Of the $60 million allocated to the ARM Climate Research Facility by the American Recovery and Reinvestment Act, nearly half that amount is designated for 18 new scanning radars as well as upgrades to the baseline ARM millimeter wave cloud radars (MMCR) located throughout the Facility. In November, ARM engineering staff led a series of preliminary design reviews with the radar vendors to discuss progress thus far. All participants agreed to move forward with the plans and detailed designs presented, marking the completion of a key milestone in achieving the Recovery Act deployment schedule.

“This review gives us the first look of what the radar physically looks like and its operational characteristics at a level of detail beyond the procurement specification,” said Kevin Widener, an engineer at Pacific Northwest National Laboratory and the leader of ARM’s Radar Group. “It also gives us a chance to do a ‘course correction’ in the event there are misunderstandings in the implementation of the procurement specification.”

Widener also explained that review was the first opportunity to expose the vendors to the full spectrum of interests within the user facility, including discussions about the science expectations, data usage, communications, and many other topics. Based on their successful progress, the vendors will receive a significant payment on their contract and can place orders for long lead-time items that they need to build the systems.

So Many Radars, So Little Time

The radars work by sending a beam of energy into the atmosphere and recording the return signals. Software for the signal processing is programmed to provide specific information about clouds and precipitation at different frequencies that researchers need to improve climate models. Several new types of radars are under development:

• Scanning ARM Precipitation Radar (SAPR) – two “C-band” and three “X-band” versions of the SAPR operate at frequencies of approximately 4.5 gigahertz and 9.5 gigahertz, respectively. These radars will be deployed several kilometers from the baseline instrument clusters at the ARM sites.
• Scanning ARM Cloud Radar (SACR) – three combined “W- and Ka-band” SACRs will cover the 95- and 35-gigahertz frequencies, respectively. In addition, three combined “X- and Ka-band” SACRs will cover the 9.5-gigahertz and 35-gigahertz frequencies, respectively. These radars will be located with the baseline instrument suites at the ARM sites for comparative measurements.

In addition to the new radars, the baseline MMCR is also benefiting from the Recovery Act with a significant upgrade to its signal processing software. This upgrade will result in increased sensitivity and more accurate measurements.  The preliminary design review for this effort also took place in November and received approval to move forward.  The radar vendors will now work toward the critical design reviews planned for January 2010.

According to Widener, the volume of radar procurements associated with the Recovery Act is “unusual for non-military procurements and unheard of in the climate research arena.” He added that the accelerated schedule requires close choreography with ARM operations so that the sites are ready when the vendors finish building the radars.

Site Surveys Hit the Spot

Prior to the design reviews, several radar siting trips were completed for the SAPRs due to their requirement for a fully unobstructed field of view. The site surveys are important steps in the deployment plan for these radars, as they take into consideration additional factors such as readily available power and dependable, all-weather access. Another consideration is minimizing potential future impacts to data quality.

“A couple of areas to the east of the [Southern Great Plains] SGP Central Facility are being looked at for wind farm development. While wind farms are attractive in that they supply ‘green energy,’ they are a bane to Doppler radars, as experienced by the National Weather Service,” said Widener.  “Our siting strategy is to avoid this situation if at all possible.”

In September, a visit to Manus Island in Papua New Guinea identified a potential location outside the Naval Base—about 7 kilometers from the ARM site near Momote—for the C-band SAPR.  An October visit to the North Slope of Alaska resulted in a potential location on top of the Barrow Arctic Research Center for the X-band SAPR.  And finally, a visit to the  SGP site identified several locations to the northwest, southwest, and southeast of the Central Facility for both types of precipitation radars.

Discussions with the landowners are the next step toward securing these spots.  In addition, the ARM site managers are working on the appropriate NEPA actions to ensure compliance with environmental regulations.