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Measurements at the mast
This plot shows the air temperature, snow depth, ice thickness and water depth measured at the mast of the Mass Balance Site.
Snow depth and ice thickness are derived from acoustic sounders that take one measurement every 15 minutes. The accuracy is about ±1 cm (±1/2 inch).
Data are filtered for this plot; unfiltered data are shown below.
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Temperature profile
This is the temperature profile through air, snow, ice, and water.
The grayed area indicates the position of the ice (bottom may be off by 0.1 m). The bounds of the red funnel are the highest
and lowest temperatures recorded during the past 24 hours. The black line with data points (spaced 0.1 m, 4 inches)
is the latest temperature profile. Air, snow, ice, and water can often be discriminated easily in winter and early spring: daily
temperature swings are more pronounced in the air than in the snow; the temperature profile in the ice is usually linear and steeper
than in the snow; the temperature in the water is approximately independent of depth. Towards summer the ice acts as a heat sink
with the coldest temperature registered inside the ice rather than in the air.
Temperature measurements are accurate to approx. ±0.2 °C. Further, measurements in summer may be affected by solar heating of the probe.
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Water temperature
This figure shows the water temperature approx. 1 to 2 m below the ice as detected by the bottom-most thermistor at the string of
temperature sensors (blue), and by the thermistor 30 cm (1 ft) above (red). Data are smoothed by a
running average filter with 6 hour window. The temperature readings are only crudely calibrated to ±0.2 °C.
Note that both sensors may be heated by incident solar energy. The line in light gray is the tidal signal.
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Relative humidity
These are air temperature and relative humidity, both measured by the Campbell CS500 probe enclosed in a radiation shield on the pinger mast.
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Depth and thickness soundings
This plot shows the air temperature, snow depth (three locations), ice thickness and water depth measured at the mast at the Mass Balance Site (see figure above). Snow depth and ice thickness are derived from acoustic sounders that take one measurement every 15 minutes. The accuracy is about ±1 cm (±1/2 inch). The colored lines are snow depth and ice thickness data smoothed by a median filter with a 24-hour window. The actual measurements are shown in light gray underneath.
Snow depth and ice thickness are spot measurements rather than aerial averages. There are snow dunes on the ice that may be 60 cm (2 ft) deeper than the thinnest snow; the measurements by the pingers are probably somewhere between the extremes. Similarly, the thickness of level ice varies in the general area surrounding the Mass Balance Probe.
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Temperature Probe
The temperature probe measures the vertical temperature at 10 cm (4 inches) intervals, starting 70 cm (2 ft) above the ice surface at the time of deployment. This plot shows those temperature measurements, i.e. temperature in air, snow, ice, and water.
In winter and spring, the coldest and warmest temperatures are measured in the air and water, respectively. In summer, the air temperature exceeds the melting point and snow and ice melt both from the top and from the bottom.
The current temperature profile is shown above.
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Temperature Profile
Color-coded temperature vertical profile through air, snow, ice, and water. Also indicated are
are the position of the ice bottom and snow surface measured at the pinger mast.
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Supply voltage
The Mass Balance Site is powered by two lead acid batteries attached to a wind turbine. On windy days (10 knots and above) power is delivered by the turbine and the batteries are being charged. The charge voltage increases with wind speed but is capped by a temperature-compensated charge controller. On windy days,
the voltage should be above 14 V, indicating that the batteries are being charged.
On windless days, the battery voltage can be used to estimate the available charge.
Currently, the voltage is 12.31 V.
A voltage of 10.5 V is typical for drained lead acid batteries. This is higher than the minimum voltage required for the data logger (9.6 V) and for the UHF radio (6 V). Our goal is to maintain the battery voltage above 11.5 V.
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Recent weather and forecast
This is a summary of recent weather observations at the Barrow airport (courtesy NOAA)and a weather forecast for Barrow based on a regional weather forecast model (courtesy Zhang and Krieger, ARSC). Refer to NOAA ET-SURGE for surge prediction.
Note that weather forecasts are unreliable beyond approx. 3 days.
See also webcam
(archive)
snapshots of the
last 24 h and the
last 14 days, and
tundra albedo.
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This project is supported through the Alaska Ocean Observing System (AOOS) with logistical and technical support provided by the Barrow Arctic Science Consortium (BASC). We also gratefully acknowledge the Arctic Slope Regional Corporation (ASRC) for supporting installation of the webcam and radar. This material is also based upon work supported by the National Science Foundation under Grant No. OPP-0856867. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).
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