Optical characteristics of aerosol determined by Cimel, Prede, and Microtops II sun photometers over Belsk, Poland

Evgenieva, Tsvetina; Iliev, I.; Kolev, Nikolay Ivanov; Sobolewski, Piotr; Pieterczuk, Aleksander; Holben, B. N.; Kolev, Ivan

doi:10.1117/12.822507

Cited by 12 publications

(10 citation statements)

References 8 publications

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“…The deviation is higher at 440 nm and lower at 870 nm in good agreement with previous comparisons of AOD between Prede (elaborated by SKYNET) and Cimel (elaborated by AERONET) (Sano et al, 2003;Evgenieva et al, 2008;Campanelli et al, 2004b). It is also in very good agreement with our previous findings involving direct sun measurements only (Estellés et al, 2010(Estellés et al, , 2012.…”

Section: Optical and Radiative Propertiessupporting

confidence: 80%

Comparison of AERONET and SKYRAD4.2 inversion products retrieved from a Cimel CE318 sunphotometer

Estellés

Campanelli

Utrillas³

et al. 2012

Atmos. Meas. Tech.

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Abstract. SKYNET is an international research network of ground based sky -sunphotometers for the observation and monitoring of columnar aerosol properties. The algorithm developed by SKYNET is called SKYRAD.pack, and it is used on Prede instruments only. In this study, we have modified the SKYRAD.pack software in order to adapt it to Cimel sunphotometers. A one month database of Cimel data obtained at Burjassot (Valencia, Spain) has been processed with this program and the obtained inversion products have been compared with AERONET retrievals. In general, the differences found were consistent with the individual error assessments for both algorithms. Although the aerosol optical depth compared well for any aerosol burden situation (rmsd of 0.002-0.013 for all wavelengths), inversion products such as the single scattering albedo, refractive index and asymmetry parameter compared better for higher turbidity situations. The comparison performed for cases with an aerosol optical depth at 440 nm over 0.2 showed rms differences of 0.025-0.049 for single scattering albedo, 0.005-0.034 for the real part of refractive index, 0.004-0.007 for the imaginary part of the refractive index and 0.006-0.009 for the asymmetry parameter. With respect to the volume distributions, the comparison also showed a good agreement for high turbidity cases (mainly within the 0.01-7 µm interval) although the already known discrepancy in the extremes of the distribution was still found in 40 % of the cases, in spite of eliminating data and instrumental differences present in previous studies.

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Section: Optical and Radiative Propertiessupporting

confidence: 80%

Comparison of AERONET and SKYRAD4.2 inversion products retrieved from a Cimel CE318 sunphotometer

Estellés

Campanelli

Utrillas³

et al. 2012

Atmos. Meas. Tech.

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“…The calibration drift found in any wavelength channel is adjusted at the time of calibration by changing the irradiance calibration factors for that channel to maintain the accuracy. Moreover, the Microtops-measured spectral AODs have been found in very good agreement with the measurements using other radiometers such as Cimel [e.g., Evgenieva et al, 2008;Giles et al, 2011], Prede [e.g., Evgenieva et al, 2008], MFRSR (Multi-Filter Rotating Shadowband Radiometer), and multi-wavelength solar radiometer [Kompalli et al, 2010]. In the present study, the AOD data for only four wavelengths (340, 500, 870, and 1020 nm), which are common to both the Microtops, have been used.…”

Section: Measurement Site Instrument and Datasupporting

confidence: 70%

Aerosol climatology at Delhi in the western Indo‐Gangetic Plain: Microphysics, long‐term trends, and source strengths

