Combining satellites, radar provides path for better forecasts

November 11, 2019

Every minute counts when it comes to predicting severe weather. Combing data from cutting-edge geostationary satellites and traditional weather radar created a path toward earlier, more accurate warnings, according to Penn State researchers who studied supercell thuderstorms in the Midwest.

"We know satellites have an advantage in producing forecasts earlier, and radar has more confidence in where clouds should be and where thunderstorms will be moving," said Yunji Zhang, assistant research professor in meteorology and atmospheric sciences at Penn State. "The question was whether these two types of observations would complement each other if combined together. We found, for at least one severe weather event, assimilating satellite and radar simultaneously leads to the best forecasts."

Data assimilation is a statistical method used to paint the most accurate possible picture of current weather conditions, important because even small changes in the atmosphere can lead to large discrepancies in forecasts over time.

The scientists assimilated satellite and radar data separately and simultaneously to see which combination could best recreate conditions during a large storm system that struck Wyoming and Nebraska in 2017. The best results came from combining infrared brightness temperature observations from satellites, and radial wind velocity observations from radar, the scientists reported in the American Meteorological Society journal Monthly Weather Review.

"Our results suggest that each sensor provides unique information about the storm," said David Stensrud, head of the Department of Meteorology and Atmospheric Science at Penn State. "While these results need to be evaluated across a large spectrum of cases, they point to a path forward that could extend lead times for severe weather events, thereby providing improved information to the public when severe weather strikes."

The researchers were previously the first to use data from the new U.S. Geostationary Operational Environmental Satellite, GOES-16, to predict severe thunderstorms through the all-sky radiance method.

The all-sky method, developed by Penn State's Center for Advanced Data Assimilation and Predictability Techniques, can assimilate data from all weather conditions, including cloudy and rainy skies. Forecasting previously relied on clear-sky observations, due to challenges in diagnosing the complex physical processes within clouds, the scientists said.

Instruments on GOES-16 can see storm clouds as they form, tens of minutes earlier than traditional Doppler radar, which senses storms only after rain begins to fall, the scientists said. Satellites can also detect important surrounding environmental conditions, like how much water vapor is in the air.

But satellites also have limitations. Those same infrared sensors can only scan the tops of clouds and may miss details about what is happening underneath. Doppler radar observations provide 3D scans of the storms, leading to more accurate information about the storm's structure and potentially cutting down on false alarms, according to the researchers.

The scientists found they could increase warning times by up to 40 minutes, which supports the findings of their previous work. According to the researchers, current warning times for tornadoes average about 14 minutes.

"Say you have severe weather heading toward a football game or a large event," Zhang said. "If you can have a longer forecast lead time of 20 to 40 minutes, you have more time to evacuate. I believe that more human lives can be saved by increasing forecast times."
Also involved from Penn State was Fuqing Zhang, distinguished professor of meteorology and atmospheric science. Zhang died unexpectedly in July 2019.

NASA and the National Oceanic and Atmospheric Administration funded this research.

Penn State

Related Satellites Articles from Brightsurf:

Satellites have drastically changed how we forecast hurricanes
The powerful hurricane that struck Galveston, Texas on September 8, 1900, killing an estimated 8,000 people and destroying more than 3,600 buildings, took the coastal city by surprise.

Spotting air pollution with satellites, better than ever before
Researchers from Duke University have devised a method for estimating the air quality over a small patch of land using nothing but satellite imagery and weather conditions.

New patented invention stabilizes, rotates satellites
Many satellites are in space to take photos. But a vibrating satellite, like a camera in shaky hands, can't get a sharp image.

Satellite broken? Smart satellites to the rescue
The University of Cincinnati is developing robotic networks that can work independently but collaboratively on a common task.

Combining satellites, radar provides path for better forecasts
Every minute counts when it comes to predicting severe weather.

Satellites are key to monitoring ocean carbon
Satellites now play a key role in monitoring carbon levels in the oceans, but we are only just beginning to understand their full potential.

New safer, inexpensive way to propel small satellites
A team at Purdue University has developed a new safer and inexpensive way to propel small satellites.

New developments with Chinese satellites over the past decade
To date, 17 Chinese self-developed FengYun (FY) meteorological satellites have been launched, which are widely applied in weather analysis, numerical weather forecasting and climate prediction, as well as environment and disaster monitoring.

First detection of rain over the ocean by navigation satellites
In order to analyse climate change or provide information about natural hazards, it is important to gather knowledge about the rain.

Earth's dust cloud satellites confirmed
A team of Hungarian astronomers and physicists may have confirmed two elusive clouds of dust, in semi-stable points just 400,000 kilometres from Earth.

Read More: Satellites News and Satellites Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to