Organization: Department of Energy (DOE)

Research Title: Atmospheric Radiation Measurement (ARM) Program

Funding Level (millions of dollars):

FY94 35.3
FY95 38.2
FY96 38.7

Committee on Environment and Natural Resources (CENR) Component:
(a) Subcommittee: Global Change Research Subcommittee (100%) Air Quality Research Subcommittee (contributing) Biodiversity Research Subcommittee (contributing)
(b) Environmental Issue: Climate Change (100%)
(c) Research Activity: System structure and function: Understanding (100%)

Organizational Component:
Environmental Sciences Division
Office of Health and Environmental Research
Office of Energy Research
U.S. Department of Energy (DOE)
Washington, DC 20585

Point of Contact:
Peter W. Lunn
Phone: 301-903-4819

Research Goals:
The general goal of ARM is to improve the performance of General Circulation Models (GCMs) and related models of the atmosphere as tools for more credibly predicting and assessing global and regional climate change. The specific goals are (1) to improve the treatment of radiative transfer in GCMs under clear sky, general overcast, and broken cloud conditions, and (2) to improve the parameterization of the properties and formation of clouds in GCMs.

Research Description:
ARM has created an experimental framework in which large arrays of instruments are used over extended periods of time. Measurement platforms include a wide variety of ground-based and airborne instruments. Instruments designed for deployment on unmanned aerospace vehicles (UAVs) are being developed and test flights of state- of-the-science UAVs have already been made over the first ARM site. Periodic intensive observational periods are scheduled in support of ARM objectives as well as other USGCRP projects. There are three ARM sites, representing the highest priority range of climatically significant regimes in which observational data is required. Each site will be operated for approximately 10 years. The first site covers much of southern Kansas and northern Oklahoma and has been in operation since April, 1992. The first site is often utilized in conjunction with other national and international programs, e.g., GEWEX, VORTEX, etc. The second site is the tropical western Pacific (TWP) and will begin operations in the fall of 1995. A pilot study conducted during TOGA COARE provided exciting new data as well as confirmation of feasibility of our technical approach. The TWP site is already attracting collaborators. The third site is the north slope of Alaska (NSA) and will begin operations in the spring of 1997. The NSA site will also support the NSF SHEBA program with an extended deployment of ARM instruments on the SHEBA ice island. The ARM Data System provides data tailored to the specific needs of each of the ARM customers and peer reviewed science team members. An Adjunct Science Team has also been formed to allow scientists not funded by ARM to participate more directly in the ARM data stream. The ARM Science Team consists of 15-20% NASA and NOAA scientists and almost 50% university and private sector scientists. There are also a number of important international collaborators.

Program Interfaces:
The national and international measurement, modeling, and integrated assessment communities require specific data on atmospheric processes to reduce scientific uncertainty and establish the link between increasing greenhouse gases and global change. ARM provides such critical data in the area of clouds and radiation processes. GCM developers in the CHAMMP and FANGIO programs are using the three ARM locales as a basis for GCM intercomparison and improvement. ARM is also closely linked to GEWEX. ARM is broadening its suite of instrumentation to accommodate requirements of other elements of the ecological and environmental communities, e.g., radiometers with photosynthetic spectrum, UVB instruments, etc.

Program Milestones:
Annual ARM Science Team Meeting. Continue data deliveries from the first ARM site to the ARM Science Team and Global Change community (1995). Begin operations at the second ARM site (tropical western Pacific) (1995). Expand longitudinal coverage at the second ARM site (1996). Improvements in general circulation model (GCM) parameterizations of mid-latitude cloud and radiation processes, e.g., cloud liquid water structure and resultant radiation field (1996). Begin operations at the third ARM site (north slope of Alaska) (1997). Improvements in GCM parameterizations of tropical cloud and radiation processes, e.g., understanding the forcing and associated feedbacks along the west-east gradient (1998). Begin deployment of Atmospheric Cloud and Radiation Stations in collaborative campaigns beyond the three ARM sites (1999).

Policy Payoffs:
ARM research is directly relevant to improving the credibility of climate prediction and assessment. Clouds and radiation represent very critical uncertainties in climate prediction. Clouds provide either positive or negative radiative forcing, depending on the circumstances. Effective treatment of clouds and radiation is crucial to understanding how the earth's energy balance may change under various global warming scenarios. The actual behavior of clouds may change, further disturbing or improving the energy balance and underscoring the need for credible prediction of these effects. ARM is resulting in improved parameterizations, reducing the current large uncertainties in predictive model results. Improved GCM results are applicable to scientific and technical assessment, to adaptation and mitigation, and will clarify the need for future research investment.