The Coordinated Influence of Indian Ocean Sea Surface Temperature and Arctic Sea Ice on Anomalous Northeast China Cold Vortex Activities with Different Paths during Late Summer

The Northeast China cold vortex(NCCV)during late summer(from July to August)is identified and classified into three types in terms of its movement path using machine learning.The relationships of the three types of NCCV intensity with atmospheric circulations in late summer,the sea surface temperature(SST),and Arctic sea ice concentration(SIC)in the preceding months,are analyzed.The sensitivity tests by the Community Atmosphere Model version 5.3(CAM5.3)are used to verify the statistical results.The results show that the coordination pattern of East Asia-Pacific(EAP)and Lake Baikal high pressure forced by SST anomalies in the North Indian Ocean dipole mode(NIOD)during the preceding April and SIC anomalies in the Nansen Basin during the preceding June results in an intensity anomaly for the first type of NCCV.While the pattern of high pressure over the Urals and Okhotsk Sea and low pressure over Lake Baikal during late summer-which is forced by SST anomalies in the South Indian Ocean dipole mode(SIOD)in the preceding June and SIC anomalies in the Barents Sea in the preceding April-causes the intensity anomaly of the second type.The third type is atypical and is not analyzed in detail.Sensitivity tests,jointly forced by the SST and SIC in the preceding period,can well reproduce the observations.In contrast,the results forced separately by the SST and SIC are poor,indicating that the NCCV during late summer is likely influenced by the coordinated effects of both SST and SIC in the preceding months.

An Extreme Gale Event in East China under the Arctic Potential Vorticity Anomaly through the Northeast China Cold Vortex

Arctic changes influence not only temperature and precipitation in the midlatitudes but also contribute to severe convection.This study investigates an extreme gale event that occurred on 30 April 2021 in East China and was forced by an Arctic potential vorticity(PV)anomaly intrusion.Temperature advection steered by storms contributed to the equatorward propagation of Arctic high PV,forming the Northeast China cold vortex(NCCV).At the upper levels,a PV southward intrusion guided the combination of the polar jet and the subtropical jet,providing strong vertical wind shear and downward momentum transportation to the event.The PV anomaly cooled the upper troposphere and the northern part of East China,whereas the lower levels over southern East China were dominated by local warm air,thus establishing strong instability and baroclinicity.In addition,the entrainment of Arctic dry air strengthened the surface pressure gradient by evaporation cooling.Capturing the above mechanism has the potential to improve convective weather forecasts under climate change.This study suggests that the more frequent NCCV-induced gale events in recent years are partly due to high-latitude waviness and storm activities,and this hypothesis needs to be investigated using more cases.

Modulation of the late summer Northeast China cold vortex by previous-winter ENSO

本文利用再分析资料,研究了前冬ENSO对夏末东北冷涡(NCCV)的调制作用.结果表明,前冬ENSO与夏末NCCV强度之间存在显著的相关性,El Nino(La Ni?a)对应于弱(强)的NCCV.印度洋海盆模态(IOBM)在前冬ENSO对夏末东北亚地区大气环流的影响中起着至关重要的作用.作为东部型El Nino的被动响应,IOBM可以从前冬一直持续至夏末,并在夏末激发“中国中部上空气旋—东北亚地区上空反气旋”的经向遥相关模态,从而不利于NCCV增强.反之亦然.此外,印度洋的信号在中部型El Nino和中性年份相对较弱,使得它们对于NCCV的影响不显著.

The Influence of SST Warm-water Region and ITCZ in the North-West Pacific Ocean on the Northeast Cold Vortex and the Subtropical High

By using the monthly mean grid data of NCAR/NCEP reanalysis at 500 hPa geopotential height from 1958 to 1997,the relationship between the Northeast cold vortex and the western Pacific subtropical high was analyzed.The influence of the sea surface temperature(SST) and outgoing longwave radiation(OLR) on the Northeast cold vortex and subtropical high was studied.As was shown in the results,in summer,there was a positive correlation between the Northeast cold vortex and the subtropical high,and an anti-phase relationship existed between the threshold characteristic line of GMS-SST=28 ℃ and the height index of the Northeast cold vortex and the subtropical high.With the gradual northward moving of the threshold characteristic line,the subtropical high was weakening,and the Northeast cold vortex was increasing and strengthening.

