Summary

CoCoRaHS (Community Collaborative Rain, Hail, and Snow Network) is a nationwide collaboration of volunteers who work together to measure precipitation in an effort to provide high quality precipitation data for natural resource services, as well as educational and research opportunities. The goal of this project is to modify the existing non-automatic CoCoRaHS precipitation gauge into a semi-automated, weight based precipitation gauge, providing additional data including time and intensity/rate of precipitation. This will be done by creating a new gauge bracketing system that holds a load cell, microcontroller, and communication subsystems. The new bracketing system will accommodate the existing precipitation gauge by simply replacing the original bracket with the new bracket unit. Under optimal conditions, each bracket will be low cost (less than $50 per unit) and high accuracy (1/100th of an inch).

Project Background

This project is being sponsored by MetStat, Inc., a Fort Collins-based meteorological engineering company, who is passionately pursuing the novel design and concept of this project. This project is an extension and execution of Jieqi Lin’s thesis “Proof of Concept of an Automated CoCoRaHS Precipitation Gauge” completed in April 2016. In her thesis, Lin determined that the development and production of a low cost and high accuracy automated precipitation gauge bracket (to accommodate the existing CoCoRaHS precipitation gauge) is attainable. The current gauge performs very well over a wide range of conditions and is an excellent choice as a lower cost alternative to the traditional National Weather Service Standard Precipitation Gauge (1). By creating an automated attachment, sub-daily and even sub-hourly precipitation data will be captured and shared routinely in real-time. The new bracket will not include self-emptying functionality and still require observers to take manual measurements and empty the precipitation gauge once-a-day; this will maintain the CoCoRaHS protocol and provide valuable interaction with the gauge, hence the “semi-automatic” nomenclature.

Constraints and Goals

  • Manual measurements are still required. The gauge should be manually read and emptied every 24 hours.
  • The large collection cylinder, small measuring cylinder, and funnel not be altered. This is to help keep the cost of the upgrade as low as possible.
  • The final per unit cost be under $50.00. This cap is necessary to help ensure that people will be able to afford the upgrade. Other systems available in the market are cost prohibitive and our aim is to ensure both a reliable and affordable product.
  • The new bracket should not interfere with the collection of precipitation, hail, or snow. The new bracket must also allow the volunteer to remove, inspect and replace the gauge without the bracket altering the data gathered, either by extra precipitation splashing into the collection funnel or causing variations on the load cell.
  • The unit needs to be battery powered, however, units for preliminary testing may be power by alternate means. An overall battery life of 6 months is expected.
  • The unit needs to transmit data wirelessly. Several different protocols should be explored during testing. This is to enable easy collection of data without further burden to the volunteers.
  • The load cell should have a total capacity of 5kg and be capable of at least the same resolution as the load cell that was tested by Lin.
For more information, please email info@metstat.com

Current Status

This project will continue next fall (2017) semester. Below is a synopsis of the current status:

Mechanical Engineers: The mechanical work for the prototyping phase of the project has been completed. The large milestones for the mechanical side of the project - design and manufacture of a new bracketing system that accommodates the CoCoRaHS precipitation gauge, houses all necessary electronics, and transfers the load directly to a load cell - have been met. The mechanical team has also designed and built a test fixture and a wind guard that can be utilized by the electrical and software teams for continued testing. Mechanical work is not projected to be necessary until the project is ready to be redesigned for mass production.

Computer Engineers: A webpage has been constructed to view gathered precipitation data and a web service is available to retrieve and store precipitation. Once testing of the gauge commences the team will be transitioning to help to construct software precipitation data correction algorithms.

Electrical Engineers: The electrical components have been selected and integrated. We are currently troubleshooting stability issues. Once this has been completed we will begin atmospheric chamber testing in order to develop an algorithm to handle the error in the output due to temperature variation.

References

1) Doesken, N. J., 2005: A ten-year comparison of daily precipitation from the 4" diameter clear plastic precipitation gauge versus the 8" diameter metal standard precipitation gauge. 13th Symposium on Meteorological Observations and Instrumentation, Savannah, GA, Amer. Meteor. Soc., 2.2.