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Numerical Simulation of the Effect of the SST Anomalies in the Tropical Western Pacific on the Blocking Highs over the Northeastern Asia 被引量:7
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作者 陆日宇 黄荣辉 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1996年第4期411-424,共14页
The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributi... The effects of the sea surface temperature (SST) anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are simulated by the IAP-GCM with an observed and idealized distributions of the SST anomalies in the tropical western Pacific,respectively.Firstly,the atmospheric circulation anomalies during July and August,1980 are simulated by three anomalous experiments including the global SST anomaly experiment,the tropical SST anomaly experiment and the extratropical SST anomaly experiment,using the observed SST anomalies in 1980.It is shown that the SST anomalies in the tropical ocean greatly influence the formation and maintenance of the blocking high over the northeastern Asia,and may play a more important role than the SST anomalies in the extratropical ocean in the influence on the atmospheric circulation anomalies.Secondly,the effects of the SST anomalies in the tropical western Pacific on the atmospheric circulation anomalies over East Asia are also simulated with an idealized distribution of the SST anomalies in the tropical western Pacific.The simulated results show that the negative anomalies of SST in the tropical western Pacific have a significant effect on the formation and maintenance of the blocking high over the northeastern Asia. 展开更多
关键词 blocking high SST anomaly Atmospheric circulation anomaly
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Remote Impact of Blocking Highs on the Sudden Track Reversal of Tropical Cyclones 被引量:1
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作者 LUO Xia FEI Jianfang +2 位作者 HUANG Xiaogang CHENG Xiaoping YU Kun 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2015年第11期1517-1532,共16页
Previous work showed that some tropical cyclones (TCs) in the western Pacific Ocean undergo sudden track reversal, and the onset, maintenance and decay of blocking highs (BHs) coexisted with 19 of the studied TCs ... Previous work showed that some tropical cyclones (TCs) in the western Pacific Ocean undergo sudden track reversal, and the onset, maintenance and decay of blocking highs (BHs) coexisted with 19 of the studied TCs with sudden track reversal. In these cases, the phase relations between the BH, the continental high (CH), the subtropical high (SH) and the suddenly reversed TCs could be classified into types A, B, C and D. Types C and D were the focal point of this follow-up study, in which Typhoon Pabuk (2007) and Lupit (2009) were employed to conduct numerical simulations. The results showed that the reversed tracks of Pabuk (2007) and Lupit (2009) could have been affected by the BH, particularly in terms of the turning location and the trend of movement after turning. Specifically, the two main features for Pabuk (2007) in the BH perturbations were the deflection of its turning point and a distinct anticlockwise rotation. Lupit (2009) deviated to the southwest and finally made landfall in the Philippines, or experienced further eastward movement, in the perturbed BH. The impact mechanisms can be attributed to the change in the vorticity field transported from the BH, leading to an intensity variation of midlatitude systems. BHs may have a positive feedback effect on the strength of the westerly trough (TR), as indicated by a weakened and strengthened TR corresponding to negative and positive BH perturbations, respectively. 展开更多
关键词 blocking high tropical cyclone suddenly reversed track numerical simulation
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Numerical Study of Ural Blocking High's Effect Upon Asian Summer Monsoon Circulation and East China Flood and Drought 被引量:4
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作者 何金海 周学鸣 叶荣生 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1995年第3期361-370,共10页
In terms of Kuo-Qian pesigma incorporated coordinate five-level primitive equation spheric band (70°N-30°S)model with the Ural high's effect introduced into it as initial and boundary conditions, study i... In terms of Kuo-Qian pesigma incorporated coordinate five-level primitive equation spheric band (70°N-30°S)model with the Ural high's effect introduced into it as initial and boundary conditions, study is made of the high's influence on Asian summer monsoon circulation and dryness / wetness of eastern China based on case contrast andcontrol experiments. Rusults show that as an excitation source, the blocking high produces a SE-NW stationarywavetrain with its upper-air atnicyclonic divergent circulation oust over a lower-level trough zone) precisely over themiddle to lower reaches of the Changjiang River, enhancing East Asian westerly jet, a situation that contributes toPerturbation growth, causing an additional secondary meridional circulation at the jet entrance, which intensifies theupdraft in the monsoon area. As such, the high's presence and its excited steady wavetrain represent the large-scalekey factors and acting mechanisms for the rainstorm over the Changjiang-Huaihe River catchment in the easternpart of the land. 展开更多
