Weather stations in Longyearbyen

A rain gauge measures precipitation (rain and snow) in millimeters (mm). Snow is measured in mm water equivalent, which is the amount of water it would produce if it melted. One mm of precipitation is equal to one liter of water spread over one square meter.
Precipitation falls into the Rain Garage opening. Rain flows into a container, while snow melts first. Antifreeze is used to melt any solid precipitation in the container. The amount of precipitation is measured by vibrating wire load sensors.
The metal parts around the rain garage reduce the effects of wind, but wind can still affect measurements by changing how much precipitation enters the gauge.
The use of vibrating wire load sensors can cause precipitation to be measured even when it is not present. Therefore, the rain gauge is used in combination with the yes/no sensor on the Weather Station.

The Ultrasonic Anemometer 2D measures wind speed, direction, and virtual temperature. Its high measurement rate makes it ideal for capturing gusts.
It consists of four ultrasonic transducers arranged in pairs. These act as both transmitters and receivers. Wind influences the speed of sound. When it moves with the sound wave, the signal travels faster. If it blows against it, the signal takes longer to arrive. By measuring travel times in both directions, the device calculates wind components.
Since sound speed depends on air temperature, the measured propagation time also allows for temperature estimation.

Snow depth is measured using a laser, which provides millimetre-accurate readings in all weather conditions. The laser works by sending a pulse towards the surface and measuring the time it takes for the beam to return. This determines the distance to the ground. When snow is present, the distance decreases, indicating the snow depth.

During measurement, a red light dot appears on the surface. To ensure accurate readings, avoid standing in this spot or disturbing the surface.

This sensor measures horizontal wind speed and direction. The vane rotates so that the propeller faces the wind, indicating wind direction. The propeller’s speed is used to calculate wind speed.
In meteorology, wind direction always refers to where the wind is coming from.

This is the lower temperature and humidity sensor of the weather station. It measures air temperature and relative humidity. Relative humidity is the amount of water vapour in the air compared to the maximum it can hold at a given temperature, expressed as a percentage.
To ensure accurate readings, the sensor is placed inside a radiation shield, which protects it from direct sunlight. The radiation shield allows air to flow freely around the sensor while blocking solar radiation, which could otherwise cause temperature overestimation. This setup ensures the sensor measures the actual air temperature rather than being influenced by external heat sources.

This is the upper temperature and humidity sensor of the weather station. It measures air temperature and relative humidity. Relative humidity is the amount of water vapour in the air compared to the maximum it can hold at a given temperature, expressed as a percentage.
To ensure accurate readings, the sensor is placed inside a radiation shield, which protects it from direct sunlight. The radiation shield allows air to flow freely around the sensor while blocking solar radiation, which could otherwise cause temperature overestimation. This setup ensures the sensor measures the actual air temperature rather than being influenced by external heat sources.

This is a radiometer. It measures incoming shortwave radiation in the wavelength range of 400–700 nm, corresponding to visible sunlight. The measurement unit is watts per square metre (W/m²), representing the power received per unit area.

This sensor is an infrared radiometer that measures the surface temperature below the station. Knowing whether the surface is warmer or colder than the air is important for the temperature stratification of the air near the ground.
All objects emit infrared radiation depending on their temperature. Infrared radiometers measure this radiation, allowing surface temperature to be measured without direct contact.

Precipitation in the form of drizzle, rain, snow, or hail is detected by a light barrier system, which triggers a signal. The precipitation sensor records the start and end of precipitation, as well as its duration.
Only when this sensor detects precipitation, the amount of precipitation measured by the rain gauge is recorded.