Using Trace Gas Measurements as a Transport Diagnostic for Tropical Convection: A Combined Model and Observation Study

This study builds on recent research that used airborne measurements of volatile organic compounds (VOCs) from the CONTRAST field campaign over the tropical western Pacific (TWP) to develop a convective transport diagnostic known as tropospheric transit time distributions (TTDs). Following these previous works, we explore the use of in situ observation-based TTDs in evaluating the representation of convective transport in global models. The TTDs derived using simulated fields from the Whole Atmosphere Community Climate Model (WACCM) are analyzed in conjunction with the results of the previous work. Our goal is to explore the application of this method as a model diagnostic. A comprehensive comparison of the model-derived lifetimes and TTDs with those obtained from VOC observations will be presented. Beyond basic comparisons, we assess the model’s ability to capture the spatial and temporal variabilities of TTDs from those derived from the field campaign observations. We also examine the sensitivity of modeled TTDs to various factors, such as different definitions of VOC lifetimes and treatments of source regions. These analyses shed light on the key factors that influence the accurate representation of convective transport in global models. Additionally, uncertainty quantification is conducted to identify the sources of uncertainty and their impact on TTDs. These findings enhance our understanding of convective transport and its representation in chemistry-climate models, emphasizing the critical role of integrating observational data with model simulations to gain insights into the dynamics of transport.