关键词 Ural blocking high Asian summer monsoon circulation East China flood and drought
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Interannual Variations of the Blocking High over the Ural Mountains and Its Association with the AO/NAO in Boreal Winter 被引量:2
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作者 李超 张庆云 +1 位作者 纪立人 彭京备 《Acta meteorologica Sinica》 SCIE 2012年第2期163-175,共13页
This paper analyzes interannual variations of the blocking high over the Ural Mountains in the boreal winter and their association with the Arctic Oscillation/North Atlantic Oscillation(AO/NAO).In January,the relati... This paper analyzes interannual variations of the blocking high over the Ural Mountains in the boreal winter and their association with the Arctic Oscillation/North Atlantic Oscillation(AO/NAO).In January,the relationship between the Ural blocking high(UR) and the AO index is statistically significant.The UR tends to occur more frequently and with greater strength during negative AO periods.Some strong URs also occur during positive AO phases(positive UR-AO events),as in January 2008.This paper discusses the characteristics of atmospheric circulation in the cases of positive UR-AO events and contrast cases(negative UR-AO events).The eastward extending of the Icelandic Low(IL) center and the associated NAO dipole anomaly pattern in the upstream region may play a more important role for the UR-AO events.When the center of the IL shifts eastward to 30 W,the amplitude of zonal wavenumber 2(wavenumber 3) is intensified in the positive(negative) UR-AO events,which favors positive(negative) height anomalies over the Urals.Further analyses indicate that the intensified zonal wind in high latitudes and weakened zonal wind in midlatitudes over the North Atlantic Ocean render the eastward shift of the IL and the NAO dipole anomaly pattern.The Ural blocking in January 2008 bears similar characteristics to the positive UR-AO events. 展开更多
关键词 Ural blocking high AO NAO dipole anomaly pattern Icelandic Low
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NUMERICAL STUDY ON EFFECTS OF THE QINGHAIXIZANG PLATEAU ON FORMATION OF THE URAL BLOCKING HIGH 被引量:1
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作者 郑庆林 古瑜 +1 位作者 宋青丽 蒋平 《Acta meteorologica Sinica》 SCIE 1993年第1期61-69,共9页
By employing the improved T42L5 spectral model and utilizing the ECMWF data covering the period from 1 July to 7 July 1982,a numerical research on the formation of the Ural blocking system has been made.The results sh... By employing the improved T42L5 spectral model and utilizing the ECMWF data covering the period from 1 July to 7 July 1982,a numerical research on the formation of the Ural blocking system has been made.The results show that the model forecasts for the upstream U ral area turn out to be worse if the dynamic effect of the Qinghai-Xizang Plateau is not considered.The correlation coefficient between the model forecasts and observed 500 hPa geopotential height anomaly decreases by 9% for the 5-day mean,and their averaged root mean square (RMS) error increases 15 m.Due to the dynamic effect of the Plateau,the trough being on the northwest of the Plateau is barricaded and turns to be a transversal trough.Consequently southwest flow occurs along the northwest of the Plateau in front of the trough,while northeast flow prevails over the west of the trough,causing the formation of the blocking high over the Ural area.When the dynamic effect of the Plateau is not taken into consideration,the trough develops and moves southeastward and the Ural blocking high changes into a migratory high.All these result in the failure of the simulation.The dynamic effect of the Plateau helps to increase the negative vorticities over the Plateau and its north periphery as well as the Ural area,and also helps to increase the positive vorticities over the Black Sea and the Caspian Sea area.On the other hand,the thermodynamic effect mainly influences the Plateau and its downstream area and plays an less important role in the formation of the blocking high over the upstream Ural area. 展开更多
关键词 Qinghai-Xizang Plateau T42L5 spectrum model numerical simulation Ural blocking high dynamic effect
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Energetics of Boreal Wintertime Blocking Highs around the Ural Mountains 被引量:1
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作者 Ning SHI Yicheng WANG Suolangtajie 《Journal of Meteorological Research》 SCIE CSCD 2022年第1期154-174,共21页
