Parameterization of the ion convection and the auroral oval in the NCAR Thermospheric General Circulation Models by Barbara A. Emery, Raymond G. Roble, E. Cicely Ridley, Arthur D. Richmond, Delores J. Knipp, Geoff Crowley, David S. Evans, Frederick J. Rich and Sawako Maeda

2012-06

Technical Report

The ion convection and auroral precipitation are important inputs to the global thermospheric energy and momentum balance. In the NCAR TGCM, they are described by analytical models whose characteristics are specified by three parameters: total polar cap potential drop Ψ, IMF By component, and hemispheric power input HP. The characteristics of the ion convection model are determined from electric potential patterns derived from ionospheric electrodynamic mapping on 3 days using incoherent scatter radars, satellites and magnetometers. These characteristics are sorted in By and compared with various models that have been described in the literature. NOAA and DMSP satellite electron precipitation data over 20 days have been averaged to specify the characteristics of the auroral precipitation. The relationship of hemispheric power to other parameters is explored. Finally, a specific period is examined and the parameterization is adjusted to fit the observations. Updates to the parameterizations since 1989 are then described in the section 6 before the Conclusions. All parameterizations, original and 2012 values, are listed along with cross-referenced equation and figure numbers in Table A of Appendix A.

The parameterizations of the ion convection and the auroral oval in the National Center for Atmospheric Research (NCAR) Thermospheric General Circulation Models (TGCMs) were finished in 1989, with a written report finished on April 11, 1989 labeled ‘Draft for NCAR Technical Report’ (TR) and the same title (except for the word ‘Models’ in this TR instead of ‘Model’). The author list also changed slightly with the substitution of Rich for Gussenhoven to represent the Air Force Research Laboratory (AFRL). However, it took 23 years to move this report into an actual NCAR TR. Over that time, some of the parameterizations were revised, and the report only existed as a hard-copy, with no chance of recovering the software or data to revise the plots.
Thus this 2012 TR is essentially that old 1989 report, where updates are in italics, including Section 6 on ‘Updates to the parameterizations’. All different plot versions as well as the ‘Extra Figures’ at the end of the original report are now placed within the body of the report since a TR can be relatively lengthy. The plots are unchanged and thus are of poor quality, although some of the text around the plot axes was revised to be more readable. Equations were added for parameterizations, numbered, and cross-referenced with accompanying figures in Table A of the Appendix. Subsections were introduced in Sections 2 and 3, and the content of Section 3 was re-arranged. In spite of poor figures, it was important to regularize the parameterization of the high-latitude inputs for the various NCAR TGCMs as an official document. Hence this belated TR.
My apologies to my co-authors for such a long wait on this report. I had intended to do a TR and then a regular scientific article. Now, just the TR is accomplished, and a scientific article will appear on our future revised TGCM parameterizations based on new data sources. The Heelis ion convection is still used and described in this report, but it is often replaced with the Weimer [2005] ion convection. The auroral parameterization is essentially the same as described here, with a simplified mean electron energy described in Section 6 and Table A of this report. However, we will be revising the aurora with a parameterization based on image data between 2002 and 2007 from the GUVI (Global UltraViolet Imager) instrument onboard the TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics) satellite.
The major URL describing the various NCAR TGCMs in use is located at http://www.hao.ucar.edu/modeling/tgcm/ which includes various documentation on the models.
Signed: Barbara A Emery Dated: 29 June 2012. - Preface, page vii.