Aircraft observations and sub‐km modelling of the lake–land breeze circulation over Lake Victoria

The lake–land breeze circulation over Lake Victoria was observed in unprecedented detail with a research aircraft during the HyVic pilot flight campaign January 2019. An evening and morning lake land breezes respectively under mostly dry conditions. at various heights along transect across onshore Tanzania. Profiles of lower troposphere were recorded by dropsondes land. Convection-permitting MetUM simulations different horizontal grid-spacings (including sub-km) run for periods. During flight, crossed front 1627 LT, approximately 50 km to east shore, recording 6 g · kg − 1 decrease specific humidity reversal wind direction ∼ 5 km. shallow eastern shore 0545 LT. At least one region increased deeper moisture (previously seen but never observed) sampled surface between 0527 0855 This bulge likely formed from lifting near-surface moist air above low-level convergence. observations model suggest that convergence occurred leading edge breeze, which had detached main independently propagated westward wave-like characteristics. able reasonably reproduce front, feature, its propagation, is major achievement given sparse observational data initialisation this region. However, some timing, resolution boundary-layer depth biases require further investigation. Overall, provided an snapshot motivates more comprehensive field future.