Circulation Pattern Controls of Summer Temperature Anomalies in Southern Africa

This study investigates the relationship between circulation patterns and austral summer temperature anomalies in southern Africa. The results show that the formation of continental lows tends to increase the thickness of the lower atmosphere. Further, the distinct variabilities of high and low pressure under the circulation types, influence air mass advection from the adjacent oceans, as well as atmospheric stability over land. Stronger anticyclonic circulation at the western branch of the Mascarene high-pressure system enhances the low-level cold air advection by southeast winds,decreases the thickness, and lowers the temperature over a majority of the land in southern Africa. Conversely, a weaker Mascarene High, coupled with enhanced cyclonic activity in the southwest Indian Ocean increases low-level warm air advection and increases temperature anomalies over vast regions in southern Africa. The ridging of a closed South Atlantic anticyclone at the southern coast of southern Africa results in colder temperatures near the tip of southern Africa due to enhanced low-level cold air advection by southeast winds. However, when the ridge is weak and westerly winds dominate the southern coast of southern Africa, these areas experience temperature increases. The northward track of the Southern Hemisphere mid-latitude cyclone, which can be linked to the negative Southern Annular Mode, reduces the temperature in the southwestern part of southern Africa. Also, during the analysis period, El Ni?o was associated with temperature increases over the central parts of southern Africa;while the positive Indian Ocean dipole was linked to a temperature increase over the northeastern, northwestern, and southwestern parts of southern Africa.

Arctic summertime anticyclonic circulation mode and its influence on substantial sea ice depletion:a review

The summertime anticyclonic circulation mode(SACM)is related to recent substantial loss of sea ice in the Arctic.This review outlines the potential causes of the SACM and considers its influence on sea ice depletion.Local triggers(i.e.,sea ice loss and sea surface temperature(SST)variation)and spatiotemporal teleconnections(i.e.,extratropical cyclone intrusion,tropical and mid-latitude SST anomalies,and winter atmospheric circulation preconditions)are discussed.The influence of the SACM on the dramatic loss of sea ice is emphasized through inspection of relevant dynamic(i.e.,Ekman drift and export)and thermodynamic(i.e.,moisture content,cloudiness,and associated changes in radiation)mechanisms.Moreover,the motivation for investigation of the underlying physical mechanisms of the SACM in response to the recent substantial sea ice depletionis also clarified through an attempt to better understand the shifting ice-atmosphere interaction in the Arctic during summer.Therecord low extent of sea ice in September 2012 could be reset in the near future if the SACM-like scenario continues to exist during summer in the Arctic troposphere.

Simulation of the Equatorially Asymmetric Mode of the Hadley Circulation in CMIP5 Models

The tropical Hadley circulation （HC） plays an important role in influencing the climate in the tropics and extra-tropics. The realism of the climatological characteristics, spatial structure, and temporal evolution of the long-term variation of the principal mode of the annual mean HC （i.e., the equatorially asymmetric mode, EAM） was examined in model simulations from the Coupled Model Intercomparison Project Phase 5 （CMIP5）. The results showed that all the models are moderately successful in capturing the HC＇s climatological features, including the spatial pattern, meridional extent, and intensity, but not the spatial or temporal variation of the EAM. The possible reasons for the poor simulation of the long-term variability of the EAM were explored. None of the models can successfully capture the differences in the warming rate between the tropical Southern Hemisphere （SH） and Northern Hemisphere （NH）, which is considered to be an important driver for the variation of the AM. Most of the models produce a faster warming in the NH than in the SH, which is the reverse of the observed trend. This leads to a reversed trend in the meridional gradient between the SH and NH, and contributes to the poor simulation of EAM variability. Thus, this aspect of the models should be improved to provide better simulations of the variability of the HC. This study suggests a possible reason for the poor simulation of the HC, which may be helpful for improving the skill of the CMIP5 models in the future.

Seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring and the associated surface heat budget

This study investigates the seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring using snow water equivalent （SWE）, snow cover frequency （SCF）, and 500 hPa geopotential height data. It is found that the Eurasian SWE/SCF and circulation dominant modes are stably coupled from autumn to the subsequent spring.The temporal coherence of the seasonal evolution of the dominant modes is examined.The seasonal evolution of the Eurasian circulation and SWE dominant modes exhibit good coherence, whereas the evolution of the Eurasian SCF dominant mode is incoherent during the autumn-winter transition season. This incoherence is associated with a sign-change in the SCF anomalies in Europe during the autumn-winter transition season, which is related to the wind anomalies over Europe. In addition, the surface heat budget associated with the Eurasian SWE/SCF and circulation dominant modes is analyzed. The sensible heat flux （SHF） related to the wind-induced thermal advection dominates the surface heat budget from autumn to the subsequent spring, with the largest effect during winter. The surface net shortwave radiation is mainly modulated by snow cover rather than cloud cover, which is estimated to be as important as, or likely superior to, the SHF for the surface heat budget during spring.The NCEP-NCAR surface heat flux reanalysis data demonstrate a consistency with the SWE/SCF and air temperature observational data, indicating a good capability for snow-atmosphere interaction analysis.

Effect of medical care linkage-continuous management mode in patients with posterior circulation cerebral infarction undergoing endovascular interventional therapy

BACKGROUND Acute cerebral infarction is a severe type of ischemic stroke that can be divided into anterior circulation cerebral infarction and posterior circulation cerebral infarction(PCCI).PCCI affects the structure of the posterior circulation brain,because posterior part of the brain,which has more complex anatomical structures and more prone to posterior circulation vascular variation.Therefore,improving the prognosis of PCCI patients is necessary.AIM To explore the effect of medical care linkage-continuous management mode(MCLMM)on endovascular interventional therapy(EIT)for PCCI.METHODS Sixty-nine patients with PCCI who received EIT and conventional nursing intervention were selected as the control group,and 78 patients with PCCI who received EIT and MCLMM intervention were selected as the observation group.The incidence of postoperative complications,compliance and disease selfmanagement behavior after six months of intervention,modified Rankin scale(mRS)and Barthel index(BI)scores in the acute phase and after one year of intervention,and recurrence within one year were compared between the two groups.RESULTS The total incidence rate of postoperative complications in the observation group(7.69%)was lower than that in the control group(18.84%)(P<0.05).The scores for medical compliance behavior(regular medication,appropriate diet,and rehabilitation cooperation rates)and disease self-management behavior(self-will,disease knowledge,and self-care ability)in the observation group were higher than those in the control group(P<0.05).After one year of intervention,in the observation group,the mRS score was significantly lower,and the BI score was significantly higher than those in the control group(P<0.05).The recurrence rate within one year in the observation group(3.85%)was significantly lower than that in the control group(13.04%)(P<0.05).CONCLUSION MCLMM can reduce the incidence of complications after EIT for PCCI,improve patient compliance behavior and disease self-management ability,and promote the recovery of neurological function.

THE COUPLED MODE BETWEEN THE KUROSHIO REGION MARINE HEATING ANOMALY AND THE NORTH PACIFIC ATMOSPHERIC CIRCULATION IN WINTERTIME

Using monthly reanalysis data of the National Center for Environmental Research/National Center for Atmospheric Research(NCEP/NCAR) and Objectively Analyzed Air-Sea Heat Flux(OAFlux) gathered during the winter,singular vector decomposition(SVD) analysis was conducted to reveal the coupled mode between the Kuroshio marine heating anomaly and the geopotential height at 500 hPa(Z500) over the North Pacific.The first SVD mode showed that when the northern Kuroshio marine heating anomaly was positive,the Z500 in the central and western sections of the North Pacific was anomalously low.By composing the meteorological field anomalies in the positive(or negative) years,it has been revealed that while the Aleutian Low deepens(or shallows),the northwesterly wind overlying the Kuroshio strengthens(or weakens) and induces the near-surface air to be cool(or warm).Furthermore,this increases(or decreases) the upward heat flux anomaly and cools(or warms) the sea surface temperature(SST) accordingly.In the vicinity of Kuroshio and its downstream region,the vertical structure of the air temperature along the latitude is baroclinic;however,the geopotential height is equivalently barotropic,which presents a cool trough(or warm ridge) spatial structure.The divergent wind and vertical velocities are introduced to show the anomalous zonal circulation cell.These are characterized by the rising(or descending) air in the central North Pacific,which flows westward and eastward toward the upper troposphere,descends(or rises) in the Kuroshio and in the western section of North America,and then strengthens(or weakens) the mid-latitude zonal cell(MZC).

