focused on the time derivative of the horizontal magnetic field vector dB/dt at a set of preselected ground stations. NOAA SWPC is planning to utilize the results of this geospace model validation project in their selection of operational geospace model. Three global MHD magnetosphere models (SWMF v20110131, OpenGGCM v4.0, and LFM-MIX vLTR- 2_1_1) and two empirical delta-B models (Weimer and Weigel) participate in this activity. Lutz described the tool developed at CCMC that extracts the ground magnetic field perturbations from the global MHD model outputs (through integration over magnetospheric and ionospheric current systems). The sensitivity of the results to methods of dB/dt calculations (e.g.,the CCMC post-processing tool vs. run-time calculations implemented in SWMF); and to ground station locations were discussed. Everybody agreed that all time series to be used in the final metrics study should be made available for download at the CCMC ftp site and for on-line ploting using an interactive on- line ploting tool. It was also agreed that the results will be used as a basis for the second round of the delta-B metrics study that will illustrate models’ progress over time (2011 vs. 2008). Antti Pulkkinen described the process of metrics format selection and presented the final results of the threshold-based metrics with crossings of thresholds (0.3, 0.7, 1.1 and 1.5 nT/s) detected using 20-min analysis window length. The first draft of the joint paper on geospace model validation to be prepared by September 1st. Information in the paper will be included in the CCMC report to NOAA SWPC. The second half of the session was focused on another important parameter - the regional K index. Several new metrics that could be used for this study and would be useful for SWPC, were proposed and presented by Howard Singer. Dan Welling presented his approach on how to extract region K from model outputs. It was agreed to build upon D. Welling's study and continue the discussion at the GEM mini-workshop in San Francisco. M&V Focus group leadership transition and mid-term report preparation were discussed. The following GEM metrics studies were recommended for continuation: * Regional K (in support of operational geospace model selection and model scientific capability) * A second round of the delta-B metrics study to trace models' improvement over time It was also agreed to continue the Joint GEM-CEDAR Challenge initiated at the 2011 Joint Workshop and to arrange an additional session at the next GEM-CEDAR session. Metrics studies to be addressed by the GEM- CEDAR Challenge will include: * Auroral Oval Boundaries * Joule Heating in the Ionosphere * Role of magnetosphere drivers on the ionosphere. The second session, titled "Measuring Models Climatologically" was intended to solicit some new ideas about model validation from the GEM community. Historically, the majority of model validation exercises have been focused on comparing model output to short time-series of observations, such as geosynchronous magnetic field observations or Dst during a storm. This session solicited ideas and presentations devoted to non-standard methods of model validation, especially over "climatological" intervals (weeks to years). Climatological validation of a model is complementary to validating the dynamics during a storm, ensuring that the model performs well "on average," and also aids in identifying missing physics in models where there is a difference between model and observation. Despite this call for long-term (climatological) validation presentations, the contributed presentations focused more on "global" or "statistical" validation exercises, a good example of the GEM community steering the topic to their interests. Tim Guild opened the session by summarizing what climatology means for space science, and what science questions long-term modeling is well- positioned to answer. Slava Merkin described some comparisons between simulated high-resolution LFM field-aligned current (FAC) patterns and globally-distributed field aligned current patterns derived from Iridium observations under the AMPERE project. These global patterns are derived from delta-B measurements by ~70 Iridium satellites in 6 orbital planes via a spherical harmonic fitting procedure. In many cases there is good agreement between the Birkeland current patterns in the LFM simulation and AMPERE inversions. In some cases (e.g. a northward IMF case) however, the patterns do not agree as well even though the AMPERE magnetic perturbations seemed highly consistent with the simulated currents, possibly reflecting limitations in the initial version of AMPERE inversions. Slava emphasized that though global validation is now possible and may be extremely valuable, it needs be done carefully understanding the strengths, limitations, and uncertainties of models, data sets, and derived data products. Colby Lemon discussed how we could use statistical validation exercises to mine geospace models for physical understanding. For instance, we can run a variety of simulations and test their agreement (or not) with data-based empirical models, and determine what modeled physical processes are responsible for that agreement (or not). The audience contributed many good empirical models which are well posed for statistical validation exercises. Some include the Young et al., 1981 composition of the tail, many Newell et al., 2007 empirical relations, and the Thomsen et al., 1998 relation showing the ring current strength (Dst) is best correlated with VBsouth times the plasma sheet density averaged over the previous 12 hours. Tim Guild, Amy Keesee and Mike Wiltberger showed a unique comparison of simulated (LFM) plasma sheet temperatures in the equatorial plane during a storm and temperatures inferred from TWINS ENA observations in the plasma sheet. Both model and observations showed a suggestive hotter dusk-side plasma sheet. Vahe Peroomian suggested that this hotter dusk side plasma sheet was due to direct entry of sheath plasma under strong negative IMF By. Pontus Brandt discussed the need for and progress toward developing an empirical model of inner magnetosphere pressure derived from inverting ENA observations and combining them optimally with in-situ observations. This was followed with good discussion of how physics-based simulations could be used to understand the functional dependencies of a number of empirical models or well-known geophysical relations. +-------------------------------------------------------------------+ | To subscribe GEM Messengers, send an e-mail to | | | | with the following command in the body of your e-mail message: | | subscribe gem | | To remove yourself from the mailing list, the command is: | | unsubscribe gem | | | | To broadcast a message to the GEM community, please contact | | Peter Chi at | | | | Please use plain text as the format of your submission. | | | | GEM Messenger is also posted online via newsfeed at | | http://heliophysics.blogspot.com and | | http://www.facebook.com/heliophysics | | | | Back issues are available at ftp://igpp.ucla.edu/scratch/gem/ | | | | URL of GEM Home Page: http://aten.igpp.ucla.edu/gemwiki | | Workshop Information: http://www.cpe.vt.edu/gem/index.html | +-------------------------------------------------------------------+