Anasphere's water content sensors operate by measuring the buildup of mass due to water or ice accumulation on a vibrating wire. The following documents provide the mathematical derivations of the equations and also provide guidance for processing the data. There are two sections. The first addresses the current dual-wire Universal Water Content sensor (UWC2), along with its single-wire derivatives for supercooled liquid water content (SLWC) and total water content (TWC) measurement. The second addresses the older single-wire sensor SLWC sensor (still in production) and LWC sensor (out of production).
Universal Water Content Sensor
Note: two different wire lengths have been shipped with UWC2 sensors, and these affect base frequencies and lengths to be input into the equations. Late 2021/early 2022 sondes used shorter wires (44 mm outer sensing section). All other sondes, including current production, use longer wires (62 mm long outer sensing section). Be certain to input the correct wire lengths for your sondes; the following papers and examples may not use the correct length for your situation.
This paper covers the detailed derivation of the SLWC and TWC equations as used with Anasphere's UWC2 sensor. UWC Detailed Derivation (pdf)
The following Python program provides an example of data processing using those equations. UWC Python program (Python code)
The following instructions address the basic use of the UWC2 sonde, including how to replace the wires. This also covers the single-wire SLWC and TWC derivatives of the UWC2 sonde. UWC Sonde Instructions (pdf)
Single-Wire SLWC and LWC sondes
This paper covers the detailed derivation of the SLWC equations as used with Anasphere's SLWC sensor. SLWC Detailed Derivation (pdf)
The following paper covers the processing of LWC sonde data. It is recommended that users review the SLWC processing paper first, as it is a slightly simpler and easier to understand case. LWC Equation Implementation (pdf)
The following instructions address the basic use of the SLWC and LWC sondes, including how to replace the wires. In the case of LWC sondes, wires should be replaced after each flight. LWC and SLWC Sonde Instructions (pdf)
XDATA is an open data format developed by NOAA which is used to exchange digital data with radiosondes. This format is implemented with our SLWC and LWC sondes, and our SmartTether systems are also able to accept XDATA. Details of the XDATA format can be found here.
An example of complete data reduction is given by Serke et al.1
The SLWC sensor was featured in NASA's Spinoff magazine.2
1Serke, D. et al. "Supercooled Liquid Water Content Profiling Case Studies with a New Vibrating Wire Sonde Compared to a Ground-Based Microwave Radiometer." Atmospheric Research 149,77-87(2014). DOI: 10.1016/j.atmosres.2014.05.026. 2"Wire Sensors Alert to Dangerous Conditions in the Clouds" NASA Spinoff, 2017.