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Caldera Chronicles

Caldera Chronicles is a weekly article written by U.S. Geological Survey Yellowstone Volcano Observatory scientists and colleagues.

August 20, 2018 Article Link

The Norris temperature network—a unique system for monitoring Yellowstone's thermal features

Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week's contribution is from Michael Poland, geophysicist with the U.S. Geological Survey and Scientist-in-Charge of the Yellowstone Volcano Observatory.

Norris Geyser Basin is one of the most dynamic geyser basins in Yellowstone National Park. It frequently experiences "disturbances" when thermal activity waxes and wanes and water chemistry changes over the course of a season. Earthquake swarms are common nearby, and the surface moves up and down with some regularity. This dynamic behavior was emphasized by the 2003 disturbance, which was associated with an increase in ground and water temperatures, the formation of new springs, mudpots, and geysers, an uptick in overall geyser activity, and an expansion of areas of heated ground. Temporary monitoring instruments were installed to track the activity, but these had to be downloaded manually and were not easily accessible by the public. Clearly, a different solution for monitoring Norris activity was needed.

Map of locations for temperature measurement sites in Norris Geyser Basin, Yellowstone National Park (Click image to view full size.)
Map of locations for temperature measurement sites in Norris Geyser Basin, Yellowstone National Park

With funding provided by the American Recovery and Reinvestment Act (ARRA) in 2009, a system of 10 temperature monitors was installed at the Norris geyser basin in the summer of 2010. Each station consists of a datalogger with a radio antenna and a thermal probe and is powered by batteries that will last for nearly 2 years. The sensors are carefully hidden under boardwalks or in vegetation, so unless you know where to look it is doubtful that you would ever notice the stations.

Temperature data are collected every 2 minutes, and once a day the data are downloaded to a base station located near the Norris Museum. From there, the data are uploaded to the Internet and posted to the YVO website for public viewing. The once-per-day download is meant to conserve battery power, but the sensors, individually or collectively, can also be downloaded on an as-needed basis at any time.

The temperature sensors are situated in three different types of environments: geyser outlets, pools, and streams. Measuring the temperature in geyser outlets allows for easy recognition of geyser eruptions—increases in temperature likely mean that the geyser has erupted. At Norris, temperature sensors monitor Steamboat, Constant, and Echinus geysers. Tracking the temperature of pools, like Porkchop and Opalescent, provides a sense of whether new inputs of hot water might be occurring. Stream channel monitoring gives an indication of what is happening in the overall geyser basin, especially in terms of environmental conditions—for example, sudden decreases in temperature due to rainfall events.

Echinus temperature record during October 17-20, 2017 (Click image to view full size.)
Temperature record from Echinus geyser outflow channel for October 17–20, 2017. The plot captures a time when the geyser went from occasional eruptions to semi-regular eruptions (signified by temperature spikes after about 12:00 on October 18) occurring about every 2 hours.

Interpreting the temperature data collected by these sensors requires careful analysis. Most sensors record daily variations that reflect temperature differences between day and night. Precipitation can cause sudden temperature decreases. Changes in water level might expose sensors to air, creating temperature artifacts. Even mechanical issues can create challenges to interpretation, like power or radio connectivity outages. Some thermal probes also degrade with time and may gradually become unreliable in terms of the temperatures they record.

For these reasons, it is critical to also monitor parameters like air temperature and precipitation, which is done at several stations throughout the Norris Geyser Basin. In addition, regular maintenance is conducted on the temperature sensors—replacing batteries and thermal probes, troubleshooting radio problems, and addressing other issues. The maintenance is a constant battle against the elements, since Norris is inaccessible for many months of the year due to snow accumulation.

Even now, in the summer months, maintenance is needed. For example, power has unexpectedly failed at the Echinus datalogger, and replacement batteries, and possibly a new datalogger, are needed. The Steamboat logger—of obvious interest given the recent eruptions of that geyser—has also been unreliable, but that is due to a weak radio link with the base station owing to poor line of sight. Fortunately, temperature data are being recorded by the logger, and Yellowstone National Park geologists are helping to ensure that these data are recovered and not lost.

All of the Norris temperature data can be accessed on line via the new and improved monitoring page of the YVO website—zoom in to the Norris area and click on any of the thermometer icons to see data over various time periods. If you are interested in more details on the monitoring network itself, there is a website dedicated to the subject, as well as individual pages for every monitoring site. You are invited to take part in tracking temperature changes at Yellowstone's dynamic Norris geyser basin!