Mechanism of The Summer Rainfall Variation in Transitional Climate Zone in East Asia From the Perspective of Moisture Supply During 1979-2010 Based On The Lagrangian Method

Abstract Transitional Climate Zone (TCZ) over East Asia, characterized by semi-arid climate, is ecologically fragile environment with limited water resources, making atmospheric moisture supply being the key influential factor. This study investigates the moisture sources of summer (JJA) rainfall in the TCZ over East Asia during 1979-2010 with the Lagrangian particle dispersion model. Seven moisture source regions and associated contribution are quantified: Eurasia continent to northwest of the TCZ (EC, 18.01%), central-eastern China (CEC, 17.14%), western Pacific Ocean (WPO, 7.46%), South China Sea and Indonesia (SCSI, 3.56%), Bay of Bengal (BOB, 2.55%), Arabian Sea (AS, 2.13%) and local evaporation (TCZ, 19.96%). The moisture contribution from ocean (16.06%) is less than those from the continent (55.11%), due to the great loss en-route. In particular, the local evaporation not only contributes the most moisture among 7 selected source regions, but also has the greatest influence in summer precipitation variability in TCZ. Furthermore, westerlies precipitation and monsoon precipitation are discriminated according to the dominant system of water vapor source regions. It is found that summer monsoon contributes most of water vapor (33.2%) to summer rainfall in TCZ, while only 18.01% comes from the mid-latitude westerlies dominant area. Finally, further analysis of dry and wet years shows that summer monsoon system also takes more responsibility for a drier or wetter summer in TCZ from the perspective of moisture supply, followed by local evaporation and mid-latitude westerlies.

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Modulation of coupled modes of Tibetan Plateau heating and Indian Summer Monsoon on summer rainfall over Central Asia

Journal of Climate ◽

10.1175/jcli-d-20-0813.1 ◽

2021 ◽

pp. 1-54

Keyword(s):

Water Vapor ◽

Tibetan Plateau ◽

Central Asia ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Diabatic Heating ◽

Summer Rainfall ◽

Hadley Cell ◽

Vapor Transport ◽

Water Vapor Transport

Abstract It has been suggested that summer rainfall over Central Asia (CA) is significantly correlated with the summer thermal distribution of the Tibetan Plateau (TP) and the Indian summer monsoon (ISM). However, relatively few studies have investigated their synergistic effects of different distribution. This study documents the significant correlations between precipitation in CA and the diabatic heating of TP and the ISM based on the results of statistical analysis and numerical simulation. Precipitation in CA is is dominated by two water vapor transport branches from the south which are related to the two primary modes of anomalous diabatic heating distribution related to the TP and ISM precipitation, that is, the “+-” dipole mode in the southeastern TP and the Indian subcontinent (IS), and the “+-+” tripole mode in the southeastern TP, the IS, and southern India. Both modes exhibit obvious mid-latitude Silk Road pattern (SRP) wave trains with cyclone anomalies over CA, but with different transient and stationary eddies over south Asia. The different locations of anomalous anticyclones over India govern two water vapor transport branches to CA, which are from the Arabian Sea and the Bay of Bengal. The water vapor flux climbs while being transported northward and can be transported to CA with the cooperation of cyclonic circulation. The convergent water vapor and ascending motion caused by cyclonic anomalies favor the precipitation in CA. Further analysis corroborates the negative South Indian Ocean Dipole (NSIOD) in February could affect the tripole mode distribution of TP heating and ISM via the atmospheric circulation, water vapor transport and an anomalous Hadley cell circulation. The results indicate a reliable prediction reference for precipitation in CA.

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Distinct Principal Modes of Early and Late Summer Rainfall Anomalies in East Asia*

Journal of Climate ◽

10.1175/2009jcli2850.1 ◽

2009 ◽

Vol 22 (13) ◽

pp. 3864-3875 ◽

Cited By ~ 83

Author(s):

Bin Wang ◽

Jian Liu ◽

Jing Yang ◽

Tianjun Zhou ◽

Zhiwei Wu

Keyword(s):

