Instrument : Microwave Radiometer (MWR)

Instrument Categories
Radiometric, Cloud Properties, Atmospheric Profiling

Picture of the Microwave Radiometer (MWR)
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

Output Datastreams

  • mwrlos : Microwave Water Radiometer (MWR): water liq. & vapor along line of sight (LOS) path

Primary Measurements

The following measurements are those considered scientifically relevant.

Locations

  • North Slope Alaska (NSA)
    • Central Facility, Atqasuk AK (C2)
    • Central Facility, Barrow AK (C1)
  • Southern Great Plains (SGP)
    • Central Facility, Lamont, OK (C1)
    • Hillsboro, KS (Boundary) (B1)
    • Lamont, OK (Extended, secondary) (E14)
    • Morris, OK (Boundary) (B5)
    • Purcell, OK (B6)
    • Supplemental 2, Lamont, OK (S02)
    • Vici, OK (Boundary) (B4)
  • SHEBA (Surface HEat Budget of the Arctic) (SHB)
    • Ice Station SHEBA (C1)
  • Tropical Western Pacific (TWP)
    • Central Facility, Darwin, Australia (C3)
    • Central Facility, Manus I., PNG (C1)
    • Central Facility, Nauru Island (C2)
  • ARM Mobile Facility (FKB)
    • Black Forest, Germany (M1)
  • ARM Mobile Facility (GAN)
    • Gan Airport, Gan Island, Maldives (M1)
  • ARM Mobile Facility (GRW)
    • Graciosa Island, Azores, Portugal (M1)
  • ARM Mobile Facility (HFE)
    • Shouxian, Anhui, China (M1)
  • ARM Mobile Facility (NIM)
    • Niamey, Niger (M1)
  • ARM Mobile Facility (PGH)
    • ARIES Observatory, Nainital, Uttarkhand, India (M1)
  • ARM Mobile Facility (PYE)
    • Point Reyes, CA (M1)
  • ARM Mobile Facility (SBS)
    • Steamboat Springs CO, Thunderhead Lodge (S1)
    • Steamboat Springs CO, Valley Site (M1)

Contact(s)

Maria Cadeddu
(630) 252-7408
mcadeddu@anl.gov