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Atmosphere 2013, 4(3), 299-314; doi:10.3390/atmos4030299
Article

Failure and Redemption of Multifilter Rotating Shadowband Radiometer (MFRSR)/Normal Incidence Multifilter Radiometer (NIMFR) Cloud Screening: Contrasting Algorithm Performance at Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) and Southern Great Plains (SGP) Sites

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Received: 3 July 2013; in revised form: 10 August 2013 / Accepted: 28 August 2013 / Published: 11 September 2013
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Abstract: Well-known cloud-screening algorithms, which are designed to remove cloud-contaminated aerosol optical depths (AOD) from Multifilter Rotating Shadowband Radiometer (MFRSR) and Normal Incidence Multifilter Radiometer (NIMFR) measurements, have exhibited excellent performance at many middle-to-low latitude sites around world. However, they may occasionally fail under challenging observational conditions, such as when the sun is low (near the horizon) and when optically thin clouds with small spatial inhomogeneity occur. Such conditions have been observed quite frequently at the high-latitude Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) sites. A slightly modified cloud-screening version of the standard algorithm is proposed here with a focus on the ARM-supported MFRSR and NIMFR data. The modified version uses approximately the same techniques as the standard algorithm, but it additionally examines the magnitude of the slant-path line of sight transmittance and eliminates points when the observed magnitude is below a specified threshold. Substantial improvement of the multi-year (1999–2012) aerosol product (AOD and its Angstrom exponent) is shown for the NSA sites when the modified version is applied. Moreover, this version reproduces the AOD product at the ARM Southern Great Plains (SGP) site, which was originally generated by the standard cloud-screening algorithms. The proposed minor modification is easy to implement and its application to existing and future cloud-screening algorithms can be particularly beneficial for challenging observational conditions.
Keywords: Multifilter Rotating Shadowband Radiometer (MFRSR); Normal Incidence Multifilter Radiometer (NIMFR); aerosol optical depth and Angstrom exponent; ground-based multi-spectral measurements; cloud-screening algorithms; direct-beam sun transmittance; Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) sites Multifilter Rotating Shadowband Radiometer (MFRSR); Normal Incidence Multifilter Radiometer (NIMFR); aerosol optical depth and Angstrom exponent; ground-based multi-spectral measurements; cloud-screening algorithms; direct-beam sun transmittance; Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) sites
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Kassianov, E.; Flynn, C.; Koontz, A.; Sivaraman, C.; Barnard, J. Failure and Redemption of Multifilter Rotating Shadowband Radiometer (MFRSR)/Normal Incidence Multifilter Radiometer (NIMFR) Cloud Screening: Contrasting Algorithm Performance at Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) and Southern Great Plains (SGP) Sites. Atmosphere 2013, 4, 299-314.

AMA Style

Kassianov E, Flynn C, Koontz A, Sivaraman C, Barnard J. Failure and Redemption of Multifilter Rotating Shadowband Radiometer (MFRSR)/Normal Incidence Multifilter Radiometer (NIMFR) Cloud Screening: Contrasting Algorithm Performance at Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) and Southern Great Plains (SGP) Sites. Atmosphere. 2013; 4(3):299-314.

Chicago/Turabian Style

Kassianov, Evgueni; Flynn, Connor; Koontz, Annette; Sivaraman, Chitra; Barnard, James. 2013. "Failure and Redemption of Multifilter Rotating Shadowband Radiometer (MFRSR)/Normal Incidence Multifilter Radiometer (NIMFR) Cloud Screening: Contrasting Algorithm Performance at Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) and Southern Great Plains (SGP) Sites." Atmosphere 4, no. 3: 299-314.


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