[1] Kirchstetter T W, Novakov T, Hobbs P V. Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon[J]. Journal of Geophysical Research: Atmospheres, 2004, 109(D21): D21208.

[2] Olson M R, Victoria Garcia M, Robinson M A, et al. Investigation of black and brown carbon multiple-wavelength-dependent light absorption from biomass and fossil fuel combustion source emissions[J]. Journal of Geophysical Research: Atmospheres, 2015, 120(13): 6682-6697.

[3] Yan Caiqing, Zheng Mei, Zhang Yuanhang. Research progress and direction of atmospheric brown carbon[J]. Environmental Science, 2014, 35(11): 4404-4414.

[4] Bergstrom R W, Pilewskie P, Russell P B, et al. Spectral absorption properties of atmospheric aerosols[J]. Atmospheric Chemistry and Physics, 2007, 7(23): 5937-5943.

[5] Pschl U. Aerosol particle analysis: Challenges and progress[J]. Analytical and Bioanalytical Chemistry, 2003, 375(1): 30-32.

[6] Chakrabarty R K, Moosmüller H, Chen L W A, et al. Brown carbon in tar balls from smoldering biomass combustion[J]. Atmospheric Chemistry and Physics, 2010, 10(13): 6363-6370.

[7] Krivácsy Z, Kiss G, Varga B, et al. Study of humic-like substances in fog and interstitial aerosol by size-exclusion chromatography and capillary electrophoresis[J]. Atmospheric Environment, 2000, 34(25): 4273-4281.

[8] Andreae M O, Gelencsér A. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols[J]. Atmospheric Chemistry and Physics, 2006, 6(10): 3131-3148.

[9] Zhi Guorui, Cai Jing, Yang Junchao, et al. Origin, properties, measurement and emission estimation of brown carbon aerosols[J]. Research of Environmental Sciences, 2015, 28(12): 1797-1814.

[10] Cheng Y, He K B, Zheng M, et al. Mass absorption efficiency of elemental carbon and water-soluble organic carbon in Beijing, China[J]. Atmospheric Chemistry and Physics, 2011, 11(22): 11497-11510.

[11] Bond T C, Bussemer M, Wehner B, et al. Light absorption by primary particle emissions from a lignite burning plant[J]. Environmental Science and Technology, 1999, 33(21): 3887-3891.

[12] Liu J, Scheuer E, Dibb J, et al. Brown carbon aerosol in the North American continental troposphere: Sources, abundance, and radiative forcing[J]. Atmospheric Chemistry and Physics, 2015, 15(14): 7841-7858.

[13] Yan C, Zheng M, Bosch C, et al. Important fossil source contribution to brown carbon in Beijing during winter[J]. Scientific Reports, 2017, 7: 43182.

[14] Moise T, Flores J M, Rudich Y. Optical properties of secondary organic aerosols and their changes by chemical processes[J]. Chemical Reviews, 2015, 115(10): 4400-4439.

[15] Laskin A, Laskin J, Nizkorodov S A. Chemistry of atmospheric brown carbon[J]. Chemical Reviews, 2015, 115(10): 4335-4382.

[16] Zhang Hua, Huang Jianping. Interpretation of the IPCC fifth assessment report on anthropogenic and natural radiative forcing[J]. Progressus Inquisitiones DE Mutatione Climatis, 2014, 10(1): 40-44.

[17] Bahadur R, Praveen P S, Xu Y, et al. Solar absorption by elemental and brown carbon determined from spectral observations[J]. Proceedings of the National Academy of Sciences of the United States of America, 2012, 109(43): 17366-17371.

[18] Alexander D T L, Crozier P A, Anderson J R. Brown carbon spheres in east Asian outflow and their optical properties[J]. Science, 2008, 321(5890): 833-836.

[19] Feng Y, Ramanathan V, Kotamarthi V R. Brown carbon: A significant atmospheric absorber of solar radiation?[J]. Atmospheric Chemistry and Physics, 2013, 13(17): 8607-8621.

