While the athletes at the Winter Olympics in Pyeongchang are concerned with skiing and snowboarding through the snow, researchers from NASA are focused on the snow itself.
Working with 19 other agencies from 11 countries, and led by the Korea Meteorological Administration, NASA is measuring snow during the Olympic and Paralympic games in Korea to improve snowstorm forecast models. The project is called the International Collaborative Experiments for Pyeongchang 2018 Olympic and Paralympic Winter Games, or ICE-POP.
"We are interested in South Korea because we can improve our understanding of the physics of snow in mountainous areas to help improve the accuracy of our observations and models," Walt Petersen, research physical scientist at NASA's Marshall Space Flight Center explained in a NASA statement.
Predicting the next snow day
NASA, along with other U.S.-based researchers from Colorado State University, the National Center for Atmospheric Research and National Oceanic and Atmospheric Administration (NOAA), are using a series of ground-based instruments, satellites and weather models to craft reports about current snow conditions and test new, experimental models for forecasts. This information will then be given to Olympic officials to help them prepare for changes in the weather.
What makes South Korea challenging, but also exciting for the researchers, is its diverse terrain. Beaches and mountains are easy for humans to travel between and the same applies to snowstorms. Air flow can change rapidly given these geographical shifts and result in big snowstorms in Pyeongchang. So scientists are doing what they can to observe the snow as it moves through the area.
Observations are made at 16 different sites near Olympic venues, with a combination of ground- and space-based methods. On the ground, NASA is using snow imagers that use high-speed cameras and software to image every snowflake as it falls in its viewing area. These imagers are useful for counting the snowflakes and determining how much water is falling at that moment. Helping with that is the Dual-frequency, Dual-polarized, Doppler Radar (D3R) system. This large piece of machinery measures the quantity and types of falling snow, registering if it is sleet or fluffy snow.
Ground-based observations are only so helpful, however, since it's difficult to get equipment to mountainous terrain. That's when space-based tools come into play. NASA will track snowstorms with the Global Precipitation Measurement (GPM) Core Observatory. This satellite is designed to estimate rainfall rates and detect falling snow from space. While the satellite is good for big picture observations, it has trouble measuring size, shape and water content of snow, which varies.
Improving the forecast
Researchers think that using both of these approaches will provide an accurate picture of snow in the area and will help them to better predict when the next snowstorm will form, how it will move, and even what kind of snow will fall. This will help not only Olympic officials know what to expect, but it will also improve NASA's own forecasting models.
To that end, the NASA teams in Pyeongchang are using a forecast model developed by NASA's Short-term Prediction Research and Transition Center (SPoRT). SPoRT, which seeks to improve short-term weather forecasts in a region, designed the model to do a couple of different things. First, the model can determine what a cloud is made of and then provides specific details on whether it's producing rain or snow. Second, the model uses data from three different satellites — NASA's Terra and Aqua satellites and the NASA/NOAA/Department of Defense Suomi-National Polar Orbiting Partnership satellite — to determine sea surface temperatures. This information tells researchers how much energy is available and how much moisture could end up evaporated and becoming snow.
"This model includes a complex representation of clouds in atmospheric models to better characterize rain, ice, and snow content in clouds. It also includes one of the highest resolution sea surface temperature products available in real time," Brad Zavodsky, the project manager for SPoRT, said in the NASA statement. "We're excited to see how well this high-resolution model will perform."
The Korean Meteorological Administration gets forecasts four times a day from SPoRT and compares the SPoRT model with the other ICE-POP models before passing them along to Olympic officials.
"When you run these models together from the different agencies, you can see how one model behaves versus another one. You learn a great deal about your abilities to predict in a forecast model and how to improve it," Zavodsky said.