HR: 1330h
AN: P32A-1071    [PDF]
TI: The Effect of Strong Crustal Magnetic Fields on the Ionosphere/Atmosphere in the Southern Hemisphere of Mars: MGS Magnetometer Electron Reflectometer, Accelerometer and Radio Science Data
AU: * Ness, N F
EM: nfness@bartol.udel.edu
AF: Bartol Research Institute, 104 Center Mall, Room 217 University of Delaware, Newark, DE 19716 United States
AU: Krymskii, A M
EM: amkrym@yahoo.com
AF: Rostov State University, ul. Zorge 5 Space Physics Department, 344104 Rostov-on-Don, 117810 Russian Federation
AU: Crider, D H
EM: dcrider@lepvax.gsfc.nasa.gov
AF: The Catholic University of America, Department of Physics, Washington, DC 20064 United States
AU: Breus, T K
EM: breus@space.ru
AF: Space Research Institute (IKI), Profsoyuzaya, 84/32, Moscow, 117810 Russian Federation
AU: Acuna, M H
EM: mario.acuna@gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Mail Code 695, Greenbelt, MD 20771 United States
AU: Hinson, D P
EM: hinson@rocc.stanford.edu
AF: Department of Electrical Engineering, Stanford University, Stanford, CA 94305-9515 United States
AU: Barashyan, K K
AF: Rostov State University, ul. Zorge 5 Space Physics Department, 344104 Rostov-on-Don, 117810 Russian Federation
AB: In the Southern hemisphere, the strongest crustal magnetic fields lead to the formation of large-scale mini-magnetospheres. Reconnection with the interplanetary magnetic field (IMF) occurs in many localized regions. Reconnection will permit solar wind (SW) and more energetic particles to precipitate into and heat the neutral atmosphere. This may occur not only in cusp-like structures above nearly vertical field anomalies but also in halos extending several hundreds of kilometers from these sources. Initially, the scale-height of the neutral atmosphere density derived from the Mars Global Surveyor (MGS) Accelerometer (ACC) experiment has been compared with the crustal magnetic fields measured by the MGS Magnetometer/Electron Reflectometer (MAG/ER) experiment. The neutral atmosphere scale-height was found to be more variable in the Southern Hemisphere. It is also usually larger than the mean value near the boundaries of potential mini-magnetospheres. This may indicate (a) local heating of the thermosphere by precipitating energetic particles and (b) the paleo-magnetic/IMF field reconnection is characteristic of the mini-magnetospheres at Mars. The electron density profiles of the ionosphere of Mars, which are derived from radio occultation data obtained by the MGS Radio Science (RS) experiment, have been analyzed. The available profiles are concentrated in two narrow latitude intervals. The Effective Scale-Height (ESH) of the neutral atmosphere density in the vicinity of the ionization peak has been derived for each of the profiles studied. The ESH of the Southern Hemisphere profiles is close to the MGS ACC scale-heights that accurately characterize the neutral atmosphere temperature at 130-140 km. It is found that the neutral atmosphere and ionosphere parameters, which are derived from the MGS RS data, are also more variable in the Southern Hemisphere than in the Northern one. This correlates with variability of the magnetic field angle with local zenith as derived from the MGS MAG/ER data. Thus, in the Southern Hemisphere the complex magnetic field structure determines the neutral atmosphere and ionosphere characteristics.
DE: 2459 Planetary ionospheres (5435, 5729, 6026, 6027, 6028)
DE: 5407 Atmospheres--evolution
DE: 5421 Interactions with particles and fields
DE: 5440 Magnetic fields and magnetism
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting