Efficient transport of tropospheric aerosol into the stratosphere via the Asian summer monsoon anticyclone

Yu, Pengfei; Rosenlof, Karen H.; Liu, Shang; Telg, Hagen; Thornberry, T. D.; Rollins, A. W.; Portmann, R. W.; Bai, Zhihui; Ray, E. A.; Duan, Yunjun; Pan, Laura L.; Toon, O. B.; Bian, Jianchun; Gao, R. S.

doi:10.1073/pnas.1701170114

Cited by 128 publications

(160 citation statements)

References 40 publications

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“…Whether these differences result from model design, incorrect boundary conditions (e.g. underestimated anthropogenic (Yu et al, 2017) or volcanic (Bandoro et al, 2018) aerosol contributions), or missing chemistry remains an open question.…”

Section: Comparison Of Stratospheric Spatial and Partial Column Ozonementioning

confidence: 99%

Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery

et al. 2018

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Abstract. Ozone forms in the Earth's atmosphere from the photodissociation of molecular oxygen, primarily in the tropical stratosphere. It is then transported to the extratropics by the Brewer-Dobson circulation (BDC), forming a protective "ozone layer" around the globe. Human emissions of halogen-containing ozone-depleting substances (hODSs) led to a decline in stratospheric ozone until they were banned by the Montreal Protocol, and since 1998 ozone in the upper stratosphere is rising again, likely the recovery from halogeninduced losses. Total column measurements of ozone between the Earth's surface and the top of the atmosphere indicate that the ozone layer has stopped declining across the globe, but no clear increase has been observed at latitudes between 60 • S and 60 • N outside the polar regions (60-90 • ). Here we report evidence from multiple satellite measurements that ozone in the lower stratosphere between 60 • S and 60 • N has indeed continued to decline since 1998. We find that, even though upper stratospheric ozone is recoverPublished by Copernicus Publications on behalf of the European Geosciences Union. 1380 W. T. Ball et al.: Continuous stratospheric ozone decline ing, the continuing downward trend in the lower stratosphere prevails, resulting in a downward trend in stratospheric column ozone between 60 • S and 60 • N. We find that total column ozone between 60 • S and 60 • N appears not to have decreased only because of increases in tropospheric column ozone that compensate for the stratospheric decreases. The reasons for the continued reduction of lower stratospheric ozone are not clear; models do not reproduce these trends, and thus the causes now urgently need to be established.

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Section: Comparison Of Stratospheric Spatial and Partial Column Ozonementioning

confidence: 99%

Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery

et al. 2018

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“…Vernier et al (2018) and Yu et al (2017) provided additional in situ verification of the ATAL from recent balloon launches in India and Saudi Arabia, and from China, respectively. The presence of an ATAL suggests that the ASM may provide a conduit for aerosols, and/or precursor gases, to reach and be dispersed in the UTLS (Neely et al, 2014;Yu et al, 2017). In addition, the proximity of ATAL aerosols to ice clouds in the ASM anticyclone (Vernier et al, 2018) indicates the potential for ATAL aerosols to alter cloud optical properties (Fadnavis et al, 2013(Fadnavis et al, , 2017Li et al, 2005), which could impact regional climate.…”

Section: 1029/2019jd031506mentioning

confidence: 99%

Estimates of Regional Source Contributions to the Asian Tropopause Aerosol Layer Using a Chemical Transport Model

et al. 2020

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The Asian Tropopause Aerosol Layer (ATAL) represents an accumulation of aerosol in the upper troposphere and lower stratosphere associated with the Asian Summer Monsoon. Here we simulate the ATAL for summer 2013 with the GEOS‐Chem chemical transport model and explore the likely composition of ATAL aerosols and the relative contributions of regional anthropogenic sources versus those from farther afield. The model indicates significant contributions from organic aerosol, nitrate, sulfate, and ammonium aerosol, with regional anthropogenic precursor sources dominant. The model underestimates aerosol backscatter in the ATAL during summer 2013, compared with Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite instrument. Tests of a more physically based treatment of wet scavenging of SO2 in convective updrafts raise sulfate, eliminating the low bias with respect to CALIPSO backscatter in the ATAL, but lead to an unacceptable high bias of sulfate compared with in situ observations from aircraft over the United States. Source apportionment of the model results indicate the dominance of regional anthropogenic emissions from China and the Indian subcontinent to aerosol concentrations in the ATAL; ~60% of sulfate in the ATAL region in August 2013 is attributable to anthropogenic sources of SO2 from China (~30%) and from the Indian subcontinent (~30%), twice as much as in previously published estimates. Nitrate aerosol is found to be a dominant component of aerosol composition on the southern flank of the Asian Summer Monsoon anticyclone. Lightning sources of NOx are found to make a significant (10–15%) contribution to nitrate in the ATAL for the case studied.

