Global Surface-Based Sun Photometer Network for Long-Term Observations of Column Aerosol Optical Properties: Intercomparison of Aerosol Optical Depth

Figures & data

TABLE 1 Description of field network Sun photometers used in this study for AOD comparison

Instrument	Wavelength (nm)	Method of measurement	Sampling Rate	FOV	Measurement site(s) in this study ^1	Reference
AERONET CIMEL	340, 380, 500, 670, 870, 1020	Active Tracking, Direct Sun	Every 15 minutes	1.2°	MLO, BOU, BER, ANM	Holben et al. (1998, 2001)
WMO/GAW PFR	368, 412, 500, 862	Active Tracking, Direct Sun	Once per minute	2.5°	MLO	Wehrli (2000) McArthur et al. (2003)
NOAA/ESRL SP02A	412, 500, 675, 862	Mounted on solar tracker, Direct Sun	Once per minute	2.5°	BOU, THD, GOS	NOAA/ESRL (2003) Kim et al. (2005)
NOAA/ESRL SP02B	368, 500, 610, 778	Mounted on solar tracker, Direct Sun	Once per minute	2.5°	THD, GOS	NOAA/ESRL (2003) Kim et al. (2005)
NOAA/ESRL MFRSR	415, 500, 615, 673, 870, 940	Residual calculation from global and diffuse measurements	20 s averaged over 3 minutes	Equivalent FOV	BRM	NOAA/ESRL (2003)
KMA/NIMR EKO	368, 500, 675, 778, 862	Active Tracking, Direct Sun	Once per minute	2.5°	ANM	Kim et al. (2005)

FIG. 1 Scatter plots of AOD data for selected six sites in this study.

TABLE 2 Comparison of long-term AODs determined from ground-based network Sun photometers at 6 sites, where 2 active network instruments are co-located ¹

Measurement site	Identification No.	Sun photometer x (Mean ± 1 S.D.)	Sun photometer y (Mean ± 1 S.D.)	BD	RMSD	SDD	Percentage Difference	No. of Data	Analysis Periods
Mauna Loa (MLO) (19.54N, 155.58W, 3397m)	1	CIMEL 500 nm (0.01 8 ± 0.009)	PFR 501 nm (0.019 ± 0.010)	0.0010	0.0034	0.0010	5.2	9724	Nov 1999–Jan 2003
	2	CIMEL 500 nm (0.075 ± 0.046)	SP02 500 nm (0.072 ± 0.045)	−0.0026	0.0127	0.0125	12.4	9370
Boulder (BOU) (40.05N, 105.01W, 1584m)	3	CIMEL 670 nm (0.052 ± 0.039)	SP02 675 nm (0.043 ± 0.036)	−0.0092	0.0149	0.0117	20.1	9396	May 2001– July 2003
	4	CIMEL 870 nm (0.042 ± 0.025)	SP02 862 nm (0.034 ± 0.026)	−0.0075	0.0116	0.0088	21.8	9330
Trinidad Head (THD) (41.05N, 125.14W, 107m)	5	SP02A 500 nm (0.094 ± 0.062)	SP02B 500 nm (0.086 ± 0.064)	0.0064	0.0136	0.0120	20.0	35436	Apr 2001– Sept 2002
	6	CIMEL 500 nm (0.1 13 ± 0.062)	MFRSR 500 nm (0.132 ± 0.060)	0.0190	0.0267	0.0188	24.3	1557
Bermuda (BRM) (32.30N, 64.77W, 60m)	7	CIMEL 670 nm (0.085 ± 0.049)	MFRSR 673 nm (0.109 ± 0.047)	0.0238	0.0309	0.0196	41.4	1282	Oct 1997– Dec 2001
	8	CIMEL 870 nm (0.070 ± 0.045)	MFRSR 870 nm (0.088 ± 0.046)	0.0181	0.0268	0.0199	39.9	1560
Gosan (GOS) (33.29N, 126.16E, 71m)	9	SP02A 500 nm (0.191 ± 0.128)	SP02B 500 nm (0.196 ± 0.127)	0.0054	0.0093	0.0076	4.4	19898	Apr 2001– Jan 2002
Anmyon (ANM) (36.54N, 126.33E, 47m)	10	CIMEL 500 nm (0.253 ± 0.185)	EKO 500 nm (0.263 ± 0.178)	0.0106	0.0368	0.0353	9.4	3587	Dec 2000– Mar 2002

FIG. 2 Standard deviation differences (SDD) in AOD plotted against bias difference (BD). In addition to the long-term comparison datasets of this study, four additional results from McArthur et al. (2003), Mitchell and Forgan (2003), Kim et al. (2005), and Schmid et al. (1999) are included. The instrument type and wavelength used in the comparisons as well as observational sites appear in the introductory remarks, right of the figure. More detailed information can be found in each paper.

FIG. 3 Comparison of uncertainty U₉₅ of AOD. The label appeared at the top of each bar graph is the same in Figure 2.

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