Variation of Aerosol Optical Depth from Terra and Aqua MODIS Satellites in Turkey

Abstract

Aerosol Optical Depth (AOD) data produced by satellites are used to monitor atmospheric aerosols. In short, Terra and Aqua satellites are the primary satellites that successfully produce this parameter, which is defined as the reduction of electromagnetic energy at a specific wavelength due to aerosols in the atmosphere on a global scale. Both satellites produce daily AOD observations globally with a unique sensor called Moderate Resolution Imaging Spectroradiometer (MODIS). However, several factors make the detection of AOD difficult and region-specific. In this study, the variations in the AOD data produced by two different algorithms (Dark Target-DT and Deep Blue-DB) from the current MODIS data collection (C6.1) of Terra and Aqua satellites in Turkey were determined. Two different spatial resolution (3 km and 10 km) products produced with the DT algorithm were examined in the study. In contrast, a single product (10 km) was evaluated with the DB algorithm because the DB algorithm produced only 10 km resolution data. While examining spatial variations throughout the country, normalized difference vegetation index (NDVI) data were used. According to the results of the study, it was seen that the DT algorithm is more successful than the DB algorithm in regions with high NDVI values in our country. In our country, it was observed that the AOD data differ according to the seasons, and generally, larger AOD values were obtained in the spring and summer months. In addition, it was concluded that the Terra satellite produced more data than Aqua, and 10 km products were more successful than 3 km products. In terms of the scope of this study, it is the first study carried out in our country, and it is thought that it will guide the researchers who will use AOD data in the future for selection of satellites, algorithms, and sutiable products for a study region. In particular, it will also contribute to the statistical estimation models to be prepared to estimate the ground-level particulate matter (PM10, PM2.5) concentrations measured in residential areas with the help of AOD data.

Keywords

• Aerosol
• AOD
• MODIS
• Turkey

Türkiye’de Terra ve Aqua MODIS Uydularından Elde Edilen Aerosol Optik Derinliğinin Zamansal ve Mekansal Değişimi

Abstract

Atmosferik aerosollerin izlenmesi amacıyla uydular tarafından üretilen Aerosol Optik Derinliği (AOD) verisi kullanılmaktadır. Kısaca, belli bir dalga boyundaki elektromanyetik enerjinin atmosferdeki aerosoller nedeniyle azalması olarak tanımlanan bu parametreyi küresel ölçekte başarı ile üreten uyduların başında Terra ve Aqua uyduları gelmektedir. Her iki uydu sahip oldukları Moderate Resolution Imaging Spectroradiometer (MODIS) isimli özel bir sensör ile yerküre üzerinde günlük AOD gözlemi yapmaktadır. Ancak, AOD tespitini zorlaştıran ve bölgelere göre değişkenlik gösteren çeşitli etmenler vardır. Bu çalışmada, Terra ve Aqua uydularının güncel MODIS veri koleksiyonundan (C6.1) iki farklı algoritma (Dark Target-DT ve Deep Blue-DB) kullanılarak üretilen AOD verilerinin Türkiye’deki değişimleri belirlenmiştir. Çalışmada DT algoritması ile üretilen iki farklı mekansal çözünürlüklü (3 km ve 10 km) ürün incelenirken DB algoritmasının sadece 10 km çözünürlüklü veri üretmesi nedeniyle tek ürün değerlendirilmiştir. Ülke genelinde mekansal değişimler irdelenirken normalleştirilmiş fark bitki örtüsü indeksi (NFBÖİ) verileri kullanılmıştır. Çalışma sonuçlarına göre ülkemizde NFBÖİ değeri yüksek olan bölgelerde DT algoritmasının DB algoritmasına göre daha başarılı olduğu görülmüştür. Ülkemizde AOD verilerinin mevsimlere göre farklılık gösterdiği, genelde ilkbahar ve yaz aylarında daha büyük AOD değerleri elde edildiği görülmüştür. Ayrıca, Terra uydusunun Aqua’ya göre daha fazla veri ürettiği ve 10 km’lik ürünlerin 3 km’lik ürünlere göre daha başarılı olduğu sonucu elde edilmiştir. Bu çalışma kapsamı itibariyle ülkemizde gerçekleştirilen ilk çalışma olup, gelecekte AOD verisi kullanacak araştırmacılara çalışılacak bölgeye uygun uydu, algoritma ve ürün seçiminde yol göstereceği düşünülmektedir. Özellikle, yerleşim alanlarında ölçülen yer seviyesindeki partikül madde (PM10, PM2.5) konsantrasyonlarını AOD verisi yardımıyla tahmin etmeye yönelik hazırlanacak istatistiksel tahmin modellerine de katkı sağlayacaktır.

