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 has a provisional patent on 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

The mechanical engineering team, consisting of Megan Wilbanks and Graham Williams, have completed the initial design phase. Prototype production of design components is underway. The team is using acetal for the majority of part production. Stock pieces of acetal are being machined in the CSU EMEC. The CSU EMEC contains two HAAS 3 Axis CNC Vertical Milling Machines. These CNC machines operate off of G Code. The team is using MasterCam to generate G Code based off of speed calculations, feed calculations, and the CAD models of the current prototype design. The ME team is grateful for the assistance of Professor Dr. Steven L. Schaeffer, Lab Support Engineer Steve Johnson, and Graduate Student Tucker Hensen. The ME team looks forward to the completion of the manufactured prototypes and the testing of those prototypes that will begin in the Spring 2017 semester.

The computer engineer, David Jump, has selected the web service and protocols used to transmit the precipitation data. Currently the webserver and the preliminary database is configured and built. Basic preliminary code has been built to allow for the transmitting of data from the microcontroller into the webserver. The computer engineer is currently helping the electrical engineering team to work on the rest of the code to read the amount of precipitation collected in the gauge. Next semester I will start constructing the code on the web service to allow for the retrieving of the data.

The electrical engineering team, consisting of Clare Boehler and Mitch Roberts, have completed selecting components for the design. The microcontroller, power supply, switches, LED, load cell with corresponding analog to digital converter, and temperature sensor have been selected, ordered, and received. The electrical team is collaborating with David Jump to develop code for the microcontroller in order to read and transmit data from the load cell and temperature sensor. Next semester we will continue to develop this code to incorporate the barometric pressure sensor, tare switch, and LED indicator. We will begin testing the device in varying atmospheric conditions in order to further develop the code to handle the error that will arise from the different atmospheric conditions.

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.