The frictional layer in the observed momentum budget of the trades.

Profiles of eddy momentum flux divergence are calculated as the residual in the momentum budget constructed from airborne circular dropsonde arrays ( 220 km) for 13 days during the EUREC A/ATOMIC field campaign. The observed dynamical forcing averaged over all flights agrees broadly with European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS) forecasts. In the direction of the flow, a mean flux divergence (friction) exists over a 1.

Surface-Layer Wind Shear and Momentum Transport From Clear-Sky to Cloudy Weather Regimes Over Land.

This study investigates how wind shear and momentum fluxes in the surface- and boundary layer vary across wind and cloud regimes. We use a 9-year-long data set from the Cabauw observatory complemented by (8.2 × 8.

The Morphology of Simulated Trade-Wind Convection and Cold Pools Under Wind Shear.

A growing body of literature investigates convective organization, but few studies to date have sought to investigate how wind shear plays a role in the spatial organization of shallow (trade-wind) convection. The present study hence investigates the morphology of precipitating marine cumulus convection using large-eddy-simulation experiments with zonal forward and backward shear and without shear. One set of simulations includes evaporation of precipitation, promoting cold-pool development, and another set inhibits the evaporation of precipitation and thus cold-pool formation.

Counter-Gradient Momentum Transport Through Subtropical Shallow Convection in ICON-LEM Simulations.

It is well known that subtropical shallow convection transports heat and water vapor upwards from the surface. It is less clear if it also transports horizontal momentum upwards to significantly affect the trade winds in which it is embedded. We utilize unique multiday large-eddy simulations run over the tropical Atlantic with ICON-LEM to investigate the character of shallow convective momentum transport (CMT).

How Wind Shear Affects Trade-wind Cumulus Convection.

Motivated by an observed relationship between marine low cloud cover and surface wind speed, this study investigates how vertical wind shear affects trade-wind cumulus convection, including shallow cumulus and congestus with tops below the freezing level. We ran large-eddy simulations for an idealized case of trade-wind convection using different vertical shears in the zonal wind. Backward shear, whereby surface easterlies become upper westerlies, is effective at limiting vertical cloud development, which leads to a moister, shallower, and cloudier trade-wind layer.