CoCoRaHS: The Evolution and Accomplishments of a Volunteer Rain Gauge Network

Abstract

he Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) is a large and growing community of volunteers measuring and reporting precipitation and is making this information broadly available for the research and operational community. CoCoRaHS has evolved through several phases since its beginnings in 1998, first starting as a flood-motivated local Colorado Front Range project, then through a 5-yr nationwide expansion period (2005?09), followed by five years (2010?14) of internal growth and capacity building.As of mid-2015, CoCoRaHS volunteers have submitted over 31 million daily precipitation reports and tens of thousands of reports of hail, heavy rain, and snow, representing over 1.5 million volunteer hours. During the past 10 years, there has been wide demand for and use of CoCoRaHS data by professional and scientific users with an interest in its applicability to their different areas of focus. These range from hydrological applications and weather forecasting to agriculture, entomology, remote sensing validation, city snow removal contracting, and recreational activities, just to name a few. The high demand for CoCoRaHS data by many entities is an effective motivator for volunteer observers, who want to be assured that their efforts are needed and appreciated.Going forward, CoCoRaHS hopes to continue to play a leading role in the evolution and growth of citizen science while contributing to research and operational meteorology and hydrology.