Classification of Northeast China Cold Vortex Activity Paths in Early Summer Based on K-means Clustering and Their Climate Impact

The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the atmospheric circulation field and temperature field data of ERA-Interim for every six hours,the NCCV processes during the early summer(June)seasons from 1979 to 2018 were objectively identified.Then,the NCCV processes were classified using a machine learning method(k-means)according to the characteristic parameters of the activity path information.The rationality of the classification results was verified from two aspects,as follows:(1)the atmospheric circulation configuration of the NCCV on various paths;and(2)its influences on the climate conditions in the NEC.The obtained results showed that the activity paths of the NCCV could be divided into four types according to such characteristics as the generation origin,movement direction,and movement velocity of the NCCV.These included the generation-eastward movement type in the east of the Mongolia Plateau(eastward movement type or type A);generation-southeast longdistance movement type in the upstream of the Lena River(southeast long-distance movement type or type B);generationeastward less-movement type near Lake Baikal(eastward less-movement type or type C);and the generation-southward less-movement type in eastern Siberia(southward less-movement type or type D).There were obvious differences observed in the atmospheric circulation configuration and the climate impact of the NCCV on the four above-mentioned types of paths,which indicated that the classification results were reasonable.

Objective identification research on cold vortex and mid-summer rainy periods in Northeast China

Considering the differences between the Northeast China Cold Vortex （CV） and the Mid-Summer （MS） rainy period and their corresponding atmospheric circulations are comprehensively analyzed, and the objective identification methods of defining the annual beginning and ending dates of Northeast China CV and MS rainy periods are developed respectively. The annual beginning date of the CV （MS） rainy period is as follows. In a period from April to August, if daily regional mean precipitation ryi is larger than yearly regional mean precipitation R （or 2R） on a certain day, the station precipitation rs is larger than the station yearly mean precipitation （r/ （or 2（r）） in at least 50% of stations in Northeast China, and this condition is satisfied in the following 2 （7） days, then this date is defined as the beginning date of the CV （MS） rainy period. While the definition of the ending date of the MS rainy period shows the opposite process to its beginning date. With this objective identification method, the multi-year average （1981-2010） beginning date of the CV rainy period is May 3, the beginning date of the MS rainy period is June 27, the ending day of the CV rainy period is defined as the day before the beginning date of the MS rainy period, and the ending date of the MS rainy period is August 29. Meanwhile, corresponding anomaly analysis at a 500-hPa geopotential height, 850-hPa wind, Omega and relative humidity fields all show that the definitions of the average beginning and ending dates of the CV and MS rainy periods have a certain circulation meaning. Furthermore, the daily evolution of the CV index, meridional and zonal wind index, etc. all show that these objectively defined beginning and ending dates of the CV and MS rainy periods have climate significance.

Study on the Evolution of a Northeast China Cold Vortex during the Spring of 2010

Based on the final analysis data with horizontal resolution of 1°× 1°(four times a day) from the National Centers for Environmental Prediction(NCEP), a typical Northeast China cold vortex(NCCV) during the spring of 2010 was examined with the quasi-Lagrange- form eddy flux circulation(EFC) budget equation. Results indicated that the mechanisms that account for the development, maintenance, and attenuation of the cyclone varied with levels and stages. Displacement of the cyclone and transports by background environmental circulations dominated the variation of the cyclone in the middle and upper levels, whereas displacement and divergence associated with the cyclone dominated the evolution of the NCCV in the middle and lower levels. Moreover, interactions between the NCCV and other subsynoptic weather systems were important for the development of the cyclone, and the pattern of background environmental circulations was also important for the evolution of the NCCV, since the cyclone enhanced(weakened) as it moved from areas of low(high) vorticity to high(low) ones.

