AEROSOL OPTICAL DEPTH (AOD) OVER FOUR INDONESIAN CITIES FROM THE AERONET MEASUREMENT: AN OVERVIEW

Abstract

Abstract A large amount of aerosol, commonly known as Particulate Matter (PM), is emitted to the atmosphere from land-use conversion, urbanization, and the use of fossil fuels from a variety of sectors. Aerosol affect climate, environment, to human health. Each location might have different aerosols types due to various sources, sinks, and local characteristics. Aerosol Robotic Network (AERONET) has been established to investigate and monitor aerosol world-wide included in Indonesia. This work aims to study aerosol optical properties retrieved from AERONET in four locations namely Bandung, Jambi, Pontianak, and Palangkaraya. Seasonal and daily variability in AOD and Angstrom exponent (α), also aerosol classification, is analyzed. The result shows that aerosol characteristics such as AOD and α in Bandung are different from Jambi, Palangkaraya, and Pontianak due to different aerosol sources. AOD clearly increases during the burning period (dry period) in Jambi, Palangkaraya, and Pontianak. The highest AOD monthly maximum recorded in Palangkaraya as of 4.51 during September. On the other hand, AOD in Bandung does not show significant variation during dry and rainy season. Mixed aerosols (coarse and fine mode) are present in all locations. However, the dominance of fine mode is depicted from high percent frequency of occurrence in Jambi, Palangkaraya, Pontianak, and Bandung, which are 33.4%, 31.38%, 25.14% (α range bin 1.6-1.8) and 37.16% (α range bin 1.4-1.6) respectively. There was a period of α1 with 1AOD6 in Jambi, Palangkaraya, and Pontianak suggesting smoke fire from peatland, while AOD close to 1 with α1 as the character of urban aerosol is prominent in Bandung.   IntisariSejumlah besar aerosol, atau yang dikenal dengan partikulat, diemisikan ke atmosfer dari aktivitas konversi penggunaan lahan, urbanisasi, dan pembakaran bahan bakar fosil dari berbagai sektor. Aerosol memengaruhi iklim, lingkungan, hingga kesehatan manusia. Setiap lokasi memiliki jenis aerosol berbeda karena perbedaan sumber polusi dan cara penyerapannya, serta karakteristik lokal daerah tersebut. Aerosol Robotic Network (AERONET) dibentuk untuk menginvestigasi dan memantau aerosol di seluruh dunia termasuk di Indonesia. Tujuan dari penelitian ini untuk mempelajari sifat optik aerosol yang diperoleh dari AERONET di empat lokasi yaitu Bandung, Jambi, Pontianak, dan Palangkaraya. Variabilitas musiman dan harian parameter AOD dan Angstrom eksponen (α) serta klasifikasi aerosol juga dianalisis. Hasil dari studi menunjukkan karakteristik aerosol seperti AOD dan α di Bandung berbeda dari Jambi, Palangkaraya, dan Pontianak karena perbedaan sumber aerosol. AOD meningkat selama periode kebakaran lahan (musim kemarau) di Jambi, Palangkaraya, dan Pontianak. Maksimum bulanan AOD tertinggi tercatat di Palangkaraya sebesar 4.51 pada September. Di sisi lain, AOD di Bandung tidak menunjukkan variasi yang besar pada musim kemarau dan hujan. Aerosol campuran (partikel kasar dan halus) terdapat di semua lokasi. Namun, dominasi aerosol berukuran halus digambarkan oleh tingginya frekuensi kejadian di Jambi, Palangkaraya, Pontianak, dan Bandung masing-masing 33,4%, 31,38%, 25,14% (α range bin 1,6-1,8) dan 37,16% (α range bin 1,4-1.6). Terdapat periode dimana α 1 dengan 1 AOD 6 di Jambi, Palangkaraya, dan Pontianak menunjukkan sumber aerosol berasal dari kebakaran asap dari lahan gambut, sementara AOD mendekati 1 dengan α 1 sebagai karakter dari aerosol perkotaan menonjol di Bandung.