2025 Data (Information)

Modulation of Stratosphere-to-Troposphere Transport of Ozone by North Pacific Weather Patterns, version 2

Lee, Jaewon

Stratosphere-to-troposphere transport (STT) of ozone is a major natural source of tropospheric ozone and is tightly linked to both stratospheric and tropospheric circulations. However, the complex interactions of drivers make it challenging to understand the subseasonal variability of STT. Here, we apply a weather pattern perspective to address the midlatitude internal variability of STT over western North America, the strongest global hotspot. Seven North Pacific weather patterns are identified using self-organizing maps applied to year-round 500 hPa geopotential height anomalies from a nudged WACCM6 simulation. Extreme STT occurs preferentially in the pattern with a deep trough south of Alaska, resembling the previously-defined Pacific Trough regime. A larger ozone source and an aligned strong jet lead to frequent intrusions in this pattern. The weather pattern framework explains the impact of ENSO on STT variability and its temporally evolving preference. It also suggests potential predictability of stratospheric intrusions through weather patterns.