objective to understand how much natural decadal variations in dust affect clouds approach

Objective● To understand how much natural

decadal variations in dust affect clouds

Approach● Run the Community Earth System

Model for 150 years under pre-industrial conditions, with no emissions from human activity

● Examine cloud-aerosol relationships across inter-annual timescales

Dust Increases Low Cloud Cover

DeFlorio MJ, SJ Ghan, B Singh, AJ Miller, DR Cayan, LM Russell and RCJ Somerville. 2014 “Semi-Direct Dynamical and Radiative Impact of North African Dust Transport on Lower Tropospheric Clouds over the Subtropical North Atlantic in CESM 1.0.” Journal of Geophysical Research, early online. DOI: 10.1002/2013JD020997

Interannual correlation between June – August mean dust burden and lower tropospheric cloud fraction anomalies simulated by the CESM over the tropical/subtropical Atlantic Ocean.

Impact● Found a strong enhancement of cloud cover below

plumes of dust transported from Africa● The mechanism is identified to be suppression of vertical

mixing due to absorption of sunlight by the dust.