scholarly journals A New Paradigm for Continental U.S. Summer Rainfall Variability: Asia–North America Teleconnection

2016 ◽  
Vol 29 (20) ◽  
pp. 7313-7327 ◽  
Author(s):  
Zhiwei Zhu ◽  
Tim Li
Keyword(s):  
North America ◽  
East Asia ◽  
North American ◽  
El Niño ◽  
Monsoon Rainfall ◽  
El Nino ◽  
Rainfall Variability ◽  
East Asian ◽  
Summer Rainfall ◽  
Boreal Summer

Abstract The present study reveals a close relationship between the leading mode of continental U.S. (CONUS) summer rainfall and the East Asian subtropical monsoon rainfall (viz., mei-yu in China, baiu in Japan, and changma in the Korean peninsula). The East Asian subtropical monsoon rainfall and the CONUS dipole rainfall patterns are connected by an upper-level Asia–North America (ANA) teleconnection. The Rossby wave energy propagates along the path of the westerly jet stream (WJS) from East Asia to North America, affecting the CONUS summer rainfall. Mechanisms through which East Asian summer monsoon heating influence North American rainfall are illustrated by idealized anomaly atmospheric general circulation model experiments. In boreal winter, because of the southward shift of the WJS, the Pacific–North American (PNA) pattern can be excited by the tropical central/eastern Pacific heating associated with El Niño, affecting the rainfall over CONUS. In boreal summer, because the WJS is weaker and locates farther to the north, an equatorial heating anomaly cannot directly perturb the WJS. A perturbation heating over subtropical East Asia, however, can trigger an ANA pattern along the path of the WJS, affecting the rainfall over North America. The season-dependent teleconnection scenario illustrates that the predictability source of CONUS rainfall variability is different between winter and summer. While the PNA pattern generated by El Niño is critical for CONUS rainfall in northern winter, the CONUS dipole rainfall variation in boreal summer is mainly governed by the remote forcing over subtropical East Asia via the ANA teleconnection.

scholarly journals Impact of the El Niño type and PDO on the winter sub-seasonal North American zonal temperature dipole via the variability of positive PNA patterns

2021 ◽  
Author(s):  
Yao Ge ◽  
Dehai Luo
Keyword(s):  
North America ◽  
North American ◽  
El Niño ◽  
El Nino ◽  
Hadley Cell ◽  
Height Anomaly ◽  
Central Pacific ◽  
The West ◽  
Anticyclonic Anomaly ◽  
The Impact

Abstract In recent years, the winter (from December to February, DJF) North American surface air temperature (SAT) anomaly in midlatitudes shows a “warm west/cold east” (WWCE) dipole pattern. To some extent, the winter WWCE dipole can be considered as being a result of the winter mean of sub-seasonal WWCE events. In this paper, the Pacific SST condition linked to the sub-seasonal WWCE SAT dipole is investigated. It is found that while the sub-seasonal WWCE dipole is related to the positive Pacific North American (PNA+) pattern, the impact of the PNA+ on the WWCE dipole depends on the El Niño SST type and the phase of Pacific decadal Oscillation (PDO). For a central-Pacific (CP) type El Niño, the positive (negative) height anomaly center of PNA+ is located in the west (east) part of North America to result in an intensified WWCE dipole, though the positive PDO favors the WWCE dipole. In contrast, the WWCE dipole is suppressed under an Eastern-Pacific (EP) type El Niño because the PNA+ anticyclonic anomaly dominates the whole North America.Moreover, the physical cause of why the type of El Niño influences the PNA+ is further examined. It is found that the type of El Niño can significantly influence the location of PNA+ through changing North Pacific midlatitude westerly winds (NPWWs). For the CP-type El Niño, the eastward migration of PNA+ is suppressed to favor its anticyclonic (cyclonic) anomaly appearing in the west (east) region of North American owing to reduced NPWWs. But for the EP-type El Niño, NPWWs are intensified to cause the appearance of the PNA+ anticyclonic anomaly over the whole North America due to enhanced Hadley cell and Ferrell cell.

scholarly journals The Genus Pachyma (Syn. Wolfiporia) Reinstated and Species Clarification of the Cultivated Medicinal Mushroom “Fuling” in China