Quadrant-Averaged Structure and Evolution Mechanisms of a Northeast Cold Vortex during Its Mature Stage

A Northeast China cold vortex(NCCV) that maintained from 0200 UTC 3 July to 0500 UTC 3 July 2013 and caused several heavy rainfall events was analyzed in detail to reveal its quadrant-averaged structure and main maintaining mechanisms during its mature stage. Results indicated the vortex's intensity, divergence, ascending motions, precipitable water(PW), and thermal structures were all characterized by significant unevenness, and their main pattern changed gradually during the mature stage. Mechanisms accounting for the maintenance of the NCCV were also characterized by remarkable unevenness. Within different quadrants, dominant factors for the vortex's evolution may have differed from each other significantly. The NCCV-averaged vorticity budget revealed that the vertical advection of vorticity, which is closely related to convective activities, was the most favorable factor for maintaining the NCCV, whereas the tilting effect, which is closely related to the vertical shear of the horizontal wind(horizontal vorticity), was the most detrimental factor.

Comparative Forecast Verification for a Rainfall Process Caused by the Northeast Cold Vortex in Different Valid Time

The forecast of precipitation,height,temperature,divergence and water vapor divergence during a rainfall process in Northeast China during June 13-14 in 2012 were analyzed. The results showed that the rainfall process in Northeast China on June 13 and 14 in 2012 was mainly caused by the typical northeast cold vortex at 500 h Pa,southwest low-level jet at 850 and 700 h Pa,and surface cyclone. The rainfall forecast valid in 60 h was obviously better than those valid in 36 and 84 h,and the forecast error mainly resulted from the prediction error of vertical water vapor transportation.

Sub-Seasonal Predictability of the Northeast China Cold Vortex in BCC and ECMWF S2S Model Forecasts for 2006-2021

As an important atmospheric circulation system in the mid-high latitudes of East Asia,the Northeast China cold vortex(NCCV)substantially influences weather and climate in this region.So far,systematic assessment on the performance of numerical prediction of the NCCVs has not been carried out.Based on the Beijing Climate Centre(BCC)and the ECMWF model hindcast and forecast data that participated in the Sub-seasonal to Seasonal(S2S)Prediction Project,this study systematically examines the performance of both models in simulating and forecasting the NCCVs at the sub-seasonal timescale.The results demonstrate that the two models can effectively capture the seasonal variations in the intensity,active days,and spatial distribution of NCCVs;however,the duration of NCCVs is shorter and the intensity is weaker in the models than in the observations.Diagnostic analysis shows that the differences in the intensity and location of the East Asian subtropical westerly jet and the wave train pattern from North Atlantic to East Asia may be responsible for the deficient simulation of NCCV events in the S2S models.Nonetheless,in the deterministic forecasts,BCC and ECMWF provide skillful prediction on the anomalous numbers of NCCV days and intensity at a lead time of 4-5(5-6)pentads,and the skill limit of the ensemble mean is 1-2 pentads longer than that of individual members.In the probabilistic forecasts of daily NCCV activities,BCC and ECMWF exhibit a forecasting skill of approximately 7 and 11 days,respectively;both models show seasonal dependency in the simulation performance and forecast skills of NCCV events,with better performance in winter than in summer.The results from this study provide helpful references for further improvement of the S2S prediction of NCCVs.

2023年3月河南省一次极端暴雪和雷电天气成因分析

选用自动气象站、双偏振雷达、风廓线雷达和ERA5再分析等资料,分析2023年3月16日河南省一次极端暴雪和雷电天气成因。结果表明:此次极端暴雪过程主要天气系统为低槽、切变线、急流以及东北冷涡。冷涡配合-39℃冷中心稳定维持,其后部冷空气持续南下,850 hPa以下形成深厚冷垫,中高层西南暖湿气流沿冷垫爬升,形成河南省典型的降雪天气类型“天南地北型”。此次强降雪区位于整层大气可降水量大于20 mm区域的北部与700 hPa强辐合中心重叠的区域,河南中西部地形的抬升作用利于此极端降雪天气发生。冷平流与其次级环流共同作用,使局地气温骤降,导致降水相态转换较预期提前,以致多站降雪量或积雪深度超历史极值。双偏振雷达零滞后相关系数产品(CC)为相态转换监测提供了重要参考。850 hPa以下大气温度均低于0℃,且2 m气温降至1℃左右,可作为降雪预报指标。辐合切变及锋面次级环流有利于高架雷暴天气出现,20 dBz回波高度超过-20℃层高度可作为产生雷暴的关键指标。

