Monday, February 27, 2017
Q and A: How NOAA team created new engine to improve global weather forecast model

Q and A: How NOAA team created new engine to improve global weather forecast model

Thursday, July 28, 2016

Meet Shian-Jiann Lin, Ph.D., the leader of the team at NOAA’s Geophysical Fluid Dynamics Laboratory that created the new dynamic core that NOAA announced this week will be used to develop a state-of-the-art global weather forecasting model over the next three years.

What is a dynamic core?  

The dynamic core is the engine for weather and climate prediction models. We created the Finite-Volume on a Cubed-Sphere or FV3 dynamic core by writing a complete set of computer software to describe the motion of the atmosphere, based on physical laws and mathematics.

What is new and different about the FV3 dynamic core?

The FV3 has been undergoing continuous improvements and enhancements since we first developed it at NASA and began using it at NOAA’s Geophysical Fluid Dynamics Lab for climate models a decade ago. It’s now mature and ready to be used to improve the U.S. Global Forecast System.  NOAA’s selection of FV3 for the GFS represents the coming together of climate and weather modeling, which will enhance short-term forecasts and long-term climate prediction. I believe the FV3 is the most versatile dynamic core developed in the U.S. We use it for climate simulations at NOAA GFDL and NASA for the Intergovernmental Panel on Climate Change.

How will the FV3 improve forecasts by the Global Forecast System?

Hindcast of the 2008 hurricane season, as simulated by NOAA's FV3-powered GFDL model

Hindcast of the 2008 hurricane season, as simulated by NOAA's FV3-powered GFDL model

Hindcast of the peak of the 2008 hurricane season, one of the most active on records, simulated by an FV3-powered GFDL model at 13-km resolution. FV3 improves representation of small-scale weather features such as hurricanes while maintaining the quality of large-scale global circulation.
The FV3 offers weather forecast models the capability of fine enough resolution to represent individual clouds and yet it can also do a global weather simulation. With the previous dynamic core it’s difficult to represent the movement of clouds, snow, hail and wind at fine scales. The FV3 makes this more efficient and more accurate.

Imagine an individual thunderstorm hovering over your house. A super-cell thunderstorm that’s three to 10 kilometers wide can produce tornadoes. But if the forecast model resolution is 13 kilometers as the GFS is now, you can’t represent that small thunderstorm that will help you forecast tornadoes. The FV3 will eventually enable the GFS to represent weather events at scales as fine as one to three kilometers. The only limit to representing severe weather events at even smaller scales is computing power. Today’s supercomputer is not yet powerful enough to reach the resolution we need for predicting tornadoes.

What kind of expertise do you and your team members need to do this work?

NOAA's FV3 team

NOAA's FV3 team

The team that developed the new dynamic core for NOAA's Global Forecast System are: Back row (left to right): Xi Chen, Zhi Liang, Rusty Benson, Shian-Jiann Lin, Matthew Morin, Lucas Harris and Jan-Huey Chen Front row (left to right): Linjiong Zhou, Timothy Marchok and Shannon Rees. (NOAA GFDL)
Developing the engine for a unified weather-climate model is truly a team effort. We have great teams at GFDL and NASA working together on the FV3. Our GFDL team includes supercomputer and statistics experts as well as mathematicians and physical scientists who understand the weather and climate system.

What drives you to do this work?

I want to help create something useful to our society that can predict the environment surrounding us. Weather influences our daily life and climate controls our long-term activities. I want to be able to predict the weather and anticipate how the earth’s climate is evolving. Ultimately, what motivates me is the desire to try something new that no one has yet accomplished.

For more information, please contact Monica Allen, public affairs for NOAA Research, at 301-734-1123 or by email at 

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