Introduction: The Great Storms of 2001

3 Tharsis views - 2001 storm

The 2001 Great Dust Storms - Tharsis Region - image from NASA Photojournal

Mars: widely known as the Roman god of war, he also served less famously as the god of fertility, growth, and death - spanning the entire life cycle here on Earth. One of the more fascinating phenomenon associated with Mars the planet is an analogous cycle involving the onset, evolution, and cessation of giant (often global) wind storms which periodically enshroud the planet in a blanket of dust, dramatically altering the characteristics of both the atmosphere and surface.

With the Mars Global Surveyor (MGS) in orbit around the Red Planet, the Great Dust Storms of 2001 have provided an excellent opportunity to study the dynamics of these storms and expand our understanding of how they form and develop. 

Preliminary analyses of images from this most recent global event show many similarities to previously observed storms, including origination in the southern hemisphere subtropical zone, the coalescence of several regional storms, and the eastward zonal expansion of dust injected into the circumpolar jet stream prior to the globalization of the storm.
Telescope temperatures (click to enlarge)
Additional confirmation of theories and models of Mars atmospheric dust effects was provided by temperature measurements taken from the orbiter's telescope tube. The figure at left (from MSSS MGS MOC2-291 Release ) shows the temperature data taken during the storm (in blue) overlain on data from the previous year (in red) when there was no storm. This data is consistent with cooling of the surface (indicated by the dip in daytime temperatures) due to the atmospheric dust reflecting a greater amount of incident solar energy, and warming of the atmosphere (indicated by the rise in nighttime temperatures) due to increased radiative absorption by the dust of heat from the surface. Such behavior was observed in lesser detail during earlier storms and had been predicted by theory and modeling (e.g., Cantor et al, 2001; Murphy et al, 1995).

Despite these confirmations, the 2001 event exhibited some unexpected characteristics which had not been previously observed. Although the storm originated in typical fashion, starting in mid-June with a local storm that circulated in and around Hellas Basin for several days, it unexpectedly expanded northward on June 25 across the equator and into Arabia Terra and other areas, spawning several new regional storms (see movie below, from ASU TES site).
Temperature graph
Martian Dust Storm begins
Such early longitudinal expansion had not been observed prior to this storm. Additionally, the circumpolar winds in the southern hemisphere set up several other regional storms, most notably in the Daedalia-Claritas-Syria, Noachis-Meridiani, and Hesperia regions, which were extremely long-lived (over 90 days in the Daedalia-Claritas-Syria case). These multiple storm centers began feeding dust into the stratosphere, completely enshrouding the planet by mid-July , and continued to feed dust into the system well into August. Prior to this, storms had been thought to dissipate more quickly and dust source areas were thought to have been confined to one or two zonally restricted areas.

Additional 2001 storm image links:
ASU TES Dust Storm Movies
TES daily images - June 17 - August 26, 2001
Hubble before & after images
Hubble before, during, & after images

Other links:
MOC-MOLA map (created for National Geographic)
Clickable USGS map (with labeled regions)
Other names for Mars


The Life Cycle of Martian Dust Storms
Planetary Atmospheres Final Project
by Than Putzig
May 6, 2002