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“…They detected relatively high number concentrations (0.7-0.8 cm −3 ) of submicron-sized aerosols (0.3-1.2 μm in diameter) present near the tropopause region and inside the ASM region and were suggested to be induced by the deep convection over the TP. Later, in 2015, by analyzing measurements from the Portable Optical Particle Counter (POPS) (Gao et al 2016) in Kunming (25.01°N, 102.65°E; 1889 m ASL, as shown in figure 1), Yu et al (2017) confirmed the existence of a robust enhanced aerosol layer that extends up to 2 km above the tropopause. Both studies have indeed provided valuable observations about the aerosol layer during the ASM period; nevertheless, as specified later, in section 4, they also have their own limitations.…”

Section: Introductionmentioning

confidence: 92%

“…Previous studies showed that the ASM may transport tropospheric air into the stratosphere effectively by creating a dome or 'bubble' of tropospheric air above the zonal mean tropopause (Randel and Park 2006, Park et al 2007, Pan et al 2016. It is further noted that the ASM coupled with deep convection uplifting may serve as a more efficient chimney, venting tropospheric aerosols up to the UTLS, thereby significantly influencing the high-altitude aerosol properties (Li et al 2005, Randel et al 2010, Vernier et al 2015, Yu et al 2015, 2017.…”

Section: Introductionmentioning

confidence: 99%

In situ measurements and backward-trajectory analysis of high-concentration, fine-mode aerosols in the UTLS over the Tibetan Plateau

Liu

Bai

et al. 2019

Environ. Res. Lett.

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An aerosol layer in the upper troposphere and lower stratosphere over the Asian summer monsoon (ASM) regions, namely, the Asian tropopause aerosol layer (ATAL), has been observed based on satellite remote sensing and in situ measurements; however, its source is still under debate. In August 2018, an experimental campaign over the Tibetan Plateau at Golmud (GLM, 36.48°N, 94.93°E) was performed, during which a balloon-borne Portable Optical Particle Counter was used to measure the aerosol particle profile. Backward-trajectory simulations were conducted with the Massive-Parallel Trajectory Calculations model to investigate the possible sources and transport pathways of the observed particles. The in situ measurements showed a robust ATAL around the tropopause, 16 km above sea level, with a maximum aerosol number density of 35 cm −3 and a maximum aerosol mass concentration of 0.15 μg m −3 for particles with diameters between 0.14 and 3 μm. The aerosol particles in the ATAL are mostly smaller than 0.25 μm in diameter, accounting for 98% of all aerosol particles detected. The backward-trajectory analysis revealed that the air parcels arrived at the altitude of the ATAL through two separate pathways: (1) the uplift below the 360 K isentropic surface, where air parcels were first elevated to the upper troposphere and then joined the ASM anticyclonic circulation; and (2) the quasi-horizontal transport along the anticyclonic circulation, located approximately between the 360 and 420 K isentropic surfaces. The complex transport pathways may aggravate the challenge of analyzing the composition of the ATAL, and further observation campaigns are required to extend our knowledge.

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Efficient transport of tropospheric aerosol into the stratosphere via the Asian summer monsoon anticyclone

Cited by 128 publications

References 40 publications

Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery

Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery

Estimates of Regional Source Contributions to the Asian Tropopause Aerosol Layer Using a Chemical Transport Model

In situ measurements and backward-trajectory analysis of high-concentration, fine-mode aerosols in the UTLS over the Tibetan Plateau

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