Creating a Volunteer Observing Network

© H. Reges, CoCoRaHS

Interview with Nolan Doesken1 and Henry Reges2

Volunteers play an important role in providing climate information. Their observations are critical to track local climate variations and impacts and to monitor changes in climate over time. Volunteers also play an important role in sensitizing the general public about weather and climate issues, serving as informal climate “ambassadors.”

This year the United Nations celebrates the tenth anniversary of the International Year of Volunteers, paying tribute to the volunteers around the world who take an active part in improving the welfare of their communities.

Thomas Peterson, President of the WMO Commission for Climatology inspired these leaders of a volunteer network to share their experiences with the WMO Bulletin, in order to encourage an exchange of experiences among professionals interested in fostering volunteer networks on climate issues.

Q. Why did you create a volunteer network?

The Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) began in 1998 by the staff of the Colorado Climate Center at Colorado State University, USA, following a devastating local flash flood in 1997.

The storm caught many by surprise. Our region is normally semi-arid, but 300-370 mm of rain fell in one day in parts of Fort Collins, Colorado, much of it in less than five hours. Several people died from the resulting flood, and damage to the city of Fort Collins and our university campus exceeded US$ 200 million.

Radar, satellite and lightning detection systems underestimated the rainfall. Surface weather stations were too far apart to detect the local storm centre. In response to this local storm, a community project was started to equip interested individuals, schools and businesses with a basic rain gauge to collect rain or snow. A Website was developed to provide training materials, data entry forms and the ability for participants and users to immediately access and view rain, hail and snow data. Volunteer data collection began in 1998.

Soon, scientists and participating volunteers noted fascinating local variations in precipitation. The network spread, and has now expanded to all of the country. It is considered informal and is not an “official” federal climate observing system. Yet the accuracy of the data compares favourably to official weather station networks. Government agencies, private businesses, university scientists, educators and many others use the precipitation data for weather analysis, climate monitoring, hydrological prediction and warning, as well as for many business, research and education applications.

Q. In an era where we have sophisticated satellites, weather radar and other monitoring systems, why do we need volunteers to monitor the climate?

With the technology available today, one might be tempted to think that weather stations are less important now – especially volunteer neighbourhood measurements from low-cost plastic rain gauges. But nothing is farther from the truth. Satellite and weather radar data are very useful, but they are expensive, and are most useful when they are matched with what is happening on the ground. Furthermore, radar coverage is limited or non-existent in some areas.

That is where volunteer measurements come in. Our project has focused on the measurement and reporting of precipitation – rain, hail and snow – because precipitation is the most variable of standard climate elements and arguably the most important. By collecting data from their own communities and neighbourhoods, volunteers learn about their local conditions while providing much-needed data. The data are essential for systematic climate monitoring and the calibration and bias adjustment process that makes remotely sensed products more accurate.

Volunteers also add the human element that technology cannot provide. We encourage our volunteers to add descriptive comments along with their numeric reports. Last May, one of our observers wrote, “Line Creek is higher than I have ever seen it. Water got up to the high ground beside the highway and washed 12 rolls of my hay away over six feet (about two metres) high. I could do nothing but watch them sail away. Roads closed, school closed.”

Q. How many volunteers does your organization have?

We have over 15 000 volunteers measuring and reporting precipitation. Thousands more track precipitation patterns and follow our activities on the Internet. Most growth has come in the past four years, as we expanded swiftly to all of the United States, including urban, rural, coastal and mountainous regions.

We hope to increase participation in the coming years – perhaps doubling or tripling volunteers in the next few years. Currently, most volunteers are between 45 and 75 years old. With social networking, cell phones, smart phones and emerging technologies, we hope to engage new and broader audiences, including youth and all socio-economic levels of society.

Q. How do volunteers contribute to climate monitoring? Where and how are the data used?

Seeing data on continuously updated maps is a key to recruiting and retaining volunteers. It also helps us develop a strong user base. Our volunteers measure precipitation at or near their own homes and report their observations via the Internet. The data are immediately available on national, state and local maps; participants and users can track precipitation patterns daily or longer term.

