TY - JOUR
T1 - Semiannual oscillations in the atmosphere of Mars
AU - Kuroda, Takeshi
AU - Medvedev, Alexander S.
AU - Hartogh, Paul
AU - Takahashi, Masaaki
PY - 2008/12/16
Y1 - 2008/12/16
N2 - We report on the first detection of the semiannual oscillation (SAO) in the Martian atmosphere. The semiannual periodicity is found in the difference between day-and night-time atmospheric temperatures, a good proxy for solar tides, measured from Mars Global Surveyor. Simulations with a general circulation model proved that this modulation of tidal amplitudes is a manifestation of the SAO of zonal winds in Martian tropics. Our numerical experiments revealed significant differences in driving mechanisms of the SAO between Mars and Earth. On Mars, unlike on Earth, equatorial Kelvin waves supply only small retrograde torque to the mean circulation. Instead, thermal tides and quasi-stationary planetary waves induced by Martian topography contribute strongly to the prograde (super-rotation) acceleration. The existence of the SAO on Mars suggests that this phenomenon is not a result of the unique terrestrial environment, but a more general consequence of wave-mean flow interactions in atmospheres of fast-rotating planets.
AB - We report on the first detection of the semiannual oscillation (SAO) in the Martian atmosphere. The semiannual periodicity is found in the difference between day-and night-time atmospheric temperatures, a good proxy for solar tides, measured from Mars Global Surveyor. Simulations with a general circulation model proved that this modulation of tidal amplitudes is a manifestation of the SAO of zonal winds in Martian tropics. Our numerical experiments revealed significant differences in driving mechanisms of the SAO between Mars and Earth. On Mars, unlike on Earth, equatorial Kelvin waves supply only small retrograde torque to the mean circulation. Instead, thermal tides and quasi-stationary planetary waves induced by Martian topography contribute strongly to the prograde (super-rotation) acceleration. The existence of the SAO on Mars suggests that this phenomenon is not a result of the unique terrestrial environment, but a more general consequence of wave-mean flow interactions in atmospheres of fast-rotating planets.
UR - http://www.scopus.com/inward/record.url?scp=60149099690&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=60149099690&partnerID=8YFLogxK
U2 - 10.1029/2008GL036061
DO - 10.1029/2008GL036061
M3 - Article
AN - SCOPUS:60149099690
VL - 35
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 23
M1 - L23202
ER -