Mass Balance and Climate of the Ablation Zone of the Taylor Glacier, Antarctica
Andrew Bliss and Kurt Cuffey
Department of Geography, University of California at Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720
abliss@berkeley.edu http://geography.berkeley.edu/~abliss/
Abstract
We explore the relationships between climate and ablation on the Taylor
Glacier, Antarctica on hourly to annual timescales. A simple physicallybased model that predicts ablation from weather station measurements on
the Taylor Glacier is presented along with a set of criteria to distinguish
between predominant weather patterns on the glacier. Two case studies of
high ablation events are presented. Advanced Very High Resolution
Radiometer imagery and NOAA-NCEP Reanalysis data are included to
give the broader context of the weather station measurements and to help
connect the local scale of weather station measurements to the broader
scale of climate model output. A novel method of visualizing these
disparate data is also demonstrated.
Diurnal Calm
Index
Inde
x
Katabatic
Inde
x
Storm
Inde
x
Upw
ard LW Do wnward LWUpw ard SW Do wnward SW Sublimation
(W/m^2)
(W/m^2)
(W/m^2)
(W/m^2)
(mmWE/20 min)
VP difference Rel. Humidity T emperature Wind SpeedW
(mbar)
(%)
(de
grees C) (m/s)
(de
ind Direction
grees)
Map of Taylor Glacier, Antarctica. The squares identify weather
station locations. The red circles show ablation stake locations. North
is up. The equilibrium line is close to the cyan station, everything to
the east is blue ice. The inset map is a digital elevation model of
Antarctica, showing the location of the Taylor Glacier.
ier
lac
rG
lo
Tay
Motivations
The interactions between climate and the Antarctic Ice Sheet are interesting because the response of the
Antarctic Ice Sheet to anthropogenically-forced climate change may have large impacts on human
societies. We chose the Taylor Glacier as our study area in part because of the climate history record
provided by the Taylor Dome ice core. If we can understand how the Taylor Glacier has responded to
past climate changes, we will be more confident in our predictions of glacier and ice sheet response to
future climate changes. The interaction between the climate and the glacier itself takes many forms (ice
rheology depends on temperature, snowfall depends on storm tracks, ablation depends on temperature,
wind speed, humidity, cloudiness). This poster focuses on the connection between weather and ablation
on the Taylor Glacier where the dominant mass-loss mechanism is sublimation of ice to the
atmosphere. We present two case studies from March of 2006, one of a katabatic wind event and the
second of a storm that followed a few days later.
Weather Station Data
Each of the six weather stations that we set up on the Taylor Glacier in November of 2003 measures
wind speed, direction, temperature and relative humidity (shown in the figure at left). From these
variables, we predict sublimation at the weather station locations (also shown). While common lowsublimation rate events (around 1 mm/day) account for the bulk of the sublimation on the Taylor
Glacier, less frequent, larger events are needed to explain the total observed ablation. Two of these
events are shown in the graph at left. The first started on February 26th and lasted until March 6th,
reaching its peak intensity between the 3rd and the 6th. This pattern of wind speeds, directions, and
cloudiness (as observed by shortwave and longwave radiometers on 3 of our stations) is characteristic
rG
lo
Tay
ier
lac
of a katabatic wind event and is identified as such by a set of criteria we defined to distinguish among 4
different "modes" of weather variability on the Taylor Glacier: storm, katabatic wind, calm, and diurnal
mountain/valley wind. The mode indices are displayed in the figure at the far left. The next largesublimation event began on March 9th and lasted until the 13th. The combination of high winds,
consistent wind directions, and clouds is indicative of a storm.
Advanced Very High Resolution Radiometer Imagery
The two infrared satellite images above provide a regional perspective on the weather situation and
verify our choice of mode for each sublimation event. The image on the left is from March 4th when
katabatic winds dominated the local weather on the Taylor Glacier. The dark (warm) trace of the
katabatic wind can be seen emanating from the Skelton Glacier, just south of the Taylor Glacier. White
(cold) cloud streaks are also visible, indicating fast winds aloft. The image on the right was taken
March 12th, when the Taylor Glacier was in the midst of the storm. A comma cloud is clearly visible
and the Taylor Glacier is under thick clouds. The imagery comes from http://avhrr.acecrc.org.au/
NOAA-NCEP Reanalysis Data
The plots below show data from the NOAA-NCEP reanalysis corresponding to the days when the
images above were captured. All four fields are from the surface layer of the model. The blue star and
box show the approximate locations of the Taylor Glacier and the AVHRR images respectively. The
synoptic conditions are remarkably similar between the two cases. In both cases the reanalysis is fairly
consistent with our weather station data. Data from http://iridl.ldeo.columbia.edu/
Sublimation During Different Modes
Sublimation happens at different rates under different conditions. In the
two examples just shown, rates were slightly higher for the katabatic
event because the relative humidity was lower which increases the
moisture transport from the surface (assumed to be saturated) to the
atmosphere. The figure above shows that high-sublimation events occur
during storms and katabatic events while low-sublimation events have
predominantly calm conditions.
Google Maps Data Interface
The figure in the bottom right corner shows a screenshot of an AVHRR
image and weather station data presented on the web using the Google
Maps API. The data figures are inserted as a custom tile layer for the map
and the AVHRR images, maps of reanalysis data, and comments on the
data are displayed in popup info windows.