Seminar

Abstract

The South Eastern Pacific (SEP) is a region with a large expanse of persistent marine stratocumulus clouds.Formed by the interaction of cold, upwelling ocean currents and warm, dry air subsiding from aloft, these uniform cloud decks impact the Earth's climate by reflecting more sunlight back into space than the underlying ocean. In this region, they are part of a coupled system that includes ocean heat transport, coastal topography, clouds, and aerosol.Motivated by the need to more accurately represent the climate of the SEP in numerical models, an observational study was undertaken in the Fall of 2008 off the coast of Chile.This regional experiment (REx) was part of a broader study that brought together observations and modeling in order to improve understanding, model simulations, and predictions of the SEP coupled ocean-atmosphere-land system, on diurnal to interannual timescales.The VAMOS Ocean-Cloud-Atmosphere-Land Study (VOCALS) is part of the CLIVAR VAMOS (Variability of the American MOnsoonS) program.

Continuous Doppler lidar measurements of sub-cloud atmospheric dynamics were made from the NOAA Research Vessel Ronald H. Brown during VOCALS-REx. We will present results from these measurements that show the strength and driving mechanism of turbulence in the marine atmospheric boundary layer and their dependence on diurnal cycle and atmospheric decoupling. We will show examples of the complex dynamics associated with precipitation driven, open-cell convection and the resulting large-scale openings in the cloud deck that can greatly reduce albedo by exposing the ocean surface.