Balloon-borne radiosondes

Radiosondes play a vital role in the validation of space-based observations of our atmosphere. These instruments provide high-resolution profile observations of pressure, temperature, relative humidity, and winds from the surface to the middle stratosphere. Radiosondes are launched at around 800 stations worldwide and by research organizations during intensive field campaigns. A detailed understanding of the sensor technology and sounding operation is essential for adequately interpreting these measurements. The history and the special considerations of using radiosonde observations for the validation and calibration of satellite instruments highlight the importance of these instruments. Radiosondes play an essential role in validating space-based observations of temperature, humidity, atmospheric motion vectors, and even surface winds by hyperspectral infrared and microwave radiometers. With the advent of space-based wind lidars, they also play an essential role in validating satellite-based wind profile observations. Numerical weather prediction models also play an important role in the validation and calibration of space-based observations but require anchoring, which among others is provided by radiosonde observations.