Determination of the chemical equator from GEOS-Chem model simulation: a focus on the Tropical Western Pacific region

Abstract. The Tropical Western Pacific (TWP) is an active interhemispheric transport region that contributes significantly to global stratosphere-troposphere exchange. We developed a method called Chemical Equator based on model simulations of a virtual passive tracer to analyze atmospheric transport in the tropics, with a focus on the TWP region. We compare the chemical equator to common indicators of transportation such as tropical rain belts and wind fields. We obtained a vertical pattern of interhemispheric transport processes from the model's three-dimensional output.