A Polar Mars Climate Database built on Mesoscale Simulations · A Polar Mars Climate Database built...
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A Polar Mars Climate Database built on Mesoscale Simulations Aymeric Spiga 1 & Isaac B. Smith 2 1 Laboratoire de M´ et´ eorologie Dynamique, Universit´ e Pierre et Marie Curie, Paris, France ([email protected]) 2 SouthWest Research Institute, Boulder, Colorado, USA ([email protected]) An interest for Martian geologists and glaciologists Martian polar regions are, meteorogically speaking, very active regions. This activity is evidenced by numer- ous surface morphologic features, from frost streaks to dune fields, which putative inferred direction is roughly compatible with directions obtained by mesoscale mod- els [1]. The varying spectral signatures (H 2 O or CO 2 ) over polar slopes during seasonal retreat have been pos- sibly ascribed to winds too [2]. The occurrence of trough clouds has possibly been linked to the migration of spiral troughs thanks to mesoscale modeling of polar katabatic winds, both over the northern polar cap [3] and the south- ern polar cap [4]. Furthermore, smaller-scale sedimen- tation waves than troughs over the Martian polar caps are thought to be controlled by katabatic winds [5]. The control of surface morphology by winds might even be extended to the paleo-topography revealed by radar im- agery [6]. An interest for Martian climate scientists The inter- est for Martian polar regions is not restricted to surface- atmosphere interactions. Studying the meteorology of the Martian polar regions is a means to address key ques- tions for the Martian climate at all scales. The fact that many flushing storms originate from the Martian polar regions [7] indicates that the mesoscale wind activity in polar regions is likely to play a decisive role [8, 9]. At the same time, the wind variability itself in the polar regions is a matter of active research to disentangle the combined influence of katabatic acceleration [10, 11], sea-breeze circulations caused by the ice-soil contrasts [8], polar transients [9], and, last but not least, the large-scale po- lar vortex [12, 13]. Polar regions also play a key role as a seasonal source/sink for the water annual cycle, where mesoscale transport processes [14] and cloud formation with radiatively-induced effect [15] play a crucial role. As far as the upper troposphere / lower mesosphere is concerned, the polar atmosphere is also prone to a par- ticularly strong mesoscale activity with the frequent oc- currence of gravity waves [16]. Why use mesoscale simulations for polar regions? Mesoscale models are well-suited to get insights into at- mospheric and surface processes in polar regions. Con- trary to global circulations models [GCMs], mesoscale models integrate the atmospheric dynamics at high reso- lution in a specific region of interest on the planet with Figure 1: The retreat of the seasonal CO 2 cap is the primary driver of the variability of the surface wind speeds in spring. Results of a dx = 18 km mesoscale simulation (nested domain in a dx = 54 km mother domain) at Ls = 60, 75, 90 ◦ (northern spring) in the northern polar region. Wind vectors in m s -1 are shown each 3 grid points. Sur- face temperature is contoured. An albedo map of the Martian northern polar region is included in the background to provide context. 6055.pdf Sixth Mars Polar Science Conference (2016)
Transcript of A Polar Mars Climate Database built on Mesoscale Simulations · A Polar Mars Climate Database built...
A Polar Mars Climate Database built on Mesoscale SimulationsAymeric Spiga1 & Isaac B. Smith21Laboratoire de Meteorologie Dynamique, Universite Pierre et Marie Curie, Paris, France ([email protected])2SouthWest Research Institute, Boulder, Colorado, USA ([email protected])
An interest for Martian geologists and glaciologistsMartian polar regions are, meteorogically speaking, veryactive regions. This activity is evidenced by numer-ous surface morphologic features, from frost streaks todune fields, which putative inferred direction is roughlycompatible with directions obtained by mesoscale mod-els [1]. The varying spectral signatures (H2O or CO2)over polar slopes during seasonal retreat have been pos-sibly ascribed to winds too [2]. The occurrence of troughclouds has possibly been linked to the migration of spiraltroughs thanks to mesoscale modeling of polar katabaticwinds, both over the northern polar cap [3] and the south-ern polar cap [4]. Furthermore, smaller-scale sedimen-tation waves than troughs over the Martian polar capsare thought to be controlled by katabatic winds [5]. Thecontrol of surface morphology by winds might even beextended to the paleo-topography revealed by radar im-agery [6].
