Variability in the position and strength of the subtropical jet (STJ) and polar front jet (PFJ) streams has important implications for global and regional climate. Previous studies have related the position and strength of the STJ to tropical thermodynamic processes, whereas the position and strength of the PFJ are more associated with mid-latitude eddies. These conclusions have largely resulted from studies using idealized models. In this study, ERA-Interim reanalysis and CMIP6 global climate models are used to examine month-to-month and interannual variability of the wintertime Northern Hemisphere (NH) STJ and PFJ. This study particularly focuses on the regional characteristics of the jet variability, extending previous studies on zonal-mean jet streams. Consistent with idealized modeling studies, a close relationship is found between tropical outgoing longwave radiation (OLR) and the STJ, and between mid-latitude surface temperature gradients and the PFJ. Variations of both jets are also linked to well-known teleconnection patterns. Variations in tropical convection over the Pacific Ocean are associated with variations of the NH STJ at most longitudes, with different phases of the El Niño-Southern Oscillation (ENSO) associated with the shift and strengthening of the STJ in different regions. CMIP6 models generally capture these relationships, but the models’ tropical convection is often displaced westward when compared to observations, reflecting a climatological bias in OLR in the western tropical Pacific Ocean in many models. The displaced tropical convection in models excites different paths of Rossby wave propagation, resulting in different ENSO teleconnections on the STJ over North America and Europe.

The pediatric population is at a unique and increased risk of immediate and long-term health effects of asthma from air pollution. The years 2012-16 marked the worst drought in California, USA, in over a century. Imperial County’s landlocked Salton Sea is almost entirely dependent on agricultural runoff, where the water level has receded with drought conditions. Lakebed soil exposure may cause increased airborne particulate matter (PM), exacerbating asthma. Emergency department admissions and diagnosis codes for asthma were obtained for children ages 2-18, alongside population data to create population-weighted ZIP code buffers. Trajectory analysis, dispersion modeling, and meteorological data were used to determine likely PM exposure days. Drought severity data were used to establish a relationship between drought, exposure, and admissions. Conditional Poisson regression was used to determine the risk of Salton Sea dust exposure to asthma and moderating effects of drought. There is a significant relationship between exposure from the Salton Sea and admissions on exposure days (ERR 18.70%, p=0.012, 95%CI=3.936-35.623). Moderation analysis for drought indicated no significant effect from two indicators (ERR 1.005%, 95%CI =-0.0.084-1.111, p=0.714; ERR 104.44%, 95%CI=8.44-285.426, p=0.316), pointing to the possibility that particulates from the Salton Sea influence pediatric asthma. The large confidence interval is notable, suggesting the influence of additional pollutant sources, which is consistent with the study area, where a variety of factors may contribute to air quality. Drought severity was not a significant moderator between exposure and admissions, possibly due to the slow-response impact of drought that was not captured.