WERA1012: Managing and Utilizing Precipitation Observations from Volunteer Networks
Statement of Issues and JustificationPrecipitation (rain, hail and snow) is one of the most variable and extreme elements of the climate system. Precipitation totals can vary by 50% or more from year to year in parts of the U.S. Local precipitation at the county level can differ greatly from place to place in mountainous and coastal areas and also in areas dominated by convective precipitation. The need for timely, accurate and site-specific precipitation data continues to grow. However, resources to implement spatially dense observing networks over large areas of the country simply do not exist. Gauges that automatically measure all forms of precipitation over all ranges of climatic conditions are expensive, require maintenance and are not always reliable.
The presence or absence of precipitation and its accumulation over time regularly and profoundly impact nature and human activities. Agriculture, recreation, commerce and much of our natural and built environment are responsive (positively or negatively) to precipitation. More lives are lost in this country to flooding than to most other natural disasters. In many cases, the floods that claim lives are a result of highly localized storms that may not be well detected by existing weather-observing networks. Drought is arguably the most costly (in terms of dollars) of all natural disasters and occurs with varying degrees of severity and extent every year in our country. Yet we struggle to adequately monitor the onset, duration and termination of drought at a local level for the purposes of planning, assessment, emergency assistance, and relief.
Many activities, agencies and applications benefit from accurate, timely and local precipitation data. Examples include agricultural production and markets; water utilities who manage the collection and distribution of ground and surface water for municipal and industrial uses; irrigation districts who distribute large volumes of water from runoff for agricultural production: storm water managers and flood plain administrators who help protect society from the catastrophic impacts caused by flooding; engineers and contractors who use available precipitation data to size, design and build bridges, culverts, roofs, drains, sewers, etc. to safely handle the vast majority of precipitation events; and insurance programs that require accurate precipitation data to determine where and when claims should be filed and payments made. The list of uses and applications of precipitation data is long and continues to grow.
The monitoring and reporting of precipitation has traditionally been addressed by several federal weather observing networks. Some states and local entities have added additional monitoring capabilities for specific purposes. Tens of millions of dollars are spent each year to monitor weather conditions. Still, in many parts of the country there are at best one or two observing stations per county collecting year-round precipitation data. Observation of snowfall and hail is even more problematic. Remote sensing (radar, satellite) is used increasingly to provide continuous estimates of precipitation, soil moisture and evapotranspiration. These technologies need ground truth measurements for calibration and adjustment, and such measurements are often not available from the present networks.
There is a long and colorful history in the U.S. of volunteer weather observations helping meet information needs. The first climate observing network was established by the Smithsonian Institute in the early 1800s to begin to document and map the climate resources (temperature and precipitation) of our country. Later, the U.S. Weather Bureau (more recently called the National Weather Service) established a nationwide network of several thousand weather stations measuring daily temperature, rainfall and snowfall. Known as the Cooperative Observer Network, this 120-year-old network is the sole source of long-term precipitation data in our country and the only data source suitable for assessing long-term climate patterns, interannual variability and potential trends. This is an extraordinary long-lived and critically important network, but its ongoing support is marginal. Attempts to strengthen and modernize this network have been inadequate.
A highly cost-effective approach to the challenge of precipitation measurement, utilizing inexpensive manual rain gauges and volunteers to read them, may be a viable approach to addressing current needs. The recent successes of the Community Collaborative Rain, Hail and Snow (CoCoRaHS) network initiated by Colorado State University suggests that volunteer networks still have an important place in earth science monitoring, research and education in the 21st century. However, we must learn how to effectively manage and sustain networks of volunteers with limited staff and human resources. This coordinating committee will address these needs and opportunities.
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