The U.S. Department of Energy has established an unmanned aerospace vehicle (UAV) measurement program. The purpose of this paper is to describe the evolution of the program since its inception, review the progress of the program, summarize the measurement capabilities developed under the program, illustrate key results from the various UAV campaigns carried out to date, and provide a sense of the future direction of the program. The Atmospheric Radiation Measurement (ARM)–UAV program has demonstrated how measurements from unmanned aircraft platforms operating under the various constraints imposed by different science experiments can contribute to our understanding of cloud and radiative processes. The program was first introduced in 1991 and has evolved in the form of four phases of activity each culminating in one or more flight campaigns. A total of 8 flight campaigns produced over 140 h of science flights using three different UAV platforms. The UAV platforms and their capabilities are described as are the various phases of the program development. Examples of data collected from various campaigns highlight the powerful nature of the observing system developed under the auspices of the ARM–UAV program and confirm the viability of the UAV platform for the kinds of research of interest to ARM and the clouds and radiation community as a whole. The specific examples include applications of the data in the study of radiative transfer through clouds, the evaluation of cloud parameterizations, and the development and evaluation of cloud remote sensing methods. A number of notable and novel achievements of the program are also highlighted.
aDepartment of Atmospheric Sciences, Colorado State University, Fort Collins, Colorado.
bDepartment of Meteorology, University of Maryland, College Park, Maryland.
cSandia National Laboratories, Livermore, California.
dScripps Institution of Oceanography, San Diego, California.
eAtmospheric Science Division, NASA Langley Research Center, Hampton, Virginia.
fNASA Ames Research Center, Sunnyvale, California.
gSandia National Laboratories, Albuquerque, New Mexico.
hUniversity of Massachusetts, Amherst, Massachusetts.
iLawrence Livermore National Laboratory, Livermore, California.
jCrocker Nuclear Laboratory, University of California, Davis, Davis, California.