2020 ◽  
Vol 11 ◽  
Author(s):  
Fang Wu ◽  
Shou-Jian Li ◽  
Cai-Hong Dong ◽  
Yu-Cheng Dai ◽  
Viktor Papp
Keyword(s):  
North America ◽  
East Asia ◽  
North American ◽  
Biological Activities ◽  
Phylogenetic Analyses ◽  
East Asian ◽  
New Combination ◽  
Medicinal Mushroom ◽  
Morphological Examination ◽  
Wide Range

The fungus “Fuling” has been used in Chinese traditional medicine for more than 2000 years, and its sclerotia have a wide range of biological activities including antitumour, immunomodulation, anti-inflammation, antioxidation, anti-aging etc. This prized medicinal mushroom also known as “Hoelen” is resurrected from a piece of pre-Linnean scientific literature. Fries treated it as Pachyma hoelen Fr. and mentioned that it was cultivated on pine trees in China. However, this name had been almost forgotten, and Poria cocos (syn. Wolfiporia cocos), originally described from North America, and known as “Tuckahoe” has been applied to “Fuling” in most publications. Although Merrill mentioned a 100 years ago that Asian Pachyma hoelen and North American P. cocos are similar but different, no comprehensive taxonomical studies have been carried out on the East Asian Pachyma hoelen and its related species. Based on phylogenetic analyses and morphological examination on both the sclerotia and the basidiocarps which are very seldomly developed, the East Asian samples of Pachyma hoelen including sclerotia, commercial strains for cultivation and fruiting bodies, nested in a strongly supported, homogeneous lineage which clearly separated from the lineages of North American Wolfiporia cocos and other species. So we confirm that the widely cultivated “Fuling” Pachyma hoelen in East Asia is not conspecific with the North American Wolfiporia cocos. Based on the changes in Art. 59 of the International Code of Nomenclature for algae, fungi, and plants, the generic name Pachyma, which was sanctioned by Fries, has nomenclatural priority (ICN, Art. F.3.1), and this name well represents the economically important stage of the generic type. So we propose to use Pachyma rather than Wolfiporia, and subsequently Pachyma hoelen and Pachyma cocos are the valid names for “Fuling” in East Asia and “Tuckahoe” in North America, respectively. In addition, a new combination, Pachyma pseudococos, is proposed. Furthermore, it seems that Pachyma cocos is a species complex, and that three species exist in North America.

scholarly journals On the Role of the Eastern Pacific Teleconnection in ENSO Impacts on Wintertime Weather over East Asia and North America

2019 ◽  
Vol 32 (4) ◽  
pp. 1217-1234 ◽  
Author(s):  
Ying Dai ◽  
Benkui Tan
Keyword(s):  
North America ◽  
Surface Temperature ◽  
East Asia ◽  
El Niño ◽  
El Nino ◽  
Eastern Pacific ◽  
Frequency Of Occurrence ◽  
Temperature Anomalies ◽  
La Nina ◽  
Weather Events

Previous studies have mainly focused on the influence of El Niño–Southern Oscillation (ENSO) on seasonal-mean conditions over East Asia and North America. This study, instead, proposes an ENSO pathway that influences the weather events over East Asia and North America, in which the eastern Pacific teleconnection pattern (EP) plays an important role. On the one hand, the EP pattern can induce significant surface temperature anomalies over East Asia during its development and mature stages, with the positive (negative) EPs causing colder (warmer) than normal weather events. Besides, the frequency of occurrence of EPs is significantly modulated by ENSO, with 50% of the positive EPs occurring in La Niña winters, and 47% of the negative EPs occurring in El Niño winters. As a result, in El Niño winters, more negative and fewer positive EPs tend to occur, and thus more warm and fewer cold weather events are expected in East Asia. For La Niña winters, the reverse is true. On the other hand, for the EP pattern without its canonical convection pattern (referred to as the nonconvective EP), extremely cold anomalies over the northern United States and western Canada are induced in its negative phase. Moreover, when there are positive sea surface temperature anomalies in the central equatorial Pacific, the frequency of occurrence of negative nonconvective EPs is 2.0 times greater than the climatological value, and thus an enhanced likelihood of extremely cold spells over North America may be expected.

