On the use of the field Sunset semi-continuous analyzer to measure equivalent black carbon concentrations

Figures & data

Figure 1. Examples of placements of filters in the Sunset semi-continuous analyzer during the wall reflection experiments.

Figure 2. Laser signal detected behind filters during experiments with black filters in the Sunset semi-continuous analyzer.

Table 1. Results of linear fits y = ax of the EBC_aeth, EBC_Sunset, and EBC_micro concentrations versus EBC_MAAP concentrations, as derived from original and corrected data for both campaigns.

		Winter		Summer
		Slope a	R^2	Slope a	R^2
Original data	Aethalometer	0.83	0.97	0.97	0.93
	Sunset analyzer	0.77	0.99	0.89	0.92
	Microaethalometer	1.79	0.85	0.96	0.98
Wall reflection correction	Sunset analyzer + w	0.85	0.99	0.99	0.92
Loading correction (Virkkula et al. 2007)	Aethalometer	0.93	0.99	1.03	0.92
	Sunset analyzer + w	1.15	0.91	1.22	0.70
Loading correction k (Virkkula et al. 2007)	Aethalometer	0.96	0.89	1.05	0.93
	Sunset analyzer + w	1.26	0.78	1.37	0.71
Total correction (Collaud Coen et al. 2010)	Aethalometer	0.92	0.73	1.23	0.79
	Sunset analyzer + w	1.09	0.68	1.30	0.83
	Microaethalometer	2.26	0.74	1.34	0.84

The “wall corrected” EBC_Sunset are denoted with “+w.” The loading correction “k” denotes the approach with constant k.

Figure 3. Original EBC concentrations as measured by the Sunset analyzer (EBC_Sunset), the AE31 aethalometer (EBC_aeth), and the microaethalometer (EBC_micro) compared to EBC concentration data from the MAAP (EBC_MAAP). Left: winter campaign; right: summer campaign.

Figure 4. Time series of the original EBC_micro, EBC_aeth, EBC_MAAP, and EBC_Sunset concentrations during the winter (top) and summer (bottom) campaigns.

Figure 5. Original and wall reflection corrected EBC_Sunset concentrations data compared to EBC_MAAP concentrations in winter (left) and summer (right).

Figure 6. Top: One-day time series of original EBC_MAAP (uncorrected), and EBC_aeth and EBC_Sunset corrected for loading according to Virkkula et al. (2007) in winter (a) and summer (b). Middle: Time series of EBC_MAAP (uncorrected), and EBC_Sunset corrected for loading according to Virkkula et al. (2007) either by a k value calculated for each Sunset semi-continuous analyzer filter spot change (EBC_Sunset) or by a constant k value (EBC_{Sunset_K}) in winter (c) and summer (d). Bottom: Time series of EBC_MAAP (uncorrected), and EBC_aeth, EBC_Sunset, and EBC_micro corrected for loading according to Collaud Coen et al. (2010) in winter (e) and summer (f).

Figure 7. Loading corrected EBC_Sunset, EBC_aeth, and EBC_micro data according to the correction by Collaud Coen et al. (2010), compared to EBC_MAAP concentrations in winter (left) and summer (right).

Table 2. Multiple scattering correction factors C_ref for the aethalometer, the microaethalometer, and the Sunset semi-continuous analyzer, calculated from Equation (9)[9] separately for both campaigns, and from low (10–20%) and medium (30–50%) attenuation values.

		Aethalometer	Microaethalometer	Sunsetanalyzer
ATN 10–20%
Winter	Median	3.2		3.7
	Mean ± st. dev	4.5 ± 6.7		4.8 ± 7.8
Summer	Median	4.0		4.3
	Mean ± st. dev	6.4 ± 12.5		9.9 ± 34.8
ATN 30–50%
Winter	Median	3.2	10.7	3.7
	Mean ± st. dev	3.4 ± 1.2	11.4 ± 8.0	3.9 ± 1.1
Summer	Median	4.2	4.9	4.6
	Mean ± st. dev	6.3 ± 15.7	6.5 ± 13.5	6.7 ± 17.9

Virkkula, A., Mäkelä, T., Hillamo, R., Yli-Toumi, T., Hirsikko, A., Hämeri, K., and Koponen, I. K. (2007). A Simple Procedure for Correcting Loading Effects of Aethalometer Data. J. Air Waste Manag. Assoc., (1995) 57:1214–1222.

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Collaud Coen, M., Weingartner, E., Apituley, A., Ceburnis, D., Fierz-Schmidhauser, R., Flentje, H., Henzing, J. S., Jennings, S. G., Moerman, M., Petzold, A., Schmid, O., and Baltensperger, U. (2010). Minimizing Light Absorption Measurement Artifacts of the Aethalometer: Evaluation of Five Correction Algorithms. Atmos. Meas. Tech., 3(2):457–474.

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