Radiosonde Observations

The foundation of radiosonde devices stems from the development work of French researchers Bureau and Idrac in the early 1920s, and Russian scientist Pavel Molchanov who worked with them. These devices were designed to collect information about atmospheric conditions at various levels and transmit this data via radio waves to ground stations. In 1930, Molchanov developed the first radiosonde, recognized today as the precursor to modern radiosonde systems. Within a few years, this device began to be used by meteorological offices in many countries.

A radiosonde is an instrument that measures temperature, pressure, humidity, wind direction, and wind speed in the atmosphere. Attached to a balloon filled with hydrogen or helium gas, it is released into the atmosphere and transmits real-time data to ground stations via radio waves. Modern radiosonde devices are equipped with GNSS (Global Navigation Satellite System) technology, and the collected data are used in meteorological analyses, weather forecasting models, and other research applications.

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The radiosonde device ascends to altitudes of 30–40 kilometers using a balloon. During this ascent, it measures temperature, pressure, and humidity parameters at different atmospheric levels. Using GNSS technology, the device’s position data are also obtained, from which wind direction and speed are calculated. The data transmitted by the device are received and analyzed by ground stations for use in weather forecasting and other meteorological studies.

The balloon rises at a rate of approximately 360 meters per minute. When it reaches a diameter of about 10 meters, it bursts due to internal pressure, and the device descends safely to the ground with the aid of a parachute.

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1. Balloon:
2. 1. Made of latex or neoprene material.
   2. Filled with hydrogen or helium as the lifting gas.
   3. The size of the balloon varies depending on the target altitude and the weight of the radiosonde device.
2. Radiosonde Device:
3. 1. Meteorological sensors for measuring temperature, pressure, and humidity.
   2. Electronic data encoder and telemetry transmitter.
   3. GNSS sensors used to determine the device’s position.
3. Parachute:
4. 1. Ensures the controlled descent of the device to the ground after the balloon bursts.
4. Ground Station:
5. 1. Composed of antennas and receiver systems.
   2. Collects, analyzes, and processes data for use in meteorological forecasting models.

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Türkiye has nine radiosonde stations. These are:

• Samsun (41°20’ N, 36°15’ E)
• İstanbul (40°54’ N, 29°09’ E)
• Ankara (39°58’ N, 32°51’ E)
• İzmir (38°23’ N, 27°04’ E)
• Isparta (37°47’ N, 30°34’ E)
• Diyarbakır (37°54’ N, 40°12’ E)
• Adana (37°00’ N, 35°20’ E)
• Erzurum (39°54’ N, 41°15’ E)
• Kayseri (38°41’ N, 35°30’ E)

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These stations have been strategically located to monitor air masses affecting Türkiye and to meet national meteorological requirements. The World Meteorological Organization (WMO) recommends establishing radiosonde stations at intervals of 250 kilometers over land and 1000 kilometers over oceans. The Turkish stations are positioned in accordance with these criteria and conduct observations twice daily (at 00 UTC and 12 UTC).

Radiosonde observations are used in the following areas:

1. Weather Forecasting and Analysis:
2. 1. Pressure, temperature, humidity, and wind data from different atmospheric levels are mapped to generate weather forecasts.
   2. Height, pressure, temperature, humidity, and wind data at standard isobaric levels are mapped to support analytical studies.
2. Aviation:
3. 1. Play a critical role in civil and military flight planning.
3. Air Quality Analysis:
4. 1. Provide data for air pollution forecasting and modeling.
4. Digital Weather Forecasting Models:
5. 1. Form the foundational data for modern meteorological models.

Hydrogen gas is commonly used to inflate radiosonde balloons. Due to hydrogen’s high flammability, safety measures such as gas leak detectors, fire suppression systems, and flame detection sensors are implemented. Alternatively, helium gas may be used, especially in areas where safety is a critical concern.