Multiyear Mars Orbiter Camera (MOC) observations of repeated Martian weather phenomena during the northern summer season

[1] The Mars Global Surveyor Mars Orbiter Camera (MGS MOC) has observed several atmospheric events repeat within a few degrees of L-s from one year to the next over 3 Mars years during a portion of the northern summer, southern winter seasons (L-s = 124degrees-140degrees). 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.