This is a follow up to Marcia's post below at http://www.habitablezone.com/space/messages/22199.html

Marcia wrote:
Although it's colder, the Martian North has a more stable/predictable annual weather patterns than the South. True?

Alex writes:
Generally speaking, yes, though predicting actual weather at a specific locale on Mars for any given time is, of course like on Earth, inherently unpredictable. That said, in a recently published paper Cantor et al. [2002] showed that 3 Martian years of MOC monitoring showed little interannual variability of weather in the Martian northern polar regions. Specifically, the authors concluded:

"1. MOC observations obtained over the past 3 Mars years, during part of the northern summer/southern winter seasons, have revealed that several local-scale meteorological phenomena (extratropical annular cloud, north polar and Valles Marineris dust storms, and Amazonis dust devils) reoccur annually at nearly the same locations and about the same time of year (within ~12 Mars days or 6° of Ls ). These reoccurrences suggest an interannual repeatability in select Martian weather events during the north summer season that has not been observed in any extent since the Viking 1 Lander from 1976 to 1982.

"2. It now seems possible to predict, with some success, when and where a select group of large-scale atmospheric phenomena (dust storms, dust devils, and clouds) will form during the northern summer season.

"3. The interannual variations in the south polar cap interior and in the recession of the residual north polar cap appear to have had a negligible effect in perturbing Mars' northern summer seasonal weather. The variations represented by the retreat and resurgence of the residual north polar cap appear to have been self-correcting on fairly short timescales, suggesting a state of limited variability in the present northern summer seasonal climate."

Reference:

Cantor, B., M. Malin, K. S. Edgett, Multiyear Mars Orbiter Camera (MOC) observations of repeated Martian weather phenomena during the northern summer season, Journal of Geophysical Research, 107,(E3), 10.1029/2001JE001588, 2002.

Abstract

The Mars Global Surveyor Mars Orbiter Camera (MGS MOC) has observed several atmospheric events repeat within a few degrees of Ls from one year to the next over 3 Mars years during a portion of the northern summer, southern winter seasons (Ls = 124°–140°). The repeatability suggests a previously unobserved lack of significant variation in the present Martian northern summer seasonal climate. Nonetheless, interannual variations in the seasonal south polar cap and in the residual north polar cap were observed. These appear to have had a negligible effect in perturbing Mars' weather during the northern summer season.

Received 4 September 2001; revised 4 December 2001; accepted 6 December 2001; published 21 March 2002.

Keywords: Mars, dust, clouds, weather, meteorology.

Index Terms: 6225 Planetology: Solar System Objects: Mars; 5445 Planetology: Solid Surface Planets: Meteorology (3346).

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Alex R. Blackwell
University of Hawaii