Relationships among the Monsoon-like Southwest Australian Circulation,the Southern Annular Mode, and Winter Rainfall over Southwest Western Australia

This study examines the relationships among the monsoon-like southwest Australian circulation （SWAC）, the South- ern Annular Mode （SAM）, and southwest Western Australia winter rainfall （SWR）, based on observed rainfall, reanalysis datasets, and the results of numerical modeling. By decomposing the SWAC into two components using a linear model, i.e. the component related to SAM （RSAM） and the component unrelated to SAM （SWACI＊）, we find it is the SWACI＊ that shows a significant influence on SWR. Similarly, it is the component of SAM associated with SWAC that exhibits an impact on SWR, whereas the component unrelated to SAM. A similar result is obtained in terms of the circulation associated with SWAC and the SAM. These facts suggest the SAM plays an indirect role in influencing SWR, and raise the possibility that SWAC acts as a bridge between the SAM and SWR, by which the SAM passes its influences onto SWR. This is due to the fact that the variations of SWAC are closely linked to the thermal contrast between land and sea across the southern Indian Ocean and southwest Australia. By contrast, the SAM does not significantly relate to this thermal structure, particularly for the component unrelated to SWAC. The variations of surface sea temperature over the southern Indian Ocean contribute to the favored rainfall circulation patterns. This finding is supported by the numerical modeling results. The strong coupling between SWAC and SWR may be instrumental for understanding the interactions between SWR and the southern Indian Ocean, and provides another perspective in examining the variations in SWR.

The Mode of Promoting Industrial Targeted Poverty Alleviation through Land Circulation in Western Mountainous Region of China——A Case Study of Luquan Yi and Miao Autonomous County in Yunnan Province

In the industrial targeted poverty alleviation,land circulation is a key process. Based on the national strategy of targeted poverty alleviation,this paper combined the industrial development of targeted poverty alleviation with land circulation. According to the field survey on the current situation of land circulation and promotion of the industrial poverty alleviation in the typical project area of Zhongping Village in Zhongping Town and Jiaowuying Village in Jiulong Town in Luquan Yi and Miao Autonomous County in Yunnan Province,located in the high mountain canyon area of Jinsha River in the upper reaches of the Yangtze River in the west of China. This paper summarized and analyzed the organization and operation mechanism,basic practices and main results of the land circulation and promotion of industrial poverty alleviation model in the typical project area of the county. It also summarized the innovation and successful experience of the model,and then came up with measures to further promote the implementation of the model,so as to provide necessary reference for the implementation of land circulation and industrial targeted poverty alleviation for the poverty-stricken counties in Yunnan Province and similar provinces( cities,regions).

基于主客观环流分型的强降水数值预报MODE检验方法及其在2019年暖季东北地区的应用

本文构建了基于主客观环流分型的强降水数值预报空间检验(MODE)方法框架,并利用该框架对欧洲中期天气预报中心全球模式(ECMWF)和中国气象局区域中尺度数值天气预报模式(CMA_MESO)的2019年暖季东北地区强降水预报进行检验。结果表明,2019年暖季东北地区54个强降水日的环流型可分为:西风槽型(15个)、副热带高压影响型(13个)、急流型(5个)、西部(12个)和东部冷涡型(9个)。其中,西风槽型和急流型以区域性强降水为主,模式对其强降水发生与否的预报能力强,TS评分较高;西部、东部冷涡型强降水的局地性强,模式对其强降水发生与否的预报能力差,TS评分低;副热带高压影响型也以区域性强降水为主,模式对其强降水发生与否的预报能力也比较强,但是对其强降水质心位置、强度、面积等属性预报偏差较大,TS评分也相对较低。另外,从两种模式预报性能对比看,CMA_MESO强降水强度和面积预报较实况普遍偏强,虽然其预报的TS评分一般高于ECMWF,但其对强降水预报的空报率也都比ECMWF大,对强降水的属性预报偏差一致性一般也低于ECMWF,其预报的可订正性整体上不及ECMWF。

