Feedback of 10–20-day intraseasonal oscillations on seasonal mean SST in the tropical Western North Pacific during boreal spring through fall

Wu, Renguang

doi:10.1007/s00382-016-3362-6

Cited by 14 publications

(11 citation statements)

References 37 publications

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“…This weakens seasonal mean surface winds and reduces seasonal mean wind‐related LHF in the tropical western Pacific. On the other hand, the intraseasonal oscillations and synoptic wave activities are enhanced over these regions under favorable background due to atmospheric response to El Niño events (Wu, 2018; Wu et al, 2015; Wu & Cao, 2017; Wu & Song, 2018). This leads to a large accumulation of high‐frequency LHF in a season.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…Tropical Indo‐western Pacific is a region of large high‐frequency (intraseasonal and synoptic) activity (Maloney & Dickinson, 2003; Straub & Kiladis, 2003; Teng & Wang, 2003; Wu & Cao, 2017). As surface latent heat flux (LHF) depends upon surface wind speed, the LHF induced by high‐frequency wind variations may accumulate when it is averaged over a season, and thus, they can contribute to seasonal mean LHF (Wu, 2018; Wu & Cao, 2017). As ENSO‐induced wind anomalies evolve with the stage of ENSO, a question is how the contribution of LHF related to high‐frequency wind variations varies with the stage of ENSO.…”

Section: Introductionmentioning

confidence: 99%

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High‐Frequency Wind‐Related Seasonal Mean Latent Heat Flux Changes Over the Tropical Indo‐Western Pacific in El Niño and La Niña Years

Jiao²,

Wang

et al. 2020

JGR Atmospheres

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By decomposing the variations of daily mean variables into synoptic, intraseasonal, and low-frequency components, the present study compares seasonal mean latent heat flux (LHF) anomalies related to the three components over the tropical Indo-Pacific region during El Niño and La Niña years. It is found that the high-frequency (intraseasonal and synoptic) LHF has an important contribution to total seasonal mean LHF anomalies over the tropical eastern Indo-western Pacific region. Large seasonal mean LHF anomalies related to high-frequency wind variations are identified in weak low-frequency seasonal mean wind regions where high-frequency LHF may accumulate over a season as it increases in both westerly and easterly phases of high-frequency wind variations. In those regions, the LHF anomalies related to high-frequency wind variations cancel part of the low-frequency LHF anomalies, reducing total seasonal mean LHF anomalies. As El Niño-Southern Oscillation (ENSO)-induced lower-level wind anomaly region moves with the stage of ENSO, large seasonal mean LHF anomalies related to high-frequency wind variations displace with the season. The intensity of high-frequency wind fluctuations is also a factor influencing the seasonal mean LHF related to high-frequency wind variations. Thus, the ENSO affects the high-frequency LHF variations through modulating both the location of weak low-frequency wind region and intensity of high-frequency wind fluctuations.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High‐Frequency Wind‐Related Seasonal Mean Latent Heat Flux Changes Over the Tropical Indo‐Western Pacific in El Niño and La Niña Years

Jiao²,

Wang

et al. 2020

JGR Atmospheres

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“…These oscillations could modulate the synoptic and interannual variations of surface winds over ISM region and influences the rainfall patterns (e.g., Goswami et al 1999). Over the WNP region, the intensity of 10–20‐day oscillations is modulated by ENSO through variations of vertical shear in zonal winds, moisture transport and ascending/descending motion (e.g., Wu, 2018). As this 10–20 days mode propagates westward to the BOB and Indian landmass from tropical WNP, changes in the characteristics of these oscillations would alter the rainfall patterns over India especially during ENSO years.…”

Section: Enso‐monsoon Teleconnections In Different Epochs: Observationsmentioning

confidence: 99%

Interdecadal modulation of interannual ENSO‐Indian summer monsoon rainfall teleconnections in observations and CMIP6 models: Regional patterns

