About ARM

Road to Cerro Toco
Road to Cerro Toco

The world’s premier ground-based observations facility advancing climate change research


The Atmospheric Radiation Measurement (ARM) Program was created in 1989 by the U.S. Department of Energy (DOE) to develop several highly instrumented ground stations to study cloud formation processes and their influence on radiative transfer. As the program evolved to include additional measurements of aerosol and precipitation, the original ground sites were supplemented with three mobile facilities and an aerial facility. This comprehensive scientific infrastructure and data archive were designated by DOE as a scientific user facility—the ARM Climate Research Facility—in 2003, and are freely available for use by scientists worldwide.

A primary objective of the facility is improved scientific understanding of the fundamental physics related to radiative feedback processes in the atmosphere, particularly the interactions between clouds and aerosols. ARM focuses on obtaining continuous measurements—supplemented by field campaigns—and providing data products that promote the advancement of climate models.

Sponsored by DOE's Office of Science and managed by the Office of Biological and Environmental Research, ARM is a multi-laboratory, interagency program, and a key contributor to national and international research efforts related to global climate change. This user facility holds enormous potential to advance scientific knowledge in a wide range of interdisciplinary Earth sciences.

Brief History

During the early years of the program, efforts focused on establishing field research sites, developing and procuring instruments, and developing techniques for both atmospheric retrievals and model evaluation. To obtain the most useful climate data, three main sites were chosen that represented a broad range of weather conditions.

  • The Southern Great Plains site in Oklahoma, established in 1992, provides a wide variability of climate cloud type and surface flux properties, and large seasonal variation in temperature and specific humidity. The SGP site is the workhorse for the ARM Facility, and is the world's largest "laboratory without walls" for studying atmospheric processes.
  • The North Slope of Alaska sites, established in 1997, provide data about cloud and radiative processes at high latitudes, which have been identified as one of the most sensitive regions to climate change.
  • The Tropical Western Pacific sites, established in 1996 and closing in 2014, obtained data from the "warm pool" where the warmest sea surface temperatures on the planet and widespread convective clouds play a large role in the interannual variability observed in the global climate system.

Since 1993, airborne measurements have been an integral part of the program. Through the ARM Aerial Facility a variety of aerial platforms and instruments are available for intensive field campaigns or long-term, regularly-scheduled flights. And in 2005, ARM Mobile Facilities, containing most of the same instruments as the fixed sites, began supporting experiments in different climate regions for a year or so at time.

Through the American Recovery and Investment Act of 2009, the ARM Facility received $60 million for new and upgraded instruments and infrastructure at all its sites. These enhancements were carefully selected based on site needs. The modernized ARM Facility now provides unmatched measurement capabilities that permit the world's most detailed documentation ever obtained of cloud characteristics and their evolution.

All data obtained through the ARM Facility are monitored for quality and made freely available through the ARM Data Archive. In addition to routine datastreams, ARM also develops "value-added products" or VAPs. These advanced algorithms are applied to existing datastreams, and provide an important translation between the instrumental measurements and the geophysical quantities needed for scientific analysis, particularly model parameterization and development.