The new Atmospheric Radiation Measurement (ARM) 3-channel microwave radiometers: initial data and retrievals

Description

In January 2011 two new 3-channel microwave radiometers (MWR3C) began operations. The new MWR3Cs have been acquired partially with funding provided by the American Recovery and Reinvestment Act (ARRA), and their initial operational deployment marks the completion of a year-long series of acceptance tests conducted at the SGP. The tests led to a substantial redesign of the instrument's hardware and software to meet the high quality standards required by the ARM instrumentation. One unit was installed on January 11 at the ARM Mobile Facility (AMF2) site in Steamboat Springs, Colorado, and one unit was installed on January 26 at the Southern Great Plains (SGP) Central Facility site. The new radiometers measure sky brightness temperatures at 23.8, 30, and 89 GHz, providing improved sensitivity to small amounts of cloud liquid water. The new 3-channel radiometers will gradually be deployed at all ARM sites where they will operate next to the MWRs before replacing them. We present the instrument design and capabilities and give an overview of the instrument's standard mode of operation. Data from the two deployments are presented. Initial retrievals of precipitable water vapor and liquid water path are examined and compared with those obtained from the 2-channel MWR at the SGP site. Future plans for the development of new retrievals are discussed.