North American Warm-west/Cold-East air temperature pattern and its linkage to different El Nino types

2020 ◽  
Author(s):  
Yao Ge ◽  
Dehai Luo
Keyword(s):  
North America ◽  
North American ◽  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Anticyclonic Anomaly ◽  
The North ◽  
Westerly Winds ◽  
Dipole Pattern ◽  
Midlatitude Westerly

<p><strong> </strong></p><p>In recent years, the surface air temperature (SAT) anomalies in winter over North America show a “warm-West/cool-East” (WWCE) dipole pattern. The underlying mechanism of the North American WWCE dipole pattern has been an important research topic. This study examines the physical cause of the WWCE dipole generation.</p><p>It is found that the positive phase (PNA<sup>+</sup>) of the Pacific North American (PNA) pattern can lead to the generation of the WWCE SAT dipole. However, the impact of the PNA<sup>+ </sup>on the WWCE SAT dipole over North America depends on the type of the El Nino SST anomaly. When an Eastern-Pacific (EP) type El Nino occurs, the anticyclonic anomaly center of the PNA<sup>+ </sup>over the North American continent is displaced eastward near 100°W due to intensified midlatitude westerly winds over North Pacific so that its anticyclonic anomaly dominates the whole North America. In this case, the cyclonic anomaly of the PNA<sup>+</sup> almost disappears over the North America. Thus, the WWCE SAT dipole over the North America is weakened. In contrast, when a central-Pacific (CP) type El Nino appears, the anticyclonic anomaly center of the associated PNA<sup>+</sup> is located over the North America west coast due to reduced midlatitude westerly winds over North Pacific. As a result, the cyclonic anomaly of the PNA<sup>+</sup> can appear over the east United States to result in an intensified WWCE SAT dipole over the North America</p>

scholarly journals Orographically Anchored El Niño Effect on Summer Rainfall in Central China

2017 ◽  
Vol 30 (24) ◽  
pp. 10037-10045 ◽  
Author(s):  
Kaiming Hu ◽  
Shang-Ping Xie ◽  
Gang Huang
Keyword(s):  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Rainfall Variability ◽  
Eastern China ◽  
Summer Rainfall ◽  
Central China ◽  
Northwest Pacific ◽  
The Tibetan Plateau ◽  
Rainfall Anomalies

Year-to-year variations in summer precipitation have great socioeconomic impacts on China. Historical rainfall variability over China is investigated using a newly released high-resolution dataset. The results reveal summer-mean rainfall anomalies associated with ENSO that are anchored by mountains in central China east of the Tibetan Plateau. These orographically anchored hot spots of ENSO influence are poorly represented in coarse-resolution datasets so far in use. In post–El Niño summers, an anomalous anticyclone forms over the tropical northwest Pacific, and the anomalous southwesterlies on the northwest flank cause rainfall to increase in mountainous central China through orographic lift. At upper levels, the winds induce additional adiabatic updraft by increasing the eastward advection of warm air from Tibet. In post–El Niño summers, large-scale moisture convergence induces rainfall anomalies elsewhere over flat eastern China, which move northward from June to August and amount to little in the seasonal mean.

Indian summer monsoon rainfall variability in response to differences in the decay phase of El Niño

2016 ◽  
Vol 48 (7-8) ◽  
pp. 2707-2727 ◽  
Author(s):  
Jasti S. Chowdary ◽  
H. S. Harsha ◽  
C. Gnanaseelan ◽  
G. Srinivas ◽  
Anant Parekh ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
El Niño ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
El Nino ◽  
Rainfall Variability ◽  
Summer Monsoon Rainfall ◽  
Decay Phase

scholarly journals Contribution of Tropical Cyclones to Rainfall at the Global Scale

2017 ◽  
Vol 30 (1) ◽  
pp. 359-372 ◽  
Author(s):  
Abdou Khouakhi ◽  
Gabriele Villarini ◽  
Gabriel A. Vecchi
Keyword(s):  
East Asia ◽  
Tropical Cyclones ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Extreme Rainfall ◽  
Annual Rainfall ◽  
Boreal Summer ◽  
Western Coast ◽  
Daily Precipitation Data