Based on the daily Japanese 55-yr reanalysis data,this study analyzes the maintenance mechanism for 53 boreal winter blocking highs around the Ural Mountains(UBHs)during 1958-2018 based on the atmospheric energy budge... Based on the daily Japanese 55-yr reanalysis data,this study analyzes the maintenance mechanism for 53 boreal winter blocking highs around the Ural Mountains(UBHs)during 1958-2018 based on the atmospheric energy budget equations.After decomposing the circulation into background flow,low-frequency anomalies,and high-frequency eddies,it was found that the interaction between the background flow and low-frequency anomalies is conducive to the maintenance of the UBHs.Due to the southwestward gradient in the climatological mean air temperature over the Eurasian continent,it is easy for the air temperature anomalies as well as the wind velocity anomalies in the middle and lower troposphere induced by the UBHs to facilitate the positive conversion of baroclinic energy associated with the background flow into the UBHs.Likewise,the conversion of barotropic energy associated with the background flow is also evident in the upper troposphere,in which the climatological mean westerlies have evident southward gradient to the northwest of Lake Baikal and southwestward gradient over Barents Sea.Note that the conversion of baroclinic energy associated with the background flow is dominant throughout the lifecycle of UBHs,acting as the major contributor to the maintenance of the UBHs.Although transient eddies facilitate maintenance of the UBHs via positive conversion of barotropic energy in the middle and upper troposphere,they hinder the maintenance of UBHs via negative conversion of baroclinic energy in the lower troposphere.The diabatic heating anomalies tend to counteract the local air temperature anomalies in the middle and lower troposphere,which damps the available potential energy of UBHs and acts as a negative contributor to the UBHs. 展开更多
关键词 blocking highs around the Ural Mountains energy budget background flow transient eddies
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INFLUENCE OF THE SURFACE AIR TEMPERATURE OVER ASIAN-PACIFIC REGION ON THE SUMMERTIME NORTHEASTERN ASIAN BLOCKING HIGH 被引量:1
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作者 曹杰 董慧林 姚平 《Acta meteorologica Sinica》 SCIE 2004年第4期455-466,共12页
Synthesis analysis and singular value decomposition (SVD) methods were used to study the impact of surface air temperature (SAT) over Asian-Pacific region on the summertime northeastern Asian blocking high (NABH) with... Synthesis analysis and singular value decomposition (SVD) methods were used to study the impact of surface air temperature (SAT) over Asian-Pacific region on the summertime northeastern Asian blocking high (NABH) with NCEP/NCAR Reanalysis Data.The results showed that 500 hPa geopotential height and SAT fields over Asian-Pacific region shared the similar pattern of East Asian Pacific (EAP) wave train;there was steady remote response relationship between the EAP wave train in summer and the '+-+' pattern of tropical SAT in zonal direction from former winter to summer;there were two relative negative(positive) Walker circulations over the tropical Indian Ocean and Pacific when being more(less) summertime NABH. The influence of sea surface temperature anomaly (SSTA) on the summertime NABH was possibly as follows.The special distribution of SSTA in tropical zonal direction continuously forced the tropical convection and zonal circulation from former winter to summer,and led them to act anomaly.Finally the abnormal conditions were transported to middle-high latitudes through EAP wave train and yielded the advantageous or disadvantageous atmospheric circulation background for the summertime NABH. 展开更多
关键词 summertime northeastern Asian blocking high (NABH) surface air temperature (SAT) synthesis analysis SVD analysis East Asian Pacific wave train
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STUDY OF THE NONLINEAR MECHANISM ABOUT THE FORMATION OF BLOCKING HIGH
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作者 郑祖光 李秀玲 +1 位作者 刘莉红 吴洪 《Acta meteorologica Sinica》 SCIE 2004年第4期423-440,共18页
In this paper,a nonlinear dynamical system considering the interactions among ultra-long wave,long wave and zonal flow in a baroelinic atmosphere was found.In this system,thermal forcing and frictional dissipation are... In this paper,a nonlinear dynamical system considering the interactions among ultra-long wave,long wave and zonal flow in a baroelinic atmosphere was found.In this system,thermal forcing and frictional dissipation are regarded as the external parameters.The procedure,in which the maps of orbit in phase space,contour of stream function and section of Poincaré mapping are combined with each other,is used to determine the distributions of system states and circulation patterns and to draw the corresponding diagrams.The results show that by using the Galerkin method,there is no essential influence of the increasing of orders of truncated-spectrum in a certain range on the distributions of system states and circulation patterns,but it makes them somewhat complexities.By contrast,the changing of distribution of thermal forcing exerts a great influence on the system.Blocking high links closely with the oscillating of the atmospheric circulation and the meridional growing intensely,while the development of synoptic wave can promote the oscillating. 展开更多