Mahendra

Chowdary

Darshana

et al. 2021

Intl Journal of Climatology

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This study examined the Inter‐decadal modulations of interannual El Niño‐Southern Oscillation (ENSO)‐Indian Summer Monsoon (ISM) rainfall regional teleconnection patterns in the observations and Coupled Model Intercomparison Project Phase 6 (CMIP6) models. Observations show strong epochal changes of the relationship between ENSO and all‐India summer rainfall (AISR) with weak teleconnections in epoch‐1 (centred around 1915) and epoch‐4 (recent epoch) and strong teleconnections in epoch‐2 (centred around 1940) and epoch‐3 (centred around 1970) during the study period of 1901–2014. While on the regional point of view, it is found that epochal/decadal ENSO teleconnections to rainfall over northern central India and southern peninsular India are stronger and stable in all epochs. Whereas the rainfalls over the regions like Central India and Eastern Central India (ECI) displayed strong epochal changes in teleconnections, similar to that of AISR. This suggests that changes in ENSO‐ISM rainfall teleconnections are highly influenced by regional rainfall response. Anomalous upward motion over the head Bay of Bengal (BOB) and ECI regions related to Indian Ocean Dipole (IOD) and the westward extension of low‐level cyclonic circulation from the Western‐North Pacific (WNP) region are mainly responsible for the epochal changes in regional rainfall patterns over India associated with ENSO. We have assessed the fidelity of 29 CMIP6 models in representing the epochal changes in ENSO‐monsoon teleconnections. Nearly, 35% of models simulate epochal changes in teleconnections reasonably well. In most of the models, epochal changes in teleconnections are influenced by the strength and location of large‐scale subsidence coupled to the strength of Walker circulation associated with ENSO. It is noted that the drivers of epochal changes in ENSO‐monsoon teleconnections vary from model to model. Whereas, in the observations, the variance of ENSO itself in summer could influence modulations in the ENSO‐ISM teleconnections apart from IOD and WNP forcing.

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“…In addition to seasonal mean atmospheric circulation anomalies, high-frequency atmospheric activities, including synoptic scale variations and intraseasonal oscillations, can contribute largely to seasonal LHF variations over the tropical WNP (Wu 2018;Wu et al 2020a). Highfrequency atmospheric activities are strong over the tropical WNP during boreal summer and accompanied by prominent high-frequency surface heat flux variations within their life cycles (Woolnough et al 2000;Kemball-Cook and Wang 2001;Waliser et al 2004;Duvel and Vialard 2007).…”

Section: Introductionmentioning

confidence: 99%

Factors of boreal summer latent heat flux variations over the tropical western North Pacific

Wang

2021

Clim Dyn

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Surface latent heat flux (LHF) is an important component in the heat exchange between the ocean and atmosphere over the tropical western North Pacific (WNP). The present study investigates the factors of seasonal mean LHF variations in boreal summer over the tropical WNP. Seasonal mean LHF is separated into two parts that are associated with low-frequency (> 90-day) and high-frequency (≤ 90-day) atmospheric variability, respectively. It is shown that low-frequency LHF variations are attributed to low-frequency surface wind and sea-air humidity difference, whereas high-frequency LHF variations are associated with both low-frequency surface wind speed and high-frequency wind intensity. A series of conceptual cases are constructed using different combinations of low- and high-frequency winds to inspect the respective effects of low-frequency wind and high-frequency wind amplitude to seasonal mean LHF variations. It is illustrated that high-frequency wind fluctuations contribute to seasonal high-frequency LHF only when their intensity exceeds the low-frequency wind speed under which there is seasonal accumulation of high-frequency LHF. When high-frequency wind intensity is smaller than the low-frequency wind speed, seasonal mean high-frequency LHF is negligible. Total seasonal mean LHF anomalies depend on relative contributions of low- and high-frequency atmospheric variations and have weak interannual variance over the tropical WNP due to cancellation of low- and high-frequency LHF anomalies.

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Feedback of 10–20-day intraseasonal oscillations on seasonal mean SST in the tropical Western North Pacific during boreal spring through fall

Cited by 14 publications

References 37 publications

High‐Frequency Wind‐Related Seasonal Mean Latent Heat Flux Changes Over the Tropical Indo‐Western Pacific in El Niño and La Niña Years

High‐Frequency Wind‐Related Seasonal Mean Latent Heat Flux Changes Over the Tropical Indo‐Western Pacific in El Niño and La Niña Years

Interdecadal modulation of interannual ENSO‐Indian summer monsoon rainfall teleconnections in observations and CMIP6 models: Regional patterns

Factors of boreal summer latent heat flux variations over the tropical western North Pacific

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