Error source in AOD retrieval from filter radiometer data in the UV due to filter band function

Galisteo, José Pablo Ortiz de; Cachorro, Victoria E.; Toledano, Carlos; Rodríguez, Edith; Berjón, A.; Baraja, Angel Máximo de Frutos

doi:10.1016/j.jaerosci.2009.03.006

Cited by 6 publications

(3 citation statements)

References 8 publications

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“…However, the importance of using different narrowband filter responses was not clearly established in this study. Ortiz de Galisteo et al (2009) showed the importance of the "wings of the filter" effect, which might introduce an overestimation in the aerosol optical depth, and thus inaccuracies in PWV retrieval due to uncertainties on Rayleigh and gaseous absorption total optical depth. This problem was also studied by Alexandrov et al (2009).…”

Section: The New Lunar Cimel Ce-318umentioning

confidence: 99%

Column water vapor determination in night period with a lunar photometer prototype

Barreto¹,

Cuevas²,

Damiri³

et al. 2013

Preprint

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In this paper we present the preliminary results of atmospheric column integrated water vapor (PWV) obtained with a new Lunar Cimel photometer (LC) at the high mountain Izaña Observatory in the period July–August, 2011. We have compared nocturnal PWV from LC with PWV from a Global Positioning System (GPS) receiver and nighttime radiosondes (RS92). LC data have been calibrated using the Lunar Langley Method (LLM). We complemented this comparative study using quasi-simultaneous daytime PWV from Cimel AERONET (CA), GPS and RS92. Comparison of daytime PWV from CA shows differences against GPS and RS92 up to 0.18 cm. Two different filters, with and approximate bandwidth of 10 nm and central wavelengths at 938 nm (Filter#1) and 937 nm (Filter#2), were mounted into the LC. Filter#1 is currently used in operational AERONET sunphotometers. PWV obtained with LC-Filter#1 showed an overestimation above 0.18 and 0.25 cm compared to GPS and RS92, respectively, meanwhile Filter#2, with a reduced out-of-band radiation, showed very low differences compared with the same references (≤0.03 cm). <br><br> These results demonstrate the ability of the new lunar photometer to obtain accurate and continuous PWV measurements at night in addition to the notably influence of the filter's transmissivity response on PWV determination at nighttime. The use of enhanced bandpass filters in lunar photometry, which is affected by more important inaccuracies than sun-photometry, is necessary to infer PWV with similar precision than AERONET

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Section: The New Lunar Cimel Ce-318umentioning

confidence: 99%

Column water vapor determination in night period with a lunar photometer prototype

Barreto¹,

Cuevas²,

Damiri³

et al. 2013

Preprint

View full text Add to dashboard Cite

show abstract

“…However, the importance of using different narrowband filter responses was not clearly established in this study. Ortiz de Galisteo et al (2009) showed the importance of the "wings of the filter" effect, which might introduce an overestimation in the aerosol optical depth, and thus inaccuracies in PWV retrieval due to uncertainties in Rayleigh and gaseous absorption total optical depth. This problem was also studied by Alexandrov et al (2009).…”

Section: Methodsmentioning

confidence: 99%

Column water vapor determination in night period with a lunar photometer prototype

Barreto

Cuevas

Damiri³

et al. 2013

Atmos. Meas. Tech.

View full text Add to dashboard Cite

In this paper we present the preliminary results of atmospheric column-integrated precipitable water vapor (PWV) obtained with a new Lunar Cimel photometer (LC) at the high mountain Izaña Observatory in the period July–August 2011. We have compared quasi-simultaneous nocturnal PWV from LC with PWV from a Global Positioning System (GPS) receiver and nighttime radiosondes (RS92). LC data have been calibrated using the Lunar Langley method (LLM). We complemented this comparative study using quasi-simultaneous daytime PWV from Cimel AERONET (CA), GPS and RS92. Comparison of daytime PWV from CA shows differences between GPS and RS92 up to 0.18 cm. Two different filters, with and approximate bandwidth of 10 nm and central wavelengths at 938 nm (Filter#1) and 937 nm (Filter#2), were mounted onto the LC. Filter#1 is currently used in operational AERONET sun photometers. PWV obtained with LC-Filter#1 showed an overestimation above 0.18 and 0.25 cm compared to GPS and RS92, respectively, and root-mean-square errors (RMSEs) up to 0.27 cm and 0.24 cm, respectively. Filter#2, with a reduced out-of-band radiation, showed very low differences compared with the same references (≤ 0.05 cm) and RMSE values ≤ 0.08 cm in the case of GPS precise orbits.

These results demonstrate the ability of the new lunar photometer to obtain accurate and continuous PWV measurements at night, and the remarkable influence of the filter's transmissivity response to PWV determination at nighttime. The use of enhanced bandpass filters in lunar photometry, which is affected by more important inaccuracies than sun photometry, is necessary to infer PWV with similar precision to AERONET

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“…Besides, UV wavelengths are especially difficult to calibrate for several reasons, either with the Langley plot method or by comparison (Slusser et al, 2000). In summary, special care must be taken when analysing AOD at UV wavelengths (Ortiz de Galisteo et al, 2009).…”

Section: Aerosol Input Parametersmentioning

confidence: 99%

Comparison of measured and modelled spectral UV irradiance at Izaña high mountain station: estimation of the underlying effective albedo

et al. 2015

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In this work, we have carried out a comparison study between measured and modelled direct and global ultraviolet (UV) (300–400 nm) spectral irradiances and the determination of the surface effective albedo at the high altitude Izaña Observatory [IZO; 2400 m above sea level (a.s.l.)] located in Tenerife (Canary Islands, Spain). The spectral measurements were performed with a Bentham spectroradiometer during the Quality Assurance of Solar Ultraviolet Spectral Irradiance Measurements (QASUME) comparison campaign in June 2005. The simulations were obtained with the LibRadtran radiative transfer model. The model input parameters, such as total ozone and aerosol optical depth (AOD), were measured at IZO. The comparison between measured and modelled direct solar radiation component was made at 0.5 nm spectral resolution, showing excellent agreement, with differences below 5% for solar zenith angle (SZA) < 60°. These differences were attributed to the effect of the underlying surface albedo due to the frequent existence of a sea of clouds below the station altitude. The underlying surface albedo was determined using different methods. In spite of the variability of this parameter through the day due to the strong influence and variable structure of these underlying clouds, the mean of this effective surface albedo in the UV region gives a value between 0.2 and 0.5 in the UV range, 10 times higher than the local surface albedo (0.02–0.05).

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Error source in AOD retrieval from filter radiometer data in the UV due to filter band function

Cited by 6 publications

References 8 publications

Column water vapor determination in night period with a lunar photometer prototype

Column water vapor determination in night period with a lunar photometer prototype

Column water vapor determination in night period with a lunar photometer prototype

Comparison of measured and modelled spectral UV irradiance at Izaña high mountain station: estimation of the underlying effective albedo

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