Award Abstract # 0730158
Equatorial Superrotation on Earth Induced by Optically Thick Dust Clouds

NSF Org: AGS
Division of Atmospheric and Geospace Sciences
Recipient: THE JOHNS HOPKINS UNIVERSITY
Initial Amendment Date: September 13, 2007
Latest Amendment Date: October 3, 2008
Award Number: 0730158
Award Instrument: Standard Grant
Program Manager: Eric DeWeaver
edeweave@nsf.gov
 (703)292-8527
AGS
 Division of Atmospheric and Geospace Sciences
GEO
 Directorate for Geosciences
Start Date: October 1, 2007
End Date: September 30, 2009 (Estimated)
Total Intended Award Amount: $0.00
Total Awarded Amount to Date: $50,000.00
Funds Obligated to Date: FY 2007 = $50,000.00
History of Investigator:
  • Xun Zhu (Principal Investigator)
    xun.zhu@jhuapl.edu
  • Steven Lloyd (Co-Principal Investigator)
  • Darryn Waugh (Co-Principal Investigator)
Recipient Sponsored Research Office: Johns Hopkins University
3400 N CHARLES ST
BALTIMORE
MD  US  21218-2608
(443)997-1898
Sponsor Congressional District: 07
Primary Place of Performance: Johns Hopkins University Applied Physics Laboratory
11100 JOHNS HOPKINS RD
LAUREL
MD  US  20723-6005
Primary Place of Performance
Congressional District:
03
Unique Entity Identifier (UEI): FTMTDMBR29C7
Parent UEI: GS4PNKTRNKL3
NSF Program(s): Climate & Large-Scale Dynamics
Primary Program Source: app-0107 
Program Reference Code(s): 0000, OTHR
Program Element Code(s): 574000
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.050

ABSTRACT

The atmosphere of Venus displays extreme equatorial superrotation, in that upper-level winds over the equator blow in the direction of planetary rotation at speeds nearly a hundred times greater than the absolute motion of the solid surface. This project is based on the idea that the phenomenon of equatorial superrotation is not confined to slowly rotating planets, such as Venus, but, given sufficiently strong solar tides, occurs on Earth. Very strong tides could result from the presence of dense dust clouds, such as were produced by the asteroid impact believed to have caused the extinction of the dinosaurs. The stratospheric overturning circulation in the presence of equatorial superrotation may have played an important role in spreading the dust cloud over the entire globe, and, therefore, in causing the extinctions. Atmospheric superrotation could also be important for the response of the climate to a nuclear exchange (so-called "nuclear winter") or to extreme vulcanism.

Zhu has demonstrated, in an idealized two-dimensional (latitude-altitude) model, that strong solar tides in the stratosphere can cause Earth's atmosphere to superrotate. Now he and his collaborators will conduct a set of exploratory experiments using a three-dimensional global climate model with a well resolved stratosphere, incorporating stratospheric particles with distributions and physical properties relevant to volcano super-eruptions. These experiments will test, in a fully three-dimensional dynamical context, the new and intriguing hypothesis that tidal forcing from strong solar absorption in the stratosphere can cause equatorial superrotation on Earth.

The results of this work should be of general interest to the public, and the investigators plan to describe them in an article in a general-audience science magazine.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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Zhu, X., D. F., Strobel, M. F. Flasar "Exchange of global mean angular momentum between an atmosphere and its underlying planet." Planetary and Space Science , v.56 , 2008 , p.1524

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