关键词 dynamical system thermal forcing friction dissipation blocking high NONLINEARITY
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Atmospheric Structure Observed over the Antarctic Plateau and Its Response to a Prominent Blocking High Event
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作者 Jinhuan ZHU Libo ZHOU +4 位作者 Han ZOU Peng LI Fei LI Shupo MA Linlin KONG 《Journal of Meteorological Research》 SCIE CSCD 2021年第6期1091-1103,共13页
Studies on the atmospheric structure over the Antarctic Plateau are important for better understanding the weather and climate systems of polar regions.In the summer of 2017,an observational experiment was conducted a... Studies on the atmospheric structure over the Antarctic Plateau are important for better understanding the weather and climate systems of polar regions.In the summer of 2017,an observational experiment was conducted at Dome-A,the highest station in Antarctica,with a total of 32 profiles obtained from global positioning system(GPS)radiosondes.Based on observational data,the atmospheric temperature,humidity,and wind structures and their variations are investigated,and compared with those from four other stations inside the Antarctic circle.Distinguished thermal and dynamic structures were revealed over Dome-A,characterized by the lowest temperature,the highest tropopause,the largest lapse rate,and the most frequent temperature and humidity inversion.During the experiment,a prominent blocking event was identified,with great influence on the atmospheric structure over Dome-A.The blocking high produced a strong anticyclone that brought warm and moist air to the hinterland of the Antarctic Plateau,causing a much warmer,wetter,and windier troposphere over the Dome-A station.Meanwhile,a polar air mass was forced out of the Antarctic,formed a cold surge extending as far as southern New Zealand and affected the weather there.Our results proved that there would be a direct interaction between the atmosphere over the hinterland of the Antarctic Plateau and mid latitudes with the action of a blocking high.Further studies are needed to explore the interaction between the atmospheric systems over the Antarctic and mid latitudes under intense synoptic disturbance,with longterm data and numerical modeling. 展开更多
关键词 Antarctic Plateau atmospheric structure blocking high middle and high latitude interaction
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EFFECT OF LOCAL BASIC FLOW STRUCTURE PATTERN IN FORMATION OF BLOCKING HIGHS
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作者 罗哲贤 《Acta meteorologica Sinica》 SCIE 1990年第3期354-360,共7页
The effect of local basic flow structure pattern(BFSP)on a blocking high formation is investigated within the framework of forced dissipation KDV dynamics.The zonal and meridional positions of the high's center ex... The effect of local basic flow structure pattern(BFSP)on a blocking high formation is investigated within the framework of forced dissipation KDV dynamics.The zonal and meridional positions of the high's center excited by a heat source depend on the BFSP selected. 展开更多
关键词 EFFECT OF LOCAL BASIC FLOW STRUCTURE PATTERN IN FORMATION OF blocking highS BFI
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Simple Metrics for Representing East Asian Winter Monsoon Variability:Urals Blocking and Western Pacific Teleconnection Patterns
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作者 Hoffman H.N.CHEUNG Wen ZHOU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2016年第6期695-705,共11页
Instead of conventional East Asian winter monsoon indices (EAWMIs), we simply use two large-scale teleconnection patterns to represent long-term variations in the EAWM. First, the Urals blocking pattern index (UBI... Instead of conventional East Asian winter monsoon indices (EAWMIs), we simply use two large-scale teleconnection patterns to represent long-term variations in the EAWM. First, the Urals blocking pattern index (UBI) is closely related to cold air advection from the high latitudes towards western Siberia, such that it shows an implicit linkage with the Siberian high intensity and the surface air temperature (SAT) variations north of 40°N in the EAWM region. Second, the well-known western Pacific teleconnection index (WPI) is connected with the meridional displacement of the East Asian jet stream and the East Asian trough. This is strongly related to the SAT variations in the coastal area south of 40°N in the EAWM region. The temperature variation in the EAWM region is also represented by the two dominant temperature modes, which are called the northern temperature mode (NTM) and the southern temperature mode (STM). Compared to 19 existing EAWMIs and other well-known teleconnection patterns, the UBI shows the strongest correlation with the NTM, while the WPI shows an equally strong correlation with the STM as four EAWMIs. The UBI-NTM and WPI-STM relationships are robust when the correlation analysis is repeated by (1) the 31-year running correlation and (2) the 8-year high-pass and low-pass filter. Hence, these results are useful for analyzing the large-scale teleconnections of the EAWM and for evaluating this issue in climate models. Int particular, more studies should focus on the teleconnection patterns over extratropical Eurasia. 展开更多
