What started as a conversation between Yunji Zhang, assistant director of Penn State’s Center for Advanced Data Assimilation and Predictability Techniques, and his colleague led to research that could help provide a better forecast for regions where there are little to no areas that have ground-based weather monitoring infrastructure.
Lead author Zhang and fellow professors of meteorology David Stensrud and Eugene Clothiaux worked together to produce new satellite data assimilation in the journal, Geophysical Research Letters.
“There have been a lot of efforts that have been worked on during the past eight years or so at the department, basically trying all different ways to improve how satellite observations can be integrated into models to produce a better forecast,” Zhang said.
In this particular study, the team reported that adding microwave data gathered by low-Earth-orbiting satellites to preexisting weather forecast models produces more accurate forecasts of surface gusts.
“(The satellites) are circling around the Earth, so they cannot provide as frequent as the geostationary ones, but they can provide additional information,” Zhang said. “They can provide a look into, into the cloud itself.”
Clothiaux got involved in 2015 when Fuqing Zhang was a faculty member at Penn State and Yunji worked for him.
“(Fuqing) was a visionary. And he realized before the rest of the community, that we were going to have to bring in satellite information into the system, into the numerical weather prediction models to help with forecasting for tropical cyclones,” Clothiaux said.
According to Clothiaux, Fuqing knew the group needed to get satellite information involved since hurricanes form over oceans where there are no measurements from the ground. However, once satellites are involved, radiation has to be dealt with.
“If we sent out visible wavelength radiation it wouldn't make it to the tower because it would be scattered by the haze, the cloud drops…We would not use infrared either because infrared interacts very strongly with the haze also…it would not make it to the towers either, but the microwaves do,” Clothiaux said.
David Stensrud, professor of meteorology, worked with Yunji before he got involved with the research.
“Certainly, it's my area of interest trying to use observations in different ways or using new observations to improve forecasts of severe weather,” Stensrud said.
According to Stensrud, when looking at new data sets, it’s often a matter of trying to understand if it may be useful.
“The microwave data, we've learned, is telling us something about the precipitation particles up at the top of the clouds, which is information you don't get from other sensors,” Stensrud said.
By combining gathered infrared and microwave data, the group was able to predict surface gusts and maximum wind values more accurately.
“It's really how you blend that data together. Some of it is highly correlated, and so it doesn't add a lot of value,” Stensrud said. “But the microwave data, it adds a unique aspect that we hadn't seen with the infrared. It provides new information that we can then take advantage of.”
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Editor’s Note: Chris Raymond was a former editor-in-chief of The Daily Collegian.