et al. 2013

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[1] We present the climatology of aerosol microphysics, its trends, and impact of potential sources based on the long term measurements (for a period of 11.5 years from December 2001 to May 2012) of aerosol optical depths (AOD) in the spectral range 340-1020 nm from an urban center Delhi (28.6 N, 77.3 E, 238 m mean sea level) in the western Indo-Gangetic Plain (IGP). The study is the first ever long-term characterization of aerosols over the western IGP from the ground-based measurements. AODs are known to affect the air quality, visibility, radiative balance, and cloud microphysics of the region and IGP is one of the highest populated and polluted regions of the world. Our measurements show consistently high AOD during the entire period of observation. The seasonal variations of spectral AODs and Angstrom parameters are generally consistent every year. The AODs show a weak but statistically significant (in 95% confidence level) decreasing trend approximately À0.02/year at 500 nm, possibly, modulated by the pre-monsoon heavy dust loading during the first half of the observation period. The climatological monthly mean AOD at shorter wavelengths peaks twice, during June and November, while at longer wavelengths it shows only one peak in June. The annual variations of Angstrom exponent, a and its derivative, a′ suggest the prevalence of multi-modal aerosol size distributions at Delhi. The coarse-mode aerosols dominate during summer (March-June) and monsoon (July-September) seasons, whereas fine/accumulation mode enhances during post-monsoon (October-November) and winter (December-February) seasons. Potential advection pathways have been identified using concentration weighted trajectory (CWT) analysis of the 5 day isentropic air mass back trajectories at the observation site and their seasonal variations are discussed.

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“…9), but the coefficient of determination (R 2 ) remains high at around 0.95 for all wavelengths. Previous (unpublished) comparisons between Microtops and CIMEL CE318 resulted in an RMSE of between 0.01 and 0.02; an agreement to within 10 % between Microtops, CIMEL and POM instruments has been reported in Poland under a variety of conditions (Evgenieva et al, 2008). However, the previous studies alluded to above have been for land-based observations and therefore no uncertainties due to the platform motion are present.…”

Section: Corrected Aerosol Optical Depth Comparisonsmentioning

confidence: 64%

Autonomous marine hyperspectral radiometers for determining solar irradiances and aerosol optical properties

Wood¹,

Smyth

Estellés

2017

Atmos. Meas. Tech.

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Abstract. We have developed two hyperspectral radiometer systems which require no moving parts, shade rings or motorised tracking, making them ideally suited for autonomous use in the inhospitable remote marine environment. Both systems are able to measure direct and diffuse hyperspectral irradiance in the wavelength range 350-1050 nm at 6 nm (Spectrometer 1) or 3.5 nm (Spectrometer 2) resolution. Marine field trials along a 100 • transect (between 50 • N and 50 • S) of the Atlantic Ocean resulted in close agreement with existing commercially available instruments in measuring (1) photosynthetically available radiation (PAR), with both spectrometers giving regression slopes close to unity (Spectrometer 1: 0.960; Spectrometer 2: 1.006) and R 2 ∼ 0.96; (2) irradiant energy, with R 2 ∼ 0.98 and a regression slope of 0.75 which can be accounted for by the difference in wavelength integration range; and (3) hyperspectral irradiance where the agreement on average was between 2 and 5 %. Two long duration land-based field campaigns of up to 18 months allowed both spectrometers to be well calibrated. This was also invaluable for empirically correcting for the wider field of view (FOV) of the spectrometers in comparison with the current generation of sun photometers (∼ 7.5 • compared with ∼ 1 • ). The need for this correction was also confirmed and independently quantified by atmospheric radiative transfer modelling and found to be a function of aerosol optical depth (AOD) and solar zenith angle. Once Spectrometer 2 was well calibrated and the FOV effect corrected for, the RMSE in retrievals of AOD when compared with a CIMEL sun photometer were reduced to ∼ 0.02-0.03 with R 2 > 0.95 at wavelengths 440, 500, 670 and 870 nm. Corrections for the FOV as well as ship motion were applied to the data from the marine field trials. This resulted in AOD 500 nm ranging between 0.05 in the clear background marine aerosol regions and ∼ 0.5 within the Saharan dust plume. The RMSE between the handheld Microtops sun photometer and Spectrometer 2 was between 0.047 and 0.057 with R 2 > 0.94.

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Optical characteristics of aerosol determined by Cimel, Prede, and Microtops II sun photometers over Belsk, Poland

Cited by 12 publications

References 8 publications

Comparison of AERONET and SKYRAD4.2 inversion products retrieved from a Cimel CE318 sunphotometer

Comparison of AERONET and SKYRAD4.2 inversion products retrieved from a Cimel CE318 sunphotometer

Aerosol climatology at Delhi in the western Indo‐Gangetic Plain: Microphysics, long‐term trends, and source strengths

Autonomous marine hyperspectral radiometers for determining solar irradiances and aerosol optical properties

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