Can RAdio Detection And Ranging be passive? First looks at measurements from a prototype “mesoscale radiometer”

We have developed an instrument to monitor temperature, moisture, and clouds on the mesoscale. The instrument, named “mesoscale radiometer”, is a close cousin to the weather radar. It works in the 16 GHz – 27 GHz water vapor emission band. Its scanning strategy, which resembles that of a weather radar, is able to provide low-level and three dimensional measurements of water vapor as well as path integrated liquid and temperature. Ranging is also possible with this instrument by combining the measurement at different frequencies, although the resolution is much coarser than that of a radar.

The instrument was used for tracking the movement of liquid water clouds as well as examining the variation of liquid water at different heights in the cloud. This is possible thanks to its radar like scanning strategy. The variation in the distribution of boundary layer humidity was also examined. Some of these variation were caused by thermals found the growing atmospheric boundary layer. In addition to these liquid water and water vapor observations, the mesoscale patterns of humidity and near-surface temperature were monitored.

The radiometer was deployed at the McGill's J.S. Marshall Weather Radar Observatory in Montreal, Quebec, Canada in spring 2009 and at the Department of Energy Atmospheric Radiation Measurement program's Southern Great Plains Central Facility in Lamont, Oklahoma, USA in summer 2009. During these deployments, the mesoscale radiometer measurements were compared with that from other sources including microwave radiometers, global positioning system receivers measuring precipitable water, radiosondes, and radars.

In this presentation, we will showcase some of the measurements done with the “mesoscale radiometer” and illustrate how it complements the measurements made by radar and other sensors.