Atmospheric Radiation Measurement Climate Research Facility US Department of Energy

mwrretv2 > MWR Retrievals with MWRRET Version 2VAP Type(s) > Baseline • Evaluation

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.

Primary Derived Measurements


  • Fixed
  • AMF1
  • AMF2
  • AMF3


Russell LM, D Lubin, I Silber, E Eloranta, J Muelmenstaedt, S Burrows, A Aiken, D Wang, M Petters, M Miller, A Ackerman, A Fridlind, M Witte, M Lebsock, D Painemal, R Chang, J Liggio, and M Wheeler. 2021. Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) Science Plan. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-21-009.

Fridlind A, C Chiu, S Collis, J Comstock, S Giangrande, N Hickmon, M Jensen, M Kumjian, P Muradyan, R Newsom, A Sockol, M Sturm, and A Theisen. 2021. ARM Cloud and Precipitation Measurements and Science Group (CPMSG) Workshop Report. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-21-005.

Cadeddu MP. 2021. Microwave Radiometer – 3-Channel (MWR3C) Instrument Handbook. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM/TR-108.

Dorsey KS, R Jundt, CB Ireland, MR Wasem, RA Stafford, and A Hunzinger. 2021. 2020 Atmospheric Radiation Measurement (ARM) Annual Report. Ed. by Kathryn Dorsey, U.S. Department of Energy. DOE/SC-ARM-20-020.


Zhang C, S Xie, and C Tao. 2020. ARM Data-Oriented Metrics and Diagnostics Package for Climate Model Evaluation. Ed. by Robert Stafford, ARM Climate Research Facility. DOE/SC-ARM-TR-202.

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Damao Zhang
Pacific Northwest National Laboratory

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