A PRINCIPAL MODE OF CIRCULATION COVARIATION BETWEEN THE NORTHERN AND SOUTHERN HEMISPHERES AND ITS ASSOCIATION WITH ENSO DURING BOREAL WINTER

By employing the singular value decomposition(SVD) analysis, we have investigated in the present paper the covariations between circulation changes in the Northern(NH) and Southern Hemispheres(SH) and their associations with ENSO by using the NCEP/NCAR reanalysis, the reconstructed monthly NOAA SST, and CMAP precipitation along with NOAA Climate Prediction Center(CPC) ENSO indices. A bi-hemispheric covariation mode(hereafter BHCM) is explored, which is well represented by the first mode of the SVD analysis of sea surface pressure anomaly(SLPA-SVD1). This SVD mode can explain 57.36% of the total covariance of SLPA. BHCM varies in time with a long-term trend and periodicities of 3—5 years. The long term trend revealed by SVD1 shows that the SLP increases in the equatorial central and eastern Pacific but decreases in the western Pacific and tropical Indian Ocean, which facilitates easterlies in the lower troposphere to be intensified and El Ni觡o events to occur with lower frequency. The spatial pattern of the BHCM looks roughly symmetric about the equator in the tropics, whereas it is characterized by zonal disturbances in the mid-latitude of NH and is highly associated with AAO in the mid-latitude of SH. On inter-annual time scales, the BHCM is highly correlated with ENSO. The atmosphere in both the NH and SH responds to sea surface temperature anomalies in the equatorial region, while the contemporaneous circulation changes in the NH and SH in turn affect the occurrence of El Ni觡o/La Ni觡a. In boreal winter, significant temperature and precipitation anomalies associated with the BHCM are found worldwide. Specifically, in the positive phase of the BHCM,temperature and precipitation are anomalously low in eastern China and some other regions of East Asia. These results are helpful for us to better understand interactions between circulations in the NH and SH and the dynamical mechanisms behind these interactions.

Wind-Driven,Double-Gyre,Ocean Circulation in a Reduced-Gravity,2.5-Layer,Lattice Boltzmann Model

A coupled lattice Boltzmann （LB） model with second-order accuracy is applied to the reduced-gravity, shallow water, 2.5-layer model for wind-driven double-gyre ocean circulation. By introducing the secondorder integral approximation for the collision operator, the model becomes fully explicit. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretization accuracy of the LB equation. The feature of the multiple equilibria solutions is found in the numerical experiments under different Reynolds numbers based on this LB scheme. With the Reynolds number increasing from 3000 to 4000, the solution of this model is destabilized from the anti-symmetric double-gyre solution to the subtropic gyre solution and then to the subpolar gyre solution. The transitions between these equilibria states are also found in some parameter ranges. The time-dependent variability of the circulation based on this LB simulation is also discussed for varying viscosity regimes. The flow of this model exhibits oscillations with different timescales varying from subannual to interannual. The corresponding statistical oscillation modes are obtained by spectral analysis. By analyzing the spatiotemporal structures of these modes, it is found that the subannual oscillation with a 9-month period originates from the barotropic Rossby basin mode, and the interarmual oscillations with periods ranging from 1.5 years to 4.6 years originate from the recirculation gyre modes, which include the barotropic and the baroclinic recirculation gyre modes.

