Retrieval of the aerosol optical depth in the UV‐B at Uccle from Brewer ozone measurements over a long time period 1984–2002

Cheymol, A.; Backer, H. De

doi:10.1029/2003jd003758

Cited by 72 publications

(124 citation statements)

References 24 publications

(36 reference statements)

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“…However, the Brewer ozone spectrometer at ALOMAR indicated a maximum AOD (320 nm) of 0.41 during this episode . Brewer AOD data were retrieved according to Cheymol et al (2003Cheymol et al ( , 2006.…”

Section: Aerosol Events Over Andenesmentioning

confidence: 99%

Aerosol characterization at the sub‐Arctic site Andenes (69°N, 16°E), by the analysis of columnar optical properties

Rodríguez

Toledano

Cachorro

et al. 2011

Quart J Royal Meteoro Soc

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Section: Aerosol Events Over Andenesmentioning

confidence: 99%

Aerosol characterization at the sub‐Arctic site Andenes (69°N, 16°E), by the analysis of columnar optical properties

Rodríguez

Toledano

Cachorro

et al. 2011

Quart J Royal Meteoro Soc

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“…To derive the AOD at 340 nm from the measurements described above, we apply the Langley Plot Method (LPM), in a similar way as described in Cheymol and De Backer (2003), to the weighted irradiances. The Langley Plot Method is a linear regression technique that can be used for the retrieval of the Aerosol Optical Depth from direct radiation measurements.…”

Section: Methodsmentioning

confidence: 99%

“…Research also shows that the standard Brewer direct sun (DS) measurements allow AOD retrieval at the wavelengths used for ozone determination (mainly 320.1 nm). Some authors base their retrieval on the absolute calibration of the solar spectral irradiance measured by the Brewer (Bais, 1997;Marenco et al, 1997;Kazadzis et al, 2005) whereas others use the Langley extrapolation method to determine the absolute calibration of the irradiance (Kirchhoff et al, 2001;Marenco et al, 2002;Cheymol and De Backer, 2003). Arola and Koskela (2004) discussed the systematic errors in the AOD retrieval from Brewer DS measurements, which led to improvements of the conventional Langley Plot Method (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Instead of using the standard direct sun measurements from the Brewer instrument dedicated to ozone retrieval (which are performed at 5 specific wavelengths) (as in Cheymol and De Backer, 2003), we will use sun scan measurements between 335 and 345 nm, convoluted with the band pass function of the Cimel sunphotometer filter at 340 nm, to obtain AOD values at 340 nm. This will allow for a direct comparison between these retrieved AOD values and the AODs from the Cimel sunphotometer at the same wavelength.…”

Section: Introductionmentioning

confidence: 99%

“…Aerosols are particles in the solid or liquid phase that are suspended in the atmosphere and have an important influence on the atmospheric chemistry and physics (Cheymol and De Backer, 2003;Raghavendra Kumar et al, 2010). They affect the tropospheric chemical composition, they can reduce visibility and they have important impacts on human health (Unger et al, 2009;Lyamani et al, 2010;Raghavendra Kumar et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Aerosol Optical Depth measurements at 340 nm with a Brewer spectrophotometer and comparison with Cimel sunphotometer observations at Uccle, Belgium

et al. 2010

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Abstract. The Langley Plot Method (LPM) is adapted for the retrieval of Aerosol Optical Depth (AOD) values at 340 nm from Brewer#178 sun scan measurements between 335 and 345 nm (convoluted with the band pass function of the Cimel sunphotometer filter at 340 nm) performed in Uccle, Belgium. The use of sun scans instead of direct sun measurements simplifies the comparison of the AOD values with quasi-simultaneous Cimel sunphotometer values. Also, the irradiance at 340 nm is larger than the one at 320.1 nm due to lower ozone absorption, thus improving the signal to noise ratio. For the selection of the cloudless days (from now on referred to as calibration quality clear days), a new set of criteria is proposed. With the adapted method, individual clear sky AOD values, for which the selection criteria are also presented in this article, are calculated for a period from September 2006 until the end of August 2010. These values are then compared to quasi-simultaneous Cimel sunphotometer measurements, showing a very good agreement (the correlation coefficient, the slope and the intercept of the regression line are respectively 0.974, 0.968 and 0.011), which proves that good quality observations can be obtained from Brewer sun scan measurements at 340 nm. The analysis of the monthly and seasonal Brewer AODs at Uccle is consistent with studies at other sites reporting on the seasonal variation of AODs in Europe. The highest values can be observed in summer and spring, whereas more than 50% of the winter AODs are lower than 0.3. On a monthly scale, the lowest AOD are observed in December and the highest values occur in June and April. No clear weekly cycle is observed for Uccle. The current cloud-screening algorithm is still an issue, Correspondence to: V. De Bock (veerle.debock@meteo.be) which means that some AOD values can still be influenced by scattered clouds. This effect can be seen when comparing the calculated monthly mean values of the Brewer with the AERONET measurements.

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Langley Calibration Analysis of Solar Spectroradiometric Measurements: Spectral Aerosol Optical Thickness Retrievals

et al. 2018

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Aerosol optical thickness (τaer) is a fundamental parameter for analyzing aerosol loading and associated radiative effects. The τaer can constrain many inversion algorithms using passive/active sensor measurements to retrieve other aerosol properties and/or the abundance of trace gases. In the next wave of spectroradiometric observations from geostationary platforms, we envision that a strategically distributed network of robust, well‐calibrated ground‐based spectroradiometers will comprehensively complement spaceborne measurements in spectral and temporal domains. Spectral τaer can be accurately obtained from direct‐Sun measurements based on the Langley calibration method, which allows for the analysis of distinct spectral features of the calibration results. In this study, we present a spectral τaer retrieval algorithm for an in‐house developed, field deployable spectroradiometer instrument covering wavelengths from ultraviolet to near‐infrared (UV‐Vis‐NIR). The spectral total optical thickness obtained from the Langley calibration method is partitioned into molecular and particulate components by utilizing a least squares method. The resulting high temporal‐resolution τaer and Ångström Exponent can be used effectively for cloud screening. The new algorithm was applied to month‐long measurements acquired from the rooftop at National Aeronautics and Space Administration Goddard Space Flight Center's Building 33. The retrieved τaer demonstrated excellent agreement with those from well‐calibrated Aerosol Robotic Network Sun photometers at all overlapping wavelengths (correlation coefficients higher than 0.98). In addition, empirical stray light corrections considerably improved τaer retrievals at short wavelengths in the UV. The continuous spectrum of τaer from UV‐Vis‐NIR spectroradiometers is expected to provide more informative constraints for retrieval of additional aerosol properties such as refractive indices, size, and bulk vertical distribution.

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Retrieval of the aerosol optical depth in the UV‐B at Uccle from Brewer ozone measurements over a long time period 1984–2002

Cited by 72 publications

References 24 publications

Aerosol characterization at the sub‐Arctic site Andenes (69°N, 16°E), by the analysis of columnar optical properties

Aerosol characterization at the sub‐Arctic site Andenes (69°N, 16°E), by the analysis of columnar optical properties

Aerosol Optical Depth measurements at 340 nm with a Brewer spectrophotometer and comparison with Cimel sunphotometer observations at Uccle, Belgium

Langley Calibration Analysis of Solar Spectroradiometric Measurements: Spectral Aerosol Optical Thickness Retrievals

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