Our data are used routinely to monitor and predict both drought and floods. The National Weather Service, the National Climatic Data Center, the US Department of Agriculture, universities, television stations and businesses automatically import data on preset intervals and integrate them with other sources. The US National Climatic Data Center began including our data in their Global Historical Climate Network in 2010. The National Weather Service River Forecast Centers routinely include our reports to better predict the levels of streams and rivers, and our data are increasingly used in the weekly US Drought Monitor.

Our volunteers provide more data points daily than all official federal observing networks in the USA combined. As the number of data points increase, the information becomes increasingly valuable. A high density of gauges close to and upstream of flood prone areas has proven valuable on many occasions to supplement official national and local monitoring. Our volunteers are encouraged to report zero on days when it did not rain. These reports, along with drought impact reports go directly to the National Drought Mitigation Center to support its drought early warning and awareness efforts.

When the West Nile virus was spreading across North America a few years ago, research scientists and local health agencies used our data to identify locations where mosquito larvae were most likely to hatch. There are relatively few sources of data on hail and snow, so we help fill important monitoring gaps for that as well.

Volunteer data collection can also contribute to climate change research and education. Combining data from our volunteers with long-term climate records is yielding useful information about the frequency and extent of both dry and wet periods.

Q. What motivates volunteers to join and to stay on over time?

Most volunteers are at least 45 years of age and have a personal curiosity or a professional interest in weather, climate, agriculture or water resources. We benefit from close partnership with the US National Weather Service and their network of “storm spotters,” many of whom have become rain gauge volunteers. Farmers, gardeners, families introducing their children to science projects and professionals who work with water projects and utilities are among our volunteers.

Many participants want to be sure that their efforts (two to five minutes a day) produce useful information. Seeing their data on TV or in print is very rewarding. Volunteers greatly appreciate seeing their data displayed on the project Website and sharing it easily with friends and family.

Schools and students are a small but growing part of our network. Schools are a logical group to target as they are well distributed across the country, but the school schedule, vacations, and the heavy load on teachers make it hard to maintain long-term commitment.

Strong local leadership provided on a volunteer basis from many climate, water and university professionals has been a key ingredient to fuel our expansion.

As we have grown, our volunteers do much of our recruitment, as they reach out to friends, family and coworkers. Early on, our best recruitment efforts came by working with local broadcast meteorologists, agricultural extension programmes, national weather service forecasters and natural resource non-governmental organizations.

It takes ongoing outreach to maintain high participation levels. Overall, about half of those who initially sign up become data collectors and continue for many years. Some volunteer observers have stayed for the full 13 years we have been in operation. Others drop out due to illness or lack of time. Some participate a year or two. Still others sign up with good intentions, but never manage to make that first observation, even with encouragement.

Incentives can help initiate and maintain participation. In some communities, we have provided additional instrumentation, training and face-to-face communication with local weather and water officials.

Q. Do you think volunteers are climate service “ambassadors,” talking about the experiences of what they do with a broader public of non-specialists? Do you work with them to ensure they help communicate complex climate concepts accurately?

Definitely. Our volunteers are becoming climate service “ambassadors” whether they realize it or not. As climatologists, we share what we learn with our volunteers through the project Website, through daily messages that appear each time a volunteer submits a data report and from personalized e-mails sent to every participant every two to three weeks.

We have surveyed our volunteers and found that they share their experience with an average of six to ten additional people each year. By telling their stories and sharing their observations, they extend aspects of climate literacy to friends, neighbours, family and coworkers.

Volunteers frequently ask “Are scientists really using our data?” As they come to appreciate how much their data are used, that becomes a strong motivation. Some of our volunteers then become some of our best recruiters and trainers.

Our hope is to develop more ways to convey practical and important weather, climate and water information to our observers, thus providing them with the tools to make informed decisions and to better understand and interpret information they gather from other sources.

Q. For the world’s poorest countries, how are these experiences relevant? What kind of resources does one need – finance, institutional support, educational programmes? How many stations are enough?

Strategies and expectations change depending on the socio-economic environment (including in the USA). Yet precipitation remains an important asset or liability, no matter where one lives in the world.

