Martian north polar cap 1979–1980

Abstract

A regression curve for the north polar cap of Mars is extracted from the photographs obtained at Kwasan Observatory and at Hida Observatory during the 1979–1980 apparition. The north polar cap was first observed at Ls = 26°, and the latitude of the edge of the cap was about 66°N. The retreat of the cap stopped until Mars reached Ls = 57° when the cap started to shrink. The edge reached a latitude around 80°N at Ls = 85° and then became almost stationary. The roughly constant dimension of the north polar cap before mid‐spring appears to be a regular phenomenon. But the onset time when the cap starts to shrink after the temporary stop appears to be different from year to year. The measurements of the edge of the permanent cap showed an asymmetric shape in relation to the pole. The cap extends farther to the south for longitudes near 0° than for those near 180°. The shape of the permanent cap for Ls = 84°–101° in 1980 agrees very well with that for Ls = 97° in 1972 obtained by Mariner 9.

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

“…The rates of seasonal polar cap recession observed by MOC James et al, 2000 are consistent with those observed previously from Earth-based [Fischbacher et al, 1969;Capen and Capen, 1970;Dollfus, 1973;Baum and Martin, 1973;Iwasaki et al, 1979Iwasaki et al, , 1982Iwasaki et al, , 1984Iwasaki et al, , 1999James et al, 1990] and spacecraft [Soderblom et al, 1973;Briggs, 1974;Christensen and Zurek, 1984;Cantor et al, 1998;James, 1979James, , 1982James and Lumme, 1982;James et al, 1979James et al, , 1987James et al, , 1996James et al, , 2000Kieffer et al, 2000] studies. However, the interior of the polar caps displayed substantial variations in albedo patterns from year to year.…”

Martian North Polar Cap Recession: 2000 Mars Orbiter Camera Observations

“…This is the seasonal period when the plateau or standstill in the cap recession has been frequently reported previously (Iwasaki et al 1979(Iwasaki et al , 1982James 1979). There is no evidence for this effect in the average cap recession curve, Fig.…”

“…Antoniadi (1930), and Fischbacher et al (1969) summarized many of the early, prespacecraft, observations. More recent ground-based observers have included Dollfus (1973), Capen and Capen (1970), James et al (1987), and Iwasaki et al (1982Iwasaki et al ( , 1984Iwasaki et al ( , 1987Iwasaki et al ( , 1999. Mariner 9 (Soderblom et al 1973) and Viking (James 1979(James , 1982) also made north polar observations.…”

Structure of the martian north polar cap and vernal hood system at L s 61‡–66‡ of the 1995 apparition

“…Confer Table IV. Dollfixs, 1973Dollfixs, ), 72" (1948Fischbacker et al, 1969Fischbacker et al, ), 73" (1963Capen, 1970), 72.5" (1963;Fischbacker et al, 1969Fischbacker et al, ), 73" (1963Parker et al, 1983Parker et al, ), 70" (1965Capen, 1970), 71" (1965;Fischbacker et al, 1969Fischbacker et al, ), 71" (1965Parker et al, 19X3), 65" (1967;Capen, 1970), 65" (1967;Parker et al, 1983Parker et al, ), 56" (1969Parker et al, 1983Parker et al, ), 73" (1978Iwasaki et al, 1979Iwasaki et al, ), 71" (1980Iwasaki et al, 1982), 71" (1980James, 1982James, ), 72" (1980McKim, ),-75"(1980Jamesetal., 1987bJamesetal., ),71"(1980Parkeretal., 1983Parkeretal., ),72" (1982Parker et al, 1983Parker et al, ), 70" (1982Iwasaki et al, 1984Iwasaki et al, ), 71" (1984Beish, 1996), 72" (1993;Troiani et al, 1996Troiani et al, ), 74" (1995Minami et al, 1995), and74" (1995;Parker and Beish, 1996).…”