Throughout ARM, measurements of precipitable water vapor and liquid water path are provided by microwave radiometers. These measurements are essential for improving scientific understanding of clouds and how they are represented in climate models. In late September, ARM added the latest generation microwave radiometer technology at its Southern Great Plains site. The increased capabilities and improved performance of the 3-channel microwave radiometers (MWR3C) will be evaluated during an operational test period at the site.
Scientists identified several improvements to the current microwave radiometers that would significantly reduce the uncertainty associated with their measurements. Notable among these improvements are:
- A higher frequency channel (90-GHz) to the two-channel (20-30 GHz) system to improve sensitivity to liquid water when the liquid water path is less than 100 g/m2
- Improvements in the spatial and temporal resolution of the measurements
- Matching (as closely as possible) the field of view for all channels.
Based on the performance of the MWR3C during its test period, plans are to deploy the new technology to both ARM Mobile Facilities and the Tropical Western Pacific sites in Darwin, Australia, and Manus Island, Papua New Guinea. In addition, two spares will be kept on hand for use throughout the user facility. Excluding the initial SGP instruments, the additional deployments are possible through funding from the American Recovery and Reinvestment Act.