Keywords

• AOD
• MODIS
• Zamansal ve Mekansal Değişim
• Türkiye

References

1. Bibi, H., Alam, K., Chishtie, F., Bibi, S., Shahid, I., Blaschke, T. 2015. "Intercomparison of MODIS, MISR, OMI, and CALIPSO aerosol optical depth retrievals for four locations on the Indo-Gangetic plains and validation against AERONET data”, Atmospheric Environment, 111, 113–126.
2. Xu, H., Guang, J., Xue, Y., de Leeuw, G., Che, Y. H., Guo, J., HE, X. W., Wang, T. K. 2015. "A consistent aerosol optical depth (AOD) dataset over mainland China by integration of several AOD products”, Atmospheric Environment, 114, 48–56.
3. You, W., Zang, Z., Zhang, L., Zhang, M., Pan, X., Li, Y. 2016. "A nonlinear model for estimating ground-level PM10 concentration in Xi’an using MODIS aerosol optical depth retrieval”, Atmospheric Research, 168, 169–179.
4. Sever, L., Alpert, P., Lyapustin, A., Wang, Y., Chudnovsky, A. 2017. "An example of aerosol pattern variability over bright surface using high resolution MODIS MAIAC: The eastern and western areas of the Dead Sea and environs”, Atmospheric Environment, 165, 359–369.
5. Ahmad, M., Alam, K., Tariq, S., Anwar, S., Nasir, J., Mansha, M. 2019. "Estimating fine particulate concentration using a combined approach of linear regression and artificial neural network", Atmospheric Environment, 219, 117050.
6. Park, S., Shin, M., Im, J., Song, C. K., Choi, M., Kim, J., Lee, S., Park, R., Kim, J., Lee, D. W., Kim, S. K. 2019. "Estimation of ground-level particulate matter concentrations through the synergistic use of satellite observations and process-based models over South Korea”, Atmospheric Chemistry and Physics, 19(2), 1097–1113.
7. Yang, Q., Yuan, Q., Yue, L., Li, T., Shen, H., Zhang, L. 2019. "The relationships between PM2.5 and aerosol optical depth (AOD) in mainland China: About and behind the spatio-temporal variations”, Environmental Pollution, 248, 526–535.
8. Jin, Q., Crippa, P., Pryor, S. C. 2020. "Spatial characteristics and temporal evolution of the relationship between PM2.5 and aerosol optical depth over the eastern USA during 2003–2017”, Atmospheric Environment, 239, 117718.

