NCAR has developed many generations of dropsondes. The sonde model currently mass produced and supported by NCAR is the NRD41 dropsonde.
NRD41
The NRD41 dropsondes incorporate a pressure, temperature, and humidity sensor module designed by Vaisala, Inc. for their RS41 radiosonde, and a GPS receiver module independent of the sensor module. UCAR has licensed Vaisala Inc. of Louisville, Colorado, to mass produce the NCAR GPS Dropsondes NRD41 and RD41.
The NCAR Research Dropsonde NRD41 is electrically equivalent to the larger RD41 dropsonde, and has been designed to work with both automatic and manual launchers using the smaller form factor.
NCAR developed NRD41 (left) and RD41 (right) dropsonde models. Both dropsonde models have been licensed to Vaisala for mass production.
xRD41 Sensor Specifications
| Range | Uncertainty | Resolution | |
| Pressure | 1080-100 hPa | ± 0.5 hPa | 0.01 hPa |
| Temperature | -90 to +60 C | ± 0.2 C | 0.01 C |
| Humidity | 0-100% | ± 3% | 0.01% |
| Horizontal Wind | 0-200 m/s | ± 0.5 m/s | 0.01 m/s |
Older sonde models
RD41
The RD41 is the last of the larger form factor produced dropsondes. It is the same physical size as the older models RD94 and RD93 but uses the PTU sensor module of the Vaisala RS41 radiosonde. Electronically it is identical to the smaller NRD41 dropsonde, but uses a the older ribbon delayed parachute release. It can only be used in manual launchers.
NRD94
The NCAR Research Dropsonde NRD94 is electrically equivalent to the RD94 dropsonde, but has been designed to work with automatic or manual launchers using the smaller form factor. It was in used between 2010 and 2018.
RD94
The RD94 was produced between 2009 and 2018 and was the first dropsonde to incorporate a code correlating GPS for improved wind and position measurements.
MIST
The Miniature In situ Sounding Technology (MIST) dropsonde was used for driftsonde projects between 2006 and 2008. It was the first dropsonde in the 1.75"x12" form factor.
RD93
The RD93 was designed in the mid 90's and was used until 2010. It was the first dropsonde to use the GPS navigation system for wind finding.
Overview of NCAR GPS dropsonde models
| Dropsonde Type | Diameter (cm) | Length (cm) | Weight (g) | Parachute size (cm x cm) |
Launcher Type | Comments |
|---|---|---|---|---|---|---|
| NRD41 | 4.5 | 30.5 | 169 | 20 x 20 | Manual/Automatic | Currently in production at NCAR and licensed for production to Vaisala |
| RD41 | 7.0 | 40.6 | 323 | 30 x 30 | Manual | Produced from 2018-2023 |
| RD94 | 7.0 | 40.6 | 320 | 30 x 30 | Manual | Produced 2009-2018 |
| NRD94 | 4.5 | 30.5 | 167 | 20 x 20 | Manual/Automatic | Produced by NCAR for automatic launchers on NASA Global Hawk and NSF/NCAR G-V |
| MIST | 4.5 | 30.5 | 184 | 20 x 20 | Gondola only | Produced for Driftsonde in 2010 |
| RD93 | 7.0 | 40.6 | 400 | 30 x 30 | Manual | Produced 1996-2009 |
Historic dropsonde models
Dropsondes have been designed and built at NCAR since the 1960s. These include the Omega DropWindsonde (ODW), the Lightweight Loran Digial Dropsonde (L2D2) and the Lightweight Omega Digital Dropsonde (LOD2), which were in use between 1980 and 1995. These older models used the Omega and LORAN radio navigation systems for wind finding.