关键词 East Asian winter monsoon Urals blocking high western Pacific teleconnection pattern TELECONNECTION
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High Producing Well Discovered in Zhaodong Contract Block
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作者 Liu Mingfa(Deputy of International Cooperation Department, Dagang Oilfields Grouo Ltd. Company) 《China Oil & Gas》 CAS 1998年第1期41-42,共2页
关键词 high Producing Well Discovered in Zhaodong Contract Block
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The Warm Arctic-Cold Eurasia Pattern and Its Key Region in Winter in CMIP6 Model Simulations
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作者 Liang ZHAO Yunwen LIU +6 位作者 Yihui DING Qingquan LI Wei DONG Xinyong SHEN Wei CHENG Haoxin YAO Ziniu XIAO 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第12期2138-2153,I0002-I0006,共21页
An enhanced Warm Arctic-Cold Eurasia(WACE)pattern has been a notable feature in recent winters of the Northern Hemisphere.However,divergent results between model and observational studies of the WACE still remain.This... An enhanced Warm Arctic-Cold Eurasia(WACE)pattern has been a notable feature in recent winters of the Northern Hemisphere.However,divergent results between model and observational studies of the WACE still remain.This study evaluates the performance of 39 climate models participating in the Coupled Model Intercomparison Project Phase 6(CMIP6)in simulating the WACE pattern in winter of 1980-2014 and explores the key factors causing the differences in the simulation capability among the models.The results show that the multimodel ensemble(MME)can better simulate the spatial distribution of the WACE pattern than most single models.Models that can/cannot simulate both the climatology and the standard deviation of the Eurasian winter surface air temperature well,especially the latter,usually can/cannot simulate the WACE pattern well.This mainly results from the different abilities of the models to simulate the range and intensity of the warm anomaly in the Barents Sea-Kara seas(BKS)region.Further analysis shows that a good performance of the models in the BKS area is usually related to their ability to simulate location and persistence of Ural blocking(UB),which can transport heat to the BKS region,causing the warm Arctic,and strengthen the westerly trough downstream,cooling central Eurasia.Therefore,simulation of UB is key and significantly affects the model’s performance in simulating the WACE. 展开更多
关键词 warm Arctic-cold Eurasia pattern Arctic amplification CMIP6 simulation evaluation extreme climate blocking highs
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Outcomes in patients with COVID-19 and new onset heart blocks: Insight from the National Inpatient Sample database
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作者 Sami J Shoura Taha Teaima +8 位作者 Muhammad Khawar Sana Ayesha Abbasi Ramtej Atluri Mahir Yilmaz Hasan Hammo Laith Ali Chanavuth Kanitsoraphan Dae Yong Park Tareq Alyousef 《World Journal of Cardiology》 2023年第9期448-461,共14页
BACKGROUND Coronavirus disease 2019(COVID-19)caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has resulted in a worldwide health crisis since it first appeared.Numerous studies demonstrated the... BACKGROUND Coronavirus disease 2019(COVID-19)caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has resulted in a worldwide health crisis since it first appeared.Numerous studies demonstrated the virus’s predilection to cardiomyocytes;however,the effects that COVID-19 has on the cardiac conduc-tion system still need to be fully understood.AIM To analyze the impact that COVID-19 has on the odds of major cardiovascular complications in patients with new onset heart blocks or bundle branch blocks(BBB).METHODS The 2020 National Inpatient Sample(NIS)database was used to identify patients admitted for COVID-19 pneumonia with and without high-degree atrioven-tricular blocks(HDAVB)and right or left BBB utilizing ICD-10 codes.The patients with pre-existing pacemakers,suggestive of a prior diagnosis of HDAVB or BBB,were excluded from the study.The primary outcome was inpatient mortality.Secondary outcomes included total hospital charges(THC),the length of hospital stay(LOS),and other major cardiac outcomes detailed in the Results section.Univariate and multivariate regression analyses were used to adjust for confounders with Stata version 17.RESULTS A total of 1058815 COVID-19 