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Southerly wind in the lower troposphere is an essential feature of East Asian summer monsoon (EASM) circulation, which is reported to be enhanced under global warming scenarios and interglacial epochs. Based on an analysis of an ensemble of CMIP6 models, this study shows that the magnitude of intensification of the EASM circulation is much smaller under global warming scenarios than during interglacial epochs. Distinct changes in the western North Pacific subtropical high (WNPSH) are responsible for the different responses of the EASM circulation. The WNPSH is substantially enhanced during interglacial epochs, which acts to strengthen the southerly wind associated with the EASM on the western flank of the WNPSH. However, the change in the WNPSH is insignificant and cannot strengthen the EASM under global warming scenarios, and the weakly enhanced EASM circulation may be a direct response to intensified heating over the Tibetan Plateau. The land-ocean thermal contrast explains the different responses of the WNPSH. During interglacial epochs, the summertime surface warming over the subtropical North Pacific is much weaker than over Eurasia due to the large thermal inertia of the ocean to increased insolation, and the WNPSH is intensified as a response to the suppressed latent heating over the subtropical North Pacific. The fast response of the WNPSH to abrupt quadrupling of CO2 without sufficient ocean warming is an analog to the interglacial epochs, but it is offset by the effect of slow oceanic warming, resulting in an insignificant change of the WNPSH under global warming scenarios. [ABSTRACT FROM AUTHOR]

The Silk Road pattern (SRP) is a well-known teleconnection pattern along the upper-level westerly jet over the Eurasian continent during boreal summer. The SRP has experienced an interdecadal change around the late 1970s. The present study identified a new change of the SRP around the late 1990s, which is characterized by significant weakening and zonal phase shift of the major centers of the SRP during the recent decades. The recent reshaping of the SRP is attributed to an enhanced impact of precipitation anomalies over the northeastern Indian summer monsoon (ISM), which is associated with the leading mode change of the ISM precipitation anomalies around the late 1990s. The interdecadal weakening of the upper-level westerly jet over central and East Asia also favors the southward movement of the SRP during recent periods. The differences of the features, climate impact, and causes related to the recent SRP change from those related to the SRP change around the late 1970s are also contrasted in this study. [ABSTRACT FROM AUTHOR]

Recent developments have emphasized the global impacts of climate change and have renewed commitments in renewable energy and energy meteorology. Wind energy depends largely on prevailing meteorological conditions on both local and large scales, thus, wind power optimization should aid its assessment and development. This study uses ERA-Interim daily data from 1979 to 2014 to investigate the impact of the East Asian Monsoon on wind power in Asia. Wind power increase in the Bay of Bengal region as wind vectors strengthened from winter (DJF, December-January-February) to summer (JJA, June-July-August), while the predominant direction shifted to southwesterly. The influence of the South China Sea on South East Asia resulted in increased wind power that peaked in winter. Probability distribution functions for four sub-regions revealed higher probabilities of relatively lower wind speeds in JJA, except for the South East region, where most probable wind speeds were reached in winter. The capacity factor also varied by region and by season. Power generation was lowest in JJA for all the regions except the South West. The South East region also had the highest power generated over the domain. This variation of wind power impacts the amount of energy that must be supplied by non-wind sources, termed Demand NetWind (DNW). Knowledge of DNW fluctuations thus becomes an important consideration for optimization of power plants, grid networking and reliability, and energy markets. [ABSTRACT FROM AUTHOR]

Abstract: Volume transport in the Taiwan Strait is usually northward for most of the year and varies seasonally because of the adjustment of the East Asian monsoon. Based on model simulations, the influence on this northward transport of every typhoon formed during the period 2005–2009 was examined. The results showed that there were four typhoons which enhanced northward transport during these five years. The current measurements, obtained from a buoy deployed in the Taiwan Strait, matched these events exactly. These typhoons had special moving tracks and life histories. They traveled westward in the area south of the strait or moved northward from the south to the north. Under the influence of such a typhoon, the prophase southward atmospheric forcing in the strait was weak and the anaphase northward atmospheric forcing (mainly along-strait wind stress) was strong, which is necessary and crucial in enhancing the northward transport. The ageostrophic process, another important driving factor in transport change, was generated mainly by local atmospheric forces inside the strait under the typhoon weather conditions and its effect on transport magnitude was comparable to that of direct atmospheric forcing. It first stored some energy from the atmospheric forcing to restrain the transport change, and then released the stored energy to prolong and even to intensify the enhanced northward transport. [Copyright &y& Elsevier]

The summer moisture circulation anomaly over East Asia and the western North Pacific (WNP) couples well with the El Niño-Southern Oscillation (ENSO) in a quasi-4-yr period. The moisture circulation is dominated by two well-separated modes. The first mode exhibits an anticyclonic (cyclonic) moisture circulation over tropical-subtropical East Asia-WNP with an easterly (westerly) transport over the tropical WNPIndian Ocean; the second mode displays an alternating pattern with an anticyclonic (cyclonic) moisture circulation over the subtropical WNP layered between two cyclonic (anticyclonic) circulations. Both modes couple well with the ENSO signal during its quasi-4-yr cycle. Within the cycle, in the summer of a developing warm episode, the positive phase of the second mode plays a key role, while in the transitional summer between a decaying warm episode and a developing cool episode, the positive phase of the first mode tends to take effect. In the summer of a developing cool episode, the negative phase of the second mode plays an important role, while the negative phase of the first mode tends to take effect in the transitional summer between a decaying cool episode and a developing warm episode. The anticyclone (cyclone) over the Philippine Sea region serves as a bridge in the quasi-four-year coupling. Its establishment and eastward extension modify moisture circulation over East Asia-WNP. Conversely, the easterly (westerly) wind to the south of the anticyclone (cyclone) is beneficial for the formation and eastward propagation of the Kelvin wave and, hence, to the development of the quasi-4-yr periodic ENSO episode. [ABSTRACT FROM AUTHOR]

