AVAPS Dropsondes

The various generations of dropsondes that have been developed by EOL.

NCAR has developed many generations of the GPS Dropsondes. Below is a list of all GPS based NCAR GPS Dropsondes.


The RD93, though now obsolete, was for many years the mainstay AVAPS instrument. It was first designed in the mid 90's and was used until ~2008.  It was the first dropsonde to use the GPS navigation system for wind finding. The RD94, the successor to the RD93, has the same dimensional size, but if slightly lighter.


The RD94 is the currently produced dropsonde.  It is the same physical size as the RD-93, but with upgraded electronics and PTU sensor module, slightly lighter weight, and incorporates a different telemetry data transmission scheme. It can only be used in manual launchers


The Miniture Insitiu Sounding Technology (MIST) dropsonde is exclusively used for driftsonde. It is shown here because it was the first dropsonde in the 1.75"x12" form factor.


The Mini dropsonde is electrically equivalent to the RD-94 dropsonde. The chief difference is that is has been designed to work with automated automatic or manual launchers.


Summary of Current Dropsondes

Dropsonde Type Diameter (in [cm]) Length (in [cm]) Weight (oz [g]) Launcher Type Comments
RD-93 2.75 [6.99] 16.0 [40.6] 14.1 [400] Manual Obsolete Last Produced in 2009
MIST 1.75 [4.45] 12.0 [30.48] 6.5 [184] Gondola only Produced for Driftsonde
RD-94 2.75 [6.99] 16.0 [40.6] 11.3 [320] Manual Commercial Production started in 2008
Mini 1.75 [4.45] 12.0 [30.48] 5.9 [167] Manual/Automatic Produced by NCAR for Automatic Launchers


UCAR/Intellectual Property and NCAR/EOL have licensed Vaisala Inc. of Louisville, Colorado to build the NCAR GPS Dropsonde, as Vaisala model RD93 and the subsequent RD94. Throughout the years, many dropsondes have be used (see a more detailed history), but in the recent past, only 4 variations of dropsondes have been produced in noteworthy quantities.