East Asia ◽

Summer Monsoon ◽

Land Surface ◽

Southern Oscillation ◽

Southern China ◽

Late Summer ◽

Summer Rainfall ◽

Seasonal Prediction ◽

Early Summer ◽

Rainfall Anomalies

Abstract The current seasonal prediction of East Asia (EA) summer monsoon deals with June–July–August (JJA) mean anomalies. This study shows that the EA summer monsoon may be divided into early summer [May–June (MJ)] and late summer [July–August (JA)] and exhibits remarkable differences in mean state between MJ and JA. This study reveals that the principal modes of interannual precipitation variability have distinct spatial and temporal structures during the early and late summer. These principal modes can be categorized as either El Niño–Southern Oscillation (ENSO) related or non-ENSO related. During the period of 1979–2007, ENSO-related modes explain 35% of MJ variance and 45% of JA variance, and non-ENSO-related modes account for 25% of MJ variance and 20% of JA variance. For ENSO-related variance, about two-thirds are associated with ENSO decaying phases, and one-third is associated with ENSO developing phases. The ENSO-related MJ modes generally concur with rapid decay or early development of ENSO episodes, and the opposite tends to apply to ENSO-related JA modes. The non-ENSO MJ mode is preceded by anomalous land surface temperatures over southern China during the previous March and April. The non-ENSO JA mode is preceded by lasting equatorial western Pacific (the Niño-4 region) warming from the previous winter through late summer. The results suggest that 1) prediction of bimonthly (MJ) and (JA) anomalies may be useful, 2) accurate prediction of the detailed evolution of ENSO is critical for prediction of ENSO-related bimonthly rainfall anomalies over East Asia, and 3) non-ENSO-related modes are of paramount importance during ENSO neutral years. Further establishment of the physical linkages between the non-ENSO modes and their corresponding precursors may provide additional sources for EA summer monsoon prediction.

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Relationship between interdecadal variability of North China summer rainfall, East Asia summer monsoon, and atmospheric circulation anomaly

10.1117/12.746936 ◽

2007 ◽

Author(s):

Qing-jiu Gao ◽

Li-sheng Hao ◽

Jin-zhong Min ◽

Zhenhe Ren

Keyword(s):

East Asia ◽

Atmospheric Circulation ◽

Summer Monsoon ◽

North China ◽

Summer Rainfall ◽

Interdecadal Variability ◽

Circulation Anomaly ◽

East Asia Summer Monsoon ◽

Atmospheric Circulation Anomaly

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Relations of Water Vapor Transport from Indian Monsoon with That over East Asia and the Summer Rainfall in China

Advances in Atmospheric Sciences ◽

10.1007/bf03403519 ◽

2001 ◽

Vol 18 (5) ◽

pp. 1005-1017 ◽

Cited By ~ 84

Author(s):

Zhang Renhe

Keyword(s):

Water Vapor ◽

East Asia ◽

Indian Monsoon ◽

Summer Rainfall ◽

Vapor Transport ◽

Water Vapor Transport

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Synergy Effects of the Indian Summer Monsoon and the Tibetan Plateau Heating on Summer Rainfall over North China

Advances in Meteorology ◽

10.1155/2020/8395269 ◽

2020 ◽

Vol 2020 ◽

pp. 1-16

Author(s):

Siwen Zhao ◽

Jie Zhang ◽

Zhihong Lv

Keyword(s):

Water Vapor ◽

Tibetan Plateau ◽

Summer Monsoon ◽

Rossby Wave ◽

North Africa ◽

Indian Summer Monsoon ◽

North China ◽

Summer Rainfall ◽

The Tibetan Plateau ◽

The Pacific

An analysis based on July-August precipitation reveals that there is a tripole pattern of the precipitation distribution, that is, significantly increased rainfall over North China (NC) is related to the increased rainfall over the Indian subcontinent (IS) and the decreased rainfall over the southeastern Tibetan Plateau (TP) and vice versa, that corresponds to the Indian summer monsoon (ISM) and TP heating pattern, which are interactive. Therefore, it is necessary to investigate the effect of NC rainfall-related atmospheric circulation and the physical linkage with the two thermal forcings together. The linear baroclinic model (LBM) is applied to determine the dynamics of the process. The results show that an enhanced ISM is accompanied by reduced TP heating, favors convection and easterly anomaly over the IS, and produces a Gill-type Rossby wave that affects the vorticity over North Africa. Meanwhile, there is another Rossby wave originating in North Africa and moving eastward to the Pacific Ocean, which interferes with circulation at mid- to high-latitudes, i.e., it strengthens the cyclone over the Baikal region and stretches the western Pacific subtropical high (WPSH) northward to northeastern Asia, and results in abundant water vapor transported to NC. Furthermore, the strong convection over the IS excites the Kelvin waves over the equatorial region, which moves eastward and generates anticyclones over Philippines, consequently leading to the Pacific-Japan (PJ) pattern. The PJ pattern cooperates with the wave train at midlatitudes, resulting in abundant water vapor being transported to NC. The summer rainfall over NC is therefore modulated by synergistic effect of both the ISM and TP heating.