9. Douglas, A.D., 2015. A Geographical Comparison of the Relationship Between Aerosol Optical Depth and Fine Particulate Matter in Indiana. Master Thesis, Indiana University, 34 sayfa.
10. Wang, C., Liu, Q., Ying, N., Wang, X., Ma, J. 2013. "Air quality evaluation on an urban scale based on MODIS satellite images”, Atmospheric Research, 132–133, 22–34.
11. Lee, H. J., Kang, C. M., Coull, B. A., Bell, M. L., Koutrakis, P. 2014. "Assessment of primary and secondary ambient particle trends using satellite aerosol optical depth and ground speciation data in the New England region, United States”, Environmental Research, 133, 103–110.
12. Van Donkelaar, A., Martin, R. V., Brauer, M., Boys, B. L. 2015. "Use of satellite observations for long-term exposure assessment of global concentrations of fine particulate matter”, Environmental Health Perspectives, 123(2), 135–143.
13. Zhang, Y., Li, Z. 2015. "Remote sensing of atmospheric fine particulate matter (PM2.5) mass concentration near the ground from satellite observation”, Remote Sensing of Environment, 160, 252–262.
14. Lee, H. J., Chatfield, R. B., Strawa, A. W. 2016. "Enhancing the Applicability of Satellite Remote Sensing for PM2.5 Estimation Using MODIS Deep Blue AOD and Land Use Regression in California, United States”, Environmental Science and Technology, 50(12), 6546–6555.
15. Tian, X., Liu, Q., Li, X., Wei, J. 2018. "Validation and comparison of MODIS C6.1 and C6 aerosol products over Beijing, China”, Remote Sensing, 10(12), 1–18.
16. Wei, J., Li, Z., Peng, Y., Sun, L. 2019. "MODIS Collection 6.1 aerosol optical depth products over land and ocean: validation and comparison”, Atmospheric Environment, 201, 428–440.
17. Zhang, M., Liu, J., Li, W., Bilal, M., Zhao, F., Zhang, C., … Khedher, K. M. 2019. "Evaluation of the aqua-MODIS C6 and C6.1 aerosol optical depth products in the Yellow River Basin, China”, Atmosphere, 10(8), 426.
18. Wei, J., Li, Z., Sun, L., Peng, Y., Liu, L., He, L., Qin, W., Cribb, M. 2020. "MODIS Collection 6.1 3 km resolution aerosol optical depth product: global evaluation and uncertainty analysis”, Atmospheric Environment, 240, 117768.
19. NASA (National Aeronautics and Space Administration). https://modis.gsfc.nasa.gov/about/design.php, Son erişim tarihi: 20 Kasım 2020.
20. Levy, R. C., Mattoo, S., Munchak, L. A., Remer, L. A., Sayer, A. M., Patadia, F., Hsu, N. C. 2013. "The Collection 6 MODIS aerosol products over land and ocean”, Atmospheric Measurement Techniques, 6(11), 2989–3034.
21. Remer, L. A., Mattoo, S., Levy, R. C., Munchak, L. A. 2013. "MODIS 3 km aerosol product: Algorithm and global perspective”, Atmospheric Measurement Techniques, 6(7), 1829–1844.
22. Gupta, P., Remer, L. A., Levy, R. C., Mattoo, S. 2018. "Validation of MODIS 3km land aerosol optical depth from NASA’s EOS Terra and Aqua missions”, Atmospheric Measurement Techniques, 11(5), 3145–3159.
23. NASA (National Aeronautics and Space Administration). https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/science-domain/l3-atmosphere/, Son erişim tarihi: Kasım 2020.
24. Floutsi, A. A., Korras-Carraca, M. B., Matsoukas, C., Hatzianastassiou, N., Biskos, G. 2016. "Climatology and trends of aerosol optical depth over the Mediterranean basin during the last 12 years (2002-2014) based on Collection 006 MODIS-Aqua data”, Science of the Total Environment, 551–552, 292–303.
25. Georgoulias, A. K., Alexandri, G., Kourtidis, K. A., Lelieveld, J., Zanis, P., Pöschl, U., Levy, R., Amiridis, V., Marinou, E., Tsikerdekis, A. 2016. "Spatiotemporal variability and contribution of different aerosol types to the aerosol optical depth over the Eastern Mediterranean”, Atmospheric Chemistry and Physics, 16(21), 13853–13884.
26. Glantz, P., Freud, E., Johansson, C., Noone, K. J., Tesche, M. 2019. "Trends in MODIS and AERONET derived aerosol optical thickness over Northern Europe”, Tellus, Series B: Chemical and Physical Meteorology, 71(1), 1–21.