hospitalizations were identified within the 2020 NIS database,of which 3210(0.4%)and 17365(1.6%)patients were newly diagnosed with HDAVB and BBB,respectively.We observed a significantly higher odds of in-hospital mortality,cardiac arrest,cardiogenic shock,sepsis,arrythmias,and acute kidney injury in the COVID-19 and HDAVB group.There was no statistically significant difference in the odds of cerebral infarction or pulmonary embolism.Encounters with COVID-19 pneumonia and newly diagnosed BBB had a higher odds of arrythmias,acute kidney injury,sepsis,need for mechanical ventilation,and cardiogenic shock than those without BBB.However,unlike HDAVB,COVID-19 pneumonia and BBB had no significant impact on mortality compared to patients without BBB.CONCLUSION In conclusion,there is a significantly higher odds of inpatient mortality,cardiac arrest,cardiogenic shock,sepsis,acute kidney injury,supraventricular tachycardia,ventricular tachycardia,THC,and LOS in patients with COVID-19 pneumonia and HDAVB as compared to patients without HDAVB.Likewise,patients with COVID-19 pneumonia in the BBB group similarly have a higher odds of supraventricular tachycardia,atrial fibrillation,atrial flutter,ventricular tachycardia,acute kidney injury,sepsis,need for mechanical ventilation,and cardiogenic shock as compared to those without BBB.Therefore,it is essential for healthcare providers to be aware of the possible worse predicted outcomes that patients with new-onset HDAVB or BBB may experience following SARS-CoV-2 infection. 展开更多
关键词 In-patient outcomes Severe acute respiratory syndrome coronavirus 2 Coronavirus disease 2019 high degree atrioventricular blocks Bundle branch blocks Retrospective observational study
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黑龙江省2009年6月罕见的区域性暴雨天气过程分析(英文) 被引量:1
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作者 吴英 张杰 闫中帅 《Meteorological and Environmental Research》 CAS 2010年第10期29-32,共4页
From June 18th to June 19th of 2009,Heilongjiang Province was hit by the regional rainstorm rarely paralleled in history.According to the findings based upon the conventional observation data,the precipitation occurre... From June 18th to June 19th of 2009,Heilongjiang Province was hit by the regional rainstorm rarely paralleled in history.According to the findings based upon the conventional observation data,the precipitation occurred under the double-blocking situation of Ural Mountains and the Sea of Okhotsk.The main influencing systems were the upper vortex and northward low-pressure that came from Hetao area,accompanied by the delivery of high and low level jet stream.The results showed that the evolvement of blocking high,transfer of water vapor and configuration of high and low level jet stream were the key factors resulting in the rainfall process. 展开更多
关键词 blocking high Water vapour transport high and low level jet stream China
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The Record-breaking Mei-yu in 2020 and Associated Atmospheric Circulation and Tropical SST Anomalies 被引量:36
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作者 Yihui DING Yunyun LIU Zeng-Zhen HU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2021年第12期1980-1993,共14页
The record-breaking mei-yu in the Yangtze-Huaihe River valley(YHRV)in 2020 was characterized by an early onset,a delayed retreat,a long duration,a wide meridional rainbelt,abundant precipitation,and frequent heavy rai... The record-breaking mei-yu in the Yangtze-Huaihe River valley(YHRV)in 2020 was characterized by an early onset,a delayed retreat,a long duration,a wide meridional rainbelt,abundant precipitation,and frequent heavy rainstorm processes.It is noted that the East Asian monsoon circulation system presented a significant quasi-biweekly oscillation(QBWO)during the mei-yu season of 2020 that was associated with the onset and retreat of mei-yu,a northward shift and stagnation of the rainbelt,and the occurrence and persistence of heavy rainstorm processes.Correspondingly,during the mei-yu season,the monsoon circulation subsystems,including the western Pacific subtropical high(WPSH),the upper-level East Asian westerly jet,and the low-level southwesterly jet,experienced periodic oscillations linked with the QBWO.Most notably,the repeated establishment of a large southerly center,with relatively stable latitude,led to moisture convergence and ascent which was observed to develop repeatedly.This was accompanied by a long-term duration of the mei-yu rainfall in the YHRV and frequent occurrences of rainstorm processes.Moreover,two blocking highs were present in the middle to high latitudes over Eurasia,and a trough along the East Asian coast was also active,which allowed cold air intrusions to move southward through the northwestern and/or northeastern paths.The cold air frequently merged with the warm and moist air from the low latitudes resulting in low-level convergence over the YHRV.The persistent warming in the tropical Indian Ocean is found to be an important external contributor to an EAP/PJ-like teleconnection pattern over East Asia along with an intensified and southerly displaced WPSH,which was observed to be favorable for excessive rainfall over YHRV. 展开更多
