Overview of the 2018a Global Dust Event from Mars Climate Sounder Observations
Abstract
A global (or planet encircling) dust event (GDE) initiated in early June 2018 (2018a GDE). Mars Climate Sounder (MCS) has acquired daily global observations of the GDE through its initiation, growth, peak and decay phases. These observations cover multiple local times and provide temperature, dust and water ice profiles of the atmosphere. Standard MCS observations cover a vertical range from the surface to 80 km altitude. During the growth of the GDE, significant mixing ratios of dust reached this altitude while the lower atmosphere was opaque in the limb. To continue to observe the top of the dust through the peak and early portion of the decaying phase, the MCS team modified the instrument pointing to cover a vertical range up to 90 km, from 60 S to 45 N, for the afternoon measurements.
The first obvious signatures of the 2018a GDE in the MCS observations were noted on June 4, 2018 (Ls 187°), when a seasonally-unusual strong warming was observed in the northern mid-latitudes. The GDE showed a strong signature in the dust field and in the atmospheric temperature field within three days at Ls 189°, with zonal mean temperatures at 50 Pa exceeding the 200 K threshold defining a large-scale regional dust event. Subsequent growth was relatively slow and zonal mean temperatures at 50 Pa did not exceed 225 K (beyond any observed large-scale regional dust storms) until around June 22 (Ls 198°). The peak of the storm was reached around July 10 (Ls 209°), although different aspects (temperature, dust height, etc.) reached their maxima over a week-long period and conditions remained near the peak through July 25 (Ls 218°). The GDE then segued into a decay phase that slowed down around August 14 (Ls 230°). The MCS observations clearly document the complex growth of the GDE and the influence of the dust field on the temperature structure (including the thermal tides) and water ice. The initial growth was a highly variable 4D dust field due to multiple distinct and daily varying lifting centers. As the GDE grew towards the peak, the dust became more uniformly mixed in longitude, while retaining latitudinal structure. This behavior continued during much of the decay phase of the storm. Daytime non-polar ice clouds initially moved higher in the atmosphere and then became relatively uncommon. They started to return relatively late in the decay phase of the storm.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.P34A..02K
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 6225 Mars;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTSDE: 5405 Atmospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETSDE: 5445 Meteorology;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS