Lidar-observed enhancement of aerosols in the upper troposphere and lower stratosphere over the Tibetan Plateau induced by the Nabro volcano eruption

He, Qianshan; Li, C. C.; Ma, Jianzhong; Wang, H. Q.; Yan, Xiaolu; Lu, Jiangjin; Liang, Z. R.; Gao, Qi

doi:10.5194/acp-14-11687-2014

Cited by 16 publications

(13 citation statements)

References 36 publications

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“…The anticyclone is very strong in the upper troposphere (at 15 km), and it is still clearly visible in the lower stratosphere (e.g., at 18 km), with the core area shifting northerly with increasing altitude. As found in early studies (e.g., Highwood and Hoskins, 1998), the ASM tropopause is relatively high, with a maximum around 17 km (corresponding to about 92-95 hPa) over the area of approximately 30-120 • E and 20-35 • N, including the Iranian Plateau to southern Tibetan Plateau. The air masses in the ASM anticyclone are characterized more by tropospheric than stratospheric properties.…”

Section: General Featuressupporting

confidence: 57%

Modeling the aerosol chemical composition of the tropopause over the Tibetan Plateau during the Asian summer monsoon

Brühl

et al. 2019

Atmos. Chem. Phys.

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Enhanced aerosol abundance in the upper troposphere and lower stratosphere (UTLS) associated with the Asian summer monsoon (ASM) is referred to as the Asian Tropopause Aerosol Layer (ATAL). The chemical composition, microphysical properties, and climate effects of aerosols in the ATAL have been the subject of discussion over the past decade. In this work, we use the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model at a relatively fine grid resolution (about 1.1 × 1.1 • ) to numerically simulate the emissions, chemistry, and transport of aerosols and their precursors in the UTLS within the ASM anticyclone during the years 2010-2012. We find a pronounced maximum of aerosol extinction in the UTLS over the Tibetan Plateau, which to a large extent is caused by mineral dust emitted from the northern Tibetan Plateau and slope areas, lofted to an altitude of at least 10 km, and accumulating within the anticyclonic circulation. We also find that the emissions and convection of ammonia in the central main body of the Tibetan Plateau make a great contribution to the enhancement of gas-phase NH 3 in the UTLS over the Tibetan Plateau and ASM anticyclone region. Our simulations show that mineral dust, water-soluble compounds, such as nitrate and sulfate, and associated liquid water dominate aerosol extinction in the UTLS within the ASM anticyclone. Due to shielding of high background sulfate concentrations outside the anticyclone from volcanoes, a relative minimum of aerosol extinction within the anticyclone in the lower stratosphere is simulated, being most pronounced in 2011, when the Nabro eruption occurred. In contrast to mineral dust and nitrate concentrations, sulfate increases with increasing altitude due to the larger volcano effects in the lower stratosphere compared to the upper troposphere. Our study indicates that the UTLS over the Tibetan Plateau can act as a well-defined conduit for natural and anthropogenic gases and aerosols into the stratosphere.

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Section: General Featuressupporting

confidence: 57%

Modeling the aerosol chemical composition of the tropopause over the Tibetan Plateau during the Asian summer monsoon

Brühl

et al. 2019

Atmos. Chem. Phys.

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“…Recently, Yu et al (2017) further revealed a widespread enhanced aerosol layer extending from several kilometres below the tropopause up to 2 km above the tropopause within the ASM anticyclone, by measuring the vertical profiles of particle surface area density using an optical particle spectrometer in balloon soundings 25 from Kunming, China, in August 2015. Figure 4a shows EMAC simulated temporal variation in the vertical profile of aerosol extinction over Naqu in August 2011, which coincided with the period of aerosol vertical profile measurements at Naqu reported by He et al (2014). It can be seen that EMAC predicts persistently enhanced aerosol abundance between 17-20 km altitude, with maxima occurring at 18-19 km; aerosols near the tropopause have a higher variability in the upper troposphere than in the lower stratosphere.…”

Section: Aerosol Extinctionsupporting

confidence: 70%

“…China in 1999. He et al (2014) found a 3-4 km thick aerosol layer in the UTLS peaking at an altitude of 18-19 km (1-2 km above the tropopause), by measuring the vertical profiles of the aerosol extinction coefficient with a micro-pulse lidar at Naqu, China in July-August 2011. Recently, Yu et al (2017) further revealed a widespread enhanced aerosol layer extending from several kilometres below the tropopause up to 2 km above the tropopause within the ASM anticyclone, by measuring the vertical profiles of particle surface area density using an optical particle spectrometer in balloon soundings 25 from Kunming, China, in August 2015.…”

Section: Aerosol Extinctionmentioning

confidence: 99%

Modelling the aerosol chemical composition of the tropopause over the Tibetan Plateau during the Asian summer monsoon