In low-income areas, schools, institutions, non-governmental organizations and tourist attractions can be good initial candidates for local rain gauge stations. The motivation to track and report precipitation should come from within a country, not from outside. Volunteer efforts are best when organized by local leaders and institutions.

There are costs to the logistics of recruiting and training volunteers, distributing rain gauges, receiving data reports and having sufficient computers. Reliable, fast Internet access is also important.

Still, at a cost of approximately US$ 30 per gauge and with the efficiencies of Web-based communication in many parts of the world, this investment represents good value for the money. One could start with pilot projects in areas prone to floods or drought, where some institutional support is available, and then expand from there.

There is no single answer about how many rain gauges are needed. What’s most important is to increase the number of observations from current levels. It’s also important to make data available easily to volunteers as well as users, in order to keep volunteer motivation high. What we have found is that having very large concentrations of rain gauges – more than one per 5-10 km2 – allows natural variability and extremes of rainfall to be defined. Volunteers frequently say, “I had no idea that rainfall varied so much here in our community.”

Ten lessons we learned


For those who want to begin or expand volunteer programmes, what recommendations do you have? Are quick wins, or hard lessons that you can share?

We learned several useful lessons over the thirteen years since we first started this volunteer observing network.

  1. Precipitation measurement is a good place to start. Precipitation is relevant nearly everywhere and impacts nearly everyone. The measurement is “relatively” easy for volunteers and the equipment is inexpensive.
  2. Solid infrastructure is essential. This includes a system for collecting, archiving and displaying volunteer data. It also includes enough staff or volunteers to get started.
  3. Partners with a vested interest in the process, the people and the data make a huge difference. Include local water utilities, agricultural extension services, university researchers, official climatologists and weather service personnel across the country. These partners can provide human and financial resources that help greatly.
  4. Keep things simple. Logistics need to be considered. Even for a “simple” project it is a significant challenge to pay for and distribute rain gauges. In our case, most volunteers purchase their own gauge, or local sponsors support and distribute gauges in a particular region. A small number of commercial vendors distribute gauges at a reduced cost. Giving someone a rain gauge doesn’t guarantee they will use it.
  5. Set goals and share them with your volunteer community. They may help you meet them. What coverage do you need and with how many stations? In our experience, at least one station every three to five km2 is ideal, but that just won’t be realistic in many areas. Another way to set goals is to look at the official surface observing system.  It is a good goal to match or exceed the existing number of gauges from official surface networks.
  6. Participation should be rewarding. Our volunteers have their own station names and their own dots on the maps. Having their own place where they can see their data gives them an important identity. Volunteers like their data to be visible and used for beneficial purposes that help their communities, such as better weather or flood forecasts and warnings.
  7. Provide training and positive feedback. This includes clear, understandable instructions, ideally provided by local people who give face-to-face instruction and then follow up.
  8. Engage local leaders. Strong local leadership on a volunteer basis by climate, water and university professionals is a key to fuel expansion and sustain the network. A national organization needs strong local leaders to keep volunteers engaged.
  9. Be open to ideas from volunteers and their communities. Give your volunteer leaders reasonable autonomy since they know their communities best. Stay in touch with them regularly so that there are open channels for ideas. Some desire to be connected to the larger community. E-mail and Web-based communication has worked for us, but we realize this may not work the same way everywhere. Social networking is becoming popular. Take advantage of available communications technologies and use what works best.
  10. Patient, persistent, enthusiastic leadership helps. Working with volunteers takes time. It took several years until our project reached a critical mass and then began growing quickly. There will be some unexpected outcomes and some quick wins. We found, for example, that older adults were our most committed volunteers, and our project helped many of them to use the Internet better. We also did not expect the data to be so incredibly useful and of such high quality.

© H. Reges, CoCoRaHS


1 Nolan Doesken, State Climatologist, Colorado Climate Center, Colorado State University, USA, and CoCoRaHS founder.
2 Henry Reges, CoCoRaHS National Coordinator, Colorado Climate Center, Colorado State University, USA


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