Weather data: The drought cometh
Accustomed as we are to weather forecasts that become ever more reliable, and a growing ability to get the big picture of conditions on Earth, we were startled to read that “the U.S. system of environmental satellites is at risk of collapse .” In May, the National Research Council added that a “precipitous decline in the quantity of Earth science and applications observations from space undertaken by the United States” could threaten our ability to
measure sea level and the amount of ice in glaciers and at the poles
detect remote wildfires and flows of air pollution
assess the health of forests and rangeland
measure the energy balance between Earth, sun and space
monitor global warming
Two types of satellite are the basis for much of the data that nourishes the U.S. Weather Service. Their detailed observations support a broad range of environmental science:
Geosynchronous satellites (“weather satellites”) orbit at about 22,300 miles, staying over the same region year after year; and
Polar-orbiting satellites, at altitudes of 500 to 600 miles, overfly the entire globe twice a day, providing information at a finer scale, but not continuously.
Earth-observing satellites have been plagued with cost overruns, delays, cutbacks and other embarrassments that remind us of a mini-space program.
With weather, ignorance is expensive!
At the same time, the cost of weather-related natural disasters, including hurricanes, floods and wildfires, keeps rising. In the United States, thunderstorms and the associated lightning, tornadoes and rainfall cost almost $26 billion in economic losses in 2011, a record. According to Climate Spectator , when adjusted for inflation, “the 2011 spring tornado season was the fourth-costliest disaster in U.S. history, trailing only hurricanes Katrina and Andrew and the September 11, 2001, attacks on the United States.” (Emphasis added).
Variations in weather affect everything from tourism and agriculture to manufacturing and construction, and have a $485-billion annual impact, according to a 2011 study from the National Center for Atmospheric Research.
The study was actually an underestimate, as it ignored the costs of extreme weather and global warming.
Yet the ability to predict weather relies heavily on the Earth-observing satellites (and on airplanes, radar, buoys, computers and scientists, which are likewise under budget pressure). Eyes in the sky could even help prevent some disasters, including the fires and droughts that seem to be linked to a warming climate.
A risky business
Every time there’s a hurricane, we see awesome satellite photos — without necessarily considering what it will cost to replace those satellites when they inevitably wear out. Forecasting the future of our weather satellites was assigned to a National Research Council study of satellite capacity that was published in May, 2012. “We tried to use objective, verifiable information,” said study leader Dennis Hartmann, of the University of Washington.
Using engineering estimates, current status and fuel supplies, the group predicted when existing missions would likely end, and also considered missions that were advanced enough to have a launch schedule.
A prediction is always uncertain, Hartmann admits, “But there is definitely going to be some sort of decline in the number of missions flying” by 2020. In fact, the report anticipates, three-quarters of the data flow could cease by then.
We had two questions: How has this happened, and how will it matter?
Reasoning it out
Earth-observing satellites are highly sensitive, mechanical-optical-electronic devices that are expensive to design, build and launch. They must operate hands-free in a harsh environment where repair is impossible (although reprogramming and rebooting from the ground can solve some problems).
In the United States, Earth-observing satellites are run by two government organizations:
NOAA (the National Oceanic and Atmospheric Administration) handles “operational” missions that are the primary data source for the National Weather Service and many environmental scientists.
NASA (the National Aeronautic and Space Administration) handles experimental, risky, and inherently more expensive missions that, pardon the cliché, “push the technology envelope.”
NOAA’s primary mission, says Hartmann, a professor of atmospheric science, must be weather, but when money runs short, NOAA is tempted to shunt some missions to NASA, which can raise costs enough to impair the search for new discoveries or technologies, even if it does sustain long-term studies of such matters as ice cover or sea temperatures.
“It’s the issue of doing something new for discovery versus continuity” with long-term datasets, says Steven Ackerman, director of the Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin-Madison. “We need to find the balance; we need continuing climate studies as one type of observation, but those are not going to address new and challenging problems. To learn more, we need new measures to tell us what we really don’t understand.”
Weather satellites are the source of much of the data that computer models use to provide everyday forecasts for rainfall and temperature highs and lows, says Jeff Masters, director of meteorology at Weather Underground. If the weather satellites decline, those “forecasts will degrade significantly,” he says.
Hurricane forecasts have two elements: the storm’s path (track), and its intensity. “I don’t think losing these satellites over the next five or so years will degrade our forecast of hurricane [tracking], but it will prevent them from getting better,” says Masters.
