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Two-Channel Narrow-Field-Of-View Radiometer
This instrument was developed by and belongs to the ARM Climate Research Facility (ACRF).
Surface Remote
The Two-Channel Narrow-Field-Of-View (2NFOV) Radiometer measures zenith radiance at one red and one near-infrared (NIR) wavelength. While clouds have nearly identical optical properties in these two channels, vegetated surface is much brighter at the NIR tahn at the red region. This contrast in spectral surface reflectance leads to substantially different amounts of surface-cloud interactions in these two spectral regions. From the resulting differenradiance, information on cloud optical depth and cloud fraction in a fully 3D situation can be extracted.
Christine Chiu
Suite 320, 5523 Research Park Dr., Baltimore, MD 21228
Facility Type
Locationpart of ARM mobile facility (the instrument was deloyed in Oklahoma and California, and now is in Germany)
VariablesZenith radiance at 673 and 870 nm; Retrieved cloud optical depth and effective cloud fraction.
Archive Data AvailabilityData are available in ARM archiave (http://www.archive.arm.gov/cgi-bin/arm-archive).
(1) Marshak, A., Y. Knyazikhin, K. D. Evans, and W. J. Wiscombe, 2004. “The “RED versus NIR” plane to retrieve broken-cloud optical depth from ground-based measurements.” J. Atmos. Sci., 61, 1911-1925. (2) Chiu, J. C. A. Marshak, Y. Knyazikhin, W. J. Wiscombe, H. W. Barker, J. C. Barnard, and Y. Luo, 2006. “Remote sensing of cloud properties using ground-based measurements of zenith radiance.” J. Geophys. Res., 111, D16201, doi:10.1029/2005JD006843.
3 Sep 2009 13:47