Forthcoming 2005 Mars
(14)
Water Vapours
Seen on the SH from λ=320°Ls to 360°Ls and
Masatsugu MINAMI
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he
Viking mission in 1977 brought about rather unexpected results in addition to a
lot of usual anticipated ones: As an example it revealed a rich distribution of
water vapour on the southern hemisphere at the season of southern summer
solstice λ=270°Ls,
and secondly, as this may also be related with the former, the water vapour was
seen to go down from the southern high-latitude area to lower equatorial region
from λ=330°Ls
to λ=360°Ls.
(These were treated in CMO #108 -25 August 1991-, based on B JAKOSKY et al, Icarus
73 (1988) 80, J POLLACK et al, Icarus 50 (1982) 259.)
What we recall here may be related with the second result,
and may be observable similarly this apparition. That is the observational fact
that in 1990, around from λ=340°Ls, there were observed one or two
(sometimes three) patches of the water condensates on the following terminator
from the higher to lower latitude (as reported as a Note in CMO
#108 p933). In short, from the time S Sabaeus was near the meridian to the time
when Hellas was near the morning terminator, several conspicuous condensate
patches were witnessed on at-dawn Noachis when it passed the morning
terminator, especially from 3 December 1990 (λ=344°Ls) to
10 December 1990 (λ=347°Ls)
(Just from Japan): This is first based on Mn’s 65
observations from 3 Dec to 10 Dec 1990 and also on Takashi Nakajima (Nj)’s 29
observations from 6 Dec to 10 Dec 1990, while at the same time a lot of
observations were made in Japan. On 1 Dec (λ=342°Ls)
1990, Tohru IWASAKI (Iw) visually watched at
ω=322°W,
and Tomio AKUTSU (Ak) took a B image (B390) at ω=336°W, both
show two condensate terminator patches, one at a higher region and the other at
Margaritifer S. On 3 December 1990, Isao MIYAZAKI (My) produced three
sets of TP images (B390); one at ω=320°W
showed the one at the higher region was divided into two terminator patches,
and at ω=342°W
there was added the third one over Margaritifer S. The observers of the
repeated terminator patches were counted, in addition to the above five, as
follows: Naoya MATSUMOTO (Mt, RD100), Hiroshi
ISHADOH (Id), Akinori NISHITA (Ns,
RD100), Masami MURAKAMI (Mk), Morimasa
NAKAJIMA (Nk) and others. Mt chased on
9 Dec 1990 by RD100 the planet at ω=246°W, 256°W, 262°W, 272°W, 281°W, 306°W, and
316°W.
From
Abroad, Don PARKER (DPk)
was a unique observer at that time who secured the B images. One of his colour
images taken on 24 November 1990 (λ=334°Ls)
shows this kind of patch (he produced B through the colour films). We
can say however if we compare DPk's
image on 23 Nov 1990 at ω=297°W with My's image (Int)
made on 7 Dec 1990 at ω=295°W, the latter shows the limb cloud paths more
clearly and strongly. One month later, DPk
showed a patch to the south of
Hellas even when more inside looked also irregular, and at
the western corner a strange stream swath of light matter prevailed along Yaonis Fr (the northern part of 
(3), with Figure at p989 shown
here at the rhs). This was quite apparent on 23 Oct 1990
(λ=321°Ls) at ω=303°W, 313°W: The bright part was not whitish but
slightly pinkish. This aspect was also detected by Iw, Ak and Mk. Already DPk’s TP photos made on 13 Oct 1990 (λ=315°Ls)
at ω=311°W, 317°W show this phenomenon, and so might have begun to occur
before the limb-patch phenomena. He also showed it on 19 Nov, 20 Nov, and 23
Nov 1990. In
Fifteen years ago, any concentrated observations did not reach
us except from the Japanese observers, while this apparition we can expect to
accumulate globally more complete data of the same phenomenon from around the
world, if not obstructed by the dust covering.