Wind Directions
Wind direction at the Mars Pathfinder site is indicated as the direction from which the wind is coming: i.e. a southerly wind is a wind from the south. During the initial sols of the mission, wind direction rotated in a clockwise manner with time: southerly at night, westerly in the morning, northerly during early afternoon, and from the east in the evening. Winds from the south at night are consistent with flow down the Ares Valley at whose northern end Pathfinder is located. The change in the daily wind variation seen to begin late on sol 7 occurs in conjunction with a decrease in the measured sol averaged surface pressure and modulation to its diurnal cycle. Subsequently, we have seen a return to winds rotating through a full 360 degrees during the course of a sol.
Wind speeds have still not been absolutely determined
from the signals we are receiving from the wind sensor located at the top of the ASI/MET
mast. However, our wind sensor signals are strong, and do provide some qualitative
information about wind speed (i.e., largest signal as indictaed in this plot corresponds
to the fastest winds,...). During the mission's initial 10 sols, winds were strong during
early morning hours. The time around noon also was a preferred time for relatively strong
winds. Weakest winds occur during late afternoon/early evening on most sols. This general
pattern of early morning maximum winds has persisted, as far as we can determine from our
incomplete diurnal coverage, through to Sol 23. We continue to work towards producing the
wind speed data set, and will put the data on this web page as soon as it is available.
The Mars Pathfinder Atmospheric Structure/Meteorology
Experiment measures wind speed and direction with a sensor mounted on the top of the
40-inch (1 meter) tall meteorology mast. Measurements made during the late evenings and
early mornings of the second and third Sols after landing indicate prevailing winds from
the south-south-east. The wind direction then changed in the early afternoon, such that
the prevailing winds blew from the north to north-east. These results are similar to those
obtained by the Viking Lander 1 at this season. Wind speeds have not yet been precisely
determined, but early estimates show that the winds are quite light (a few miles per hour)
during the day, and somewhat stronger (about 10 miles per hour, or 16 kilometers per hour)
at night.
Mars Pathfinder's measurements of wind direction and
speed suggest values quite similar to those measured by Viking Lander 1 at this season.
Afternoon wind directions at the Mars Pathfinder landing site show winds blowing from the
southwest (from 230 degrees) during early afternoon and then turning to the northwest and
then to the north (from 350 degrees) by 3 PM local Mars time. Wind speeds have not yet
been definitively determined, but initial indications are that the winds are quite light
(a few miles per hour) near noon but increase as the afternoon progresses and might attain
values of 10-15 miles per hour.