Mike Liemohn

Associate Professor

Department of Atmospheric, Oceanic and Space Sciences, College of Engineering, University of Michigan

Ring Current Research Activities

Ring CurrentI study the source, transport, and loss of energetic ions and electrons in the inner magnetosphere, especially during highly active times known as magnetic storms. The ring current consists of the charged particles in near-Earth space from roughly 1 keV up to several hundred keV in energy.  They carry the majority of the plasma energy density in this region, and therefore dominate the electric and magnetic field distortions in the inner magnetosphere. In particular, I like to investigate the coupling of the ring current to the ionosphere and to other magnetospheric plasma populations, especially to the plasmasphere, radiation belts, and plasma sheet. 

Publications on the ring current


Liemohn, M. W., J.-C. Zhang, M. F. Thomsen, J. E. Borovsky, J. U. Kozyra, and R. Ilie, Superstorms at geosynchronous orbit:  how different are they?, Geophys. Res. Lett., 35, L06S06, doi: 10.1029/2007GL031717, 2008. 


Khazanov, G. V., K. V. Gamayunov, D. L. Gallagher, M. W. Liemohn, and J. U. Kozyra, Self-consistent model of magnetospheric ring current and propagating electromagnetic ion cyclotron waves, 2, Wave induced ring current precipitation and thermal electron heating, J. Geophys. Res., 112, A04209, doi: 10.1029/2006JA012033, 2007. 

Zhang, J.-Ch., M. W. Liemohn, D. L. De Zeeuw, J. E. Borovsky, A. J. Ridley, S. Sazykin, M. F. Thomsen, J. U. Kozyra, T. I. Gombosi, and R. A. Wolf, Understanding storm-time ring current sources through data-model comparisons of a moderate storm, J. Geophys. Res., 112, A04208, doi: 10.1029/2006JA011846, 2007. 


Liemohn, M. W., A. J. Ridley, J. U. Kozyra, D. L. Gallagher, M. F. Thomsen, M. G. Henderson, M. H. Denton, P. C. Brandt, and J. Goldstein, Analyzing electric field morphology through data-model comparisons of the GEM IM/S Assessment Challenge events, J. Geophys. Res., 111, A11S11, doi: 10.1029/2006JA011700, 2006. 

Liemohn, M. W., Introduction to the GEM Inner Magnetosphere/Storms Assessment Challenge, J. Geophys. Res., 111. A11S01, doi: 10.1029/2006JA011970, 2006. 

Ganushkina, N., T. I. Pulkkinen, M. Liemohn, and A. Milillo, Evolution of the proton ring current energy distribution during April 21-25, 2001 storm, J. Geophys. Res., 111, A11S08, doi: 10.1029/2006JA011609, 2006. 

Zhang, J.-Ch., M. W. Liemohn, M. F. Thomsen, J. U. Kozyra, M. H. Denton, and J. E. Borovsky, A statistical comparison of hot-ion properties at geosynchronous orbit during intense and moderate geomagnetic storms at solar maximum and minimum, J. Geophys. Res., 111, A07206, doi: 10.1029/2005JA011559, 2006. 

Denton, M. H., J. E. Borovsky, R. M. Skoug, M. F. Thomsen, B. Lavraud, M. G. Henderson, R. L. McPherron, J. C. Zhang, and M. W. Liemohn, Geomagnetic storms driven by ICME- and CIR-dominated solar wind, J. Geophys. Res., 111, A07S07, doi: 10.1029/2005JA011436, 2006. 


Liemohn, M. W., A. J. Ridley, P. C. Brandt, D. L. Gallagher, J. U. Kozyra, D. G. Mitchell, E. C. Roelof, and R. DeMajistre, Parametric analysis of nightside conductance effects on inner magnetospheric dynamics for the 17 April 2002 storm, J. Geophys. Res., 110, A12S22, doi: 10.1029/2005JA011109, 2005. 

Moore, T. E., M.-C. Fok, M. O. Chandler, S.-H. Chen, S. P. Christon, D. C. Delcourt, J. Fedder, M. Liemohn, W. K. Peterson, and S. Slinker, Solar and ionospheric plasmas in the ring current, Inner Magnetosphere Interactions:  New Perspectives from Imaging, AGU Monogr. Ser., vol. 159, ed. by J. L. Burch, M. Schulz, and H. Spence, p. 179, Am. Geophys. Un., Washington, D. C., 2005. 

