Mountain Terrain Atmospheric Modeling and Observations Program.
Atmospheric Modeling and Observations
Program (MATERHORN) is a
multidisciplinary University Research Initiative (MURI) sponsered
by the Office of Naval Research. Please check the official
web-page of the MATERHORN program at the University of Notre
Dame, with links to other research groups. This webpage is an overview
of work planned and conducted at the University of Utah by the Hoch
& Whiteman research groups as part of the MATERHORN-X team.
2.: Schematic of the land-surface contrasts and flow
interactions around Granite Peak, UT.
The surroundings of Granite Peak are characterized by the land surface contrasts beween vegetated areas ("sparse sagebrush" - actually a mixture of vegetation of greasewood, saltbush, rabbitbrush, blackbrush, ephedra and sage brush) and the non-vegetated playa located west of Granite Mountain. A playa is an undrained flat basin floor between desert mountain ranges that seasonally becomes temporarily covered with water. Because the playa soil develops a salty white crust that is highly reflective during dry periods and becomes moist during wet periods, large energy budget contrasts occur between the playa and its drier surroundings. These surface contrasts drive "playa breezes" - circulations that are similar to the better-known land-sea breeze circulations.
The study site at DPG is surrounded by higher topography to the northeast (Cedar Mountains), the Simpson Mountains, Keg Mountains and the Dugway Range to the south, and Granite Mountain to the west. This geographic setup leads to a characteristic diurnal pattern of thermally driven circulation during synoptically quiescent times, with north-westerly up-valley flow at daytime and a south-easterly down-valley flow during the night.
Previous studies at DPG have shown the occurrence of up-and downslope flows along the eastern slopes of Granite Peak. The east slope of Granite Peak is on of the hot-spots for field observations during MATERHORN-X
3.: Animation of temperature and winds at each SAMS station
for days in September, October and November (SON) under
quiescent conditions. Quiescent conditions are defined by
NCEP/NCAR 700 mb wind speed of less than 5 m/s (10 kts). Days
are defined as 18 UTC -18 UTC, and both the 00 UTC and 12 UTC
times on that day must have 700mb winds less than 5 m/s to
qualify. This is fairly restrictive, with less than 10%
of days qualifying. N for each station varies due to
period-of-record differences. Source: Matt Jeglum, University
Figure 4: Diurnal cycle of shortwave incoming and shortwave outgoing radiative fluxes observed at EFS Sage and EFS-Playa, 7 October 2012.
Figure 5: Diurnal cycle of energy balance components observed at EFS Sage and EFS-Playa, 7 October 2012.
of LiDAR scans on 2 Oct 2012 on the east slope of Granite Peak
(Fig. 6). Color contours give the wind speed along the LiDAR
beam - Blue colors indicate flow towards the LiDAR (i.e.
While additional analysis is needed for this 2156 MST case, the LiDAR data depicts the interaction between a shallow downslope drainage flow and an apparent colder pool of air that is sloshing up the slope and undercutting the downslope flow layer. Patterns resembling Kelvin-Helmholtz waves can be seen at the top of the colder air layer.
Figure 6: LiDAR scan 2 October 0456 UTC.