Characterising the interaction of tropical and extratropical air masses controlling East Asian summer monsoon progression using a novel frontal detection approach

Volonté, Ambrogio; Turner, Andrew G.; Schiemann, R.; Vidale, Pier Luigi; Klingaman, Nicholas P.

doi:10.5194/wcd-3-575-2022

Cited by 6 publications

(10 citation statements)

References 56 publications

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“…To determine the location of the MYF, we use data from the front detection algorithm developed by Volonté et al (2022), which is an automated algorithm based on the meridional gradient of equivalent potential temperature at 850 hPa and is designed to detect the East Asian summer monsoon front-the summertime western portion of which is the MYF. We calculate the MYF's latitudinal location over China by averaging over longitudes of 112-122 °E, and define the front as being northward or southward of its climatological position if it is over 0.75 standard deviations of its daily variability from its climatological position for the time of year.…”

Section: Methodsmentioning

confidence: 99%

“…Given the evidence for a propagating intraseasonal SRP phase and its effect on East Asian precipitation, we wish to see whether we can link the intraseasonal SRP phase to the MYF, a dominant mode of East Asian summer atmospheric variability. Additional motivation for this analysis is provided by the result of Volonté et al (2022), who showed that the location of the MYF was influenced by the SWJ on a seasonal scale, and hence investigating their interaction on shorter timescales might help to shed light on the mechanisms of this. We consider the location of the MYF relative to its climatology at a lagged number of days after a particular intraseasonal SRP phase.…”

Section: Lagged Location Of Myf Conditional On Phase Of the Intraseas...mentioning

confidence: 99%

“…Furthermore, links have been made between the seasonal SRP and the location of the Mei Yu front (MYF) (Kosaka et al 2011), which is a summertime large-scale atmospheric front, oriented approximately zonally and which travels north across much of East Asia from April to August. On short timescales the location of the MYF can have a strong effect on Chinese rainfall (Volonté et al 2021(Volonté et al , 2022, which studies of the seasonal mean will not be able to detect. Therefore, we will perform a novel investigation of whether there are links on intraseasonal timescales, determining whether there is a time-delayed or lagged relationship between the intraseasonal SRP and the location of the MYF relative to its climatological location.…”

Section: Introductionmentioning

confidence: 99%

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Intraseasonal oscillations of the Silk Road pattern lead to predictability in East Asian precipitation patterns and the Mei Yu front

Muetzelfeldt

Schiemann

Turner

et al. 2023

Environ. Res. Commun.

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The Silk Road pattern (SRP) is analysed on intraseasonal timescales over summer using empirical orthogonal functions (EOFs) of the meridional wind at 200 hPa. The ﬁrst two principal components explain almost equal amounts of variance, hence both are required to represent the intraseasonal SRP. The associated spatial loadings are 90° out of phase with each other, providing evidence that propagating oscillations are a natural mode of variability of the intraseasonal SRP. This is supported by Hovmöller diagrams of the meridional wind at 200 hPa and by phase diagrams of the ﬁrst two EOFs, which both show a predominantly eastward-propagating oscillation. The oscillations are identiﬁed as plausibly being Rossby waves by means of waveguide theory. The subtropical westerly jet and East Asian rainfall patterns are found to be dependent on the phase of the oscillation: wet anomalies occur to the east of troughs in the jet, which are also regions where local jet entrances cause upper-level divergence via an ageostrophic circulation. Dry anomalies occur to the west of troughs, which are regions of upper-level convergence. The time-delayed location of the summer Mei Yu front relative to its climatology is dependent on the phase of the oscillation: when there is an upper-level trough located over the Korean Peninsula, the Mei Yu front is likely to be located further north than normal 3–8 days later, before returning to its climatological position. This suggests that the phase of the intraseasonal SRP acts as a potential source of predictability of the location of the Mei Yu front, which might allow for better prediction of the associated rains.

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Section: Methodsmentioning

confidence: 99%

Section: Lagged Location Of Myf Conditional On Phase Of the Intraseas...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Intraseasonal oscillations of the Silk Road pattern lead to predictability in East Asian precipitation patterns and the Mei Yu front

Muetzelfeldt

Schiemann

Turner

et al. 2023

Environ. Res. Commun.

Self Cite

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“…During the meiyu/baiu stage (occurs between mid-June and mid-July), the East Asian monsoonal front becomes strongly organised, and stretches from central eastern China to Japan (Kong & Chiang, 2020;Volonté et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Identification of the atmospheric water sources and pathways responsible for the East Asian summer monsoon rainfall

Dey,

Geen,

Lambert

et al. 2024

Quart J Royal Meteoro Soc

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The East Asian Summer Monsoon (EASM) rainfall provides water security and socio‐economic benefit for over 20% of the global population. However, the sources of this rainfall and how it is carried to the East Asian landmass is still uncertain. To address this, atmospheric water sources and pathways associated with the East Asian summer rainfall are identified and quantified in the present study using atmospheric water trajectories, calculated with a novel Lagrangian framework. Evaporated water from the East Asian landmass is found to be the major contributor to East Asian rainfall, amounting to local recycling. The results further indicated that the South Indian Ocean is a major non‐local source for rainfall over southern East Asia during June to August. The role of the South Indian Ocean as a source of atmospheric water is one of the major findings of the study and would help in better understanding and predicting the East Asian summer rainfall. Evaporated waters from the Pacific Ocean (particularly the far‐west Pacific Ocean) dominate the non‐local contribution to precipitation over northern East Asia during June to September, and over southern East Asian rainfall during September. The spatial structure of the East Asian rainfall is reported to be determined by the atmospheric waters that are evaporated and transported from the non‐local sources. The role of the North Indian Ocean and the South Asian landmass as a source of water for East Asian precipitation is minimal and restricted to southern East Asia. The cross‐equatorial Somali jet and equatorial trade winds associated with the western North Pacific Subtropical High are important pathways for East Asian precipitation sourced over the South Indian Ocean and the Pacific Ocean respectively. In contrast, minor roles are attributed to the Bay of Bengal as a source, and mid‐latitude westerlies as a transport pathway, for East Asian precipitation.This article is protected by copyright. All rights reserved.

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“…Since the WCB is also characterized by a southwesterly flow, knowledge of the boundary between the cold and the warm sector air masses is required to distinguish between the two features. Previous studies have shown that the CCB and WCB can be easily detected from reanalysis data alone by combining information on location of fronts (e.g., diagnosed from the location of the sharpest equivalent potential temperature gradient) with wind direction (Catto et al ., 2015; Hart et al ., 2017; Catto and Raveh‐Rubin, 2019; Eisenstein et al ., 2022; Volonté et al ., 2022). The CCB and WCB can also be identified objectively using criteria applied to air parcel trajectories.…”

Section: Introductionmentioning

confidence: 99%

Attribution of observed extreme marine wind speeds and associated hazards to midlatitude cyclone conveyor belt jets near the British Isles

Gentile

Gray

2023

Intl Journal of Climatology

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Extreme wind speeds, gusts, and wind wave heights associated with midlatitude cyclones pose a hazard to shipping lanes and offshore infrastructure operating in the North Atlantic Ocean seas surrounding the British Isles. Several studies have assessed the variability of wind and waves in this region using reanalyses, but few have used surface observations of extreme wind speeds and wave heights. Here, we use a network of marine surface stations to derive the 2012–2020 climatology of daily maximum wind speed events. An algorithm is used to attribute the extreme wind events, characterized as exceeding the 20 and 25 m·s−1 thresholds, to the cyclone warm conveyor belt (WCB), and early (CCBa) and returning (CCBb) cold conveyor belt jets; cyclones are matched with up to 90% of extreme wind events. The CCBb is most frequently associated with the strong wind speeds, accounting for 46 and 59% of the events exceeding the two thresholds, respectively. The CCBb also leads to the largest number of compound wind and wave hazard events (37 out of 87). Although the WCB is associated with the second largest number of extreme wind events, the CCBa accounts for the second largest number of compound extreme wind and wave events (24). The ERA5 reanalysis underestimates the observed extreme wind speeds, and associated gusts and wind‐wave heights, during extreme wind events for all the conveyor belt jets. The wind speeds and associated gusts are most underestimated, by median values of 4.5 and 5.5 m·s−1, respectively, and similar percentage error (), when associated with the CCBb; however, the wind‐wave heights are most underestimated, by a median of 3.4 m, when associated with the CCBa. Hence, while the marine CCBb jet, found in mature cyclones, is both most hazardous and underestimated in the ERA5 near the British Isles, the CCBa jet can be nearly as hazardous when considering compound wind‐wave events.

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Characterising the interaction of tropical and extratropical air masses controlling East Asian summer monsoon progression using a novel frontal detection approach

Cited by 6 publications

References 56 publications

Intraseasonal oscillations of the Silk Road pattern lead to predictability in East Asian precipitation patterns and the Mei Yu front

Intraseasonal oscillations of the Silk Road pattern lead to predictability in East Asian precipitation patterns and the Mei Yu front

Identification of the atmospheric water sources and pathways responsible for the East Asian summer monsoon rainfall

Attribution of observed extreme marine wind speeds and associated hazards to midlatitude cyclone conveyor belt jets near the British Isles

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