2021年11月7—9日辽宁省极端雨雪天气分析

选用常规气象观测资料、人工加密观测资料和NCEP/NCAR格点资料,对2021年11月7—9日辽宁省极端雨雪天气进行诊断分析。结果表明:东北冷涡和地面气旋为此次极端雨雪天气的主要影响系统,对流层中低层辐合、高层辐散以及强的冷暖气流交汇,是产生极端雨雪天气的主要原因;高低空急流耦合和高空辐散抽吸作用,配合东北冷涡动力抬升作用,暖湿低空急流沿冷垫爬升,进一步加强了上升运动。暖湿急流为此次极端雨雪天气提供了充沛的水汽条件,暖湿急流的增强对应水汽辐合作用增强,配合低层冷垫和东北冷涡的动力抬升作用,对降雪有明显增幅作用;地面辐合线沿地形分布,触发了此次极端强降雪天气。地形阻挡导致地面冷空气堆积形成冷垫,是极端降雪天气发生的重要原因。温度层结差异是鞍山、岫岩雨雪相态差异的主要原因。具有冻结层特征的低层冷垫,为鞍山极端暴雪提供了有利的温度层结条件;融化层厚度和地面温度是岫岩出现冻雨的关键因素。

东北冷涡分类及其对内蒙古东部降水的影响

利用1981—2022年6—8月内蒙古119个国家气象观测站逐日降水资料和NCEP/NCAR逐日再分析资料,分析东北冷涡年际、年代际变化特征及东北冷涡分类对内蒙古东部降水的影响。结果表明:东北冷涡发生频次在1992年之前,较常年值显著偏多,之后显著偏少,2003年以后有增多的趋势,近十年发生频次偏多。将东北冷涡分为10类,中涡东北移是致使东部降水偏多最异常的冷涡类型,中涡东移是次异常的冷涡类型。东亚地区呈现“北高南低”环流型,内蒙古东部位于负位势高度距平区,中心位于东部偏南地区,乌拉尔山和鄂霍次克海阻塞高压偏强,副热带高压偏强,内蒙古东部地区受气旋性环流控制,低层水汽通量辐合,配合越赤道气流共同作用引导的西太平洋水汽输送到东部地区,是东部降水异常偏多的主要环流配置型。

东北冷涡背景下三类区域性强对流天气过程时空分布和环境特征对比分析

东北冷涡是造成中国暖季强对流的重要天气尺度系统之一。为对比东北冷涡与不同类型强对流过程的时空关系及其环境特征差异,基于欧洲中期天气预报中心第5代大气再分析数据和中国国家气象信息中心提供的逐时大风、降水观测资料,筛选了2017—2021年4—9月东北冷涡背景下9例雷暴大风型、9例强降水型以及8例混合型强对流天气过程,通过动态合成开展了分析研究。结果表明:(1)三类强天气过程相对于冷涡的时空分布差异明显:雷暴大风型过程,超过70%的雷暴大风出现在冷涡中心的西南部或南部;而混合型过程,超过70%的大风出现在冷涡中心的东南部或南部;混合型和强降水型过程中,短时强降水均主要出现在冷涡中心南部或东南部,但后者发生在冷涡东南部的比例更高;雷暴大风型和强降水型过程主要出现在东北冷涡的发展和成熟阶段,而混合型过程主要发生在东北冷涡的成熟阶段。(2)三类强天气过程的环流形势和环境条件差异显著。雷暴大风型过程多出现在5—6月,一般对应的东北冷涡更深厚,等温线更密集,大气环境偏干,存在气温垂直递减率大和强风垂直切变条件,雷暴大风多发生在冷涡南侧的锋区附近,对流层中、高层受干冷空气控制,叠加在低层比较浅薄的暖湿空气之上有利于大气层结条件不稳定的增强,降水粒子蒸发降温形成的下沉气流和地面冷池,叠加锋区辐合更有利于形成区域性地面强风;而强降水型过程多集中在7—8月,对应的东北冷涡强度较弱,等温线较稀疏,强降水一般出现在锋前靠近暖区一侧的强层结不稳定区域内,对应水汽充沛、整层暖湿的环境条件,中低层温差较小,风垂直切变较弱。混合型过程对应的月份和冷涡强度与强降水型过程更接近,水汽、高低层温差以及风垂直切变等环境条件介于上述两类过程之间,但下沉对流有效位能在三类过程中表现为最大。总体来看,相较于中国中、低海拔地区雷暴大风和短时强降水的环境特征而言,东北冷涡背景下的强天气过程对应更强的深层风垂直切变,具有更强的天气尺度动力强迫。

