Intercontinental Chemical Transport Experiment Ozonesonde Network Study (IONS) 2004: 1. Summertime upper troposphere/lower stratosphere ozone over northeastern North America

摘要

Coordinated ozonesonde launches from the Intercontinental Transport Experiment (INTEX) Ozonesonde Network Study (IONS) (http://croc.gsfc.nasa.gov/intex/ions.html) in July-August 2004 provided nearly 300 O_3 profiles from eleven North American sites and the R/V Ronald H. Brown in the Gulf of Maine. With the IONS period dominated by low-pressure conditions over northeastern North America (NENA), the free troposphere in that region was frequently enriched by stratospheric O_3. Stratospheric O_3 contributions to the NENA tropospheric O_3 budget are computed through analyses of O_3 laminae (Pierce and Grant, 1998; Teitelbaum et al., 1996), tracers (potential vorticity, water vapor), and trajectories. The lasting influence of stratospheric incursions into the troposphere is demonstrated, and the computed stratospheric contribution to tropospheric column O_3 over the R/V Ronald H. Brown and six sites in Michigan, Virginia, Maryland, Rhode Island, and Nova Scotia, 23% ± 3%, is similar to summertime budgets derived from European O_3 profiles (Collette and Ancellet, 2005). Analysis of potential vorticity, Wallops ozonesondes (37.9°N, 75.5°W), and Measurements of Ozone by Airbus In-service Aircraft (MOZAIC) O_3 profiles for NENA airports in June-July-August 1996–2004 shows that the stratospheric fraction in 2004 may be typical. Boundary layer O_3 at Wallops and northeast U.S. sites during IONS also resembled O_3 climatology (June-July-August 1996–2003). However, statistical classification of Wallops O_3 profiles shows the frequency of profiles with background, nonpolluted boundary layer O_3 was greater than normal during IONS.