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Open AccessArticle

The Observation Path Problems and the Formation Conditions of the Elevated Layer of Black Carbon Aerosol

1
Key Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD)/CMA Key Laboratory for Aerosol-Cloud-Precipitation, Nanjing University of Information Science & Technology, Nanjing 210044, China
2
Beijing Weather Modification Office, Beijing 100089, China
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Liaoning Weather Modification Office, Shenyang 110166, China
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Author to whom correspondence should be addressed.
Atmosphere 2020, 11(5), 481; https://doi.org/10.3390/atmos11050481
Received: 17 April 2020 / Revised: 3 May 2020 / Accepted: 6 May 2020 / Published: 8 May 2020
(This article belongs to the Section Aerosols)
Studies on the detection of layers with elevated black carbon aerosol (BC) concentrations and the formation conditions of these layers help understand the vertical distribution of BC concentrations, which will provide a basis for the assessment of climate effects and early pollution warnings. By using the Weather Research and Forecasting with Chemistry (WRF-Chem) numerical model, we performed a numerical simulation analysis on the authenticity of strongly elevated BC concentration layers that were detected by an aircraft in the mixing layer over Harbin, China, which is a high-emission area, on a clear sunny afternoon in the early heating period of 2016. We then discuss possible problems and solutions when non-vertical paths are used to detect the vertical distribution of BC concentrations. Finally, we discuss the favorable conditions for the formation of elevated BC concentration layers by a weak vertical flow based on the simulation. The modeling results show that the horizontal variability of BC concentration in the mixing layer in the observation area in Harbin was sufficiently large during the measurement. This produced a false elevated layer, as detected by the aircraft during one round of spiral flight in the mixing layer. The root mean square of the horizontal distribution of BC concentration did not change with height in the mixing layer during the daytime, but it decreased with the thickness of the mixing layer and was higher in the mixing layer than in the free atmosphere. Therefore, the thinner the mixing layer, in which the vertical distribution of the BC concentration is detected in an inclined path, the stronger interference of the horizontal variability on the detected results. In the daytime, due to strong turbulence in the mixing layer, weak vertical uplift is not favorable for the occurrence of elevated BC concentration layers in the mixing layer. In the nighttime, if weak vertical uplift is well-matched with the BC concentration or its vertical gradient, elevated BC concentration layers can be formed in the atmosphere. Compared with upper layers far from the ground, nighttime elevated layers are easier to form in lower layers near the ground because high BC concentrations or large vertical gradients are more likely to occur in the lower layers. Both cases facilitate the occurrence of large vertical upward transport rates of BC. View Full-Text
Keywords: black carbon aerosol; aerosol layer; vertical distribution; numerical simulation; WRF-Chem black carbon aerosol; aerosol layer; vertical distribution; numerical simulation; WRF-Chem
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MDPI and ACS Style

Jin, L.; Lin, L.; Ding, D.; Zhao, D.; Zhu, B.; Zhai, Q.; Liu, Z. The Observation Path Problems and the Formation Conditions of the Elevated Layer of Black Carbon Aerosol. Atmosphere 2020, 11, 481. https://doi.org/10.3390/atmos11050481

AMA Style

Jin L, Lin L, Ding D, Zhao D, Zhu B, Zhai Q, Liu Z. The Observation Path Problems and the Formation Conditions of the Elevated Layer of Black Carbon Aerosol. Atmosphere. 2020; 11(5):481. https://doi.org/10.3390/atmos11050481

Chicago/Turabian Style

Jin, Lianji; Lin, Liang; Ding, Deping; Zhao, Delong; Zhu, Bin; Zhai, Qingfei; Liu, Zheng. 2020. "The Observation Path Problems and the Formation Conditions of the Elevated Layer of Black Carbon Aerosol" Atmosphere 11, no. 5: 481. https://doi.org/10.3390/atmos11050481

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