2023年麦收期河南省连阴雨的气候特征和可能成因

2023年麦收期河南省出现了罕见的连阴雨天气,降水和阴雨日数异常偏多,分别为自1961年以来的历史第五位和第二位。分析连阴雨的可能气候成因,主要结论如下:(1)造成连阴雨的环流形势为欧亚中高纬度西高东低,乌拉尔山高压脊持续发展并出现阶段性阻塞,东北冷涡活跃,冷空气能持续南下,西太平洋副热带高压(以下简称副高)偏北、偏强且异常偏西,来自副高西北侧边缘的暖湿气流和冷空气在河南省交汇。(2)副高偏强、偏北、偏西是由偏强、偏北、偏大、偏东的南亚高压和偏强、偏北的东亚副热带西风急流(以下简称西风急流)的引导所致,而东南亚对流层中高层的暖中心偏大、偏北和偏东且呈东西向带状分布,使南亚高压形成了上述的特征。暖中心和东北冷涡的共同作用,使东亚中高层的气温梯度增大,进而加强了西风急流。(3)2023年前期的La Ni1a事件有利于麦收期副高偏北,但不利于副高偏强和明显偏西。麦收期由于台风扰动由泰国湾至菲律宾群岛以东的热带西太平洋对流活跃释放的凝结潜热较多,以及麦收期前期的春季和麦收期伊朗高原至青藏高原的地面感热和潜热较强,使暖中心形成了上述的特征,进而决定了南亚高压和副高的特征。(4)2023年麦收期北大西洋海温偏高,以及北大西洋三极子为负位相,导致了乌拉尔山高压脊持续发展并出现阶段性阻塞,麦收期前期的春季和麦收期伏尔加河至贝加尔湖西北侧地面感热和潜热偏强,而下游贝加尔湖东南侧至鄂霍次克海地面感热和潜热偏弱一定程度上导致上述两区域分别出现了大范围的位势高度正距平和负距平。

2021年6月东北冷涡暴雨降水物理过程观测与模拟研究

本文针对2021年6月2~3日发生在辽宁和吉林两省的东北冷涡暴雨过程,利用多源观测和再分析数据,首先开展综合观测分析,进而利用WRF模式对此次暴雨过程的主降水时段开展高分辨率数值模拟,并结合三维降水诊断方程,开展宏、微观物理过程和暴雨形成机理模拟诊断研究。结果表明,此次暴雨过程降水范围广、局地雨强大、对流性突出;暴雨过程期间,东亚大气环流相对稳定,东北冷涡缓慢东移,携带冷空气南下,与偏南暖湿气流汇合,触发涡旋云系发展;两省位于高空急流核出口区左前方和偏南低空急流前侧,低层辐合—高层辐散的动力结构有助于强降水系统发展。伴随水汽辐合加强,云物理过程旺盛发展,水凝物含量显著升高,其中霰粒子通过融化成雨滴等云物理过程,对强降水起到重要贡献。云滴通过水汽凝结过程迅速增长,但同时由于云微物理转化过程而被大量消耗,用于云系发展和降水发生。降水强度受水汽收支和云收支过程共同影响,强降水前期,伴随强盛水汽输送与辐合,区域上空水汽含量显著增加,降水系统发展;强降水后期,伴随冷涡云系逐步东移,区域内辐合减弱,局地大气内水汽明显消耗,以继续支撑较强降水。伴随水汽局地辐合,水凝物旺盛发展(尤其是冰相水凝物)。过程初期,液相水凝物动力辐合与微物理转化过程共同支撑降水云系快速发展;降水峰值时段,上述两过程仍然活跃,但由于强降水显著消耗,水凝物含量局地变化不明显。整个暴雨过程期间,液相水凝物持续辐合,而冰相水凝物于初期短暂辐合之后,逐渐减弱为弱辐散,这一演变特征与局地热、动力结构及其演变有关。

