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Question on CS 125 and particle size


MRicks Aug 14, 2023 05:59 PM

I am in the process of setting up a CS125 for use in estimating rainfall energy. In glancing through the manual for the CS125, pg. 4 references the following: "The CS125 is capable of identifying weather type in addition to measuring visibility. It does this by analysing the amplitude and width of spikes in the APD signal corresponding to particles of precipitation passing through the sample volume. The amplitude of the signal is a guide to the size of the particle and the width, because it represents the time taken for the particle to fall through the sample volume, is proportional to the fall speed, see Figure 1-2. Figure 1-2. Signals from large, slow falling snowflakes and smaller, faster, raindrops The CS125 also has a temperature sensor. These three parameters, fall speed, size and temperature are used to identify the type of particle."

I am looking for how to pull out the fall speed and size of particle. I am using the device in a controlled outdoor environment where it will only be exposed to rainfall events. Any ideas?


JDavis Aug 15, 2023 03:47 PM

The CS125 is not capable of drop size distribution. The discontinued PWS100 had the capability. The CS125 is averaging, the PWS100 measured each discrete drop. Being a full optical disdrometer requires an extra detector and more processing. That made the PWS100 significantly more costly than a CS125.

The CS125 was designed as a scaled down PWS100 with the needed measurements for most customers to fit within budget. The CS125 is a very good sensor for operational data, but does not fit your research application.

Search for an "optical disdrometer". Campbell data loggers have been connected successfully to multiple brands.


MRicks Aug 24, 2023 05:04 PM

This post is under review.

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