Liemohn, M. W., and P. C. Brandt, Small-scale structure in the stormtime ring current, Inner Magnetosphere Interactions:  New Perspectives from Imaging, AGU Monogr. Ser., vol. 159, ed. by J. L. Burch, M. Schulz, and H. Spence, p. 167, Am. Geophys. Un., Washington, D. C., 2005. 

Liemohn, M. W., and G. V. Khazanov, Parameterization of ring current adiabatic energization, in Particle Acceleration in Astrophysical Plasmas: Geospace and Beyond, AGU Monogr. Ser., vol. 156, edited by D. Gallagher, J. Horwitz, J. Perez, R. Preece, and J. Quenby, p. 215, Am. Geophys. Un., Washington, D. C., 2005. 

Liemohn, M. W., and J. U. Kozyra, Testing the hypothesis that charge exchange can cause a two-phase decay, in The Inner Magnetosphere: Physics and Modeling, AGU Monogr. Ser., vol. 155, edited by T. I. Pulkkinen, N. Tsyganenko, and R. H. W. Friedel, p. 211, Am. Geophys. Un., Washington, D. C., 2005. 

Denton, M. H., M. F. Thomsen, H. Korth, S. Lynch, J.-Ch. Zhang, and M. W. Liemohn, Bulk plasma properties at geosynchronous orbit, J. Geophys. Res., 110, A07223, doi: 10.1029/2004JA010861, 2005. 

Siscoe, G. L., R. L. McPherron, M. W. Liemohn, A. J. Ridley, and G. Lu, Reconciling prediction algorithms for Dst, J. Geophys. Res., 110, A02215, doi: 10.1029/2004JA010465, 2005. 

Moore, T. E., M.-C. Fok, M. O. Chandler, C. R. Chappell, S. Christon, D. Delcourt, J. Fedder, M. Huddleston, M. Liemohn, W. Peterson, S. P. Slinker, Plasma sheet and (non-storm) ring current formation from solar and polar wind sources, J. Geophys. Res., 110, A02210, doi: 10.1029/2004JA010563, 2005. 


Khazanov, G. V., M. W. Liemohn, M.-C. Fok, T. S. Newman, and A. J. Ridley, Stormtime particle energization with AMIE potentials, J. Geophys. Res., 109, A05209, doi: 10.1029/2003JA010186, 2004. 

Liemohn, M. W., A. J. Ridley, D. L. Gallagher, D. M. Ober, and J. U. Kozyra, Dependence of plasmaspheric morphology on the electric field description during the recovery phase of the April 17, 2002 magnetic storm, J. Geophys. Res., 109(A3), A03209, doi: 10.1029/2003JA010304, 2004. 

Khazanov, G. V., M. W. Liemohn, T. S. Newman, M.-C. Fok, and A. J. Ridley, Magnetospheric convection electric field dynamics and stormtime particle energization: Case study of the magnetic storm of 4 May 1998, Ann. Geophys., 22, 497, 2004. 


Clauer, C. R., M. W. Liemohn, J. U. Kozyra, and M. L. Reno, The relationship of storms and substorms determined from mid-latitude ground-based magnetic maps, Disturbances in Geospace: The Storm-Substorm Relationship, AGU Monogr. Ser., vol. 142, edited by S. J. Sharma, p. 143, AGU, Washington, D. C., 2003. 

Kozyra, J. U., and M. W. Liemohn, Ring current energy input and decay, Space Sci. Rev, 109, 105, 2003. 

Liemohn, M. W., Yet another caveat to the Dessler-Parker-Sckopke relation, J. Geophys. Res., 108(A6), 1251, doi: 10.1029/2003JA009839, 2003. 

Liemohn, M. W., and J. U. Kozyra, Lognormal form of the ring current energy content, J. Atmos. Solar-Terr. Phys., 65, 871, 2003. 