[20] Hecobian A, Zhang X, Zheng M, et al. Water-soluble organic aerosol material and the light-absorption characteristics of aqueous extracts measured over the Southeastern United States[J]. Atmospheric Chemistry and Physics, 2010, 10(13): 5965-5977.

[21] Satish R, Shamjad P, Thamban N, et al. Temporal characteristics of brown carbon over the central Indo-Gangetic plain[J]. Environmental Science & Technology, 2017, 51(12): 6765-6772.

[22] Shen Z X, Zhang Q, Cao J J, et al. Optical properties and possible sources of brown carbon in PM2.5 over Xi′an, China[J]. Atmospheric Environment, 2017, 150: 322-330.

[24] Weingartner E, Saathoff H, Schnaiter M, et al. Absorption of light by soot particles: Determination of the absorption coefficient by means of aethalometers[J]. Journal of Aerosol Science, 2003, 34(10): 1445-1463.

[25] Wang J P, Nie W, Cheng Y F, et al. Light absorption of brown carbon in Eastern China based on 3-year multi-wavelength aerosol optical property observations and an improved absorption ngstrm exponent segregation method[J]. AtmosphericChemistry and Physics, 2018, 18(12): 9061-9074.

[26] Yuan J F, Huang X F, Cao L M, et al. Light absorption of brown carbon aerosol in the PRD region of China[J]. Atmospheric Chemistry and Physics, 2016, 16(3): 1433-1443.

[27] Li Z J, Tan H B, Zheng J, et al. Light absorption properties and potential sources of particulate brown carbon in the Pearl River Delta region of China[J]. Atmospheric Chemistry and Physics, 2019, 19(18): 11669-11685.

[28] Pagels J, Khalizov A F, McMurry P H, et al. Processing of soot by controlled sulphuric acid and water condensation-mass and mobility relationship[J]. Aerosol Science and Technology, 2009, 43(7): 629-640.

[29] Tan H B, Liu L, Fan S J, et al. Aerosol optical properties and mixing state of black carbon in the Pearl River Delta, China[J]. Atmospheric Environment, 2016, 131: 196-208.

[30] Cheng Y F, Eichler H, Wiedensohler A, et al. Mixing state of elemental carbon and non-light-absorbing aerosol components derived from in situ particle optical properties at Xinken in Pearl River Delta of China[J]. Journal of Geophysical Research: Atmospheres, 2006, 111(D20): D20204.

[31] Cheng Yafang, Zhang Yuanhang, Hu Min. Observation-based Method for Investigating the Atmospheric Aerosol Radiative Properties in Pearl River Delta of China[M]. Beijing: Science Press, 2008.

[32] Ma Y, Huang C C, Jabbour H, et al. Mixing state and light absorption enhancement of black carbon aerosols in summertime Nanjing, China[J]. Atmospheric Environment, 2020, 222: 117141.

[33] McMurry P H, Wang X, Park K, et al. The relationship between mass and mobility for atmospheric particles: A new technique for measuring particle density[J]. Aerosol Science and Technology, 2002, 36(2): 227-238.

[34] Ma N, Zhao C S, Müller T, et al. A new method to determine the mixing state of light absorbing carbonaceous using the measured aerosol optical properties and number size distributions[J]. Atmospheric Chemistry and Physics, 2012, 12(5): 2381-2397.

[35] Bohren C F, Huffman D R. Absorption and Scattering of Light by Small Particles[M]. Weinheim, Germany: Wiley-VCH Verlag GmbH, 2007: 499-519.

[36] D′almeida G A, Koepke P, Shettle E P. Atmospheric Aerosols: Global Climatology and Radiative Characteristics[M]. Hampton, VA : A Deepak Pub, 1991.

