Atmospher Sci & Global Chg
Research Highlights

March 2013

A Decade and Counting

An assessment of atmospheric research in the equatorial western Pacific

A C-band scanning ARM precipitation radar was installed at the ARM site on Manus Island, Papua New Guinea, in April 2011. This instrument, funded by the American Recovery and Reinvestment Act of 2009, enables a 3-D look at precipitation in the tropics. Photo courtesy of the ARM Climate Research Facility. Enlarge Image

Results: After more than a decade of site measurements, the U.S. Department of Energy (DOE) has amassed extensive atmospheric data collections from two tropical western Pacific sites. A team of scientists led by researchers at Pacific Northwest National Laboratory showed how these data are used extensively in atmospheric and climate research by scientists around the world. They found that observation-based research has significantly advanced our understanding of this important climate system as well as tropical clouds and air circulation in general. With the addition of new instrumentation, they show that additional data promises to provide expanded opportunities for tropical atmospheric science for years to come.

Why It Matters: The warmest sea surface temperatures on Earth are in the tropical western Pacific (TWP). This environment leads to abundant convection, which is clouds and precipitation caused by rising moist air, sometimes all the way to the top of our atmosphere. This plentiful deep convection-think of tall clouds-is one of the major forces in global atmospheric circulation and climate variability. It has a profound impact on global climate and precipitation. These equatorial TWP sites provide climate researchers with unique sets of data, now available for more than a decade of observations. With sophisticated, long-term site measurements like these, scientists can more accurately depict past and predict future climate changes.

Methods: To accurately evaluate tropical clouds and atmospheric systems in climate models, DOE has established stations in several locations to take measurements of clouds, the environment in which they reside, and their impact on the sunlight and terrestrial energy and water budgets for the climate. Two DOE-sponsored sites in tropical locations are the Atmospheric Radiation Measurement (ARM) Climate Research Facility measurement site set up on Manus Island, Papua New Guinea in 1996; and the site on the island republic of Nauru, established in late 1998.

In this study, the research team presented a diverse range of samples of the scientific contributions that rely on a decade-long record from the Nauru and Manus sites. Through the ARM Publications Database, they identified 143 research papers published in peer-reviewed journals, and over 250 scientific conference proceedings that used data from Manus and Nauru. These covered research topics from large-scale tropical dynamics and variability, to cloud-scale processes and precipitation, to microphysics and aerosols. While many of these topics were part of the original ARM science vision for the TWP, this study shows how the breadth of the research substantially exceeded expectations.

A recently expanded spatial view integrated through time will facilitate a new generation of process-oriented data analysis and modeling studies of cloud field evolution. While the existing decade-long record of clouds, radiation, and atmospheric state provides a unique observational record that will continue to be exploited by the research community, the next decade offers significant new opportunities for atmospheric research in this challenging region thanks to ongoing observations and the new improved instrumentation.

What's Next? The new challenge at the TWP sites lies in expanding from the vertically pointing, or "soda straw" view used by the ARM active remote sensors since operations began, to sampling the local spatial variability in clouds and precipitation. Meeting this challenge requires expanding measurement capabilities, an undertaking enabled through funding from the American Recovery and Reinvestment Act of 2009, and developing new data processing and retrieval algorithms, an activity already begun. Scanning precipitation and cloud radars will augment already upgraded versions of the vertically pointing cloud radars and lidars. 

Acknowledgments:

Sponsors: The Office of Biological and Environmental Research (OBER) of the U.S. Department of Energy (DOE) as part of the Atmospheric Radiation Measurement (ARM) Climate Research Facility and Atmospheric System Research (ASR) programs.

Research Team: Chuck Long, Sally McFarlane, Jim Mather, and Jennifer Comstock of PNNL; Tony Del Genio from NASA Goddard Space Flight Center; Pat Minnis from NASA Langley Research Center; Tom Ackerman, the University of Washington; Jay Mace from the University of Utah; Mike Jensen of Brookhaven National Laboratory; and Christian Jakob from Monash University, Australia.

Reference: Long CN, SA McFarlane, A Del Genio, P Minnis, J Mather, J Comstock, J Mace, M Jensen, C Jakob, and TP Ackerman. 2013. "ARM Research in the Equatorial Western Pacific - A Decade and Counting." Bulletin of the American Meteorological Society 94(5):695-708. DOI:10.1175/BAMS-D-11-00137.