Draft Minutes Progress meeting 06/04/2011 :
Exomars Environmental Atmospheric Support Analysis
Phase B2X2; Contract EXM-SC-LMD-0969
F. Forget, LMD
webex teleconference:
LMD (Aymeric Spiga; Arnaud Colaitis , Ehouarn Millour , Francois Forget + Luca Montabone)
TASI (Stefano Portigliotti)
ESA (Leila Lorenzoni)
Deimos (Rodrigo Haya Ramos, Mariano Sanchez [aerobraking expert])
Tessella (David Riley)
Presentation are available o:
http://www-mars.lmd.jussieu.fr/tasi/meeting_06_04_2011/
Extreme realistic LES results + resolved topography (Aymeric Spiga)
(presentation available).
· Maximum updraft : 19m/s; Maximum downdraft 10 m/s
· Impact of topography (represented by ideal hill up to 500 m/s): small impact. The impact is relatively small on updraft and downdraft. ~10% enhancement over the baseline case.
Question (SP): how is the horizontal wind ? answer : it is still structured like before, with convective cells, with slightly higher velocity on the hill.
Question (Sp) : what if we have a crater ? answer : it should be about the same, with updraft on the rim of the crater.
Question (LL): so there is an dangerous enhancement near rims ? answer: well, only if it is very steep, and even in that case our conclusions is that it is not a dominant factor
Comparison Mesoscale model / General Circulation Model (Arnaud Colaitis)
(presentation available).
- Very good agreement in atmospheric temperature (and thus density)
- Significant difference in the surface temperature due to the use of different albedo/thermal inertia maps (the new MCD v5 will use updated surface data)
- “effective winds” different for tau = 2 and especially 5
- The difference is especially strong for instance for wind at 20km. We think that the difference is due to the limited vertical domain of the mesoscale model. With high opacity, semi diurnal tides tends to dominate diurnal tides. However they are not fully resolved because of their very large vertical wavelength (100 km). Thus high opacity (tau > 2), GCM wind prediction should be preferred to mesoscale.
Discussion NetCDF:
Question (SP) Intense use of previous NeTCDF outputs from meso-scale and LES : still valid ?
Answer (AS) : yes that should be enough for your project…
Improved MCD software (=> version 4.3.EXM5) (Ehouarn Millour and François Forget):
Improved Cp, viscosity, and dust mass mixing ratio
(presentation available).
- MCD.ex now takes into account Cp variation with temperature (but only for CO2)
- After literature studies, calculation of viscosity improved. Discussion: SP will compare with the new formulation for the CFD run. Expect a improved agreement.
- Improvement of estimation of dust mixing ratio => It is suggested to provide overestimation and underestimation of mass mixing ratio, in addition to a mean value
Study of the “subgrid scale spatial variability” (Ehouarn Millour)
(presentation available).
For Meridiani, the subgrid scale temperature perturbation is conservative and can be used as before. Elsewhere, if the topography variability is larger than in a “landing site” area like Meridiani, a larger variability should be taken into account, but it is out of the scope of the Exomars work here.
Question (SP): will you implement something along these lines in version 5 ? Answer: yes, we might
Update on Observation analysis (Luca Montabone)
TES and MCS data analysed through data assimilation suggests that there is a pause in regional ‘flushing” dust storm around solstice (that includes EDM landing period). This is confirmed by dust storm statistics from MGS and MRO camera (Cantor et al. Icarus, 2010). So it is more and more likely that no regional storm will affect the EDL around Ls=240°-250°
Separate discussion (LL) : should we continue to take into account dust storm condition as a high probability cases ? Stefano: In any case we have to demonstrate that the design is robust (to be completed…)
Aerobraking (F. Forget)
presentation available
Discussion: question on the variability within one orbit.
Discussion on the 100% variability from orbit to orbit. This requirements is detailed in a document available (TBC)
Suggestion to develop a model which can predict the density (+ density uncertainty resulting from transient wave activity with random phase) from orbit to orbit, taking into account that you can “correct” your model based on the knowledge from previous orbits the available data from MGS, MO and MRO.
More information on the aerobraking strategy is available in a reference document from Deimos. The next version will be available in mid april, and could be used as a basis for future discussion.
Phase B2X2 closure
Almost done. 2 actions remains:
- Update on MCD software (for dust mixing ratio, see bove) and corresponding documentation EXM-MS-TNO-LMD-0035
- Synthesis report on aerobraking based on the presentation shown during the PM
Phase C/D :
The Exomars program may change
- following issues with the cooperation with NASA (US budget issues, in particular)
- negociation between ESA and TAS-I about the total Phase C/D costs
Details of of the LMD activities to be discussed when the context and the actual budget better known.