40 Days and Nights in the Rains

Abstract

The Beobachtung von Ozean und Wolken–Das Trans ITCZ Experiment (BOWTIE) field campaign investigated how convective storm dynamics interact with the ocean surface to shape the structure of the Atlantic intertropical convergence zone (ITCZ). Conducted aboard the German Research Vessel (R/V) Meteor during August and September 2024, the campaign targeted the full meridional extent of the ITCZ while transiting the tropical Atlantic from east to west. The research was driven by evidence suggesting that storm-scale dynamics is pivotal for shaping the broader structure of the ITCZ and its connection to global circulation patterns and energy transport. BOWTIE featured high-resolution atmospheric and oceanic profiling, with a particular focus on the coupled boundary layers. Observations included cloud and humidity profiles, winds, precipita-tion, sea surface temperature, and upper-ocean physical and biogeochemical properties. A suite of advanced instruments provided vertically resolved cross sections of convective environments and surrounding conditions. BOWTIE was part of the larger international Organized Convection and EarthCARE Studies over the Tropical Atlantic (ORCESTRA) initiative, which coordinated eight campaigns across the Atlantic. During the voyage, the R/V Meteor served as a platform for two additional ORCESTRA campaigns: Soundings and Turbulent eddy measurements in the ITCZ with a Network of Quadcopters (STRINQS), which deployed unmanned aerial vehicles for profiling near-storm environments, and Process Investigation of Clouds and Convective Organization over the Atlantic Ocean (PICCOLO), which brought Colorado State University’s Sea-Pol scanning dual-polarization C-band radar onboard. This article provides an overview of BOWTIE’s scientific goals, campaign design, and observing strategy and presents selected early results from the extensive dataset. The combination of in situ, airborne, and radar measurements offers new insight into how ocean–atmosphere interactions at convective scales shape the ITCZ’s broader structure and behavior.