Challenges and Solutions for Calibration of Rain Measurements from Novel Weather Stations

Understory designs and manufactures novel weather stations that provide an unprecedented view of weather data from the ground. One of the new, unique capabilities of our stations is the ability to make accurate rainfall measurements without any moving parts. In this contribution, we describe the approach we use to calibrate and validate our data. This effort includes a lab-based approach and a field-based approach. In the lab, we use a custom “rain cabinet” that is designed to produce artificial rainfall that mimics the properties of natural rain in simulating different droplet size distributions at various rainfall rates. This allows us to test the response of our station to a variety of rain rates efficiently. For field testing, we have developed a mobile deployment unit that we refer to as “rain chaser”. Designed to fit into the back of a pickup truck, rain chaser includes two mounts for Understory sensors as well as two mounts for reference instruments. One of the reference instruments is a disdrometer and is used to investigate the quality of our rain algorithm under different droplet size distributions. The other reference instrument is a standard tipping bucket. The mobility of rain chaser has been critical to building a statistically significant sample of high rain rate events.