Publication Abstracts

Tornow et al. 2018

Tornow, F., H.W. Barker, V. Blázquez, C. Domenech, and J. Fischer, 2018: EarthCARE's Broadband Radiometer: Uncertainties associated with cloudy atmospheres. J. Atmos. Ocean. Technol., 35, no. 11, 2201-2211, doi:10.1175/JTECH-D-18-0083.1.

The Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) satellite's Broadband Radiometer (BBR) consists of three telescopes and a rotating chopper drum (CD). Together they yield alternating measurements of total wave (TW; 0.25 to >50 µm) and shortwave (SW; 0.25-4 µm) radiances with point spread functions that translate to ∼0.6-km-diameter pixels. The mission requires that SW and TW radiances be averaged over ∼100-km2 domains. Correspondingly, the average longwave (LW) radiances are the differences between TW and SW averages. It is shown that impacts on domain-average nadir radiances resulting from alternating samples of TW and SW signals for realistic cloudy atmospheres are sensitive to the variance of cloudy-sky radiances, CD rotation rate, and along-track length of averaging domains. Over domains measuring 5×21 km2 and at a 50% rotation rate, uncertainties reached up to 3.2 and 4.1 W/m2/sr for SW and TW radiances, respectively. The BBR's design allows for in-flight alteration of the CD rate. An approximate method is provided for estimating SW and LW uncertainties resulting from the CD rate. While the nominal rotation rate meets EarthCARE's mission requirements, reducing below ∼75% of that rate will lead to uncertainties for domain-average LW radiances that will often exceed mission requirements. This could be mitigated by increasing the size of averaging domains but that would compromise the BBR's role in EarthCARE's radiative closure assessment program. Uncertainties for off-nadir radiances are largely free of impacts arising from changes to the CD rotation rate.

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BibTeX Citation

  author={Tornow, F. and Barker, H. W. and Blázquez, V. and Domenech, C. and Fischer, J.},
  title={EarthCARE's Broadband Radiometer: Uncertainties associated with cloudy atmospheres},
  journal={Journal of Atmospheric and Oceanic Technology},

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RIS Citation

ID  - to06100q
AU  - Tornow, F.
AU  - Barker, H. W.
AU  - Blázquez, V.
AU  - Domenech, C.
AU  - Fischer, J.
PY  - 2018
TI  - EarthCARE's Broadband Radiometer: Uncertainties associated with cloudy atmospheres
JA  - J. Atmos. Ocean. Technol.
JO  - Journal of Atmospheric and Oceanic Technology
VL  - 35
IS  - 11
SP  - 2201
EP  - 2211
DO  - 10.1175/JTECH-D-18-0083.1
ER  -

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