Temperature
The Dome A automatic weather station has temperature sensors at different heights. This allows us to measure the microclimate of the region. Above the snow, sensors are set at 1 m, 2 m and 4 m. Below the snow they are set at 0.1 m, 1 m, 3 m and 10 m.
The temperature graph below shows the reading from the 1 m sensor. At 10 m depth, seasonal temperature variations are damped out. The temperature at this depth is close to the annual average surface temperature.
Please note: We are aware that the data presented here is, on occasion, fluctuating beyond normal limits. This is due to a technical problem that is currently beyond our control.
Wind speed
Wind speeds at Dome A are very low. During winter, exceptionally strong surface inversions develop. It is not unusual for the air temperature 1 m above the surface to be 10 ºC colder than the temperature 2 m above the surface.
Inversions are nearly always present in the polar regions during winter. This is because the sun is very low in the sky. The inversion occurs because when there is little radiation coming in from the sun, the snow surface cools down. This cools the air that is in contact with the snow. The low wind speed prevents this cool air from mixing with warmer air above.
Wind data is not collected during winter. This is because it is too cold for the anemometers to work properly.
A wind rose shows how wind speed and direction are distributed at Dome A. It gives a graphical representation of how often winds of particular strengths blow from particular directions.
Relative humidity
Relative humidity is the amount of moisture in the air as a percentage of the amount that the air can actually hold. Warmer air can hold more moisture than cooler air. This means that for a given amount of atmospheric moisture, relative humidity will be lower if air is warmer than it would be if the air is cooler.
Air pressure
Air pressure, or atmospheric pressure, is the force exerted on a point on the earth’s surface by the mass of atmosphere above it.