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- Title
Surface Warming During the 2018/Mars Year 34 Global Dust Storm.
- Authors
Streeter, Paul M.; Lewis, Stephen R.; Patel, Manish R.; Holmes, James A.; Kass, David M.
- Abstract
The impact of Mars's 2018 Global Dust Storm (GDS) on surface and near‐surface air temperatures was investigated using an assimilation of Mars Climate Sounder observations. Rather than simply resulting in cooling everywhere from solar absorption (average surface radiative flux fell 26 W/m2), the globally averaged result was a 0.9‐K surface warming. These diurnally averaged surface temperature changes had a novel, highly nonuniform spatial structure, with up to 16‐K cooling/19‐K warming. Net warming occurred in low thermal inertia regions, where rapid nighttime radiative cooling was compensated by increased longwave emission and scattering. This caused strong nightside warming, outweighing dayside cooling. The reduced surface‐air temperature gradient closely coupled surface and air temperatures, even causing local dayside air warming. Results show good agreement with Mars Climate Sounder surface temperature retrievals. Comparisons with the 2001 GDS and free‐running simulations show that GDS spatial structure is crucial in determining global surface temperature effects. Plain Language Summary: Martian Global Dust Storms (GDS) are planet‐encircling events which fill the atmosphere with a deep layer of mineral dust. During these events the dayside of the planet cools due to the blocking of sunlight, but the nightside warms from dust scattering back surface emissions in the manner of the greenhouse effect. We combined observations of the most recent (2018) GDS from an orbiting instrument, the Mars Climate Sounder, with a Mars climate model to study the storm's effects on surface and near‐surface temperatures. We found that the net effect was actually an increase in global average surface temperatures. The cause was the significant nighttime warming of regions with low thermal inertia, which normally cool rapidly at night but are provided an atmospheric dust "blanket" by the storm. The magnitude of warming was enough to compensate for the net cooling over areas with higher thermal inertia. Near‐surface air temperatures also rose, as the storm coupled these more closely to the surface. Further simulations showed that these results are valid over various possible storm intensities. The role of thermal inertia suggests that the geographical extent of a GDS, and which regions it covers, plays a significant role in its ultimate effects. Key Points: Mars's 2018 Global Dust Storm caused a 0.9‐K globally averaged surface warming but with local 16‐K cooling/19‐K warmingThe magnitude of dayside cooling was controlled by atmospheric dust, and nightside warming by surface thermal inertiaThe effects were strongly nonuniform, with high dust loading causing net warming (cooling) over low (high) thermal inertia continents
- Subjects
DUST storms; DUST; MINERAL dusts; ATMOSPHERIC temperature; SURFACE temperature; GREENHOUSE effect
- Publication
Geophysical Research Letters, 2020, Vol 47, Issue 9, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2019GL083936