AVAPS Dropsondes

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

NCAR has developed many generations of the GPS dropsondes:

RD41

The RD41 is the currently produced dropsonde.  It is the same physical size as the older models RD94 and RD93 but uses the PTU sensor module of the Vaisala RS41 radiosonde. It can only be used in manual launchers.

NRD41

The NCAR Research Dropsonde NRD41 is electrically equivalent to the RD41 dropsonde, but has been designed to work with automatic or manual launchers using the smaller form factor.

 

The RD41 and NRD41 dropsondes incorporate a pressure, temperature, humidity sensor module (RSS421) designed by Vaisala, Inc. for their RS41 radiosonde, and a GPS receiver module independent of the sensor module. The specifications are shown in the following table.

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%
Horiz Wind  0-200 m/s ± 0.5 m/s 0.01 m/s

 

 

 

 

 

Older sonde models

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.

Older 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 and used the Omega and LORAN radio navigation systems.

 

Overview of NCAR GPS dropsonde models

Dropsonde Type Diameter (cm) Length (cm) Weight (g) Parachute size
(cm x cm)
Launcher Type Comments
RD41 7.0 40.6 323 30 x 30 Manual Currently in production at Vaisala
NRD41 4.5 30.5 169 20 x 20 Manual/Automatic Currently in production at NCAR
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

 

UCAR has licensed Vaisala Inc. of Louisville, Colorado to build the NCAR GPS Dropsonde RD41.