关键词 record-breaking mei-yu western Pacific subtropical high quasi-biweekly oscillation Tropical Indian Ocean warming low-level southwesterly jet blocking high
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1998年夏第二阶段梅雨期乌拉尔山阻塞形势的维持(英文) 被引量:5
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作者 李双林 纪立人 +1 位作者 林万涛 倪允琪 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2001年第1期87-105,共19页
The 1998 summer-time floods at the Yangtze River basin of China, the severest in last 50 years or so, directly resulted from the abnormal extension of Meiyu (rainy season), which was related to a weak East Asian summe... The 1998 summer-time floods at the Yangtze River basin of China, the severest in last 50 years or so, directly resulted from the abnormal extension of Meiyu (rainy season), which was related to a weak East Asian summer monsoon and persistent anomalies of extratropical circulation. The long persistence of blocking over the Ural Mountains is a conspicuous feature. The physical processes responsible for the prolonged maintenance of this key system are investigated in terms of internal forcing (transient eddy upon basic flow) and external forcing (tropical heating forcing) via diagnosis and numerical experiments in the paper. Using the adjoint method, the location and structure of optimal perturbations favorable for the development and maintenance of Ural blocking are identified, which shows an apparent coincidence with the observed storm track at the eastern Atlantic to Europe sector. The diagnosis of E-vector and the response of baroclinic stationary wave to transient forcing both suggest further that the enhanced transient eddy activity favors the occurrence and maintenance of positive anomalies. The upper-level jet and heat sources (sinks) during that period are calculated, and the results indicate that the anomaly of upper jet and tropical heating is evident. The ensemble forecasting experiments by a GCM, IAP T42L9 show that the anomalous heating over the tropics, especially over the central-western Pacific and Atlantic, favors the formation of positive anomalies of height at the Ural region. Finally, a self-sustain mechanism of positive anomalies through two-way interaction between planetary stationary wave and transient eddy under the stimulation of anomalous tropical heating is proposed. 展开更多
关键词 1998 floods in China blocking high over the Ural Mountains tropical abnormal heating transient eddy two-way interaction
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Physical Mechanism of Phased Variation of 2020 Extremely Heavy Meiyu in Middle and Lower Reaches of Yangtze River 被引量:1
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作者 鲍媛媛 刘华 蔡芗宁 《Journal of Tropical Meteorology》 SCIE 2022年第3期273-285,共13页
The extremely heavy Meiyu in the middle and lower reaches of the Yangtze River in 2020 features early beginning,extremely late retreat,long duration,and a dramatic north-south swing rain belt.It can be divided into th... The extremely heavy Meiyu in the middle and lower reaches of the Yangtze River in 2020 features early beginning,extremely late retreat,long duration,and a dramatic north-south swing rain belt.It can be divided into three phases.The key point of the extremely heavy Meiyu is the long duration of precipitation.The physical mechanism of the phased variation is researched here by analyzing the phased evolution of atmospheric circulation,the thermal effect of Tibetan Plateau,the sea surface temperature anomalies(SSTA),and tropical convection.The results show that:(1)Throughout the whole Meiyu season,the western Pacific subtropical high(WPSH)is stronger and westward,the South Asian high(SAH)is stronger and eastward,and blocking highs are very active with different patterns at different stages;they all form flat mid-latitude westerlies with fluctuation interacting with WPSH and SAH,causing their ridges and the rain belt to swing drastically from north to south or vice versa.(2)The higher temperatures in the upper and middle atmosphere in the eastern and southern Tibetan Plateau and the middle and lower reaches of the Yangtze River,which are produced by the warm advection transport,the heat sources in Tibetan Plateau,and the latent heat of condensation of Meiyu,contribute greatly to the stronger and westward WPSH and the stronger and eastward SAH.The dry-cold air brought by the fluctuating westerlies converges with the warm-humid air over Tibetan Plateau,resulting in precipitation,which in turn enhances the heat source of Tibetan Plateau and regulates the swings of WPSH and SAH.(3)Different from climatological analysis,real-time SSTA in the Indian Ocean has no obviously direct effect on WPSH and Meiyu.The anomalous distribution and phased evolution process of real-time SSTA in South China Sea and the tropical western Pacific affect WPSH and Meiyu significantly through tropical convection and heat sources.The maintenance of strong positive SSTA in the western equatorial Pacific is a critical reason for the prolonged Meiyu season.Both the onset and the retreat of Meiyu in 2020 are closely related to the intensified positive SSTA and corresponding typhoons on the ocean east of the Philippines. 展开更多