An interest for Martian climate scientists The inter-est for Martian polar regions is not restricted to surface-atmosphere interactions. Studying the meteorology ofthe Martian polar regions is a means to address key ques-tions for the Martian climate at all scales. The fact thatmany flushing storms originate from the Martian polarregions [7] indicates that the mesoscale wind activity inpolar regions is likely to play a decisive role [8, 9]. At thesame time, the wind variability itself in the polar regionsis a matter of active research to disentangle the combinedinfluence of katabatic acceleration [10, 11], sea-breezecirculations caused by the ice-soil contrasts [8], polartransients [9], and, last but not least, the large-scale po-lar vortex [12, 13]. Polar regions also play a key role asa seasonal source/sink for the water annual cycle, wheremesoscale transport processes [14] and cloud formationwith radiatively-induced effect [15] play a crucial role.As far as the upper troposphere / lower mesosphere isconcerned, the polar atmosphere is also prone to a par-ticularly strong mesoscale activity with the frequent oc-currence of gravity waves [16].
Why use mesoscale simulations for polar regions?Mesoscale models are well-suited to get insights into at-mospheric and surface processes in polar regions. Con-trary to global circulations models [GCMs], mesoscalemodels integrate the atmospheric dynamics at high reso-lution in a specific region of interest on the planet with
Figure 1: The retreat of the seasonal CO2 cap is the primary driverof the variability of the surface wind speeds in spring. Results ofa dx = 18 km mesoscale simulation (nested domain in a dx = 54 kmmother domain) at Ls = 60, 75, 90◦ (northern spring) in the northernpolar region. Wind vectors in m s−1 are shown each 3 grid points. Sur-face temperature is contoured. An albedo map of the Martian northernpolar region is included in the background to provide context.
6055.pdfSixth Mars Polar Science Conference (2016)
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an adapted map projection. Polar mesoscale domains aredefined through stereographic projections, hence devoidof the “pole singularity” present in most GCMs. In ad-dition, high-resolution surface thermophysical properties(albedo, thermal inertia) are used in mesoscale modeling.
A better seasonal coverage for polar mesoscale simu-lations As is detailed in the previous paragraphs, un-derstanding the diurnal, seasonal, and even interannualvariability of temperature, winds, water vapor & clouds,. . . in Martian polar regions is an important step to un-derstanding both surface and atmosphere processes. Ouridea is that, since existing published mesoscale simula-tions focused on a specific season of interest, it is nowtime to attempt a full annual coverage of polar mesoscalesimulations. We performed test mesoscale simulationswith the LMD Martian Mesoscale model [17, 10] overa wide range of seasons to demonstrate the potentialitiesof this concept and offer a first (and quite unprecedentedyet) discussion on the seasonal variability of winds in thenorthern and southern regions of Mars. For instance, forNorth pole, we provide simulations for each 5-10◦ of so-lar longitude (Ls) beginning at northern vernal equinox(Ls 0◦) and ending at northern autumnal equinox (Ls180◦) [18]. Those simulations allow us to explore theMartian polar meteorological variability: we show an ex-ample of wind changes associated with the CO2 cap re-treat in Figure 1.
Building a Polar Mars Climate Database Our pro-posal is to build an online interface to map (and moregenerally extract) the atmospheric predictions from theLMD Martian Mesoscale Model in the Martian po-lar regions, following the example of both the on-line Mars Climate database [http://www-mars.lmd.jussieu.fr/mcd_python], and similar on-line database for terrestrial polar regions [19]. The MarsPolar Conference will be an excellent vector to discusswith the community to determine the most relevant pa-rameters and fields for the various studies undertaken, aswell as to define an infrastructure of the database whichwill optimize the scientific return of the simulations.
References[1] M. Masse, O. Bourgeois, et al. Wide distribution and glacial ori-
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[3] Isaac B. Smith, John W. Holt, et al. The spiral troughs ofmars as cyclic steps. Journal of Geophysical Research: Planets,118(9):1835–1857, 2013.
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[9] D. Tyler and J. R. Barnes. A mesoscale model study of summer-time atmospheric circulations in the north polar region of Mars.Journal of Geophysical Research (Planets), 110(E9):6007–+,2005.
[10] A. Spiga, F. Forget, et al. The impact of Martian mesoscale windson surface temperature and on the determination of thermal iner-tia. Icarus, 212:504–519, 2011.
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[17] A. Spiga and F. Forget. A new model to simulate the Mar-tian mesoscale and microscale atmospheric circulation: Valida-tion and first results. Journal of Geophysical Research (Planets),114:E02009, 2009.
[18] I. B. Smith, A. Spiga, et al. Wind at the North Pole of Mars: Com-parisons of Modeling and Observations. In Lunar and PlanetaryScience Conference, volume 47 of Lunar and Planetary ScienceConference, page 1632, 2016.
[19] David H. Bromwich, Keith M. Hines, and Le-Sheng Bai. De-velopment and testing of polar weather research and forecastingmodel: 2. arctic ocean. Journal of Geophysical Research: Atmo-spheres, 114(D8):n/a–n/a, 2009. D08122.
6055.pdfSixth Mars Polar Science Conference (2016)
