Stratosphere-Troposphere Transport of Ozone Associated with Atmospheric Rivers

As a result of their important role in weather and the global hydrological cycle, understanding atmospheric rivers’ (ARs) connection to synoptic-scale climate patterns and atmospheric dynamics has become increasingly important. Here we examine case studies of two extreme AR events, and produce a December climatology of the three-dimensional structure of water vapor and ozone distributions associated with ARs in the northeastern Pacific from 2004-2014 using MERRA-2 reanalysis data products. Positive ozone anomalies reside in the dry intrusions of stratospheric air due to stratosphere to troposphere transport (STT) behind the intense water vapor transport of the AR. We find a correlation between AR strength and excess ozone concentration, and we quantify the ozone flux due to the likely irreversible mixing of stratospheric ozone in the troposphere. In light of predictions that ARs will become more intense and/or frequent with climate change, the quantification of STT ozone flux in connection with ARs provides valuable insight, particularly for future radiative forcing calculations.