Liquid water path (LWP) and precipitable water vapor (PWV) are two important geophysical variables for many areas of atmospheric research. These variables are typically retrieved from microwave radiometers.
Historically, standard ARM microwave radiometers have been 2-channel systems (23.8 and 31.4 GHz). These two channels provide sensitivity to liquid water and water vapor in the atmosphere. ARM also uses 3-channel microwave radiometers (MWR3Cs), which provide time-series measurements of brightness temperatures at 23.8, 30, and 89 GHz. The third channel at 89 GHz provides additional sensitivity to liquid water, especially at low LWPs.
MWRRETv2 is an updated version of mwrret1liljclou—documented in Turner et al. 2007—that extends the physical optimal estimation retrieval of LWP and PWV to microwave radiometers beyond ARM’s original standard 2-channel systems. The LWP retrieval from MWRRETv2 is critical to understanding low-liquid clouds.
MWRRETv2 applies the Turner et al. (2007) optimal estimation retrieval of LWP and PWV to MWR3C measurements. This VAP also includes uncertainty estimates.