On the Linkage Between the Asian Summer Monsoon and Tropopause Folds

Wu, Yutian; Chen, Gang; Taylor, Lindsey; Zhang, Pengfei

doi:10.1002/2017jd027870

Cited by 15 publications

(11 citation statements)

References 53 publications

(94 reference statements)

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“…In this study, an improved 3D labeling algorithm is used to investigate the frequency of tropopause folds over the TP in different seasons from January 1, 1979 to December 31, 2019. Figure4shows that folds occur along the subtropical jet stream and follow the northward or southward migration of the subtropical jet stream, in agreement with previous studies ((Wu et al 2018;Luo et al 2019). Tropopause folds occur mainly in the southern Tibetan Plateau in winter and spring, and move westward from winter to spring.…”

supporting

confidence: 91%

Tropopause folds over the Tibetan Plateau and their impact on water vapor in the upper troposphere-lower stratosphere

Zhang

Huang

Guo

et al. 2023

Preprint

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As one of the most important greenhouse gases, water vapor in the upper troposphere and lower stratosphere (UTLS) has a significant impact on the global earth-atmosphere system. The Tibetan Plateau (TP) is an important high terrain which exerts a profound impact on the change of weather and climate, and mass exchange. Tropopause folds occur frequently over the TP due to the impact of the subtropical westerly jet, which affects water vapor transport between the stratosphere and the troposphere. In this paper, the spatial and temporal distribution characteristics of tropopause folds over the TP are examined by applying an improved three-dimensional (3D) labeling algorithm to the ERA5 reanalysis data (1979 to 2019). The effects of different fold depths in various regions over the TP on the variations of UTLS water vapor are further studied. The results of a case study (25 February 2008) suggest that there is a good continuity in identification of the fold depth for the same fold event using the improved 3D labeling algorithm. The fold depth and height are consistent with the results of radiosonde data and ERA5 reanalysis data. The fold frequency over the TP shows an increasing trend in the last 41 years, with slightly lower frequency of medium folds than that of shallow folds, and lowest frequency of deep folds. There is increasing water vapor in the UTLS over the TP due to tropopause folds. The results indicate that tropopause folds enhance the horizontal divergence of water vapor in the UTLS and increase the vertical water vapor flux in the UTLS region. The folding over the plateau leads to increased moisture in the UTLS. It is argued that vertical velocity anomalies in the vicinity of the fold and subgrid perturbations have a significant impact on the increase of UTLS water vapor over the TP. The results of this work provide a scientific basis for a better understanding of the stratosphere-troposphere exchanges due to tropopause folds over the TP.

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supporting

confidence: 91%

Tropopause folds over the Tibetan Plateau and their impact on water vapor in the upper troposphere-lower stratosphere

Zhang

Huang

Guo

et al. 2023

Preprint

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“…In agreement with this, recent studies indicated a possible linkage between the TFs over these two hot spots with the Asian summer monsoon (Tyrlis et al 2014;Wu et al 2018). It was found that TFs tend to occur at the northwestern side of the monsoon-related upper-level anticyclone (i.e., the SAH), and become more frequent when the monsoon SAH intensifies (Tyrlis et al 2014;Wu et al 2018).…”

Section: Introductionsupporting

confidence: 65%

“…At the western flank of the SAH, convergent southerlies prevail in the upper troposphere over the eastern Mediterranean and central Asian regions, which help to accelerate the SWJ and enhance the local vertical wind shear, thus favoring the formation of a jet streak and TF occurrence there (Traub and Lelieveld 2003). In agreement with this, recent studies indicated a possible linkage between the TFs over these two hot spots with the Asian summer monsoon (Tyrlis et al 2014;Wu et al 2018). It was found that TFs tend to occur at the northwestern side of the monsoon-related upper-level anticyclone (i.e., the SAH), and become more frequent when the monsoon SAH intensifies (Tyrlis et al 2014;Wu et al 2018).…”

Section: Introductionsupporting

confidence: 53%

Tropopause Folding Events to the East of Tibetan Plateau in Boreal Summer and their Remote Relation to the Circulation Anomalies over Northeastern Atlantic

Zhu¹,

Ren²

2021

Preprint

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This study investigates the occurrence of tropopause folding (TF) events to the east of Tibetan Plateau (ETP) (TF–ETP) in boreal summer. Firstly, it is revealed that, anomalously frequent TF–ETP occurrence in summer, always corresponds to a significant dipole rainfall anomaly pattern over China, with negative rainfall anomalies over the upper and middle reaches of the Yangtze and Yellow river valleys, and positive rainfall anomalies over eastern China. Secondly, the South Asian High (SAH) center over Tibetan Plateau (TP) is found to be anomalously stronger when occurrence of TF–ETP events is frequent. Further diagnosis indicates that, the TF–ETP occurrence is related to an eastward propagating Rossby wave train (RWT) that originates from a barotropic low anomaly center over the northeastern Atlantic (NEA) about one–week before. The RWT propagates downstream via Western Europe, the west of Baikal and down to East Asia along the mid-latitude westerlies, and is connected to a high anomaly center over the north rim of TP, which enhances the SAH center over TP. The enhanced SAH in turn favors the southward and downward PV intrusion and the subsequent occurrence of TF–ETP. Furthermore, the low anomaly center that initiates the RWT is related to dynamical forcing of transient eddy activity over the NEA, which induces the low via eddy-forced upper divergence and its pumping. Finally, such local and remote processes are confirmed in a typical TF–ETP case. The ERA–Interim daily fields during 1979–2018 is used.

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“…High concentrations of carbon monoxide (CO) and other tropospheric pollutants as well as low levels of ozone are also found aloft above the monsoon regions (e.g., Li et al, ; Park et al, , ; Randel et al, ; Randel & Park, ). In addition, the summer monsoon region is also critical for stratosphere‐to‐troposphere transport (e.g., Skerlak et al, ; Tyrlis et al, ; Wu et al, ).…”

Section: Introductionmentioning

confidence: 99%

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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On the Linkage Between the Asian Summer Monsoon and Tropopause Folds

Cited by 15 publications

References 53 publications

Tropopause folds over the Tibetan Plateau and their impact on water vapor in the upper troposphere-lower stratosphere

Tropopause folds over the Tibetan Plateau and their impact on water vapor in the upper troposphere-lower stratosphere

Tropopause Folding Events to the East of Tibetan Plateau in Boreal Summer and their Remote Relation to the Circulation Anomalies over Northeastern Atlantic

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

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