2021年6月东北冷涡暴雨水汽来源和源区贡献分析

本文针对2021年6月2~3日发生在东北地区的冷涡暴雨过程,首先利用传统欧拉方法,初步分析了此次初夏东北冷涡暴雨过程的水汽输送与辐合特征,进而利用拉格朗日轨迹追踪模式FLEXPART和水汽来源与源区定量贡献分析方法,揭示出此次暴雨过程的水汽源地和源区定量贡献。结果表明:此次初夏冷涡暴雨过程期间,副热带高压偏南,东北地区主要受东北冷涡和其下游日本海弱高压脊影响,但对流层低层,副高主体与日本海弱高压脊之间存在气旋性切变流场,促成一支低空急流沿我国沿海地区北上,有利于东北地区南侧水汽向北输送,与东北冷涡后部干冷空气在辽宁和吉林省交汇,触发强降水。拉格朗日轨迹追踪显示,60%以上的目标气块来自降水区西侧和西北侧的亚欧大陆地区,这些气块初始位置高度较高,途径我国东海、黄海一带时,高度显著降低,并汇入偏南暖湿气流,进而流入目标降水区;还有部分气块来自贝加尔湖及其以东地区以及我国南海和中南部大陆地区,气块初始位置及行进过程中高度均较低。水汽源区对目标降水区的水汽定量贡献显示,东海—黄海至西北太平洋地区贡献最大(贡献率37.04%),中国大陆中东部紧随其后(贡献率30.05%),显著的水汽摄取和较低的沿途损失,使得上述两区域水汽贡献显著,而降水区局地摄取水汽的贡献排在第三位;此外,贝加尔湖及其以东地区和亚欧大陆中西部亦有一定贡献(尽管亚欧大陆中西部的水汽摄取总量亦较大,但绝大部分水汽在远距离输送过程中损耗),而印度半岛至中国南海地区水汽贡献最小。相对于传统的欧拉方法,拉格朗日方法可以更清晰地给出暴雨过程主要的水汽源地及其贡献。

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。

东北暖季冷涡降水日变化的聚类分析

使用2017~2022年5~9月逐小时三源融合实况格点降水(CMPAS)资料,采用K-均值聚类算法对东北暖季冷涡降水日变化分类,分析其特征及空间分布,结果显示:1)东北暖季冷涡降水多年平均降水量空间分布从西北到东南增加,降水频次的空间分布与其相似,降水强度大值区集中在辽东半岛附近。2)东北地区冷涡背景下降水量、降水频次和降水强度暖季平均日变化均呈双峰型,降水量的下午主峰值主要源于降水频次,而夜间次峰值与降水频次和降水强度均关系密切。3)聚类后冷涡降水量、降水频次的日变化表现为单峰型和双峰型特征,且单峰型格点占比较大,降水强度的日变化表现为单峰型。依据峰值出现时间及日变化形态间差异,降水量、频次与强度均可划分为4类不同的日变化类型。4)各类日变化空间占比统计结果显示,冷涡降水量、降水频次日变化存在下午峰值的格点均占比最大,夜间峰值次之,两者聚类后区域特征明显,与地形关系密切且分布相对规整;冷涡降水强度日变化下午单峰型格点占比最大,聚类后空间分布较为零散。

1961—2021年黑龙江省春播期东北冷涡气候影响特征

选用1961—2021年黑龙江省62站逐日地面降水、气温资料及NCEP/NCAR再分析资料,统计分析黑龙江省春播期间持续时间3 d及以上的东北冷涡活动特征及其对春播期气候要素的影响。结果表明:61 a春播期发生东北冷涡过程233次,共958 d,发生频次及日数均为增大趋势,发生频次与单次冷涡持续时间为显著负相关。东北冷涡的降水贡献率约为43.29%,冷涡过程中出现大雨及暴雨日的频率较大,分别为48.66%和59.46%;东北冷涡对春播期气温影响不显著。500 hPa位势高度场,东北冷涡与贝加尔湖至鄂霍茨克海阻塞高压存在较好的正相关,超30%的冷涡活动与鄂霍茨克海阻塞高压相伴发生。鄂霍茨克海阻塞高压对冷涡降水有显著的增强作用,而对冷涡过程低温的影响不显著。