Upper Air Observing Systems

78.3 °F / 25.7 °C
E at 5 MPH
73.9°F / 23.3 °C
29.79" (1008 mb)
10 mile(s)
partly cloudy
2021.09.21 1620 UTC

Upper Air Observing Systems

Upper air data are collected at Kwajalein Island and Roi-Namur using the International Met Systems (InterMet) IMET-2000. Radiosondes are flown daily on Kwajalein Island at 0000 UTC to collect upper air data. These data are formatted into standard World Meteorological Organization radiosonde code and are transmitted globally via the National Weather Service’s (NWS) Global Telecommunications Network for use in initializing numerical weather models and populating climatology databases. Radiosondes are also required from Kwajalein Island and/or Roi-Namur for nearly every mission supported at RTS.


The iMET radiosondes measure temperature with a bead thermistor and humidity with a thin polymer capacitive sensor.  Winds and altitude are derived using differential GPS technology, and pressure is derived from altitude.


Upper air data are routinely collected to altitudes in excess of 100,000 feet using all of these upper air systems. Additional parameters may be derived from the upper air data, including index of refraction, speed of sound, shear, and turbulence. Missions requiring upper air data at altitudes greater than 100,000 feet normally require special large balloons.

The latest radiosonde data file and skewT graphic may be found here.