New Field Campaigns Move Mobile Facility to Finland Forest and California Coast; Aircraft to Explore Aerosol and Gases

Each year, the ARM Climate Research Facility receives proposals to use key components of the Facility for extended or intensive field campaigns to improve understanding of atmospheric processes that are relevant to regional and global climate. The Department of Energy (DOE) has selected the following new field campaigns that will take place from 2013 through 2015.

Aerosol Properties Downwind of Biomass Burns*. This year between June and October, the ARM Aerial Facility will deploy the Gulfstream-1 (G-1) research aircraft to measure aerosol and trace gas emitted by biomass burning in the state of Arkansas and the Northwestern United States. In the United States, aerosols from forest fires, agricultural burns, and other forms of biomass burning comprise about one-third of the total atmospheric aerosols that modulate regional climate by scattering and absorbing solar radiation, changing clouds properties, and affecting rainfall.

Lawrence Kleinman and Arthur Sedlacek of Brookhaven National Laboratory will lead this campaign, operating instruments—some for the first time—onboard the research aircraft to obtain measurements at and downwind of burning sites. The aircraft will be on call from Pasco, Wash., its home location. The team expects that these measurements will shed light on how aerosols evolve from burning biomasses. During the month of August, at the peak of the summer wildfire season, scientists will be present in Pasco.

In addition, an intensive observational period from late-September to late-October in Little Rock, Ark., will sample agricultural burns in that area to investigate its effects on physical and chemical properties of these biologically derived atmospheric aerosols. Together, these data sets will provide a better understanding of the impacts of biogenic aerosols on regional meteorology and climate.

ARM Airborne Carbon Measurements-IV (ARM-ACME IV). There is no better way to learn about the atmosphere than being up in the air. In this campaign, reapproved for the fourth year, Sébastien Biraud of Lawrence Berkeley National Laboratory will continue to oversee 300 flight hours by a Cessna 206 to measure trace gases over and around the ARM Southern Great Plains (SGP) site in Oklahoma. Monitoring atmospheric trace gases allows in-depth understanding of the carbon cycle—i.e., how greenhouse gases circulate around the globe and interact with the land, ocean, and ecosystems.

Using these measurements, Biraud and his team hope to understand the trends and variability in the atmospheric concentrations of carbon dioxide and other greenhouse gases in North America. The research (latest results here) is expected to contribute towards a better knowledge of the carbon cycle in North America, which is a primary objective of the U.S. Global Change Research Program. In addition, the team also aims to characterize fossil fuel emissions at the SGP site.

Biogenic Aerosols-Effects on Clouds and Climate (BAECC). Beginning in January of 2014, this field campaign places the second ARM Mobile Facility (AMF2) amid 50-year-old pines that stand in Hyytiala, Finland, to investigate the formation and evolution of organic aerosols from northern boreal forests.

Organic aerosols, emitted from large forests, can cool the Earth’s surface by scattering sunlight. They can also act as nuclei for water droplets to form clouds. However, scientists still do not understand how these organic aerosol particles form and evolve, although their effects lead to large uncertainties in the current understanding of the climate system.

Over the past two decades, continuous observations from the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR-II) in Hyytiala, Finland, have demonstrated northern boreal forests emit organic aerosols in large enough quantities that could directly affect global climate. Under the leadership of Tuukka Petäjä from the University of Helsinki, the BAECC research team will acquire data from remote sensing instruments provided by the AMF2. Observations from the AMF2 will be supplemented by tower and surface-based measurements of aerosol and precursor gases. During intensive observation periods, Finnish aircraft observations of aerosol microphysics will be performed. Combining measurements from these platforms will allow scientists to test the hypothesis that boreal forests are a direct link between the atmosphere and biosphere.

ARM Cloud Aerosol Precipitation Experiment (ACAPEX). Starting in December of 2014, the AMF2 will be involved in a joint field campaign with the National Oceanic and Atmospheric Administration (NOAA). Led by Ruby Leung of Pacific Northwest National Laboratory, this comprehensive operation aims to improve the understanding of large-scale atmospheric processes, cloud, rainfall events, and climate extremes in the western United States.

The western United States receives precipitation primarily during the cold season when storms approach from the Pacific Ocean. The snowpack that accumulates on inland mountain ranges during winter storms provides about 70-90% of water supply for the region. Understanding atmospheric processes that drive large changes in rainfall and weather extremes in the region and the role of aerosols, transported over long distances, in modulating those processes is critical for climate models to predict the regional water cycle, including floods and droughts.

Stationed off the California coast, the AMF2, in combination with instruments provided by the NOAA, will obtain measurements to characterize atmospheric processes as well interactions of clouds and meteorological processes with aerosols transported to this region across the Pacific Ocean. Plans also include using a research aircraft to probe clouds that form over the ocean. This will allow scientists to analyze how the clouds transform upon landfall as well as the effects of the Sierra Nevada and the coastal range on these cloud processes.

Editor’s Note: This campaign was renamed Biomass Burning Observation Project (BBOP) after the initial publishing of this story.