Rapid emergence of massive temperature monitoring networks in streams and rivers across North America (Invited)

Thermal regimes in streams and rivers are fundamentally important to aquatic ecosystems and are monitored by resource agencies to determine regulatory compliance. The advent of miniature digital temperature sensors in the early 1990s has resulted in a steady increase in the amount of temperature data collected across North America. Recent concerns about climate change and other forms of broad environmental degradation have stimulated regional data compilation efforts (e.g., NorWeST: http://www.fs.fed.us/rm/boise/AWAE/projects/NorWeST.html; NorEaST: http://wim.usgs.gov/NorEaST/) and these 'found' databases sometimes constitute 1,000,000s of temperature recordings at 1,000s of unique stream sites. These same concerns are accelerating expansion of monitoring efforts to many areas where data are sparse and an informal, continental scale monitoring network is rapidly emerging. Temperature sensor records are a particularly rich information source because they consist of hourly measurements over periods ranging from several months to many years. The 'thermal pulse' of North American streams is readily apparent in these records as regular cycles shown at daily, seasonal, annual, and decadal time-scales but cardiac irregularities are also apparent due to long-term trends from climate change and ongoing urbanization. The massive amounts of stream temperature data now in existence provide significant opportunities to describe, understand, and predict the health of stream thermal regimes at unprecedented spatial scales and temporal resolutions.