Ma¹,

Brühl²,

He³

et al. 2019

Preprint

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<p><strong>Abstract.</strong> Enhanced aerosol abundance in the upper troposphere and lower stratosphere (UTLS) associated with the Asian summer monsoon (ASM), is referred to as the Asian Tropopause Aerosol Layer (ATAL). The chemical composition, microphysical properties and climate effects of aerosols in the ATAL have been the subject of discussion over the past decade. In this work, we use the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model at a relatively fine grid resolution (about 1.1&#8201;&#215;&#8201;1.1 degrees) to numerically simulate the emissions and chemistry of aerosols and their precursors in the UTLS within the ASM anticyclone during the years 2010&#8211;2012. We find a pronounced maximum in aerosol extinction in the UTLS over the Tibetan Plateau, which to a large extent is caused by mineral dust emitted from the northern Tibetan Plateau and slope areas, lofted to an altitude of at least 10&#8201;km, and accumulating within the anticyclonic circulation. Our simulations show that mineral dust, water soluble compounds, such as nitrate and sulfate, and associated liquid water dominate aerosol extinction in the UTLS within the ASM anticyclone. Due to shielding of high background sulfate concentrations outside the anticyclone from volcanoes, a relative minimum of aerosol extinction within the anticyclone in the lower stratosphere is simulated, being most pronounced in 2011 when the Nabro eruption occurred. In contrast to mineral dust and nitrate concentrations, sulfate increases with increasing altitude due to the larger volcano effects in the lower stratosphere compared to the upper troposphere. Our study indicates that the UTLS over the Tibetan Plateau can act as a well-defined conduit for natural and anthropogenic gases and aerosols into the stratosphere.</p>

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“…altitude over the Tibetan Plateau during summer (Tobo et al, 2007;Vernier et al, 2011). He et al (2014) examined the vertical profiles of aerosol extinction coefficients measured with a micro-pulse lidar at Naqu, about 100 km east of Nam Co station, and observed a maximum in aerosol extinction coefficient between 18 and 19 km a.s.l. during summer 2011.…”

Section: The Average Chemical Feature Of Organic Aerosolmentioning

confidence: 99%

Chemical characteristics of submicron particles at the central Tibetan Plateau: insights from aerosol mass spectrometry

Zhang

Shi

et al. 2018

Atmos. Chem. Phys.

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Abstract. Recent studies have revealed a significant influx of anthropogenic aerosol from South Asia to the Himalayas and Tibetan Plateau (TP) during pre-monsoon period. In order to characterize the chemical composition, sources, and transport processes of aerosol in this area, we carried out a field study during June 2015 by deploying a suite of online instruments including an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS) and a multi-angle absorption photometer (MAAP) at Nam Co station (90 • 57 E, 30 • 46 N; 4730 m a.s.l.) at the central of the TP. The measurements were made at a period when the transition from premonsoon to monsoon occurred. The average ambient mass concentration of submicron particulate matter (PM 1 ) over the whole campaign was ∼ 2.0 µg m −3 , with organics accounting for 68 %, followed by sulfate (15 %), black carbon (8 %), ammonium (7 %), and nitrate (2 %). Relatively higher aerosol mass concentration episodes were observed during the pre-monsoon period, whereas persistently low aerosol concentrations were observed during the monsoon period. However, the chemical composition of aerosol during the higher aerosol concentration episodes in the pre-monsoon season was on a case-by-case basis, depending on the prevailing meteorological conditions and air mass transport routes. Most of the chemical species exhibited significant diurnal variations with higher values occurring during afternoon and lower values during early morning, whereas nitrate peaked during early morning in association with higher relative humidity and lower air temperature. Organic aerosol (OA), with an oxygen-to-carbon ratio (O / C) of 0.94, was more oxidized during the pre-monsoon period than during monsoon (average O / C ratio of 0.72), and an average O / C was 0.88 over the entire campaign period, suggesting overall highly oxygenated aerosol in the central TP. Positive matrix factorization of the high-resolution mass spectra of OA identified two oxygenated organic aerosol (OOA) factors: a less oxidized OOA (LO-OOA) and a more oxidized OOA (MO-OOA). The MO-OOA dominated during the pre-monsoon period, whereas LO-OOA dominated during monsoon. The sensitivity of air mass transport during pre-monsoon with synoptic process was also evaluated with a 3-D chemical transport model.

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Lidar-observed enhancement of aerosols in the upper troposphere and lower stratosphere over the Tibetan Plateau induced by the Nabro volcano eruption

Cited by 16 publications

References 36 publications

Modeling the aerosol chemical composition of the tropopause over the Tibetan Plateau during the Asian summer monsoon

Modeling the aerosol chemical composition of the tropopause over the Tibetan Plateau during the Asian summer monsoon

Modelling the aerosol chemical composition of the tropopause over the Tibetan Plateau during the Asian summer monsoon

Chemical characteristics of submicron particles at the central Tibetan Plateau: insights from aerosol mass spectrometry

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