OTREC2019: Convection Over the East Pacific and Southwest Caribbean.

We present preliminary results from the field program Organization of Tropical East Pacific Convection (OTREC), with measurements during August and September of 2019 using the NSF/NCAR Gulfstream V over the tropical East Pacific and Southwest Caribbean. We found that active convection in this region has predominantly bottom‐heavy vertical mass fluxes, while decaying systems exhibit top‐heavy fluxes characteristic of stratiform rain regions. As in other regions that have been studied, a strong anti‐correlation exists between the low to mid‐level moist convective instability and the column relative humidity or saturation fraction. Finally, the characteristics of convection as a function of latitude differ greatly between the Southwest Caribbean and Colombian Pacific coast on one hand, and the intertropical convergence zone to the west. In particular, the strongest convection in the former is to the south, while it is to the north in the latter, in spite of similar latitudinal sea surface temperature distributions. Plain Language Summary: Understanding and modeling the physics of tropical atmospheric convection still poses a big challenge. Things are complicated over the tropical oceans because there is no easy way to gather data. Field projects such as the one presented in this paper, Organization of Tropical East Pacific Convection (OTREC2019) are of great importance to our scientific community for this reason. During OTREC, 22 research flights were performed over East Pacific and Southwest Caribbean gathering data from 13 km to surface. This paper presents early results that will help us understand the physics of convection and improve our weather and climate models. Key Points: Thermodynamic parameters instability index and saturation fraction show anti‐correlation, as explained by moisture quasi‐equilibrium theoryVertical mass flux profiles are generally bottom heavy for developing convection and top heavy for decaying convectionStrong differences exist between convection in the East Pacific ITCZ and in the Caribbean and Pacific coast of Colombia [ABSTRACT FROM AUTHOR]