Intensity may be a different story, he adds, where forecasts are much less reliable. Hurricane Katrina showed how rapidly a storm can speed up, reaching
Category 3 on August 27, 2005;
Category 4, just after midnight on August 28;
Category 5 (the strongest hurricane) 7 a.m. Aug. 28. Six hours later, maximum sustained winds were 175 miles (280 kilometers) per hour.
In just 12 hours, Katrina had burgeoned into the most fearsome of hurricanes. The death toll reached 1,883, and the economic toll is still being paid.
Hurricane intensity forecasts can save lives, says Masters, who notes that a 10-year program based on polar orbiting satellites could lead to better intensity forecasts. “When you see a particular ring-shaped feature… and other conditions are right, we can expect to see rapid intensification of a hurricane.”
In the past 20 years, Masters says, “We have improved the ability to forecast storm track more than two-fold, whereas there has been essentially no improvement in intensity. These cutbacks mean we will be hurting ourselves.”
However, Harold Brooks of NOAA told us that satellites data is less important with tornadoes. For advisories issued several hours in advance, “in some cases, it could make a few minutes difference in watch issuance.”
But satellite data would make “no difference” on tornado warnings, which rely on visual sightings and radar.
Murphy: Does he still rule the skies?
Although the NRC report warned of a data drought starting around 2015, the future could arrive sooner, says Larry Di Girolami, a professor of atmospheric sciences at the University of Illinois-Urbana-Champaign, and an expert in remote sensing. Many of the “satellites we have up already are way past their prime; they have been designed to last three to six years or so, and most of the good ones are 12 or 13 years old. It’s like owning a car that has 200,000 miles. It could go a long time, or it could die tomorrow.”
Aging satellites can have multiple problems, says James Gleason, a satellite project scientist at NASA. “They require some work to keep the data and communication channels open. The quality decays, and it’s more work to get the data out. The optics and mirrors cloud, the detectors go bad, the transmission starts to decrease, the electronics get noisy.”
Like a rusty fender separating from the chassis on a ’57 Buick Roadmaster, loose parts can even block an instrument’s view.
Satellites can suddenly go silent. In April, the European Space Agency lost contact with ENVISAT. “We have not had that happen,” says Gleason, “but we’ve had decay [with older satellites] … and we have to work around that.”
In the world of the cost overrun
You’d think you could cut costs by adapting or reusing existing designs for satellites and instruments, and indeed that’s commonly done, especially in a series of satellites with the same general mission. But the cost-cutting can fail if the hardware gets too complicated, says Hartmann. ICESat-2, a mission to assess ice on Earth — a critical register of climate change — “was supposed to be a clone of ICESat, but they changed the technology for various of reasons, and it got more expensive.”
In some cases, Hartmann adds, would-be satellites have been scrapped before launch due to ballooning development costs. To save money, NASA is working on “Venture” missions, which are supposed to be smaller, cheaper and faster satellites and have yet to be launched.
Such recycling is evident in Suomi NPP, a new satellite named for Verner Suomi, a University of Wisconsin-Madison pioneer of weather satellites. “Most of the instruments on Suomi were first demonstrated on the Earth-Observing Satellites [Aqua and Terra],” says Gleason, project scientist for Suomi. “We as a country have learned all these things from these research satellites, and we are going to continue to use them because we know we need them.”
Suomi’s visible and infrared detection equipment can measure fires, changes in river channels and ocean color, sea-surface temperature, dust storms and the material ejected by volcanoes, Gleason says.
The United States was the birthplace of weather satellites, says Ackerman, but it’s ceding that primacy. “If you look at the next generation of geostationary weather satellites, we are proposing to launch in 2015 a satellite that’s very similar to what Europe has today. That’s just not right.”
So far, we’ve done well by resting on past expertise and expenditures, Ackerman adds. “We are now at the heyday of satellite observations, and it’s exciting, but people who been at this for a while can see a decline coming. We are losing ground in both weather and climate. Currently, in the study of climate and atmospheric processes, we are still the leaders, but we are not going to be for long.”
The expected lifetimes of some existing Earth-observing satellites “have already been exceeded, and at some point they will die,” Ackerman concludes. “It’s a matter of wear and tear, like on your car; things begin to break down, and you often can’t fix them. And even if you have a backup, when both of them go, you are done.”
— David J. Tenenbaum