Recommendations for Analysis and Optimization of Vegetable Circulation Mode in Hebei Province

This paper analyzed current situations of vegetable production and circulation in Hebei Province and summarized 3 major modes of vegetable circulation in Hebei Province,namely,traditional circulation mode,production-marketing docking mode,and e-commerce channel based circulation mode.Through comprehensive analysis of advantages and disadvantages of different circulation modes,it came up with pertinent recommendations for optimizing the vegetable circulation system in Hebei Province:reducing circulation links at the operating level to reduce circulation costs;bring into full play government supervision functions at institutional guarantee level to cut down expenses in circulation links.

A 3-dimensional baroclinic circulation model of the South China Sea

The summer and winter circulations in the South China Sea (SCS) including the surface elevation and water temperature are simulated using the model described by Cai and Li (1996) with the monthly mean wind stress and air temperature field at the 1000 mb level from the European Centre for Medium-Range Weather Forecasts as inputs. The boundary conditions at Bashi Channel and Taiwan Strait are taken from the simulation results of the Kuroshio using the same numerical model with a grid size of 0.5°×0.5° and the results of Cai and Li (1996) as boundary conditions. The computational domain for the present paper is between 100°E and 123°E and between 4.5°N and 27°N. The horizontal resolution is 0.25°×0.25° and the vertical variations of the velocity components are resolved by 6 layers The computed steady flow, temperature and elevation fields are consistent with the corresponding fields observed. In particular, the temperature and elevation fields of the South China Sea Warm Current (SCSWC) have been successfully simulated. The paths of the branch of the Kuroshio entering the South China Sea (SCSBK) through Bashi Channel in winter and summer are discussed It is found that the SCSBK flows southward to the southern SCS from the coast of the Guangdong Province. A portion of the SCSBK returns to the Bashi Channel and subdivides again in deep waters in winter with a branch flows to the south along the coast of the Philippines instead of flowing back to the Pacific In addition, our results confirm the existence of a eastward current to the northeast of Dongsha in summer with the Kuroshio as its source as suggested by Huang et al. Since the value of the eddy viscosity adopted for the simulation of the Kuroshio is on the high side, resulting in a weaker west boundary current in the western Pacific as the boundary conditions for the present simulations, some deviations from the actual situations are expected although the results are in general consistent with observations.

Slow and Intraseasonal Modes of the Boreal Winter Atmospheric Circulation Simulated by CMIP5 Models

Abstract The authors evaluate the performance of models from Coupled Model Intercomparison Project Phase 5(CMIP5)in simulating the historical(1951-2000)modes of interannual variability in the seasonal mean Northern Hemisphere(NH)500 hPa geopotential height during winter(December-January-February,DJF).The analysis is done by using a variance decomposition method,which is suitable for studying patterns of interannual variability arising from intraseasonal variability and slow variability(time scales of a season or longer).Overall,compared with reanalysis data,the spatial structure and variance of the leading modes in the intraseasonal component are generally well reproduced by the CMIP5 models,with few clear differences between the models.However,there are systematic discrepancies among the models in their reproduction of the leading modes in the slow component.These modes include the dominant slow patterns,which can be seen as features of the Pacific-North American pattern,the North Atlantic Oscillation/Arctic Oscillation,and the Western Pacific pattern.An overall score is calculated to quantify how well models reproduce the three leading slow modes of variability.Ten models that reproduce the slow modes of variability relatively well are identified.

A Two-way Stratosphere–Troposphere Coupling of Submonthly Zonal-Mean Circulations in the Arctic

