Professor Johnny Luo

Department of Earth & Atmospheric Sciences, City College, City University of New York (CUNY)

Abstract:
Convective transport from the marine boundary layer (MBL) to the upper troposphere (UT) is investigated using airborne in situ measurements of chemical tracers over the tropical western Pacific (TWP). Using 42 trace gas species with photochemical lifetimes ranging from shorter than a day to multiple decades, we developed a diagnostic called Transit Time Spectrum, G(t) to characterize convective transport time scales associated with UT air parcels sampled over the convectively dominant TWP region. G(t) describes relative contributions of air masses transported from the MBL to the UT via all transport paths with different transit times (see the schematic illustration below). We further demonstrate that the tracer-derived transit time scale is broadly comparable to that estimated from convective mass flux. The observation-based Transit Time Spectrum not only provides insights into convective transport pathways, but also has the potential to serve as an effective metric for evaluating the representation of convective transport in global models.