Use of 315 nm Channel Data of the Sky Radiometer to Estimate the Columnar Ozone Concentration: A Preliminary Study

Khatri, Pradeep; Takamura, Toshinari; Yamazaki, Akihiro; Uchiyama, Akihiro

doi:10.2151/jmsj.2014-a12

Cited by 8 publications

(14 citation statements)

References 25 publications

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“…The POM-02 data were processed by Skyrad pack 4.2. They found an RMSD of 0.025 at 440 nm and 0.018 at other wavelengths, which is similar to the findings of Khatri et al(2016), even with the mean AOT at this site being as large as 0.33 at 675 nm. RMSDs of the Ångström exponent were 0.19 between 440 and 870 nm and 0.28 between 500 and 870 nm, though this is not shown in Table 5.…”

Section: Retrievals Of Parameters For Atmospheric Constituentssupporting

confidence: 80%

“…Figure 8a and Table 5 compare observed AOT values with those of AERONET at four co-located sites of Chiba (Japan), Pune (India), Valencia (Spain), and Seoul (South Korea) (Khatri et al, 2016). They found that RMSDs were 0.019 at 675 nm and about 0.015 at 870 and 1020 nm with a site dependence of 0.010, 0.033, 0.009, and 0.022 at 870 nm at the four sites, respectively, though this is not shown in Table 5.…”

Section: Retrievals Of Parameters For Atmospheric Constituentsmentioning

confidence: 99%

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An overview of and issues with sky radiometer technology and SKYNET

et al. 2020

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Abstract. This paper is an overview of the progress in sky radiometer technology and the development of the network called SKYNET. It is found that the technology has produced useful on-site calibration methods, retrieval algorithms, and data analyses from sky radiometer observations of aerosol, cloud, water vapor, and ozone. A formula was proposed for estimating the accuracy of the sky radiometer calibration constant F0 using the improved Langley (IL) method, which was found to be a good approximation to observed monthly mean uncertainty in F0, around 0.5 % to 2.4 % at the Tokyo and Rome sites and smaller values of around 0.3 % to 0.5 % at the mountain sites at Mt. Saraswati and Davos. A new cross IL (XIL) method was also developed to correct an underestimation by the IL method in cases with large aerosol retrieval errors. The root-mean-square difference (RMSD) in aerosol optical thickness (AOT) comparisons with other networks took values of less than 0.02 for λ≥500 nm and a larger value of about 0.03 for shorter wavelengths in city areas and smaller values of less than 0.01 in mountain comparisons. Accuracies of single-scattering albedo (SSA) and size distribution retrievals are affected by the propagation of errors in measurement, calibrations for direct solar and diffuse sky radiation, ground albedo, cloud screening, and the version of the analysis software called the Skyrad pack. SSA values from SKYNET were up to 0.07 larger than those from AERONET, and the major error sources were identified as an underestimation of solid viewing angle (SVA) and cloud contamination. Correction of these known error factors reduced the SSA difference to less than 0.03. Retrievals of other atmospheric constituents by the sky radiometer were also reviewed. Retrieval accuracies were found to be about 0.2 cm for precipitable water vapor amount and 13 DU (Dobson Unit) for column ozone amount. Retrieved cloud optical properties still showed large deviations from validation data, suggesting a need to study the causes of the differences. It is important that these recent studies on improvements presented in the present paper are introduced into the existing operational systems and future systems of the International SKYNET Data Center.

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Section: Retrievals Of Parameters For Atmospheric Constituentssupporting

confidence: 80%

Section: Retrievals Of Parameters For Atmospheric Constituentsmentioning

confidence: 99%

An overview of and issues with sky radiometer technology and SKYNET

et al. 2020

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“…Spectral V 0 values of two consecutive calibration dates are linearly interpolated to analyze observation data of intermediate dates. This strategy is based on the assumption of the linear change of V 0 with time, which may not always valid in the real atmosphere as shown by Khatri et al []. The uncertainty in AOT for AERONET field instruments, primarily due to V 0 uncertainty, is reported to be ~0.01 to 0.021 at different wavelengths with higher errors in the ultraviolet channels [ Eck et al , ].…”

Section: Major Differences Between Aeronet and Skynet Strategiesmentioning

confidence: 99%

Factors for inconsistent aerosol single scattering albedo between SKYNET and AERONET

et al. 2016

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SKYNET and Aerosol Robotic Network (AERONET) retrieved aerosol single scattering albedo (SSA) values of four sites, Chiba (Japan), Pune (India), Valencia (Spain), and Seoul (Korea), were compared to understand the factors behind often noted large SSA differences between them. SKYNET and AERONET algorithms are found to produce nearly same SSAs for similarity in input data, suggesting that SSA differences between them are primarily due to quality of input data due to different calibration and/or observation protocols as well as difference in quality assurance criteria. The most plausible reason for high SSAs in SKYNET is found to be underestimated calibration constant for sky radiance (ΔΩ). The disk scan method (scan area: 1° × 1° area of solar disk) of SKYNET is noted to produce stable wavelength‐dependent ΔΩ values in comparison to those determined from the integrating sphere used by AERONET to calibrate sky radiance. Aerosol optical thickness (AOT) difference between them can be the next important factor for their SSA difference, if AOTs between them are not consistent. Inconsistent values of surface albedo while analyzing data of SKYNET and AERONET can also bring SSA difference between them, but the effect of surface albedo is secondary. The aerosol nonsphericity effect is found to be less important for SSA difference between these two networks.

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“…The columnar ozone amount is retrieved from the direct solar irradiance measurement of 315 nm channel for the Huggins band. Khatri et al (2014) determined the F 0 -value by a ML method Eq. (22) assuming b g =1 for ozone without a significant line absorption structure.…”

Section: Retrievals Of Parameters For Atmospheric Constituentsmentioning

confidence: 99%

An overview and issues of the sky radiometer technology and SKYNET

Nakajima¹,

Campanelli²,

Che³

et al. 2020

Preprint

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Abstract. This paper overviews the progress in the sky radiometer technology and development of the network called SKYNET. It is found that the technology has produced useful on-site calibration methods, retrieval algorithms, and data analyses from the sky radiometer observation of aerosol, cloud, water vapor and ozone. Increasing collaborations of users in the SKYNET community are becoming a useful platform for research and operation. The paper also presents issues of the technology for future development.

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Use of 315 nm Channel Data of the Sky Radiometer to Estimate the Columnar Ozone Concentration: A Preliminary Study

Cited by 8 publications

References 25 publications

An overview of and issues with sky radiometer technology and SKYNET

An overview of and issues with sky radiometer technology and SKYNET

Factors for inconsistent aerosol single scattering albedo between SKYNET and AERONET

An overview and issues of the sky radiometer technology and SKYNET

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