[37] Yang M, Howell S G, Zhuang J, et al. Attribution of aerosol light absorption to black carbon, brown carbon, and dust in China-interpretations of atmospheric measurements during EAST-AIRE[J]. Atmospheric Chemistry and Physics, 2009, 9(6): 2035-2050.

[38] Martinsson J, Eriksson A C, Nielsen I E, et al. Impacts of combustion conditions and photochemical processing on the light absorption of biomass combustion aerosol[J]. Environmental Science & Technology, 2015, 49(24): 14663-14671.

[39] Lack D A, Cappa C D. Impact of brown and clear carbon on light absorption enhancement, single scatter albedo and absorption wavelength dependence of black carbon[J]. Atmospheric Chemistry and Physics, 2010, 10(9): 4207-4220.

[40] Liu D, Allan J D, Young D E, et al. Size distribution, mixing state and source apportionment of black carbon aerosol in London during wintertime[J]. Atmospheric Chemistry and Physics, 2014, 14(18): 10061-10084.

[41] Liu D T, Taylor J W, Young D E, et al. The effect of complex black carbon microphysics on the determination of the optical properties of brown carbon[J]. Geophysical Research Letters, 2015, 42(2): 613-619.

[42] Liu C, Chung C E, Yin Y, et al. The absorption ngstrm exponent of black carbon: From numerical aspects[J]. Atmospheric Chemistry and Physics, 2018, 18(9): 6259-6273.

[43] Lack D A, Langridge J M. On the attribution of black and brown carbon light absorption using the ngstrm exponent[J]. Atmospheric Chemistry and Physics, 2013, 13(20): 10535-10543.

[44] Moosmüller H, Chakrabarty R K, Ehlers K M, et al. Absorption ngstrm coefficient, brown carbon, and aerosols: Basic concepts, bulk matter, and spherical particles[J]. Atmospheric Chemistry and Physics, 2011, 11(3): 1217-1225.

[45] Gyawali M, Arnott W P, Lewis K, et al. In situ aerosol optics in Reno, NV, USA during and after the summer 2008 California wildfires and the influence of absorbing and non-absorbing organic coatings on spectral light absorption[J]. Atmospheric Chemistry and Physics, 2009, 9(20): 8007-8015.

[46] Cheung H H Y, Tan H B, Xu H B, et al. Measurements of non-volatile aerosols with a VTDMA and their correlations with carbonaceous aerosols in Guangzhou, China[J]. Atmospheric Chemistry and Physics, 2016, 16(13): 8431-8446.

[47] Qiu Y Q, Wu X, Zhang Y R, et al. Aerosol light absorption in a coastal city in Southeast China: Temporal variations and implications for brown carbon[J]. Journal of Environmental Sciences, 2019, 80: 257-266.

[48] Peng C, Yang F M, Tian M, et al. Brown carbon aerosol in two megacities in the Sichuan Basin of southwestern China: Light absorption properties and implications[J]. Science of the Total Environment, 2020, 719: 137483.

[49] Zhang Y, Li Z Q, Sun Y L, et al. Estimation of atmospheric columnar organic matter (OM) mass concentration from remote sensing measurements of aerosol spectral refractive indices[J]. Atmospheric Environment, 2018, 179: 107-117.

[50] Redmond H, Thompson J E. Evaluation of a quantitative structure-property relationship (QSPR) for predicting mid-visible refractive index of secondary organic aerosol (SOA)[J]. Physical Chemistry Chemical Physics, 2011, 13(15): 6872-6882.

[51] Erlick C, Abbatt J P D, Rudich Y. How different calculations of the refractive index affect estimates of the radiative forcing efficiency of ammonium sulfate aerosols[J]. Journal of the Atmospheric Sciences, 2011, 68(9): 1845-1852.

[52] Schuster G L, Dubovik O, Holben B N, et al. Inferring black carbon content and specific absorption from aerosol robotic network (AERONET) aerosol retrievals[J]. Journal of Geophysical Research: Atmospheres, 2005, 110(D10): D10S17.