Toward an Understanding of the Time Dependent Responses of the Martian Upper Atmosphere to Dust Storm Events

Details Toward an Understanding of the Time Dependent Responses of the Martian Upper Atmosphere to Dust Storm Events Toward an Understanding of the Time Dependent Responses of the Martian Upper Atmosphere to Dust Storm Events

Dec 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p23e..08b&link_type=abstract

American Geophysical Union, Fall Meeting 2011, abstract #P23E-08

Physics

[2459] Ionosphere / Planetary Ionospheres, [3369] Atmospheric Processes / Thermospheric Dynamics, [5405] Planetary Sciences: Solid Surface Planets / Atmospheres, [6225] Planetary Sciences: Solar System Objects / Mars

Scientific paper

Mars spacecraft datasets reveal that its thermosphere-ionosphere (~100-200 km) is significantly impacted by the passage of regional or global dust storm events (e.g. Kliore et al., 1972; Zhang et al., 1990; Keating et al., 1998; Bougher et al, 1999; 2011; Baird et al., 2007). The time evolving responses correspond to the rapid onset phase (~2-10 sols) of a dust event, and its gradual decay (~50 sols or more). Thermospheric responses during the regional Noachis storm (1997) during its onset include: (a) a factor of 3 enhancement of MGS Accelerometer mass densities (~5-15 kg/km3) at 130 km at ~38 N latitude, (b) a factor of 2.5 enhancement of corresponding zonal winds (~100-250 m/s) near ~120-130 km, and (c) the associated ~8 km rise in the height of the 1.26-nbar reference pressure level. These features correspond to a rapidly warming (and expanding) lower atmosphere due to "dust-lifting latitude" aerosol heating, the resulting acceleration of global winds and amplification of tidal amplitudes throughout the atmosphere, and adiabatic warming arising from downwelling winds. In addition, many years of monitoring the F1-ionospheric peak confirms that this atmospheric inflation is consistently manifested in rising ionosphere peak heights. These upper atmosphere responses to dust events, and the associated feedbacks in atmospheric energetics, dynamics, and chemistry, provide excellent constraints for the further validation and testing of Mars whole atmosphere general circulation models. This paper utilizes the recently developed and initially validated 3-D Mars Global Ionosphere-Thermosphere Model (M-GITM) (e.g. Bougher et al., 2008; 2011; Pawlowski et al., 2010) to investigate these feedbacks and the responses of the Mars thermosphere-ionosphere for a sample dust storm event. The M-GITM code simulates the conditions of the Martian atmosphere from the surface to the exosphere (~0-250 km). Physical processes (e.g. radiative transfer), formulations and subroutines required for incorporation into the M-GITM code have largely been taken from existing Mars GCM codes (e.g. Bougher et al., 2004; Haberle et al., 1999). M-GITM neutral temperatures are solved for self-consistently, but ion and electron temperatures are presently prescribed based upon Viking measurements. Key species include: (neutrals) CO2, CO, O, N2, O2, N(4S), N(2D), NO, Ar, He, and (ions) O+, O2+, CO2+, N2+, NO+. Three component neutral winds are calculated over the globe; ion velocities are not calculated, but await the coupling with a solar wind interaction code. Typically, M-GITM production runs are conducted for a 5x5 degree regular horizontal grid, with a constant 2.5 km vertical resolution (~0.25 scale height) above the lowest ~80 km. A "stretched" vertical grid is used at lower altitudes to accommodate the variable Martian terrain. A sample M-GITM dust storm simulation is driven by a prescribed time-dependent dust opacity distribution, that also varies with latitude and height. The time evolution of the resulting thermosphere and ionosphere fields is examined; general comparisons with existing Mars upper atmosphere datasets will be made.

Affiliated with

Also associated with

No associations

Rating

Toward an Understanding of the Time Dependent Responses of the Martian Upper Atmosphere to Dust Storm Events does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Toward an Understanding of the Time Dependent Responses of the Martian Upper Atmosphere to Dust Storm Events, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Toward an Understanding of the Time Dependent Responses of the Martian Upper Atmosphere to Dust Storm Events will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-870033