The article presents a study on the impacts of the Indian Ocean basin-scale sea surface temperature anomaly (SSTA) on the onset of the summer monsoon on South China Sea. It is observed that basin-wide warming in tropical Indian Ocean occurs after an El Niño event. Changes in the sea-surface temperature sustain the El Niño-Southern Oscillation (ENSO) effects towards the summer monsoon in Asia and modifies the strength of the Philippine Sea anti-cyclone, which causes delay to the South China Sea monsoon onset. The methods and the conclusion of the study are discussed.

The article presents a study on El Niño Southern Oscillation (ENSO) and the onset date of South China Sea summer monsoon (SCSSM). It mentions that the monsoon onset date (MOD) is determined by the change in direction of the zonal winds in the South China Sea from going towards the east to west in two consecutive pentads. It discusses that the ENSO is affected by the ocean heat content (OHC). The study found that the monsoon starts late in a period of warm ENSO. It also mentions that winds in the east of the Philippines affect the onset of the MOD. The study also relates the effects of cold subsurface water in the western North Pacific with SCSSM.

Summer monsoon rainfall supplies over 55% of annual precipitation to global monsoon regions. As shown by more than 70% of models, including 30 models from CMIP5 and 30 models from CMIP6 under high-emission scenarios, North American (NAM) monsoon rainfall decreases in a warmer climate, in sharp contrast to the robust increase in Asian- African monsoon rainfall. A hierarchy of model experiments is analyzed to understand the mechanism for the reduced NAM monsoon rainfall in this study. Modeling evidence shows that the reduction of NAM monsoon rainfall is related to both direct radiative forcing of increased CO2 concentration and SST warming, manifested as fast and slow responses to abrupt CO2 quadrupling in coupled GCMs. A cyclone anomaly forms over the Eurasian-African continental area due to enhanced land-sea thermal contrast under increased CO2 concentration, and this leads to a subsidence anomaly on its western flank, suppressing the NAM monsoon rainfall. The SST warming acts to further reduce the rainfall over the NAM monsoon region, and the El Niño-like SST warming pattern with enhanced SST warming over the equatorial Pacific plays a key role in suppressing NAM rainfall, whereas relative cooling over the subtropical North Atlantic has no contribution. A positive feedback between monsoon precipitation and atmospheric circulation helps to amplify the responses of monsoon rainfall. [ABSTRACT FROM AUTHOR]

This paper investigates the role of intraseasonal oscillations (ISOs) in the onset of the South China Sea summer monsoon (SCSSM). Two major components of ISO (10–20‐day and 30–60‐day modes) are identified. The coupling of these two intraseasonal modes during the pre‐monsoon period of the SCSSM are investigated by examining the filtered outgoing longwave radiation (OLR), low‐level circulation, apparent heat source and apparent moisture sink from October of a previous calendar year to September of a calendar year.The zonal and meridional propagations of the 10–20‐day and 30–60‐day modes are found to be different, which reflects their different roles in the establishment and development of the SCSSM. The northwestward propagation of the 10–20‐day mode is associated with the weakening of the subtropical high over the western Pacific, while the northeastward propagation of the 30–60‐day mode originates from convection over the equatorial Indian Ocean. A hypothesis is then proposed to explain the observed variabilities in the SCSSM onset. When the equatorial Indian Ocean exhibits a 30–60‐day mode oscillation, an initially weak convection develops into a large convection band (or monsoon trough). Meanwhile, a convective disturbance of the 10–20‐day mode is induced when this monsoon trough extends to the western Pacific. These two processes then collaborate to cause a weakening of the subtropical anticyclone over the South China Sea. Because the monsoon trough associated with the 30–60‐day mode subsequently propagates northward into the Bay of Bengal (BOB), the induced vortex together with the 10–20‐day westward‐migrating convection from the equatorial western Pacific will substantially increase the effect of horizontal advection of moisture and heat, thus destabilizing the atmosphere and weakening the subtropical ridge there. Westerlies can then penetrate and prevail over the SCS region, and the SCSSM onset occurs. Copyright © 2005 Royal Meteorological Society. [ABSTRACT FROM AUTHOR]

The article explores the spatiotemporal features of the Indian Ocean Dipole (IOD) on the sea surface and the subsurface ocean. It was found that the previous positive IOD is associated with the normal South China Sea summer monsoon. Also, a stronger 100-hPa South Asian High is induced by a positive IOD in the summer after an IOD year. Summer rainfall in China is said to exhibit various patterns corresponding to different phases of the IOD, as influenced by the 850-hPa Asian monsoon circulations, as well as the position of the 500-hPa subtropical high ridge.