Variability of Interhemispheric Tracer Transport

Abstract:

Understanding the interhemispheric transport helps us track the movement of air and potential dispersion of pollutions. Here we examine variations of the transport from NH mid-latitudes using NCAR CAM-chem model simulations of an idealized clock tracer (that yields the “mean age”) and idealized tracers with 5-day and 50-day decay times. We examine the seasonal and interannual variations in the tracers (and inferred transport time scales), and relate to meteorological processes and climate modes. It is shown that there are large seasonal variations in the interhemispheric transport time scales but generally smaller interannual variations. The significant interannual variations are found over the Indian Ocean, and linked to the Asian monsoon and seasonal movement of intense convection. Smaller variations are found over the Eastern Pacific and linked to seasonality of the ITCZ and ENSO.