PROGRAM TITLE:	Atmospheric Radiation Measurement (ARM) 
ACTIVITY STREAM:	Process, Observations/Data
SCIENCE ELEMENT:	Climate/Hydrologic System (with strong ties to 


DESCRIPTION:  The primary focus of the Atmospheric Radiation 
Measurement program is understanding the role and representation of 
atmospheric radiative processes and clouds in models of the Earth's climate.  
The radiative transfer of energy in the atmosphere and the impact of clouds is 
one of the greatest sources of error and uncertainty in the current generation 
of general circulation models (GCMs) used for climate research and 
prediction.  Prior DOE research into the performance of the radiative 
components of GCMs concluded that further progress could only be made in 
this area by a concerted program of closely coupled modeling and process 
studies.  The heart of the ARM effort is the Cloud and Radiation Testbed 
(CART), the data from which effectively characterizes the atmosphere over 
from ground to tropopause over a spatial extent comparable to a GCM grid 
cell.  Each CART site consists of observational facilities to acquire the data 
needed for detailed investigation of process models used in climate research, 
including near real-time comparison of data with on-line model predictions.  
The facility includes a data management and communications system capable 
of acquiring and quality controlling site data, acquiring data from sources 
outside the program, particularly satellites, and communicating that data to 
the Science Team, which currently consists of 70 research teams involving 
150 to 200 scientists.  The first CART site was established in 1992 in the U.S. 
southern Great Plains.  The next two sites are in advanced stages of planning 
and preparation, for the Tropical Western Pacific Ocean (1994) and the North 
Slope of Alaska (1995 or 1996).  The final two sites, the eastern North Atlantic 
(1997) and the Gulf Stream (1999) are in the early planning stages.  While 
designed primarily to study clouds and radiation, each CART site is a highly 
flexible observational facility capable of supporting many related global 
change research objectives.

STAKEHOLDERS: The broadly based ARM Program has strong couplings to 
the USGCRP and to major international research programs.  The ARM 
Program is DOE's contribution to GEWEX and also a vehicle for supporting 
other WCRP activities, such as the recent TOGA-COARE.  The ARM Science 
Team consists of 15-20% NASA and NOAA scientists and almost 50% 
university and private sector scientists.  NOAA's Forecast Systems Laboratory 
and Wave Propagation Laboratory, and the National Center for Atmospheric 
Research have all played an integral part in site deployment, instrument 
evaluation and data management, respectively.  The first CART site shares 
data with the several research and observational programs in the area, 
including the NOAA Wind Profiler Demonstration network and the State of 
Oklahoma Mesoscale Observing Network.  Data are archived at Oak Ridge 
National Laboratory, which is also a Distributed Active Archive Center 
(DAAC) for NASA's Earth Observing System Data Information  System, 
simplifying the broader distribution of ARM data and making it an 
interactive part of the Global Change Data Information System.

SHORT-TERM POLICY PAYOFFS:  ARM will result in improved 
parameterizations of specific cloud and radiative processes within two years, 
reducing the current large uncertainties in predictive model results.  
Improved GCM results will be applicable to scientific and technical 
assessment, and to adaptation and mitigation, and will clarify the need for 
future research investment.  The design of the ARM user facility allows its 
use for related research.  Complex experiments can be designed and conducted 
quickly and efficiently in response to new research issues and to address new 
scientific uncertainties.

PROGRAM CONTACT:  Peter W. Lunn, DOE, ER-74, Washington, DC 20585,