27. Filonchyk, M., Hurynovich, V., Yan, H. 2020. "Trends in aerosol optical properties over Eastern Europe based on MODIS-Aqua”, Geoscience Frontiers, 11(6), 2169–2181.
28. Shen, L., Hao, F., Gao, M., Wang, H., Zhu, B., Gao, J., Cheng, Y., Xie, F. 2020. "Real-time geochemistry of urban aerosol during a heavy dust episode by single-particle aerosol mass spectrometer: Spatio-temporal variability, mixing state and spectral distribution”, Particuology, 53, 197–207.
29. De Meij, A., Lelieveld, J. 2011. "Evaluating aerosol optical properties observed by ground-based and satellite remote sensing over the Mediterranean and the Middle East in 2006”, Atmospheric Research, 99(3–4), 415–433.
30. Nabat, P., Somot, S., Mallet, M., Chiapello, I., Morcrette, J. J., Solmon, F., Szopa, S., Dulac, F., Collins, W., Ghan, S., Horowitz, L. W., Lamarque, J. F., Lee, Y., Naik, V., Nagashima, T., Shindell, D., Skeie, R. 2013. "A 4-D climatology (1979-2009) of the monthly tropospheric aerosol optical depth distribution over the Mediterranean region from a comparative evaluation and blending of remote sensing and model products”, Atmospheric Measurement Techniques, 6(5), 1287–1314.
31. Shaheen, A., Wu, R., Aldabash, M. 2020. "Long-term AOD trend assessment over the Eastern Mediterranean region: A comparative study including a new merged aerosol product”, Atmospheric Environment, 238, 117736.
32. Tutsak, E., Koçak, M. 2020. "Optical and microphysical properties of the columnar Aerosol burden over the Eastern Mediterranean: Discrimination of Aerosol types”, Atmospheric Environment, 229.
33. Benas, N., Beloconi, A., Chrysoulakis, N. 2013. "Estimation of urban PM10 concentration, based on MODIS and MERIS/AATSR synergistic observations”, Atmospheric Environment, 79, 448–454.
34. Seo, S., Kim, J., Lee, H., Jeong, U., Kim, W., Holben, B. N., Kim, S. W., Song, C. H., Lim, J. H. 2015. "Estimation of PM10 concentrations over Seoul using multiple empirical models with AERONET and MODIS data collected during the DRAGON-Asia campaign”, Atmospheric Chemistry and Physics, 15(1), 319–334.
35. You, W., Zang, Z., Pan, X., Zhang, L., Chen, D. 2015. "Estimating PM2.5 in Xi’an, China using aerosol optical depth: A comparison between the MODIS and MISR retrieval models”, Science of the Total Environment, 505, 1156–1165.
36. Ghotbi, S., Sotoudeheian, S., Arhami, M. 2016. "Estimating urban ground-level PM10 using MODIS 3km AOD product and meteorological parameters from WRF model”, Atmospheric Environment, 141, 333–346.
37. Kamarul Zaman, N. A. F., Kanniah, K. D., Kaskaoutis, D. G. 2017. "Estimating Particulate Matter using satellite based aerosol optical depth and meteorological variables in Malaysia”, Atmospheric Research, 193, 142–162.
38. Stafoggia, M., Bellander, T., Bucci, S., Davoli, M., de Hoogh, K., de’ Donato, F., Gariazzo, C., Lyapustin, A., Michelozzi, P., Renzi, M., Scortichini, M., Shtein, A., Viegi, G., Kloog, I., Schwartz, J. 2019. "Estimation of daily PM10 and PM2.5 concentrations in Italy, 2013–2015, using a spatiotemporal land-use random-forest model”, Environment International, 124, 170–179.
39. Jiang, T., Chen, B., Nie, Z., Ren, Z., Xu, B., Tang, S. 2021. "Estimation of hourly full-coverage PM2.5 concentrations at 1-km resolution in China using a two-stage random forest model”, Atmospheric Research, 248, 105146.
40. Kong, L., Xin, J., Zhang, W., Wang, Y. 2016. "The empirical correlations between PM2.5, PM10 and AOD in the Beijing metropolitan region and the PM2.5, PM10 distributions retrieved by MODIS”, Environmental Pollution, 216, 350–360.
41. Rea, G., Turquety, S., Menut, L., Briant, R., Mailler, S., Siour, G. 2015. "Source contributions to 2012 summertime aerosols in the Euro-Mediterranean region”, Atmospheric Chemistry and Physics, 15(14), 8013–8036.