关键词 phased variation of Meiyu blocking high WPSH real-time SSTA
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缓慢移动的行星尺度偶极子包络Rossby孤立子与双波地形相互作用(英文)
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作者 罗德海 李建平 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2001年第2期239-256,共18页
A parametrically excited higher-order nonlinear Schrodinger (NLS) equation is derived to describe the interaction of a,slowly moving planetary-scale envelope Rossby soliton for zonal wavenumber-two with a wavenumber-t... A parametrically excited higher-order nonlinear Schrodinger (NLS) equation is derived to describe the interaction of a,slowly moving planetary-scale envelope Rossby soliton for zonal wavenumber-two with a wavenumber-two topography under the LG-type dipole near-resonant condition. The numerical solution of this equation is made. It is found that in a weak background westerly wind satisfying the LG-type dipole near-resonance condition, when an incipient envelope Rossby soliton is located in the topographic trough and propagates slowly, it can be amplified though the near-resonant forcing of wavenumber-two topography and can exhibit an oscillation. However, this soliton can break up after a long the and excite a train of small amplitude waves that propagate west ward. In addition, it is observed that in the soliton-topography interaction the topographically near-resonantly forced planetary-scale soliton has a slowly westward propagation, but a slowly eastward propagation after a certain time. The instantaneous total streamfunction fields of the topographically forced planetary-scale soliton are found to bear remarkable resemblance to the initiation, maintenance and boy of observed mega-type blocking high and dipole blocking. The soliton perturbation theory is used to examine the role of a wavenumber-two topography in near-resonantly forcing omega-type blocking high and dipole blocking. It can be shown that in the amplifying process of forced planetary-scale soliton, due to the inclusion of the higher order terms its group velocity gradually tends to be equal to its phase velocity so that the block envelope and carrier wave can be phase-locked at a certain time. This shows that the initiation of blocking is a transfer of amplified envelope soliton system from dispersion to nondispersion. However, there exists a reverse process during the decay of blocking. It appears that in the higher latitude regions, the planetary-scale envelope soliton-topography interaction could be regarded as a possible mechanism of the establishment of blocking. 展开更多
关键词 Planetary-scale envelope Rossby soliton Soliton-topography interaction blocking high
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BLOCKING EFFECT OF HIGH PRESSURE SYSTEM ON THE FORMATION OF EXTRA-INTENSE HEAVY RAIN
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作者 章淹 《Acta meteorologica Sinica》 SCIE 1989年第4期458-470,共13页
Commonly the centre of an intense heavy rain occurs in a very limited area,but for the three extra- intense heavy rains of the present study,63-8 in North China,75-8 in central China and 77-8 in the desert region of I... Commonly the centre of an intense heavy rain occurs in a very limited area,but for the three extra- intense heavy rains of the present study,63-8 in North China,75-8 in central China and 77-8 in the desert region of Inner Mongolia,which all appeared under the environments of“Western Low and Eastern Blocking” (EB)pattern.From this study,the following effects of the EB are found:(1)It affects the precipitation systems staggering in a local place and/or changes the trajectories of low votices and urges them into the same raining areas intermittently.(2)It transports water vapour into raining areas.The air flows by the west side of EB produce strong cyclonic vorticity behind EB frequently,which transports water vapour and forms mesoscale precipitation systems more favourably than the low level jets.(3)Air flows behind EB con- jugate with adequate topographic relief,which enhances the precipitation and makes the raining areas over- lapped.So that extra-intense heavy rains could occur in higher latitudes of semi-aird areas,and occasionally even in the desert region of North China. Such extra-intense heavy rains could not be explained by static local humidity and temperature only. This is also a principal discrimination between the prolonged extra-intense heavy rain and the short-range convective precipitation and/or the common precipitation. 展开更多
关键词 blocking EFFECT OF high PRESSURE SYSTEM ON THE FORMATION OF EXTRA-INTENSE HEAVY RAIN PMP
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