NTN Field Methods
Every Tuesday morning at 9:00 a.m., NTN site operators across the country head
to their monitoring stations to retrieve their samples of the previous week 's precipitation,
whether rain, snow, or sleet.
Samples are collected continuously in a wet deposition collector.
The collector opens automatically during wet weather, allowing the precipitation
to fall into a collection bucket, and then closes as soon as the precipitation stops.
At the site, the operator replaces the collection bucket with one specially cleaned for
the next sample. The operator then takes the sample to a field laboratory, where it is
weighed. Next, the sample is transferred to a shipping bottle and sent to the CAL in Madison, Wisconsin.
Each site is also equipped with a weighing-bucket rain gauge that provides a continuous record of rainfall amounts. Rainfall is recorded to the nearest 0.01 in. The rain gauge also monitors the wet deposition collector, recording whether the collector was properly open during wet periods and closed during dry periods.