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Weakened Impact of the Indian Early Summer Monsoon on North China Rainfall around the Late 1970s: Role of Basic-State Change

Journal of Climate ◽

10.1175/jcli-d-17-0036.1 ◽

2017 ◽

Vol 30 (19) ◽

pp. 7991-8005 ◽

Cited By ~ 9

Author(s):

Zhongda Lin ◽

Riyu Lu ◽

Renguang Wu

Keyword(s):

East Asia ◽

Summer Monsoon ◽

North China ◽

Wave Train ◽

Summer Rainfall ◽

Early Summer ◽

The Yellow Sea ◽

Westerly Jet ◽

Indian Rainfall

Abstract Previous studies have found a link between north China and Indian rainfall during summer, with significantly increased rainfall in north China related to a stronger Indian summer monsoon. This link is weakened after the late 1970s, generally attributed to the reduced magnitude of interannual variability in the Indian summer rainfall. This study reveals a similar change in this rainfall link in early summer after the late 1970s. Related to a heavier Indian early summer rainfall, rainfall in north China enhances significantly before the late 1970s but not thereafter. The change in rainfall teleconnection is caused by the weakened impact on north China rainfall of a midlatitude wave train along the Asian jet in the upper troposphere. After the late 1970s, the portion of the wave train over East Asia displaces eastward, leading to an eastward shift in the associated ascending motion and, subsequently, enhanced rainfall from north China to the Yellow Sea. Moreover, the change in the midlatitude wave train is attributed to the change in the basic state over East Asia (i.e., a northward shift of the East Asian upper-tropospheric westerly jet after the late 1970s). The latter reduces stationary Rossby wavenumber and increases wavelength of the midlatitude wave train, leading to an eastward shift of the wave train over East Asia. Therefore, in this study a mechanism is proposed for the change in early summer, different from the previous mechanism for the entire summer period.

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Diurnal variations of southerly monsoon surge and their impacts on East Asian summer rainfall

Journal of Climate ◽

10.1175/jcli-d-21-0372.1 ◽

2021 ◽

pp. 1-49

Author(s):

Biqi Liu ◽

Guixing Chen ◽

Wenxin Zeng ◽

Lanqiang Bai ◽

Huiling Qin

Keyword(s):

Water Vapor ◽

East Asia ◽

Large Scale ◽

Western Pacific Subtropical High ◽

Summer Rainfall ◽

Diurnal Variations ◽

Water Vapor Transport ◽

Diurnal Cycles ◽

The North ◽

Rain Events

AbstractMonsoon southerlies can be particularly active for days and produce substantial rainfall over East Asia. These multiday episodes of southerly monsoon surge may exhibit distinct diurnal variations due to regional forcings under given large-scale conditions. This study categorizes the southerly surges into two types with different wind diurnal variations to clarify their influence on rainfall over East Asia. In the summer of 1998–2019, there are 63 episodes of southerly surge with large wind diurnal cycles and 55 episodes with small diurnal cycles. The first type of southerly surges usually occurs with anomalous low-level warming over southeastern China related to the westward extension of the western Pacific subtropical high. The second type of southerly surges instead occurs with anomalous cooling due to the deepened midlatitude trough. They thus represent the different mechanisms downscaling from large-scale conditions to regional diurnal forcings. After the onset of the first type, the intensified monsoon southerlies at night lead to the northward displacement of large-scale ascent and northward water vapor transport with warm moist energy. The monsoon rainband tends to move to the north of 35°N with a robust response in precipitation systems, especially in the meso-α-scale rain events from midnight to morning. As a comparison, the rainband stays at 30°–35°N after the onset of the second type when the strengthened large-scale ascent and water vapor convergence are located relatively south. These differences between the two types of southerly monsoon surges highlight that the multiday large-scale conditions interact with sub-daily regional forcings and greatly regulate the detailed evolution of summer rainband over East Asia.

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