Definition
A radiosonde (Sounding, high-altitude temperature, humidity, and pressure observation) is an observational device equipped with sensors for temperature, humidity, pressure, wind speed, and wind direction. It ascends via a sounding balloon or drone to collect temperature, humidity, and pressure data from the ground up to about 30 km altitude, forming a vertical profile of the atmosphere, providing high-altitude observational support for weather forecasting, weather modification, aviation meteorology, and numerical models. Sounding is a direct method for obtaining high-altitude atmospheric conditions, and meteorological stations around the world release them at scheduled times every day.
Radiosondes transmit data in real time to ground receiving stations via radio sounding (L-band, GPS sounding) or satellite communication. Some drone-based soundings use IoT SIM cards for data transmission, suitable for mobile observations and emergency monitoring.
Technical Features
Radiosondes use high-precision sensors, with data collection frequencies typically of 1–2 seconds. Balloon soundings transmit data via radio as the balloon ascends; drone soundings can observe while hovering at a fixed point. Sounding data is used to analyze atmospheric structure, convective available potential energy, wind shear, etc., supporting the determination of timing for weather modification operations (such as identifying conditions for rain enhancement).
Use Cases
Radiosondes are widely used in meteorological observation, weather modification operation approval, aviation forecasting, and numerical forecasting. Sounding data is linked with operation approval systems to support the selection of operation timing and regions. SimtoLink provides stable network services for meteorological observation equipment and drone soundings.
Every profile point must carry a height
On an IoT SIM, sounding covers only those mobile observations that really have moved their return path onto cellular, for example a drone hovering or climbing with sensors. The usual path for a balloon sounding is still radio down to a ground receiver. Do not read an online SIM as "every sounding in the world now uses cellular." Whichever path is used, one profile point must have a height (or a height converted from pressure) together with temperature, humidity, and wind at that level. A point with the elements and no height cannot go into a vertical profile. Time, position, and sensor readings through the ascent must come from the same release, and the ground station or the onboard recorder must be able to keep the raw points if the link breaks. When a drone returns data over a SIM, the SIM's delay must not be used to reorder height. Height follows pressure or positioning, not the order in which messages arrive.
The six surface elements are one horizontal record at a station. A sounding is the vertical series of one ascent. A similar time does not make them one profile. A surface point before release may be the start of the profile, but its source must be marked. Sampling every second or two does not require every point to succeed on cellular immediately. Points may be backfilled in height order after the drone returns or the link recovers. The backfill package must carry the release ID, so points from two flights are not mixed on one plot.
After a break, the series is joined on the ground clock
It is easy, after the link breaks during a balloon or drone ascent, for ground software to append late messages using the receiver's own clock while the height has already changed. A late low-level point is drawn up at a high level. Order by the sensor's own pressure or time. The receive time is only a log. Another mistake is to keep recording the last height after positioning fails. The aircraft or balloon is still climbing, the height is frozen, and a temperature change is explained as an anomaly at one level. When height stops updating, cut the profile off. Do not extend it horizontally.
Wind calculation depends on a change in position. A hovering drone has no horizontal displacement, so it cannot reuse the balloon method that estimates wind from displacement. Use an onboard wind sensor, and write the method into the record. Mixing the two methods without a label computes the shear wrong. For acceptance, break the link briefly: after recovery, insert points by pressure height, not by arrival order. Then freeze the height and confirm the profile stops at the freeze. Two releases' IDs must not appear on one curve. A balloon release whose radio is healthy should not be moved onto cellular just to "upload everything the same way."
Cut the profile where the height freezes
When positioning or pressure height stops updating, cut the profile at the last valid height. Do not keep extending it horizontally with time. Insert late messages by pressure height or sensor time. The receive time is only a log, so a low-level point is not drawn at a high level. Two releases use different IDs, and their points must not enter one curve. A hovering drone does not use the balloon's displacement estimate of wind. Use the onboard wind sensor and record the method.
A timed observation from the surface station may be the starting point, but mark the source. Do not append the whole surface record to the vertical profile. A cellular break does not require every point to succeed immediately. Backfill by height after return or recovery. A balloon release whose radio is healthy does not need to depend on cellular. The profile does not land on the wrong level when points after a break return to their height, the curve stops where height froze, and two flights are not mixed.