Access

Letters to Nature

Nature 416, 298-301 (21 March 2002) | doi:10.1038/416298a; Received 9 October 2001; Accepted 28 January 2002

Open Innovation Challenges

A topographically forced asymmetry in the martian circulation and climate

Mark I. Richardson1 & R. John Wilson2

  1. Division of Geological and Planetary Sciences, California Institute of Technology, MC 150-21, Pasadena, California 91125, USA
  2. Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, PO Box 308, Princeton, New Jersey 08542, USA

Correspondence to: Mark I. Richardson1 Correspondence and requests for materials should be addressed to M.I.R. (e-mail: Email: mir@gps.caltech.edu).

Top

Large seasonal and hemispheric asymmetries in the martian climate system are generally ascribed to variations in solar heating associated with orbital eccentricity1. As the orbital elements slowly change (over a period of >104 years), characteristics of the climate such as dustiness and the vigour of atmospheric circulation are thought to vary2, 3, 4, 5, as should asymmetries in the climate (for example, the deposition of water ice at the northern versus the southern pole). Such orbitally driven climate change might be responsible for the observed layering in Mars' polar deposits by modulating deposition of dust and water ice3, 5, 6. Most current theories assume that climate asymmetries completely reverse as the angular distance between equinox and perihelion changes by 180°. Here we describe a major climate mechanism that will not precess in this way. We show that Mars' global north–south elevation difference forces a dominant southern summer Hadley circulation that is independent of perihelion timing. The Hadley circulation, a tropical overturning cell responsible for trade winds, largely controls interhemispheric transport of water and the bulk dustiness of the atmosphere7, 8, 9, 10, 11. The topography therefore imprints a strong handedness on climate, with water ice and the active formation of polar layered deposits more likely in the north.

  1. Division of Geological and Planetary Sciences, California Institute of Technology, MC 150-21, Pasadena, California 91125, USA
  2. Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, PO Box 308, Princeton, New Jersey 08542, USA

Correspondence to: Mark I. Richardson1 Correspondence and requests for materials should be addressed to M.I.R. (e-mail: Email: mir@gps.caltech.edu).