Operations Updates
ARM Climate Research Facility Operations Update - March 31, 2006
This bimonthly report provides a brief summary of significant accomplishments and activities in the operations area of the ARM Climate Research Facility (ACRF).
W-Band Cloud Radar Added to ARM Mobile Facility in Africa
Most of the WACR is mounted on top of one of the AMF shelters. The WACR computer and chiller (used to keep the WACR cool in temperatures up to 47 degrees C) are located in the shelter below the radar.
A W-band ARM Cloud Radar (WACR) recently joined the suite of baseline capabilities offered by the ARM Mobile Facility (AMF). The term "W-band" refers to the specific radio frequency range of this radar, which is a 95 gigahertz pulse Doppler zenith pointing radar, providing profiles of cloud reflectivity and particle velocity. In mid-March, the WACR was installed at the AMF site in Niamey, Niger, and became operational on March 18, 2006. The WACR developed for the AMF is one of the most sensitive cloud radars in the world, and is an essential instrument to understanding cloud dynamics as part of the Radiative Divergence using ARM Mobile Facility, GERB data and AMMA Stations" (RADAGAST) field campaign. Along with characterizing the clouds during the summer monsoon season, the WACR will record the precursor activity in the "dust season" prior to the onset of the monsoons.
This reflectivity image from the newly installed WACR in Niamey demonstrates the sensitivity of the radar, as evidenced by the midlevel clouds visible above the surface dust layer, and also a cirrus layer visible at about 14km. (Click for a larger version.)
Successfully building a reliable radar capable of operating in the extreme environments expected for the diverse AMF deployments was an engineering challenge. In addition, the design for mobile application as a stand-alone system required as small a footprint as possible. This is the second operational 95 GHz cloud radar developed by ProSensing, Inc. for the ARM Program. The first was fielded at the ACRF Southern Great Plains site in Oklahoma in 2005. Due to its larger antenna, the WACR designed for the AMF is significantly more sensitive than the first model.
Increased Weather Balloon Soundings Begin at Barrow
The balloon-borne sounding system consists of a small sensor package—called a radiosonde—attached by a long string to a large balloon. As the balloon rises, atmospheric measurements recorded by the radiosonde are picked up via an antenna on the ground.
In April, ACRF operations staff at the North Slope of Alaska will begin launching balloon-borne sounding systems—better known as weather balloons—two times per day from the Great White Instrument Shelter in Barrow. Each weather balloon is equipped with a radiosonde package for measuring air pressure, temperature, and humidity. ACRF operations personnel will launch the balloons at 6 a.m. and 6 p.m. GMT, offsetting launches from the National Weather Service (NWS) research station in Barrow by 6 hours. Beginning in May, global positioning system (GPS) sondes will be used that provide profiles of wind speed and direction as well.
In November 2005, both the ARM Cloud Properties and Instantaneous Radiative Flux Working Groups supported the proposal to increase the frequency of balloon soundings at Barrow from once to twice each day. This plan was approved by the ARM Science Team Executive Committee, and activities to purchase additional supplies and labor commenced. To keep costs to a minimum and ease pressure on the delivery schedule for the new GPS sondes, an implementation schedule was developed for the twice-daily launches starting with the original sondes for the first month, and then to begin using the newly purchased GPS sondes. The additional wind data from the soundings will provide climate scientists with more information about atmospheric conditions in the sensitive Arctic environment.
New Chief Scientist Leads Annual ARM Science Team Meeting
Dr. Warren Wiscombe begins his presentation by introducing the members of his "Chief Scientist team"—a new approach for leading the ARM Science Team.
With a new Chief Scientist at the helm, just over 300 ARM scientists and ACRF infrastructure staff took part in the 16th ARM Science Team meeting held in Albuquerque, New Mexico, on March 27-31, 2006. After an initial day of focused meetings among the ARM Working Groups, Dr. David Thomassen, Acting Associate Director of DOE's Office of Biological and Environmental Research (BER), opened the meeting's plenary session with remarks about the role of ARM within the DOE, and its reputation as a world-class research program. He also briefly discussed the Office of Science 5-Year Budget plan, which includes BER's goals for the ARM Program, including a second ARM Mobile Facility and continuing advances in climate model development, testing, and application. His remarks were followed by a status report from ARM Chief Scientist, Dr. Warren Wiscombe, covering specific ARM accomplishments, challenges, and goals. The rest of the weeklong meeting was devoted to invited presentations, plus extensive evening sessions to review the 178 posters prepared by principle investigators for onsite discussions.
During an evening meeting, the ACRF Science Board—led by their newly elected chair, Dr. Sally Benson—reviewed the schedule for upcoming field campaign proposals, and provided recommendations for future uses of the ARM Mobile Facility.
This annual gathering provides an opportunity for members of the ARM Science Team and ACRF infrastructure to engage in focused technical exchanges to review scientific findings and results, as well as to discuss implementation and operation of the ACRF. The event also provides a forum for other agency programs to gain familiarity with the ARM Program, to share goals and objectives, and to suggest collaborations of mutual interest. Scientists representing 10 different countries, from the United States to Africa, Germany, and the Netherlands, attended this year's meeting. Proceedings from the meeting will be published in the fall and can be found on the ARM website, along with proceedings from previous ARM Science Team meetings.
