Instrument : Microwave Radiometer (MWR)

Instrument Categories
Atmospheric Profiling, Radiometric, Cloud Properties

Picture of the Microwave Radiometer (MWR)

General Overview

The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is a sensitive microwave receiver that detects the microwave emissions of the vapor and liquid water molecules in the atmosphere at two frequencies: 23.8 and 31.4 GHz.

Integrated water vapor and liquid water path are derived from radiance measurements with a statistical retrieval algorithm that uses monthly derived and location-dependent linear regression coefficients.

More details on the calibration algorithm can be found in:

Liljegren, JC. 1999. "Automatic self-calibration of ARM microwave radiometers." In Microwave Radiometry and Remote Sensing of the Earth’s Surface and Atmosphere. Ed. P. Pampaloni and S. Paloscia, pp. 433-443.

Available Retrievals and Uncertainty

Statistical retrievals of precipitable water vapor and liquid water path are available. The retrievals use monthly derived linear regression coefficients. The monthly rms errors of the retrievals depend on season and location and can be found in the netcdf files global variables. A rough estimate of the retrieval uncertainty is:

  • Precipitable water vapor: ~ 0.5 mm
  • Liquid water path: ~ 0.025 mm

Summary Table:

Name of Variable in the Datastream Physical Quantity Approximate Uncertainty Datastream Uncertainty Variable in the Datastream
Tbsky23 23.8 GHz brightness temperature 0.3 K mwrlos.b1 N/A
Tbsky31 31.4 GHz brightness temperature 0.3 K mwrlos.b1 N/A
vap Retrieved integrated water vapor ~0.5 mm mwrlos.b1 vapor_retrieval_rms_accuracy
liq Retrieved integrated cloud liquid water 0.025 mm mwrlos.b1 liquid_retrieval_rms_accuracy

Output Value-Added Products

This instrument is an input to the following value-added products, which provide improved measurements or derived quantities.

  • 1mwravg : Microwave Radiometer (MWR): brightness temps and water amounts, 1-minute avg
  • 5mwravg : Microwave Radiometer (MWR): 5-minute average integrated vapor and liquid water
  • mwrret1liljclou : Microwave Radiometer Retrievals (MWRRET) of Cloud Liquid Water and Precipitable Water Vapor
  • qmemwrcol : QME: derived, column water, MWR vs. instrument model

Output Datastreams

  • mwrlos : Microwave Water Radiometer (MWR): water liq. & vapor along line of sight (LOS) path
  • mwrtip : Microwave Water Radiometer (MWR): airmasses, brightness temperatures (TIP mode)

Primary Measurements

The following measurements are those considered scientifically relevant.


North Slope Alaska
NSAC1 Browse DataCentral Facility, Barrow AK
NSAC2 Browse DataCentral Facility, Atqasuk AK retired
Southern Great Plains
SGPB1 Browse DataHillsboro, KS (Boundary) retired
SGPB4 Browse DataVici, OK (Boundary) retired
SGPB5 Browse DataMorris, OK (Boundary) retired
SGPB6 Browse DataPurcell, OK (Boundary) retired
SGPC1 Browse DataCentral Facility, Lamont, OK
SGPE14 Browse DataLamont, OK (Extended, secondary) retired
SGPS02 Browse DataSupplemental 2, Lamont, OK retired
Tropical Western Pacific
TWPC1 Browse Data Browse PlotsCentral Facility, Manus I., PNG retired
TWPC2 Browse Data Browse PlotsCentral Facility, Nauru Island retired
TWPC3 Browse DataCentral Facility, Darwin, Australia retired
ARM Mobile Facility
ACXM1 Browse DataOff the Coast of California - NOAA Ship Ronald H. Brown; AMF2
ASIM1 Browse DataAscension Island, South Atlantic Ocean; AMF1
AWRM1 Browse DataMcMurdo Station Ross Ice Shelf, Antarctica; AMF2
FKBM1 Browse DataBlack Forest, Germany retired
GANM1 Browse DataGan Airport, Gan Island, Maldives; AMF2 retired
GRWM1 Browse Data Browse PlotsGraciosa Island, Azores, Portugal; AMF1 retired
HFEM1 Browse DataShouxian, Anhui, China retired
MAGM1 Browse DataLos Angeles, CA to Honolulu, HI - container ship Horizon Spirit; AMF2 retired
MAOM1 Browse DataManacapuru, Amazonas, Brazil; AMF1
NIMM1 Browse DataNiamey, Niger retired
PGHM1 Browse Data Browse PlotsARIES Observatory, Nainital, Uttarkhand, India; AMF1 retired
PVCM1 Browse DataHighland Center, Cape Cod MA; AMF1 retired
PYEM1 Browse Data Browse PlotsPoint Reyes, CA retired
SBSM1 Browse DataSteamboat Springs CO, Valley Site; AMF2 retired
TMPM1 Browse Data Browse PlotsU. of Helsinki Research Station (SMEAR II), Hyytiala, Finland; AMF2
 retired = Originating instrument has been retired at this location


Maria Cadeddu
Argonne National Laboratory
(630) 252-7408