Notes
from the
Participants:
BU, Dartmouth, NCAR, and SWRI (Crowley via speakerphone)
1) MIC Potential Solver (Astrid Maute) - The potential solver used by the TIEGCM has been adapted to allow coupling to LFM at high latitude. LFM gives the solver the high-latitude magetic perturbation due to FACs; the solver gives LFM the high-latitude potential. The low-latitude BC is constant potential. A pre-specified high-latitude BC has been used initially as a proxy for LFM data - next steps would entail actual coupling to LFM. TIEGCM time step is 3 minutes. RCM coupling, which uses/provides additional boundary conditions, has not been considered yet in this scheme; it might alternatively provide the high-latitude BC on the magnetic perturbation due to FACs. In the scheme described, it appears that TIEGCM would take over the potential solve step. Is this strategy consistent with the plug-and-play idea that the solver would be standalone and allow coupling to other TIEGCMS, GGCMs, RCMs, etc?
Reference: http://thayer.dartmouth.edu/spacescience/wl/rip/cism-mi-wg/meetings/10-06-03/Astrid-Poten-Sol.pdf
2) Outflow issues (Lotko) - The effect of Alfven-wave-induced outflow in the ionospheric ion momentum equation (provisionally O+) was discussed. The new term is a wave magnetic pressure due the fluctuating Alfven wave field. It is proposed to use the quasi-static Alfven wave approximation for the altitude dependence of the wave amplitude between the LFM inner boundary and the E-region, including the reflected component. The approximation is valid at frequencies below about 10-100 mHz There is some uncertainty in the equations and BCs used by TING for the ions and the BCs at the inner boundary of LFM. Wenbin Wang has since provided Chp 2 from his dissertation with the required information for TING (http://thayer.dartmouth.edu/spacescience/wl/rip/cism-mi-wg/meetings/10-06-03/NCAR-TIGCM.pdf). LFM information to come.
3) Validation/metrics issues (Spence) - Harlan asked what variables should be validated for the coupled codes. Some possibilities were discussed: PC boundary position, net PC potential, hemispheric asymmetries, spatial distributions. The polar cap potential and FAC distributions derived from space- and/or ground-based data seem like good candidates because these variables are critical in the code couplings. Synergy with GEM challange events may provide useful data sets for CISM code validations. This discussion needs to become more definitive in the future.
Reference: http://spacsun.rice.edu/~gem/gem2003mw/index.html
4) Data assimilation using AMIE with LFM-TING? - Idea suggested by Lotko is to use AMIE to assimilate not only observed variables but also LFM, RCM and TING output to construct the high-laitutude potential solution. The standard AMIE grid is currently about 1.7 degrees in latitude and 10 degrees in longitude. There were some questions about whether this approach is actually data assimilation. Nevertheless, it seems worthwhile to consider using AMIE to mediate the assimilation. John Lyon discussed some previous numerical experiments using AMIE to provide the ionospheric conductivity and potential for LFM; the results exhibited some inconsistencies. Geoff Crowley would like to conduct some numerical experiments along this line in the future, funding permitting.
Reference: http://thayer.dartmouth.edu/spacescience/wl/rip/cism-mi-wg/meetings/10-06-03/AMIE-diff.pdf