This paper examines the dominant submonthly variability of zonally symmetrical atmospheric circula- tion in the Northern Hemisphere （NH） winter within the context of the Northern Annular Mode （NAM）, with particular emphasis on interactive stratosphere-troposphere processes. The submonthly variability is identified and measured using a daily NAM index, which concentrates primarily on zonally symmetrical circulation. A schematic lifecycle of submonthly variability is developed that reveals a two-way coupling pro- cess between the stratosphere and troposphere in the NH polar region. Specifically, anomalous tropospheric zonal winds in the Atlantic and Pacific sectors of the Arctic propagate upwards to the low stratosphere, disturbing the polar vortex, and resulting in an anomalous stratospheric geopotential height （HGT） that subsequently propagates down into the troposphere and changes the sign of the surface circulations. From the standpoint of planetary-scale wave activities, a feedback loop is also evident when the anoma- lous planetary-scale waves （with wavenumbers 2 and 3） propagate upwards, which disturbs the anomalous zonally symmetrical flow in the low stratosphere, and induces the anomalous HGT to move poleward in the low stratosphere, and then propagates down into the troposphere. This increases the energy of waves at wavenumbers 2 and 3 in the low troposphere in middle latitudes by enhancing the land-sea contrast of the anomalous HGT field. Thus, this study supports the viewpoint that the downward propagation of stratospheric NAM signals may not originate in the stratosphere.

Southern Meridional Atmospheric Circulation Associated with IOD

Using the monthly wind and sea surface temperature （SST） data, southern meridional atmospheric circulation cells associated with the Indian Ocean Dipole Mode （IOD） events in the Indian Ocean are for the first time described and examineS. The divergent wind and pressure vertical velocity are employed for the identification of atmospheric circulation cells. During the four different phases of the positive IOD events, the anomalous meridional Hadley circulation over the western Indian Ocean shows that the air rises in the tropics, flows poleward in the upper troposphere, sinks in the subtropics, and returns back to the tropics in the lower troposphere. The anomalous Hadley circulation over the eastern Indian Ocean is opposite to that over the western Indian Ocean. During positive IOD events, the meridional Hadley circulation over the eastern Indian Ocean is weakened while it is strengthened over the western Indian Ocean. Correlation analysis between the IOD index and the indices of the Hadley cells also proves that, the atmospheric circulation patterns are evident in every IOD event over the period of record.

Mechanisms of Atlantic Meridional Overturning Circulation(AMOC)Variability in a Coupled Ocean–Atmosphere GCM

The mechanisms involved in the variability of Atlantic Meridional Overturning Circulation （AMOC） are studied using a 2000-yr control simulation of the coupled Fast Ocean-Atmosphere Model （FOAM）.This study identifies a coupled mode between SST and surface heat flux in the North Atlantic at the decadal timescale,as well as a forcing mode of surface heat flux at the interannual timescale.The coupled mode is regulated by AMOC through meridional heat transport.The increase in surface heating in the North Atlantic weakens the AMOC approximately 10 yr later,and the weakened AMOC in turn decreases SST and sea surface salinity.The decreased SST results in an increase in surface heating in the North Atlantic,thus forming a positive feedback loop.Meanwhile,the weakened AMOC weakens northward heat transport and therefore lowers subsurface temperature approximately 19 yr later,which prevents the AMOC from weakening.In the forcing mode,the surface heat flux leads AMOC by approximately 4 yr.

生鲜电商流通模式演化与服务价值创造——盒马鲜生和京东生鲜的双案例研究

通过剖析盒马鲜生以新颖导向型流通模式为起点的服务价值创造过程,京东生鲜以效率导向型流通模式为起点的服务价值创造过程,提出了以不同生鲜电商流通模式为起点的服务价值创造的实现机理;通过分析生鲜电商的服务价值创造结果,进一步提出了“双重导向”型流通模式及其服务价值创造的实现机理。研究发现,生鲜电商流通模式的关键构成包括服务提供、能力迭代、场景发展和价值变现;根据构成要素的不同组合,将流通模式细分为新颖导向型、效率导向型和“双重导向”型,其服务价值创造的实现机理反映了多样性互补和聚焦性互补的重要性作用;“双重导向”型生鲜电商流通模式是新颖导向型流通模式和效率导向型流通模式演化的共同结果。

