Drifting Automatic Radiometeorological Stations
Documentation provided by V. Radionov; edited by F. Fetterer
Overview, observations of ice drift and meteorological parameters from DARMS
The Drifting Automatic Radiometeorological Station (DARMS) for weather and sea ice drift data recording was developed at the Arctic and Antarctic Research Institute (AARI) by Yu. K. Alexeyev for operation in remote and otherwise inaccessible sites in the Arctic Ocean. Placed on the pack ice of the Arctic Ocean by aircraft or icebreaker, DARMS automatically transmitted information on wind speed and direction, air pressure and temperature. From 1957 through 1976, AARI continuously had DARMS units in operation.
Figure 9 shows the structure of a DARMS unit. A hollow steel bar that passed through ice was the principal feature of the station design. A hermetically closed container housed batteries and a clock mechanism, and was fixed to the lower end of the bar under ice. The station antenna, a 12 m duraluminum mast, was supported by three stays. These were fixed by anchors frozen into ice. The anchors were fitted with guide runners, in which the supporting tripod could move freely. This design decreased the possibility of station damage due to ice cracking. DARMS units were equipped with a special tent, stretched above the ice surface, to prevent anchors from melting out of ice due to solar heating. The duration of autonomous DARMS operation on ice with daily data transmission was about 1 year.
A radio transmitter and receiver, as well as meteorological unit, were mounted at a height of two meters over ice surface. The DARMS meteorological unit (Figure 9, right) measured air temperature, air pressure, and wind direction and speed.
A bimetallic thermometer measured air temperature. An aneroid barometer with temperature compensation by the bimetallic strip was used as pressure sensor. A large weather vane turned the meteorological unit around the vertical axis into the wind direction. Wind direction was determined by magnetic compass reading. Two smaller weather vanes measured wind speed. For that purpose the dynamic anemometer principle was used.
The mechanical systems of the sensors were damped. This excluded the influence of vibrations that came with high wind speeds on the temperature and pressure sensor readings. Wind speed and direction were averaged automatically over an eight or 10 minute period.
The DARMS units measured meteorological data within the following ranges:
Air pressure from 960 mbar up to 1050 mbar, with a precision of 1 mbar.
Air temperature from -55 °C up to +30 °C with a precision of 1 degree.
Wind speed from 1 m/s up to 25 m/s with a precision of 1 m/s.
Wind direction through 16 points (360 degrees) with a precision of 22.5 degrees (1 point).
The data were transformed into radio signals by means of a code block and transmitted by Morse code on fixed frequency in the 551- 584 kHz range. The signals were received by American radio transmitting and bearing stations DAN-2. Nine stations were mounted in the Arctic during the Second World War to guide the transit flights of airplanes from the USA (Alaska) through the Arctic and Siberia to the Soviet-German front. High-frequency radio waves were used to fix position of the DARMS unit by triangulation. The sensitivity of the antenna was 1 m V, and bearing accuracy was ± 1 degree. Signals were received from distances up to 1500 kilometers.
The long term (1957 through 1976) of the observation program for ice drift and meteorological parameters was due to the very dependable DARMS equipment and excellent radio bearing capabilities.
At the time of their acquisition, DARMS data were used in weather forecasting. Now the weather observations obtained by these stations supplement the information collected by the Russian North Pole drifting stations.
Daily values of surface air pressure, two-meter air temperature, wind speed, wind direction, and DARMS positions were prepared for this Atlas. The time of daily values is given as 0000 GMT. Values from the archive at AARI for position and the meteorological observations were quality controlled by checking them against the original daily synoptic chart.
Figure 9. (Left) A DARMS station. 1. Container for batteries and a clock mechanism. 2. Hollow steel bar. 3. Radio transmitter and receiver. 4. Meteorological unit. 5. Antenna. (Right) DARMS meteorological unit. 1. Axis 2. Wind speed vanes. 4. Temperature sensor with cover. 6. Cover of magnetic compass 7. Wind direction vane.