Investigating the Impact of Uncrewed Aircraft Observations on Weather Forecasts via Simulations

NOAA GSL and partners CIRES/CU Boulder and University of Nebraska - Lincoln have used Observing System Simulation Experiments (OSSEs) to analyze the impacts of Uncrewed Aircraft Observations on weather models and their forecasts.

Many high-impact weather phenomena such as thunderstorm initiation, tornadoes, fog, wildfires and precipitation are tied to processes that happen in the part of the atmosphere closest to the ground, known as the planetary boundary layer (PBL). The PBL is generally defined as the lowest two kilometers of the atmosphere. Currently, the PBL is only consistently measured by weather balloon launches at less than 100 sites across the nation and from commercial aircraft on ascent and descent near airports. While these observations are critical to initialize weather models, there is a data void over many parts of the U.S that aren’t in flight paths.
One potential solution to this problem is to collect observations from weather-sensing Uncrewed Aircraft Systems (WxUAS), which are already deployed in research missions. What is currently unknown, though, is if there is a notable impact of a nationwide WxUAS network on forecast quality and how the network should be configured to maximize that impact.

Researchers with GSL and their partners have set out to solve these unknowns using OSSEs. These experiments use a “truth” simulation referred to as the “nature” run. The nature run then supplies a series of observations, as if WxUAS was deployed in certain areas, which are assimilated into the GSL-led Rapid Refresh Forecast System (RRFS). Multiple scenarios were run as part of the experiment, including a control run and various numbers of WxUAS that fly up to 2 km AGL every hour. These scenarios were then compared to the nature run.

As a result of the experiment, the researchers found that assimilating WxUAS observations did improve weather forecasts from RRFS, most notably in the first few forecast hours. Generally, more WxUAS observations resulted in larger improvements, but the differences diminished after the first few hundred WxUAS deployments. This result suggests that even deploying a few hundred WxUAS over the contiguous United States can have a notable impact on RRFS forecasts.
Researchers hope that the findings in this experiment will eventually lead to better forecasts that help save lives and reduce economic disruptions from weather. Given that many high-impact weather phenomena are tied to processes in the PBL, the ability of WxUAS to improve the forecasts of these phenomena will make the investment of a WxUAS observation network worthwhile.

In the future, researchers hope to examine how much imposing constraints on WxUAS flights owing to local meteorology (e.g., not flying in winds faster than 25 m/s, not flying in icing conditions) impacts the improvement of the RRFS and examine other WxUAS network configurations, such as horizontal WxUAS flights between sites rather than vertical profiles at fixed sites.

We anticipate the first article summarizing these results will be published in the American Meteorological Society's Journal of Atmospheric and Oceanic Technology during Winter 2025.