Sleeping Giants
Cristina Ramos puts on rugged hiking boots before she drives into Quito, Ecuador’s capital. The city rests on the eastern slopes of Pichincha, an active stratovolcano made up of seven volcanoes in the Andes Mountains that backdrop the metropolitan area, where nearly 1.4 million residents depend on Ramos and other field engineers at the Instituto Geofísico de la Escuela Politécnica Nacional to monitor one of nature’s fiercest forces.
Ramos spends most of her time traveling throughout Ecuador testing systems and explaining to the community the risks associated with living next to a stratovolcano. For example, volcanic lava temperatures can reach 1250° C (more than 2000° F); however, the flow’s speed varies. In January 1977, a stratovolcano in Zaire drained in one hour and lava moved at speeds up to 40 miles per hour.
Lava could move swiftly down the steep slopes of Pichincha, so the institute uses wireless technology to notify and prepare for the evacuation of residents during potential volcanic eruptions. “It is very important to develop new wireless applications to improve the monitoring against natural hazards and mainly save lives,” Ramos said.
Wireless networks and sensor systems are at the heart of the institute’s disaster preparedness plan. Previously, adequate data collection equipment for seismic and volcanic monitoring didn’t exist in the country. The institute depended instead on existing equipment that was capable of collecting only local, short-range data, Ramos said. She did note that there was some digital telemetry used for applications that did not require continuous transmissions in real time, but it failed to meet field engineers’ needs.
The institute worked with Ecuador’s Red Nacional de Sismógrafos [National Seismograph Network] and Red de Observatorios Volcánicos [National Volcano Observatories] to develop a modern-day system that could transmit critical data to engineers in real time. The solution included myriad sensors that were placed inside volcanoes to remotely monitor volcanic and seismic activity throughout Ecuador, Ramos said.
“They include seismic, lahars, deformation, gases and thermal sensors as well as video stations — almost all of which transmit data in real time using analog and digital radios,” she said.
FreeWave’s mobile radios were recently added to expand the reach of the monitoring networks. The deployment includes real-time access to broadband seismic stations in the Imbabura and Tungurahua volcanoes, where embedded sensors track volcanic gases. Stations also house remote digital cameras to capture images and soon will include sensing systems that quantify mud flow.
Radios are tested for conditions that can range from -40° to +75° C (-40° to 167° F), said Craig Held, FreeWave’s international business adviser. He added that the company’s radios have operated at subzero temperatures 3.7 miles above sea level.
“The temperatures radios are exposed to at tops of mountains are very important from a standpoint of being reliable in those conditions,” he said.
The spectrum-hopping broadband network maintains line of sight at the top of a volcano. Data are transferred at 115 kb/s for 60 miles with an error rate of 1 bit in 4 billion, Held said.
For the deployment in Ecuador, a slave radio gathers data and sends it to a repeater that then carries it to a master radio, which serves as the collection point for data. All communications are transmitted on the 900 MHz, license-free band.
Ecuador’s seismic broadband network also uses GPS technology. Currently, five GPS receivers are deployed on the Cotopaxi volcano. The devices can determine when a caldera of lava erupts or warps the side of a volcano, making it less stable, Ramos said.
Each piece of equipment is connected to the institute’s internal network so engineers can access it from any part of the network without needing a specific PC or software. Data are transmitted to a centralized server in Quito, where volcanologists process and analyze the information.
The system also supports warning systems. Early alerts about volcanic eruptions are sent to national and local authorities so citizens have enough time to take the appropriate precautionary measures. The alerts have worked and saved lives, Ramos said. She pointed to the eruptions of the Tungurahua volcano in July and August 2006, when remote monitoring systems “warned hundreds of thousands of people early,” she said.
“As well, such data are studied to understand better the behavior of volcanoes or tectonic plates and to make risk maps for future predictions,” she said.
RAMOS and her colleagues aren’t the first team to deploy environmental monitoring systems at high altitudes. In fact, the practice has become almost ubiquitous, said Garry Schaefer, a water and climate monitoring branch leader at the Natural Resources Conservation Service’s National Water and Climate Center in Portland, Ore. Since the late 1970s, the NRCS has used automated technological systems to collect snowpack and climatic data from the 12 western U.S. states, including Alaska, to better predict year-round weather.
