Variabilitas Kualitas Udara Terhadap Aerosol Bulan Februari 2016-2019

Pengamatan Aerosol merupakan salah satu program pengukuran yang dilakukan di Stasiun Pemantau Atmosfer Global Bukit Kototabang. Penelitian ini bertujuan untuk mengetahui tren konsentrasi Aerosol (Black Carbon, Particulate Matter (PM10) dan Scattering Coefficient) di Stasiun Pemantau Atmosfer Global Bukit Kototabang dan untuk melakukan penelitian terhadap dampak kemunculan titik panas di Sumatera dengan pemantauan Aerosol. Penelitian ini dilakukan menggunakan data pengamatan pada bulan Februari 2016-2019. Metode yang digunakan yaitu dengan pengamatan yang dilakukan selama 24 jam melalui instrumen Catcos Magee Scientific Aethalometer untuk pengamatan Black Carbon, BAM 1020 untuk pengamatan PM10, Ecotech M9003 Integrating Nephelometer untuk pengamatan Scattering Coefficient dan pantauan titik panas (hotspot) di pulau Sumatera diambil dari data harian titik panas dari Satelit MODIS (Terra, Aqua, dan SNPP) dengan tingkat kepercayaan diatas 70%. Hasil penelitian ini menunjukan konsentrasi PM 10 dan Aerosol Scattering Coeficient meningkat pada Februari 2019 dengan bertambahnya jumlah titik panas yaitu 367 titik dan arah pergerakan angin dominan dari timur dan timur laut. Sedangkan peningkatan titik panas pada tahun 2018 meningkatkan konsentrasi Black Carbon dan PM10

On the interpretation of the loading correction of the aethalometer

Aerosol optical properties were measured with a seven-wavelength aethalometer and a three-wavelength nephelometer at the suburban site SORPES in Nanjing, China, in September 2013–January 2015. The aethalometer compensation parameter k, calculated with the Virkkula et al. (2007) method depended on the backscatter fraction, measured with an independent method, the integrating nephelometer. At λ = 660 nm the daily averaged compensation parameter k ≈ 0.0017 ± 0.0002 and 0.0042 ± 0.0013 when backscatter fraction at λ = 635 nm was in the ranges of 0.100 ± 0.005 and 0.160 ± 0.005, respectively. Also, the wavelength dependency of the compensation parameter depended on the backscatter fraction: when b(λ = 525 nm) was less than approximately 0.13 the compensation parameter decreased with wavelength and at larger b it increased with wavelength. This dependency has not been considered in any of the algorithms that are currently used for processing aethalometer data. The compensation parameter also depended on the single-scattering albedo ω0 so that k decreased with increasing ω0. For the green light (λ = 520 nm) in the ω0 range 0.870 ± 0.005, the average (± standard deviation) k ≈ 0.0047 ± 0.006 and in the ω0 range 0.960 ± 0.005, k ≈ 0.0028 ± 0.0007. This difference was larger for the near-infrared light (λ = 880 nm): in the ω0 range 0.860 ± 0.005, k ≈ 0.0055 ± 0.0023 and in the ω0 range 0.960 ± 0.005, k ≈ 0.0019 ± 0.0011. The negative dependence of k on ω0 was also shown with a simple theoretical analysis.

On the interpretation of the loading correction of the aethalometer

Aerosol optical properties were measured with a 7-wavelength aethalometer and a 3-wavelength nephelometer at the suburban site SORPES in Nanjing, China, in September 2013–January 2015. The aethalometer compensation parameter k, calculated with the Virkkula et al. (2007) method depended on the backscatter fraction, measured with the independent method, the integrating nephelometer. At λ = 660 nm the daily-averaged compensation parameter k ≈ 0.0017 ± 0.0002 and 0.0042 ± 0.0013 when backscatter fraction at λ = 635 nm was in the ranges of 0.100 ± 0.005 and 0.160 ± 0.005, respectively. Also the wavelength dependency of the compensation parameter depended on the backscatter fraction: when b(λ = 525 nm) was less than approximately 0.13 the compensation parameter decreased with wavelength and at larger b it increased with wavelength. This dependency has not been considered in any of the algorithms that are currently used for processing aethalometer data. The compensation parameter also depended on single-scattering albedo ω0 so that k decreased with increasing ω0. For the green light (λ = 520 nm) in the ω0 range 0.870 ± 0.005 the average (± standard deviation) k ≈ 0.0047 ± 0.006 and in the ω0 range 0.960 ± 0.005 k ≈ 0.0028 ± 0.0007. This difference was larger for the near-infrared light (λ = 880 nm): in the ω0 range 0.860 ± 0.005 k ≈ 0.0055 ± 0.0023 and in the ω0 range 0.960 ± 0.005 k ≈ 0.0019 ± 0.0011. The negative dependence of k on ω0 was also shown with a simple theoretical analysis.

Determination and analysis of in situ spectral aerosol optical properties by a multi-instrumental approach

Continuous in situ measurements of aerosol optical properties were conducted from 29 June to 29 July 2012 in Granada (Spain) with a seven-wavelength Aethalometer, a Multi-Angle Absorption Photometer, and a three-wavelength integrating nephelometer. The aim of this work is to describe a methodology to obtain the absorption coefficients (babs) for the different Aethalometer wavelengths. In this way, data have been compensated using algorithms which best estimate the compensation factors needed. Two empirical factors are used to infer the absorption coefficients from the Aethalometer measurements: C – the parameter describing the enhancement of absorption by particles in the filter matrix due to multiple scattering of light in the filter matrix – and f, the parameter compensating for non-linear loading effects in the filter matrix. Spectral dependence of f found in this study is not very strong. Values for the campaign lie in the range from 1.15 at 370 nm to 1.11 at 950 nm. Wavelength dependence in C proves to be more important, and also more difficult to calculate. The values obtained span from 3.42 at 370 nm to 4.59 at 950 nm. Furthermore, the temporal evolution of the Ångström exponent of absorption (αabs) and the single-scattering albedo (ω0) is presented. On average αabs is around 1.1 ± 0.3, and ω0 is 0.78 ± 0.08 and 0.74 ± 0.09 at 370 and 950 nm, respectively. These are typical values for sites with a predominance of absorbing particles, and the urban measurement site in this study is such. The babs average values are of 16 ± 10 Mm−1 (at 370 nm) and 5 ± 3 Mm−1 (at 950 nm), respectively. Finally, differences between workdays and Sundays have been further analysed, obtaining higher babs and lower ω0 during the workdays than on Sundays as a consequence of the diesel traffic influence.