Impact of Stratosphere on Cold Air Outbreak: Observed Evidence by CrIS on SNPP and Its Comparison with Models

A cold air outbreak (CAO) is an extreme weather phenomenon that has significant social and economic impacts over a large region of the midlatitudes. However, dynamical mechanism occurrence evolution CAO events, particularly role stratosphere, not well understood. Through analysis one episode occurred on 27–31 January 2019 across much US Midwest, this study examined its thermodynamic structure impact stratospheric downward transport using single-field-view (SFOV) satellite products (with spatial resolution ~14 km at nadir) from Cross-track Infrared Sounder (CrIS) onboard Suomi National Polar-Orbiting Partnership (SNPP) in conjunction with MERRA-2 ERA-5 reanalysis products. It found along path transport, near coldest surface center, there exists enhancement O3, deep tropopause folding, dry air, warm center above tropopause. The upper can be observed directly brightness temperature (BT) CrIS sounding channels. While similar large-scale patterns (T), relative humidity (RH), ozone (O3) are captured CrIS, MERRA-2, products, it that, regions impacted by CAO, thicker layer under difference RH up to ~10%) total column (TCO) relatively positive bias 2.8 ± 2.8% compared measured Ozone Mapping Profiler Suite (OMPS). This provides some observational evidence confirm stratosphere through demonstrates value SFOV retrieval for dynamic model evaluation.