Daglis, I. A., J. U. Kozyra, Y. Kamide, D. Vassiliadis, A. S. Sharma, M. W. Liemohn, W. D. Gonzalez, B. T. Tsurutani, and G. Lu, Intense space storms: Critical issues and open disputes, J. Geophys. Res., 108(A5), 1208, doi: 10.1029/2002JA009722, 2003.  

Khazanov, G. V., T. S. Newman, M. W. Liemohn, M.-C. Fok, R. W. Spiro, Self-consistent magnetosphere-ionosphere coupling: theoretical studies, J. Geophys. Res., 107(A3), 1122, doi: 10.1029/2002JA009624, 2003.   (and correction  )


Liemohn, M. W., and A. J. Ridley, Comment on "Nonlinear response of the polar ionosphere to large values of the interplanetary electric field" by C. T. Russell et al., J. Geophys. Res., 107(A12), 1460, doi: 10.1029/2002JA009440, 2002. 

O'Brien, T. P., R. L. McPherron, and M. W. Liemohn, Continued convection and the initial recovery of Dst, Geophys. Res. Lett., 29(23), 2143, doi: 10.1029/2002GL015556, 2002. 

Liemohn, M. W., and J. U. Kozyra, Assessing the importance of convective and inductive electric fields in forming the stormtime ring current, in Sixth International Conference on Substorms, edited by R. M. Winglee, Univ. Washington, Seattle, p.456, 2002.  

Kozyra, J. U., M. W. Liemohn, C. R. Clauer, A. J. Ridley, M. F. Thomsen, J. E. Borovsky, J. L. Roeder, and V. K. Jordanova, Two-step Dst development and ring current composition changes during the 4-6 June 1991 magnetic storm, J. Geophys. Res., 107(A8), 1224, doi: 10.1029/2001JA000023, 2002. 

Ridley, A. J., and M. W. Liemohn, A model-derived description of the penetration electric field, J. Geophys. Res., 107(A8), 1151, doi: 10.1029/2001JA000051, 2002. 

Liemohn, M. W., J. U. Kozyra, M. R. Hairston, D. M. Weimer, G. Lu, A. J. Ridley, T. H. Zurbuchen, and R. M. Skoug, Consequences of a saturated convection electric field on the ring current, Geophys. Res. Lett., 29(9), 1348, doi: 10.1029/2001GL014270, 2002. 

Liemohn, M. W., J. U. Kozyra, C. R. Clauer, G. V. Khazanov, and M. F. Thomsen, Adiabatic energization in the ring current and its relation to other source and loss terms, J. Geophys. Res., 107(A4), 1045, doi: 10.1029/2001JA000243, 2002. 


Liemohn, M. W., J. U. Kozyra, C. R. Clauer, and A. J. Ridley, Computational analysis of the near-Earth magnetospheric current system, J. Geophys. Res., 106, 29,531, 2001. 

Liemohn, M. W., J. U. Kozyra, M. F. Thomsen, J. L. Roeder, G. Lu, J. E. Borovsky, and T. E. Cayton, Dominant role of the asymmetric ring current in producing the stormtime Dst*, J. Geophys. Res., 106, 10,883, 2001. 

Pollock, C. J., K. Asamura, M. M. Balkey, J. L. Burch, H. O. Funsten, M. Grande, M. Gruntman, J.-M. Jahn, M. Lampton, M. W. Liemohn, D. J. McComas, T. Mukai, S. Ritzau, M. L. Schattenburg, E. Scime, R. Skoug, P. Valek, and M. Wüest, Initial Medium Energy Neutral Atom (MENA) images of Earth's magnetosphere during substorms and storm-time, Geophys. Res. Lett., 28, 1147, 2001. 


Liemohn, M. W., J. U. Kozyra, P. G. Richards, G. V. Khazanov, M. J. Buonsanto, and V. K. Jordanova, Ring current heating of the thermal electrons at solar maximum, J. Geophys. Res., 105, 27,767, 2000. 


Liemohn, M. W., J. U. Kozyra, V. K. Jordanova, G. V. Khazanov, M. F. Thomsen, and T. E. Cayton, Analysis of early phase ring current recovery mechanisms during geomagnetic storms, Geophys. Res. Lett., 25, 2845, 1999.