Schaefer is tasked with operating automated networks that house stream-flow forecasts based on snowpack levels in mountainous regions. His team works with the National Weather Service to increase the timeliness and frequency of snowpack measurements to produce the stream-flow forecast, which helps users, municipalities and government agencies to monitor water resources, he said.
Dubbed SNOwpack TELemetry, or SNOTEL, the $10 million project uses meteor-burst communications technology to collect data in near real time. The current system uses VHF radio signals at 40-50 MHz that are reflected at a steep angle off a band of ionized meteorites about 50 to 75 miles above Earth.
The system was developed by MeteorComm. Dale Smith, a senior systems engineer at the company, said the SNOTEL program was one of the first to use its system. Meteor communications were first tested by amateur, or ham, radio operators in the 1950s, Smith explained. Televisions became prevalent then, as did the transmitters that used the 40-50 MHz frequency to carry the signal. As a result, viewers in Chicago could pick up TV broadcasts from New York for short intervals during meteor showers.
“The transmission wouldn’t last long, but the hams, scientists and universities correlated that activity to meteor showers,” he said.
Meteors travel above the Earth and leave ionized trails behind them, called a meteor burst. Those trails reflect or reradiate communications, depending on the density of the trail and signal, to a ground-based receiver hundreds of miles away. When a meteor burst occurs, the path causes that signal to reflect back to Earth, where it is received by a remote station, Smith said. That remote station then transmits the signal to other stations placed throughout the Western states’ mountainous regions.
The main challenge is to find where and when trails are present. Master stations transmit omnidirectional signals simultaneously and continuously, “like a beacon or what we call a probe,” to find a signal, Smith said. Remote stations are always listening for a signal from the master station, but they may not get one for quite a while as the master awaits a meteor burst. During active summer months when more meteors are present, data uploads 20 to 30 times per hour. In winter months, uploads run 15 to 20 times per hour.
“During a design of the system, users have to consider the lower performance in the winter,” he said. “There are also more meteors in the morning then there are in the afternoon. Specifically, minimum wait times happen on a summer morning.”
The technology has matured and form factors have shrunk. One of the first systems was put together by the U.S. Navy and the Boeing Co., which used multiple racks to hold the receivers that sent out the signals, Smith said. The advent of microprocessors and miniaturized systems reduced the space needed to hold components.
“Remote stations now are typically in cans, 2 inches wide and 8 inches long,” he said. As a result of the smaller form factor, deployment is easier, particularly in rugged, mountainous regions. In fact, remote systems often are installed in high mountain watersheds, and the Colorado Rockies boasts the highest deployment of a master station at 12,000 feet.
NRCS engineers hike, ski or ride helicopters to access and maintain sites, but they don’t visit sites very often, Schaefer said. Sites are designed, instead, to operate unattended and without maintenance for a year. Power is supplied by battery that is backed up with a solar-cell recharger. Each site is monitored daily, and if the system senses a deteriorating performance, an alarm is sent to technicians in six data collection offices.
SNOTEL sites are polled by two master stations operated by the NRCS in Boise, Idaho, and Ogden, Utah. Sites have a pressure-sensing snow pillow, storage precipitation gauge and air temperature sensor. Wind speed is sensed every minute during the day to arrive at an average, while the snow pillow is accessed every 15 minutes for the accumulated total. Data are sent to NRCS command centers when a meteor burst occurs.
Schaefer said the stations accommodate 64 data channels and will accept analog, parallel or serial digital sensors. All data received by the SNOTEL central computer are put into a relational database, where various analysis and graphics programs are available.
The NRCS also has developed a marriage with the National Weather Service to alert first responders and residents to floods, heavy winds and rains, avalanches, and other environmental events. Schaefer said software-based alerts can be queued into the system. If an event occurs, the system can send data to mobile devices or the command center. However, the remote stations are always at the mercy of waiting for the master station to pick up a signal from a meteor trail — which could take three to four minutes.
“It’s not a real quick response, but within a few minutes the data does get through,” he said. “So it works well with environmental monitoring [applications] where you need a dozen perimeter readings per hour and alerts about major events within 10 or 15 minutes.”
