Seasonal and regional signatures of ENSO in upper tropospheric jet characteristics from reanalyses

Abstract The relationship of upper tropospheric jet variability to El Niño / Southern Oscillation (ENSO) in reanalysis datasets is analyzed for 1979–2018, revealing robust regional and seasonal variability. Tropical jets associated with monsoons the Walker circulation are weaker zonal mean subtropical shifts equatorward both hemispheres during Niño, consistent previous findings. Regional variations separately polar jets. poleward over NH eastern Pacific DJF, some SH regions MAMand SON. Subtropical altitudes increase significant changes summer/fall SH. Though correlations ENSO rarely significant, regional/seasonal occur: Asia western JJA Polar (stronger) (eastern) hemisphere, especially SH; conversely, stronger (weaker) hemisphere winter spring; these opposing changes, along an anticorrelation between windspeed, reinforce subtropical/polar strength differences suggest ENSO-related covariability latitude, altitude, windspeed can reach 4(3)°, 0.6(0.3) km, 6(3) ms −1 , respectively, (polar)