Operations Updates
ARM Climate Research Facility Operations Update - July 15, 2006
This bimonthly report provides a brief summary of significant accomplishments and activities in the operations area of the ARM Climate Research Facility (ACRF).
Kids Learn About Weather at Day Camps in June
To earn their Weather Badges, Girl Scouts rotated through a variety of learning stations, including one featuring instruments for measuring atmospheric properties. Campers blew air onto the radiation shields surrounding the temperature and humidity sensor to observe any changes recorded by the instrument.
On June 6, education and outreach staff from the ACRF Southern Great Plains (SGP) site spent four hours helping local Girl Scouts earn their Weather Badges. Nearly 100 scouts participated in the day camp held outdoors at Reeves Park in Norman, Oklahoma. Seven "learning stations" were staffed by female volunteers ranging from professional meteorologists to graduate and undergraduate students. Station topics included pressure and temperature, weather maps, fronts, tornadoes, lightning, heat, and seeing the instruments of a weather station. Troops rotated every 20 minutes through all seven stations.
Kids attending the Chickasaw Nation Aviation and Space Camp learned to decode station model plots, contour temperature maps, create tornadoes in a bottle (shown above), and build wind-resistant houses.
Additional education and outreach staff from SGP presented half-day weather sessions at two Chickasaw Nation Aviation and Space Camps held on June 14 and 20. Students were given weather maps from April 24 to see how the weather changed throughout the day, eventually producing a small tornado near El Reno, OK. Campers watched video of the El Reno tornado as it tore through an abandoned airplane hanger at the El Reno airport. Students were supplied with Styrofoam meat trays, straws, popsicle sticks, tape, cardboard, and construction paper to build a wind-resistant structure. A multi-speed leaf blower was used to test the strength of each structure. A total of 75 students attended the space camps, which took place at the Ada Municipal Airport in Ada, Oklahoma.
Education and outreach activities sponsored by the ACRF are geared toward K-12 students and teachers, as well as the communities that host ACRF sites. More information on these activities can be found on the ARM education webpages.
Infrared Sky Imager Takes a Shot in the Dark
Processed images from the Infrared Sky Imager are limited to a field-of-view (FOV) of 160 degrees to eliminate the problems inherent in retrievals along the horizon line. This is where any cloud signal is masked by the integrated infrared signal along the long path length through the atmosphere.
Imaging technologies help scientists correlate and compare data retrieved by sensors and lasers against visual data. One such technology used by ARM researchers is a Total Sky Imager (TSI), which provides real-time processing and full-color display of daytime sky conditions. However, to get the continuous picture of cloud life cycles needed for critical scientific analysis, a night-time visual technology was needed. In July 2006, a new Infrared Sky Imager system was installed at the ACRF Southern Great Plains (SGP) site. This new system captures full hemisphere (180-degree field-of-view) infrared images of the sky during both the day and night. These images can be used to calculate the fraction of clear sky or the percentage of cloud cover. The addition of a nighttime cloud fraction measurement fills a major data void (continuous, accurate measurements of hemispheric cloud coverage) for ARM researchers.
The Infrared Sky Imager operates at thermal wavelengths (the infrared range from 8 to 14 microns), using high-speed precision optics to form images of low- and mid-altitude clouds. These images are captured by a thermal infrared detector. Unlike classical cooled infrared sensors, the detector operates at room temperature and does not need a cryogenic cooling system, making the system inherently reliable and maintenance free. To improve signal to noise ratio, discreet images can be combined within the sensor electronics before being passed to the remote computer. The instrument software automatically identifies cloudy and clear regions, and calculates the percentage of cloud cover that affects downwelling longwave radiation measurements at the surface.
During development of the system, an additional user-definable field-of-view retrieval centered on zenith (90 degrees from the horizon) was incorporated into the processing software. This capability relates directly to the same user-definable "zenith circle" retrievals of the TSI. The user can also perform geometric calibrations to produce orthographically projected images. Using orthographic projection, the user can make a direct comparison with satellite images and human observations.
Now that the new system is deployed, a thorough operational testing and evaluation period will take place. This will allow ACRF operations personnel to understand the reliability and maintenance requirements of the system, as well the characteristics of the data product through comparison of cloud fraction results with those of other systems (such as the TSI). Depending on the technical performance of the Infrared Sky Imager, additional systems may be deployed to all the ACRF sites.
