Source: Climate Research Facility funded by U.S. Department of Energy's Office of Science
Principal Investigator: Jian Wang
With their extensive coverage of Earth, low clouds greatly impact global climate. Currently, the extent and brightness of marine low clouds are poorly represented in global climate models and the response of low clouds to changes in atmospheric greenhouse gases and aerosols remains a major source of uncertainty in projections of future climate. This uncertainty is due in part to inadequate observations in regions where aerosol impact is the greatest.
The Eastern North Atlantic (ENA) is one such region where persistent, but diverse, subtropical marine boundary layer clouds are highly susceptible to disturbances in aerosol properties. Boundary layer aerosol in the ENA region is influenced by
a variety of sources, leading to strong variations in cloud condensation nuclei concentration and aerosol properties. To provide the observations needed to improve models for this region, the U.S. Department of Energy recently established an Atmospheric Radiation Measurement (ARM) Climate Research Facility site on Graciosa Island in the Azores.
While data from the ARM ENA site provide much needed observations of aerosol, trace gases, cloud, drizzle, and atmospheric thermodynamics, there is a need for airborne characterization of the vertical structure, horizontal variability, and detailed physical and chemical properties of aerosol and cloud particles to understand and quantify the processes controlling the life cycle of marine boundary layer clouds and the cloud response to aerosol changes.
The Aerosol and Cloud Experiments in Eastern North Atlantic, or ACE-ENA, will bring the ARM Aerial Facility Gulfstream-1 (G-1) aircraft to the ENA site during summer (June to July) of 2017 and winter (January to February) of 2018for two intensive observational periods to measure both seasons for key aerosol and cloud processes under a variety of meteorological and cloud conditions with different aerosol
sources. During the summer, the Azores experience overcast stratocumulus that transition to broken trade cumulus, while the winter experiences maritime frontal clouds. The ARM Aerial Facility will fly the G-1 into these clouds in both spiral patterns and horizontal legs at multiple altitudes near the ARM ENA site to collect vertical profile data of aerosol and clouds in as many as 20 three to four-hour flights for each intensive operational period.