Gathered data are sent hourly directly to the National Weather Service, which then distributes it to its weather forecast centers that are responsible for issuing warnings and watches to the public, Schaefer said.
“Main sensors measure snow pack, air temperature and snow depth — which is important for recreational and highway managers to open roads in mountains,” he said. “Snow depth and water content tells the density of snow pack, which then clues us into when it might melt and produce run off or raise river levels.”
METEORCOMM’S; system also is used to monitor water reservoirs in major metropolitan areas. Glenn Horton is an associate project manager for New York City’s Department of Environmental Protection, an operations support group in the water supply bureau. The group maintains and monitors drinking water quality and levels for the entire system, and it also tracks an extensive reservoir system that covers about 2000 square miles extending from mountaintops, he said.
Horton’s group monitors 29 automated, high-altitude weather stations within the city’s watershed that also includes a network of about 25 stations in the Catskills Mountains northwest of New York City.
Before installing the system, Horton said data from stations in remote regions of the Catskills had to be physically downloaded, so each station had to be visited every four to six weeks. “Some of these are in remote sites so it took a lot of manpower and man-hours to take care of this,” he said
Horton and his team needed to deploy a new system. They looked at cell service, land mobile radio and phone lines as solutions, but the topography and remoteness of the Catskills eliminated cell and phone line options.
“The decision was whether to do an RF transmission back to the office or funnel through a line-of-sight system using meteor-burst technology,” he said. “The latter lets researchers handle their own information without having to go to a public source before reaching the command data center.”
Sensors placed throughout the region determine wind speed, wind direction, temperature and relative humidity. The system also measures solar length — measurements of the full wavelength of the sun — and the photosynthetic wavelengths of the sun. In addition, the system tracks snow depth, and recently installed snow pillows measure snow/water equivalent, which determines the runoff level from mountain streams into reservoirs.
“We just collect data to better model our reservoirs, whether to model it for evaporation, for things like algae blooms or anything that has an atmospheric influence on it,” Horton said.
Another benefit of the system is the two-way communication with the data logger. Horton can ask a remote, offsite data logger to send data while he is able to send real-time commands and data back to the station, such as a new or updated program.
“From an economic standpoint, it’s great,” he said. “The system has taken a task that usually took about five people to complete and it has basically reduced it to one person.”
Horton said that the National Weather Service has been interested in accessing real-time and long-term trend data. In the past, the system didn’t offer real-time transmissions. Running communications through the remote stations into an Internet interface makes it more real time for the national service, he explained.
Data on Catskills weather are sent every 15 minutes, from a region that once was considered “data-void,” Horton said. Precipitation data now lets the weather service send even earlier flood warnings to the public. In addition, emergency planners and officials for each county in the area receive the same information when the weather service sees a problem.
Horton’s group also set up a partnership to meet and discuss areas of improvement and how the data can be used most effectively to protect and alert the public.
“Representatives meet twice a year just to talk over where we are going, goals, new products and how it’s helping the weather service now that they’ve tapped into our data stream,” he said.
Like the SNOWTEL system, sensors and radios are powered in part by solar energy. In addition, two remote stations use wind generators for power. However, the use of solar and wind is not always reliable. Sometimes the stations lose battery power and the radios shut down. But the system generally runs at 98% connectivity, Horton said.
“We had to work through those issues as far as winter goes, especially the high-peaks regions of the Catskills when you’re getting three feet of snow building up on the solar panels,” he said. “Every once in a while I might lose a station for an hour here, an hour there, but for the most part it has been solid,” he said.
However, Rae Zimmerman, professor of planning and public administration at New York University, warns that the introduction of monitoring/communications technology into water resources has spawned some challenges. For instance, sensors sometimes are moved by sediment and often are not rugged enough to last for a long time.
“Sometimes the technology fails and just doesn’t work,” Zimmerman said. “What then?”
Nevertheless, all technological systems are prone to failure, at least to some degree, and Zimmerman concedes that the use of sensor technology to track water and reservoir systems has proliferated and will continue to be used throughout the U.S.
Regardless of the challenges, for Ramos, Horton and Schaefer, using this technology to track environmental changes will continue to be essential. More essential is the impact it has on people.
“Working for hours and traveling for days is rewarded when an event occurs and lives are saved,” Ramos said.
