Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe

Vogel, Bärbel; Müller, Rolf; Günther, G.; Spang, Reinhold; Hanumanthu, Sreeharsha; Li, Dan; Riese, Martin; Stiller, G. P.

doi:10.5194/acp-19-6007-2019

Cited by 87 publications

(177 citation statements)

References 80 publications

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“…Here we find that the local ascent over the Asian monsoon region also plays an important role in carrying the tracer in the UTLS. Similar conclusions on the role of the upward ascent, driven by radiative heating, in the transport in the UTLS over the Asian summer monsoon region are also suggested in previous studies (e.g., Bergman et al, 2012;Garny & Randel, 2016;Park et al, 2007;Ploeger et al, 2017;Vogel et al, 2019). Therefore, to summarize, for the ensemble of BIR tracers released during July, we have found a fast transport pathway from the NH surface to the UTLS over the southern slope of the Tibetan Plateau, northern India, the Arabian Sea and Saudi Arabia.…”

Section: 1029/2019jd031552supporting

confidence: 90%

Fast Transport Pathways Into the Northern Hemisphere Upper Troposphere and Lower Stratosphere During Northern Summer

Orbe

Tilmes

et al. 2020

JGR Atmospheres

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This study identifies the fast (i.e., ∼ days-weeks) transport pathways that connect the Northern Hemisphere surface to the upper troposphere and lower stratosphere (UTLS) during northern summer by integrating a large (90 member) ensemble of Boundary Impulse Response tracers in the Whole Atmosphere Community Climate Model version 5. We show that there is a fast transport pathway that occurs over the southern slope of the Tibetan Plateau, northern India, the Arabian Sea, and Saudi Arabia; furthermore, we show that during July this pathway connects the Northern Hemisphere surface to the UTLS on a modal time scale of 5-10 days. A less efficient transport pathway is also identified over the western Pacific. A detailed budget analysis reveals that, while convective processes are responsible for transport to 200-300 hPa, the resolved dynamics, specifically the vertical eddy flux, dominate at 100-150 hPa. Transport variations are analyzed on weekly, monthly, and interannual time scales and are largely related to differences in the resolved dynamics in the UTLS.

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Section: 1029/2019jd031552supporting

confidence: 90%

Fast Transport Pathways Into the Northern Hemisphere Upper Troposphere and Lower Stratosphere During Northern Summer

Orbe

Tilmes

et al. 2020

JGR Atmospheres

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“…From a more detailed analysis of the geostationary satellite images (not shown), those high injection events turn out to be very localized (convective clouds dimensions of the order of 1 • ) and fast developing (persisting for a period of around 2 hours) 5 injecting air directly into the upper troposphere. This pollution is then advected horizontally by the anticyclonic circulation, at the same time ascending, following the upward large-scale pattern suggested by Vogel et al (2019). The total vertical displacement between the convective injection of air and the moment of observation is of 2 km for the Chinese air in a time of 2-3 days and ∼ 1km for the Southeast Asia Peninsula air in a time of 5-7 hours, faster with respect to the estimated average radiative heating rate (Wright and Fueglistaler, 2013).…”

Section: Panel E) Show a Better Consistencymentioning

confidence: 70%

“…Ning, G., Wang, S., Ma, M., Ni, C., Shang, Z., Wang, J., and Li, J.: Characteristics of air pollution in different zones of Sichuan Basin, China, Science of The Total Environment, 612, 975-984, doi:10.1016/j.scitotenv.2017.08.205, https://linkinghub.elsevier.com/retrieve/ Ploeger, F., Konopka, P., Müller, R., Fueglistaler, S., Schmidt, T., Manners, J. C., Grooß, J.-U., Günther, G., Forster, P. M., and Riese, M.: Horizontal transport affecting trace gas seasonality in the Tropical Tropopause Layer (TTL), Journal of Geophysical Research: Atmospheres, 117, doi:10.1029/2011JD017267, https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2011JD017267, 2012. Ploeger, F., Günther, G., Konopka, P., Fueglistaler, S., Müller, R., Hoppe, C., Kunz, A., Spang, R., Grooß, J.-U., and Riese, M.: Horizontal water vapor transport in the lower stratosphere from subtropics to high latitudes during boreal summer, Journal of Geophysical Research: 15 Atmospheres, 118, 8111-8127, doi:10.1002/jgrd.50636, http://doi.wiley.com/10.1002/jgrd.50636, 2013.Qiao, X., Guo, H., Tang, Y., Wang, P., Deng, W., Zhao, X., Hu, J., Ying, Q., and Zhang, H.: Local and regional contributions to fine particulate matter in the 18 cities of Sichuan Basin, southwesternChina, Atmospheric Chemistry and Physics, 19, 5791-5803, doi:10.5194/acp-19- 5791-2019, https://www.atmos-chem-phys.net/19/5791/2019/, 2019. Randel, W. J. and Park, M.: Deep convective influence on the Asian summer monsoon anticyclone and associated tracer variability observed 20 with Atmospheric Infrared Sounder (AIRS), Journal of Geophysical Research, 111, doi:10.1029/2005JD006490, http://doi.wiley.com/10.…”

mentioning

confidence: 99%

Deep convective influence on the UTLS composition in the Asian Monsoon Anticyclone region: 2017 StratoClim campaign results