数字经济背景下我国绿色农产品流通模式的优化策略

当前,数字经济的高速发展对我国绿色农产品流通模式产生前所未有的冲击与挑战,正推动农产品生产方式与消费方式深刻变革,成为优化我国传统绿色农产品流通模式的重要驱动力。相较于传统经济,数字经济具有数字化、网络化与智能化等显著特征,对我国绿色农产品流通模式影响深远。在该背景下,对我国绿色农产品流通模式进行优化并找出存在的问题,最后从夯实绿色农产品流通数字化基础设施建设、推动绿色农产品流通数字化技术创新进程、加大绿色农产品流通数字化教育投入力度和提升绿色农产品流通数字化资源整合水平4个方面提出我国绿色农产品流通模式优化策略,以期能够拓宽绿色农产品流通渠道,推动绿色农产品流通业现代化发展,从而有利于提高我国绿色农产品流通效率,促进我国农业经济高质量发展。

多模式CT对急性前循环缺血性脑卒中患者缺血半暗带、梗死核心变化及预后的评估

目的 探讨多模式CT对急性前循环缺血性脑卒中患者缺血半暗带、梗死核心变化及预后的评估。方法 回顾性选取2021年1月至2023年6月来佛山市中医院诊治的疑似急性前循环缺血性脑卒中患者100例,治疗前后分别行多模式CT检查。分析头颅CT平扫(NCCT)、CT灌注成像(CTP)、CT血管成像(CTA)结果。比较急性前循环缺血性脑卒中患者缺血半暗带区、梗死核心区患侧与健侧的脑血容量(CBV)、脑血流量(CBF)、平均通过时间(MTT)、达峰时间(TTP)值;比较治疗前后急性前循环缺血性脑卒中患者缺血半暗带的灌注参数[相对脑血容量(rCBV)、相对脑血流量(rCBF)、相对平均通过时间(rMTT)和相对达峰时间(rTTP)];比较治疗前后急性前循环缺血性脑卒中患者梗死核心的灌注参数(rCBF、rCBV、rTTP、rMTT);分析脑组织异常灌注与血管狭窄的相关性。43例急性前循环缺血性脑卒中患者根据发病4.5~9.0 h内经溶栓治疗结果,比较预后良好(改良Rankin评分≤2分,n=28)与预后不良(改良Rankin评分>2分,n=15)缺血半暗带的rCBV、rCBF、rMTT、rTTP值。结果 100例疑似患者经NCCT检查发现,59例患者可见早期的低密度病灶,其余41例患者未见明显异常,NCCT阳性率为59.00%。CTP检查结果发现,100例患者中9例经过CTP检查灌注正常,其余91例患者脑灌注均有异常现象,与临床症状相符,CTP检查发现阳性率为91.00%。CTA检查结果发现,存在责任血管狭窄或闭塞者88例,无存在责任血管狭窄或闭塞者12例。多模式CT结果:急性前循环缺血性脑卒中缺血半暗带区健侧、患侧CBV比较,差异无统计学意义(P>0.05),患侧的CBF明显较健侧低,患侧的MTT、TTP明显较健侧高,差异均有统计学意义(P<0.05)。梗死核心区患侧的CBV、CBF明显较健侧低,MTT、TTP明显较健侧高,差异均有统计学意义(P<0.05)。与梗死核心区相比,缺血半暗带的rCBV、rCBF明显较高,rMTT、rTTP值明显较低,差异均有统计学意义(P<0.05)。治疗后,前缺血半暗带rCBV与治疗前比较,差异无统计学意义(P>0.05),rCBF较治疗前高,rMTT、rTTP较治疗前低,差异均有统计学意义(P<0.05)。血流灌注异常者中存在责任血管狭窄或闭塞发生率明显较血流灌注正常者高(95.6%vs.11.11%),差异有统计学意义(P<0.05)。发病4.5~9 h内经溶栓治疗患者43例,其中预后良好者28例,预后不良者15例。预后良好者前缺血半暗带rCBV与预后不良比较,差异无统计学意义(P>0.05),预后良好者rCBF较预后不良高,rMTT、rTTP较预后不良低,差异均有统计学意义(P<0.05)。结论 多模式CT可早期发现急性前循环缺血性脑卒中的缺血半暗带、梗死核心异常情况,可用于急性前循环缺血性脑卒中患者的预后判断。