The Microwave Radiometer Retrievals version 2 value-added product (MWRRETv2 VAP) has been processed for the year 2020 at the Atmospheric Radiation Measurement (ARM) user facility’s Eastern North Atlantic (ENA) atmospheric observatory.
In addition, ENA MWRRETv2 data from December 16 to 31, 2019, are now available. When the 2019 product was initially processed for the ENA, input data from the 3-channel microwave radiometer (MWR3C) were unavailable for those dates.
Liquid water path (LWP) and precipitable water vapor (PWV)—important variables to understanding radiative transfer in the atmosphere and clouds—are typically retrieved from microwave radiometers. 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 (23.8 and 31.4 GHz). 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. The MWR3C provides time-series measurements of brightness temperatures from three channels (23.8, 30, and 89 GHz), which are sensitive to the presence of liquid water and PWV (Cadeddu et al. 2013).
The VAP also includes uncertainty estimates. The 2-channel microwave radiometers give an uncertainty in the retrieved LWP of approximately 25 g/m2. The 89 GHz channel in the MWR3C has approximately three times the sensitivity to liquid water compared with the 31.4 GHz channel, thus improving the LWP accuracy when the LWP is less than 100 g/m2.
MWRRETv2 applies bias corrections to the brightness temperature data on a daily basis, using an automated bias correction process calculated using a 90-day rolling window.
Scientists can use the MWRRETv2 data now. More information about MWRRETv2 can be found on the VAP web page.
If you have questions or comments about the data, please send them to ARM translator Damao Zhang.
To cite the MWRRETv2 data, please use doi:10.5439/1566156.
References: Turner DD, SA Clough, JC Liljegren, EE Clothiaux, KE Cady-Pereira, and KL Gaustad. 2007. “Retrieving Liquid Water Path and Precipitable Water Vapor From the Atmospheric Radiation Measurement (ARM) Microwave Radiometers.” IEEE Transactions on Geoscience and Remote Sensing, 45(11), 10.1109/tgrs.2007.903703.
Cadeddu MP, JC Liljegren, and DD Turner. 2013. “The Atmospheric Radiation Measurement (ARM) program network of microwave radiometers: Instrumentation, data, and retrievals.” Atmospheric Measurement Techniques, 6, 2359-2372, 10.5194/amt-6-2359-2013.# # #
ARM is a DOE Office of Science user facility operated by nine DOE national laboratories.