42. Taheri Shahraiyni, H., Karimi, K., Habibi Nokhandan, M., Hafezi Moghadas, N. 2015. "Monitoring of dust storm and estimation of aerosol concentration in the Middle East using remotely sensed images”, Arabian Journal of Geosciences, 8(4), 2095–2110.
43. Chouza, F., Reitebuch, O., Benedetti, A., Weinzierl, B. 2016. "Saharan dust long-range transport across the Atlantic studied by an airborne Doppler wind lidar and the MACC model”, Atmospheric Chemistry and Physics, 16(18), 11581–11600.
44. Zhang, Y., Hu, R., Zheng, X. 2018. "Large-scale coherent structures of suspended dust concentration in the neutral atmospheric surface layer: A large-eddy simulation study”, Physics of Fluids, 30(4).
45. Bilal, M., Nazeer, M., Qiu, Z., Ding, X., Wei, J. 2018. "Global validation of MODIS C6 and C6.1 merged aerosol products over diverse vegetated surfaces”, Remote Sensing, 10(3).
46. Huang, Y., Zhu, B., Zhou, X., Chen, D., Zhu, Z., Zhang, T., Xia, X., Ji, Y., Gong, Y., Wang, L. 2019. "Evaluation and Comparison of MODIS Collection 6.1 and Collection 6 Dark Target Aerosol Optical Depth over Mainland China Under Various Conditions Including Spatiotemporal Distribution, Haze Effects, and Underlying Surface”, Earth and Space Science, 6(12), 2575–2592.
47. Kharol, S. K., Badarinath, K. V. S., Sharma, A. R., Kaskaoutis, D. G., Kambezidis, H. D. 2011. "Multiyear analysis of Terra/Aqua MODIS aerosol optical depth and ground observations over tropical urban region of Hyderabad, India", Atmospheric Environment, 45(8), 1532–1542.
48. Fotiadi, A., Hatzianastassiou, N., Drakakis, E., Matsoukas, C., Pavlakis, K. G., Hatzidimitriou, D., Gerasopoulos, E., Mihalopoulos, N., Vardavas, I. 2006. "Aerosol physical and optical properties in the Eastern Mediterranean Basin, Crete, from Aerosol Robotic Network data", Atmospheric Chemistry and Physics, 6(12), 5399–5413.
49. Ozdemir, E., Tuna Tuygun, G., Elbir, T. 2020. "Application of aerosol classification methods based on AERONET version 3 product over eastern Mediterranean and Black Sea”, Atmospheric Pollution Research, 11(12), 2226–2243.
50. Tutsak, E., Koçak, M. 2019. "Long-term measurements of aerosol optical and physical properties over the Eastern Mediterranean: Hygroscopic nature and source regions”, Atmospheric Environment, 207, 1–15.
51. Che, H., Yang, L., Liu, C., Xia, X., Wang, Y., Wang, H., Wang, H., Wang, H., Lu, X., Zhang, X. 2019. "Long-term validation of MODIS C6 and C6.1 Dark Target aerosol products over China using CARSNET and AERONET”, Chemosphere, 236.
52. Kalivitis, N., Gerasopoulos, E., Vrekoussis, M., Kouvarakis, G., Kubilay, N., Hatzianastassiou, N., Vardavas, I., Mihalopoulos, N., 2007. “Dust transport over the eastern mediterranean derived from total ozone mapping spectrometer, aerosol robotic network, and surface measurements”, Journal of Geophysical Research: Atmospheres, 112, D03202.
53. Sciare, J., Oikonomou, K., Favez, O., Liakakou, E., Markaki, Z., Cachier, H., Mihalopoulos, N., 2008. “Long-term measurements of carbonaceous aerosols in the Eastern Mediterranean: Evidence of long-range transport of biomass burning”, Atmospheric Chemistry and Physics,8, 5551–5563.
54. Hatzianastassiou, N., Gkikas, A., Mihalopoulos, N., Torres, O., Katsoulis, B.D., 2009. “Natural versus anthropogenic aerosols in the eastern Mediterranean basin derived from multiyear TOMS and MODIS satellite data”, Journal of Geophysical Research: Atmospheres, 114, D24202.
55. Gerasopoulos, E., Amiridis, V., Kazadzis, S., Kokkalis, P., Eleftheratos, K., Andreae, M.O., Andreae, T.W., El-Askary, H., Zerefos, C.S., 2011. “Three-year ground based measurements of aerosol optical depth over the Eastern Mediterranean: The urban environment of Athens”, Atmospheric Chemistry and Physics, 11, 2145–2159.