Bucci

Legras

Sellitto

et al. 2020

Preprint

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Abstract. The StratoClim stratospheric aircraft campaign took place in summer 2017 in Nepal (the 27th of July–10th of August) and provided a wide dataset of observations of air composition inside the Asian Monsoon Anticyclone. In the framework of this project, with the purpose of modelling the injection of pollutants and natural compounds into the stratosphere, we performed a series of diffusive back-trajectories runs along the flights' tracks. The availability of in-situ measurements of trace gases has been exploited to evaluate the capability of the trajectory system to reproduce the transport in the Upper Troposphere–Lower Stratosphere (UTLS) region. The diagnostics of the convective sources and mixing in the air parcel samples have been derived by integrating the trajectories output with high-resolution observations of cloud tops from the Meteosat Second Generation (MSG1) and Himawari geostationary satellites. Back-trajectories have been calculated using meteorological fields from European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis (ERA-Interim and ERA-5) at 3 h and 1 h resolution, using both kinematic and diabatic vertical motion. The comparison among the different trajectory runs shows, in general, a higher consistency with observed data, as well as a better agreement between the diabatic and kinematic version, when using ERA-5 based runs with respect to ERA-Interim. Overall, a better capacity in reproducing the pollution features is finally found in the diabatic version of the ERA-5 runs. Adopting this setting for the analysis, a large variety of transport conditions have been individuated during the 8 flights of the campaign. The larger influence by convective injections is found from the continental sources of China and India. Only a small contribution appears to be originated from maritime regions, in particular the South Pacific and the Bay of Bengal that, unexpectedly, was not particularly active during the period of the campaign. Thin filamentary structures of polluted air, characterized by peaks in CO, are observed, mostly associated with young convective air (age less than a few days) and a predominant South-China origin. Observed air from continental India, on the contrary, is often linked to a lower concentration of the trace gas and to air masses that recirculated within the anticyclone for 10 to 20 days. Vertical stratification in the age of air is observed: up to 15 km, the age is less than 3 days and these fresh air masses constitute almost the totality of the air composition. A transition layer is then individuated between 15 km and 17 km, where the convective contribution is still dominant and the ages vary between one and two weeks. Above this level, the mean age of the air sampled by the aircraft is estimated to be 20 days. There, the convective contribution rapidly decreases with height, and finally became negligible around 20 km.

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“…This set-up is quite similar to that of, e.g., Bergman et al (2013). Some other studies where the tracers are initialized in the boundary layer used instead the total heating rate (Vogel et al, 2015;Ploeger et al, 2017;Vogel et al, 2019;Li et al, 2019). Above the level of maximum cloud cover, the total heating rate converges rapidly to the radiative heating rate as a function of increasing potential temperature.…”

Section: Lagrangian Trajectoriesmentioning

confidence: 99%

Confinement of air in the Asian monsoon anticyclone and pathways of convective air to the stratosphere during summer season

Legras¹,

Bucci²

2019

Preprint

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Abstract. We study the transport pathways from the top of convective clouds to the lower tropical stratosphere during the Asian monsoon, using massive Lagrangian trajectories driven by observed clouds and the two reanalysis ERA-Interim and ERA5 with diabatic and kinematic vertical motions. We find that the upward propagation of convective impact is very similar for the kinematic and diabatic calculations using ERA5 while the two cases strongly differ for ERA-Interim. The separation of descending and ascending motion occurs at a crossover level which is slightly above the all sky zero level of radiative heating rate, except over the Tibetan plateau. The parcels that stay confined within the Asian monsoon anticyclone and reach 380&#8201;K are mostly of continental origin while maritime sources are dominating when the whole global 380&#8201;K surface is considered. We find that the strong impact of the Tibetan plateau with respect to its share of high clouds is entirely due to its elevated proportion of high clouds above the crossover. We find no trace of a vertical conduit above convection over the Tibetan plateau; parcels are rather entrained into an ascending spiral motion that spans the whole anticyclone. The mean age of parcels with respect to convection exhibits a minimum at the centre of the Asian monsoon anticyclone due to the permanent renewal by fresh convective air and largest values on the periphery as air spirals out. The contrast is reduced by dilution for increasing potential temperature. We find that the confinement above 360 K can be represented, on the average, by a simple 1D process of diabatic advection with loss. The mean loss time is about 13 days and uniform over the range 360&#8201;K to 420&#8201;K which is to be compared with a total circulation time of two to three weeks around the anticyclone. The vertical dilution is consequently exponential with an e-folding potential temperature scale of 15&#8201;K (about 3&#8201;km).

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Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe

Cited by 87 publications

References 80 publications

Fast Transport Pathways Into the Northern Hemisphere Upper Troposphere and Lower Stratosphere During Northern Summer

Fast Transport Pathways Into the Northern Hemisphere Upper Troposphere and Lower Stratosphere During Northern Summer

Deep convective influence on the UTLS composition in the Asian Monsoon Anticyclone region: 2017 StratoClim campaign results

Confinement of air in the Asian monsoon anticyclone and pathways of convective air to the stratosphere during summer season

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