Weather Instrument Comparisons
Using a Davis Envoy and a VantagePro Console, I can track measurements from multiple sensors. This is a robust quality control check, and allows for quick isolation of a failed or drifting sensor.
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The sensor labeled as "Davis" is a temperature/humidity sensor installed in a 24-hour fan-aspirated radiation shield. The "Envoy" temperature/humidity sensor is installed in a standard Davis radiation shield. The differences between the two are very slight, even on the hottest of days. It appears that in this mild climate, the fan aspiration isn't really necessary for accurate measurements. |
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The barometers are located in the indoor units, for both the Envoy and Vantage Pro. They have been calibrated to KHQM (Bowerman Airport), and typically track one another very closely. |
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The "Davis" sensor is remotely located in a field with generally good Southern exposure. There is a tree line immediately North of the "Davis" sensor. The "Envoy" sensor is mounted on the roof of the house, and is partially protected by trees on the Southern edge of the property. In mild wind conditions, the two track reasonably close. In storm conditions, the "Davis" sensor, with its unobstructed Southern exposure, generally captures significantly higher gust readings. |
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The "Davis" sensor is the standard Davis collector, located about five feet above the ground in an area generally clear of trees and structures. The "RainWise" sensor is a standard RainWise rain collector wired to a Davis ISS, and is located within a few feet of the Davis collector. Both sensors are .01" tipping buckets using reed switches. While it's a little unusual, the RainWise collector works just fine with the Davis ISS. Typically, the RainWise readings are higher than the Davis for high rain rates. For very low rain rates, the two readings track fairly closely. |