This study quantifies the relative contribution of tropical cyclones (TCs) to annual, seasonal, and extreme rainfall and examines the connection between El Niño–Southern Oscillation (ENSO) and the occurrence of extreme TC-induced rainfall across the globe. The authors use historical 6-h best-track TC datasets and daily precipitation data from 18 607 global rain gauges with at least 25 complete years of data between 1970 and 2014. The highest TC-induced rainfall totals occur in East Asia (>400 mm yr−1) and northeastern Australia (>200 mm yr−1), followed by the southeastern United States and along the coast of the Gulf of Mexico (100–150 mm yr−1). Fractionally, TCs account for 35%–50% of the mean annual rainfall in northwestern Australia, southeastern China, the northern Philippines, and Baja California, Mexico. Seasonally, between 40% and 50% of TC-induced rain is recorded along the western coast of Australia and in islands of the south Indian Ocean in the austral summer and in East Asia and Mexico in boreal summer and fall. In terms of extremes, using annual maximum and peak-over-threshold approaches, the highest proportions of TC-induced rainfall are found in East Asia, followed by Australia and North and Central America, with fractional contributions generally decreasing farther inland from the coast. The relationship between TC-induced extreme rainfall and ENSO reveals that TC-induced extreme rainfall tends to occur more frequently in Australia and along the U.S. East Coast during La Niña and in East Asia and the northwestern Pacific islands during El Niño.

scholarly journals Impacts of Different Types of El Niño on the East Asian Climate: Focus on ENSO Cycles

2012 ◽  
Vol 25 (21) ◽  
pp. 7702-7722 ◽  
Author(s):  
Yuan Yuan ◽  
Song Yang
Keyword(s):  
East Asia ◽  
El Niño ◽  
El Nino ◽  
East Asian ◽  
Northwestern Pacific ◽  
Southeastern China ◽  
Cp El Niño ◽  
Dry Conditions ◽  
East Asian Climate ◽  
Ep El Niño

Using multiple datasets and a partial correlation method, the authors analyze the different impacts of eastern Pacific (EP) and central Pacific (CP) El Niño on East Asian climate, focusing on the features from El Niño developing summer to El Niño decaying summer. Unlike the positive–negative–positive (+/−/+) anomalous precipitation pattern over East Asia and the equatorial Pacific during EP El Niño, an anomalous −/+/− rainfall pattern appears during CP El Niño. The anomalous dry conditions over southeastern China and the northwestern Pacific during CP El Niño seem to result from the anomalous low-level anticyclone over southern China and the South China Sea, which is located more westward than the Philippine Sea anticyclone during EP El Niño. The continuous anomalous sinking motion over southeastern China, as part of the anomalous Walker circulation associated with CP El Niño, also contributes to these dry conditions. During the developing summer, the impact of CP El Niño on East Asian climate is more significant than the influence of EP El Niño. During the decaying summer, however, EP El Niño exerts a stronger influence on East Asia, probably due to the long-lasting anomalous warming over the tropical Indian Ocean accompanying EP El Niño. Temperatures over portions of East Asia and the northwestern Pacific tend to be above normal during EP El Niño but below normal from the developing autumn to the next spring during CP El Niño. A possible reason is the weakened (enhanced) East Asian winter monsoon related to EP (CP) El Niño.

scholarly journals Tropical Origins of the Record-breaking 2020 Summer Rainfall Extremes in East Asia

2021 ◽  
Author(s):  
Sunyong Kim ◽  
Jae-Heung Park ◽  
Jong-Seong Kug
Keyword(s):  
Indian Ocean ◽  
East Asia ◽  
Wave Train ◽  
East Asian ◽  
Tropical Indian Ocean ◽  
Summer Rainfall ◽  
Ocean Basin ◽  
Boreal Summer ◽  
Rainfall Extremes ◽  
East Asian Rainfall

Abstract The East Asian countries have experienced heavy rainfalls in boreal summer 2020. Here, we investigate the dynamical processes driving the East Asian rainfall extremes during July and August. The Indian Ocean basin warming in June can be responsible for the anticyclonic anomalies in the western North Pacific (WNP), which contribute to the zonally-elongated rainfalls in East Asia during July through an atmospheric Rossby wave train. In August, the East Asian rainfall increase is also related to the anticyclonic anomalies in the subtropical WNP, although it is located further north. It is suggested that the north tropical Atlantic warming in June partly contributes to the subtropical WNP rainfall decrease in August through a subtropical teleconnection. The rainfall decrease in the subtropical WNP region during August drives the local anticyclonic anomalies that cause the rainfall increase in East Asia. The tropical Indian Ocean anomalously warmed in June and the subtropical WNP rainfall decreased in August 2020, which played a role in modulating the WNP anticyclonic anomalies. Therefore, the record-breaking rainfalls in East Asia occurred during July and August 2020 can potentially be explained by the teleconnections induced by the tropical origins, such as tropical Indian Ocean warming and subtropical WNP rainfall decrease.

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