56. Tombrou, M., Bossioli, E., Kalogiros, J., Allan, J.D., Bacak, A., Biskos, G., Coe, H., Dandou, A., Kouvarakis, G., Mihalopoulos, N., Percival, C.J., Protonotariou, A.P., Szabó-Takács, B., 2015. “Physical and chemical processes of air masses in the Aegean Sea during Etesians: Aegean-GAME airborne campaign”, Science of the Total Environment, 506,201–216.
57. Korras-Carraca, M.B., Hatzianastassiou, N., Matsoukas, C., Gkikas, A., Papadimas, C.D., 2015. “The regime of aerosol asymmetry parameter over Europe, the Mediterranean and the Middle East based on MODIS satellite data: Evaluation against surface AERONET measurements”, Atmospheric Chemistry and Physics, 15, 13113–13132.
58. Triantafyllou, E., Diapouli, E., Korras-Carraca, Manousakas, M., Psanis, C., Floutsi, A.A., Spyrou, C., Eleftheriadis, K., Biskos, G., 2020. “Contribution of locally-produced and transported air pollution to particulate matter in a small insular coastal city”, Atmospheric Pollution Research, 11, 667-678.
59. Bovchaliuk, A., Milinevsky, G., Danylevsky, V., Goloub, P., Dubovik, O., Holdak, A., Ducos, F., Sosonkin, M., 2013. “Variability of aerosol properties over Eastern Europe observed from ground and satellites in the period from 2003 to 2011”, Atmospheric Chemistry and Physics, 13, 6587–6602.
60. Barnaba, F., Gobbi, G. P. 2004. "Aerosol seasonal variability over the Mediterranean region and relative impact of maritime, continental and Saharan dust particles over the basin from MODIS data in the year 2001", Atmospheric Chemistry and Physics, 4(9–10), 2367–2391.
61. Ağaçayak, T., 2014. Investigation of impacts of aerosols on Eastern Mediterranean region climate. İstanbul Teknik Üniversitesi / Avrasya Yerbilimleri Enstitüsü / İklim ve Deniz Bilimleri Anabilim Dalı / Yer Sistem Bilimi Bilim Dalı, 116 sayfa.
62. Kabataş, B., 2016. Quantification of Saharan dust influences on Eastern Mediterranean air quality via atmospheric modelling. İstanbul Teknik Üniversitesi / Avrasya Yerbilimleri Enstitüsü / İklim ve Deniz Bilimleri Anabilim Dalı / Yer Sistem Bilimi Bilim Dalı, 102 sayfa.
63. Tuna Tuygun, G., Ozdemir, E., Elbir, T. 2020. "Evaluation of MODIS C6 and C6.1 Dark Target AOD products over Turkey based on NDVI and aerosol type”, Atmospheric Pollution Research, 11(12), 2335–2349.
64. Öztaner, Y.B., Kahraman, A., Çalışkan, E., Tilev Tanrıöver, Ş., Kahya, C., Aksoy, B., İncecik, S., Topçu, S., Aslan, Z., Barutçu, B., Sezen, İ., Sakarya, S., Deniz, A. 2014. Açık Gökyüzü Şartlarında Güneş Radyasyonunun WRF Modeli ile Kısa Vadeli Tahmininde Aerosol Etkisinin Değerlendirilmesi, Hava Kirliliği Araştırmaları Dergisi, 3, 2 – 11.
65. Oğuz, K., Akın, B.S., 2019. Doğu Akdeniz Havzasında Sıcaklık, Yağış Ve Aerosol Değişiminin İncelenmesi, Mühendislik Bilimleri ve Tasarım Dergisi, 7(2), 244–253.
66. Koçak, T. K., Ebrahimi, F., 2020. Uydulardan Elde Edilebilen Aerosol Optik Derinlik Verilerini Kullanarak Zemin Seviyesi İnce Partikül Konsantrasyonlarını Tahmin Etmek İçin Doğrusal Olmayan Bir Model Geliştirilmesi. Ulusal Çevre Bilimleri Araştırma Dergisi, 3(3), 119-127.
67. Zeydan, Ö., Wang, Y. 2019. "Using MODIS derived aerosol optical depth to estimate ground-level PM2.5 concentrations over Turkey”, Atmospheric Pollution Research, 10(5), 1565–1576.
68. Tuna Tuygun, G., Gündoğdu, S., Elbir, T. 2021. "Estimation of ground-level particulate matter concentrations based on synergistic use of MODIS, MERRA-2 and AERONET AODs over a coastal site in the Eastern Mediterranean", Atmospheric Environment, 261, 118562.
69. He, Q., Zhang, M., Huang, B., Tong, X. 2017. "MODIS 3 km and 10 km aerosol optical depth for China: Evaluation and comparison”, Atmospheric Environment, 153, 150–162.
70. Sayer, A.M., Munchak, L.A., Hsu, N.C., Levy, R.C., Bettenhausen, C., Jeong, M.J., 2014. “MODIS Collection 6 aerosol products: Comparison betweenAqua’s e-Deep Blue, Dark Target, and “merged” data sets, and usage recommendations”, Journal of Geophysical Research: Atmospheres, 119, 13965–13989.