Satellite Observations Underpin Today’s Increasingly Accurate Weather Forecasts
The dangerous polar vortex weather system that hit the U.S. during the final days of January was no surprise. The warnings came well in advance, with some indicators reported a month before the deep freeze arrived. The forecasts, including spot-on predictions of wind chills dropping to below minus-50 across parts of the Midwest, are the latest example of models correctly predicting record-breaking conditions. The accurate August 2017 predictions—more than three days in advance—that Hurricane Harvey would inundate the Houston area with more than 50 inches of rain is another dramatic example.
Accurate forecasts and early lead times help residents, local officials, and service providers properly prepare for extreme weather. For example, utilities worked ahead of the polar vortex to brace the power grid for spikes in electricity demand, while homeless shelters in Chicago added hundreds of extra beds. In the case of Hurricane Harvey, the Federal Emergency Management Agency was able to pre-position personnel and supplies to respond to the catastrophic flooding that would follow.
According to a new paper published in Science Magazine, today’s five-day forecast is as accurate as a one-day forecast in 1980.
The steady improvement in weather forecasts, with accuracy increasing approximately one day per decade, is the result of advances in several different areas, including observations, models, and computing power. The most important observations come from weather satellites, which provide more than 90 percent of the data used for weather forecasting. This is where Harris technology has led the way for nearly six decades.
Delivering Today’s Critical Systems
In 1960, Harris transmitters enabled the first weather picture from space from the first U.S. weather satellite, TIROS-1. Since then, Harris has advanced the technologies and systems for collecting, receiving, and processing weather and environmental information from remote sensing systems. Harris sensor technology has been on every NOAA polar-orbiting weather satellite since 1978 and every NOAA geostationary weather satellite since 1994.
Today Harris-built sensors and ground systems are providing imagery and data with unmatched detail and speed:
- Advanced Baseline Imager (ABI): On NOAA’s GOES-R satellite series, ABI has revolutionized weather monitoring and wildfire detection with three times more spectral bands, four times greater spatial resolution, and five times faster refresh than previous technology. Updated imagery is delivered to forecasters as fast as every 30 seconds. ABI-class imagers also fly on Japan's Himawari-8 and 9 satellites and South Korea's GEO-KOMPSAT-2A satellite. Harris advanced imagers now provide rapid-scan coverage of 85 percent of mid-latitude and equatorial regions of the world.
- Cross-track Infrared Sounder (CrIS): On NOAA’s Joint Polar Satellite System, CrIS circles the Earth 14 times per day and uses more than 2,000 spectral channels, compared to the 19 channels of previous technology, to collect vertical profiles of temperature and moisture that improve 3- to 7-day weather forecasts and nowcasts.
- GOES-R Ground System: Managing the entire GOES-R satellite series, the GOES-R Ground System operates the satellites, processes the data from all instruments on board, and distributes the data and products to thousands of users worldwide. The enterprise ground system has a data processing capacity of more than 16 terabytes per day and delivers weather products to forecasters in less than 30 seconds.
“It’s an exciting time for weather forecasting as new technology is enabling forecasters to issue earlier and more accurate warnings for severe weather, improving medium-range forecasts for extreme events, and detecting wildfires faster than ever before,” says Rob Mitrevski, vice president and general manager of Harris’ Environmental Solutions business. “We’re proud to be delivering this next generation of weather satellite technology, including five Harris weather and environmental payloads launched in 13 months for the U.S., Japan, Europe, and South Korea.”
Developing Tomorrow’s Innovative Solutions
As good as weather forecasts have gotten, there remains plenty of room to improve, especially when it comes to high-impact events, says Dan Stillman, a meteorologist and senior marketing manager for Harris’ Environmental Solutions business.
“While hurricane track forecasts have shown steady improvement over the last 30 years, hurricane intensity forecasts are only slightly better over the same period of time,” explains Stillman. “Meanwhile, people in the Mid-Atlantic and Northeast U.S. know that snowfall forecasts can fluctuate significantly even within 24 hours of a storm. And in Tornado Alley, the average warning time for potentially deadly tornadoes is only about 10 minutes.”
It is this need to provide data for even more accurate forecasts at earlier lead times that is driving Harris to evolve its weather technologies, according to Mitrevski.
One such technology in development is Harris’ hyperspectral geostationary sounder, which uses many of the same components as the ABI to collect vertical profiles of temperature and moisture data over the same area every three minutes. Studies have shown that hyperspectral geostationary sounder data has the potential to improve severe weather forecasts considerably and could help increase tornado warning times from minutes to an hour or more.
Another instrument in development is a miniaturized version of CrIS called HyperCubeTM. A constellation of 12 HyperCube™ smallsats in low Earth orbit would provide global coverage of 3-D winds—wind direction and speed at multiple levels of the atmosphere—every six hours. Satellite measurements of 3-D winds “would be transformative” to weather forecasting, according to the 2017-2027 Decadal Survey for Earth Science and Applications from Space.
“We’re advancing our sensor technologies for flagship systems like NOAA’s GOES satellites and have also been very successful in deploying smaller, affordable responsive solutions,” says Mitrevski. “To complement these augmented architectures, we’re building ground systems that not only manage today’s constellations, but are flexible and scalable for tomorrow’s as well. And we’re working to better bridge the gap between data collection and decision making by speeding up processing and delivery, all in support of our customers’ most critical missions.”