基于环流特征及海温影响的滦河流域干旱响应分析

滦河流域地处欧亚大陆东岸，降水及气候特征主要受鄂霍茨克海域附近中纬度高压与西太平洋副热带高压影响，而北极涛动（AO）和太平洋海表温度异常（SSTA）通过影响中纬度高压和西太平洋副热带高压来间接影响滦河流域的降水过程与气候特征。本文利用大气环流过程、空气比湿、位势高度变化及海表面温度异常等数据，对2009典型干旱年的大气环流特征及影响因素进行了分析。通过对影响干旱发生相关因素的监测，可对地区干旱的发生做出预报预警，为相关部门抗旱工作的决策部署及工程设计提供依据。     

ENSO事件对红水河龙滩站径流的影响分析

用多元ENSO(厄尔尼诺/南方涛动)指标,分析厄尔尼诺和拉尼娜事件对径流的影响。月径流量数据采用天峨水文站1950年~1997年共48年汛期(5月~10月)径流资料,结合美国国家环境预报中心(NCEP)和美国国家大气研究中心(NCAR)的逐月MEI指数分析红水河龙滩站来水规律。结果显示,龙滩站在汛前或汛期极强/强拉尼娜事件减弱期对应汛期流量呈放大趋势概率大,反之流量呈减少趋势概率大;在极强厄尔尼诺事件年汛期来水总量年际差异巨大,厄尔尼诺事件与流量关系并不总是保持一致,一般情况下厄尔尼诺事件年入汛偏晚概率大。     

2021年汛期我国主要天气气候特征及成因分析

利用国家气候中心实时和历史气象观测数据,对我国2021年汛期(4月1日至10月16日)气候特点进行了综合分析。分析结果显示,2021年汛期,我国气候特征总体雨多温高、旱涝并重,且气候异常特征突出、极端事件频发。一是我国降水“北多南少”,暴雨过程多,强度强、极端性显著;二是高温日数多、南方地区“秋老虎”明显;三是登陆台风数量少,出现了1949年以来在我国陆地滞留时间最长的台风;四是南北方气象干旱并发,阶段性区域性明显。分析还显示,2020年8月至2021年3月,赤道中东太平洋发生了一次中等强度的拉尼娜事件,热带西太平洋对流活动持续异常活跃,对副热带高压的持续偏北有重要作用。由此共同导致来自西北太平洋的东南暖湿气流和来自印度洋的西南暖湿气流异常强盛,并随着副热带高压北上,为北方降水提供了充沛的水汽条件。同时,欧亚中高纬环流经向度大,冷空气活动频繁,冷暖空气在我国北方地区频频交汇,导致北方地区降水持续偏多。     

减灾科普

正Q:什么是气旋?常见的气旋类型有哪些?A:气旋是指北(南)半球,大气中水平气流呈逆(顺)时针旋转的大型涡旋。气旋通常按气旋形成和活动的主要地区或热力结构进行分类。按地区可分为温带气旋、热带气旋和极地气旋性涡旋等;按热力结构可分为冷性气旋和热低压等。分类标准不同,气旋种类也不一样。     

海陆温差指数与我国华北地区降水的相关性分析

选取中国东部边缘海(渤海、黄海、东海)与我国华北地区20个站点的气温构建海陆温差序列,通过相关性分析的方法探讨三大海域海陆热力差异与华北地区降水的相关性,并利用海温或海温差定义的北极涛动(AOSST)和北太平洋涛动(NPOSSTD)分析其与华北地区降水的相关性,直接描述海气系统对我国华北地区气候的影响。结果表明:(1)华北地区降水对不同海域海陆温差的响应有所差异,其相关性非常显著,相关系数最高可达到0. 77。超前和滞后的相关系数明显高于同期相关系数,且超前和滞后的相关系数相差不大,并表现出相同的正负相关性,对应的月份形成12个月的周期变化。(2)涛动指数与三大海域海陆温差的相关性形成12个月的周期,但是SOI和Nino3. 4与三大海域海陆温差的相关系数很低,说明ENSO的发生通过其他的物理因素间接地影响我国的降水。(3) AOSST和NPOSSTD与华北地区降水的相关性与海陆温差相比没有提高,说明海洋上的大气环流与陆地的气候变化是相互影响的,其中通过中国邻近海域与陆地的热力差异可更准确地描述我国华北地区气候的变化。     

近60年江西省时段最大降水变异诊断

选取江西省91个气象站点1954—2012近60年小时尺度降水数据,采取水文变异诊断系统（HDMS）分别对各站点连续1、3、6、12、24 h年最大降水进行变异诊断分析。首先,在详细诊断中结合数理分析法利用线性趋势、Kendall、Spearman法进行趋势检验,跳跃诊断则采取M-K、累积距平、有序聚类、滑动F、滑动秩和等多种检验法判别;其次,综合诊断采取效率系数值R²判断最终诊断结果并时空分析;最后,对站点各时段最大降水量分别大于等于16、30、50 mm发生频次的空间特性分析。结果表明:（1）江西省最大1、3、6、12、24 h时段内最大降水的空间分布特征较为相似,伴随历时的增加,变异站点类型以跳跃增大居多,其中发生显著变异的站点数北部平原多于南方山岭地区,空间分布呈现为"北密南疏";（2）南方山岭与北方平原地区降水序列变异程度与高程分别成正相关性、负相关性,研究表明大气环流指数AO（北极涛动）、NAO（北大西洋涛动）、PNA（太平洋-北美涛动）与研究区域内站点降水量分别呈现负、正、负相关性,因此大气环流指数与江西省降水序列的变化有一定相关性,是造成时段最大降...     

’98气候异常防汛形势严峻

近期从水利部黄河水利委员会与海河水利委员会在银川联合主特召开的黄、海河流域汛期水文气象长期预报会商会上获悉,今年前期大气、海洋、高原积雪、气象要素、地温、地震、天文等物理因子和冬春以来气候出现不少异常特征,这些异常特征主要表现在:1997年春季发生的本世纪最强的厄尔尼诺现象至少还要持续到1998年夏季;北半球副热带高压从1998年1月以来异常偏强(历史最强);去冬今春,青藏高原积雪偏多,部分地区出现严重雪灾;1997年11月至1998年4月,长江流域及其以南地区降水异个偏多,不少地区出现了同期的历史极大值;1997～1998冬季气温较常年明显偏高,入春以来气温变化剧烈.3～4月南方出现了雷打雪的奇特现象;4月北方出现沙尘暴,其强度和范围也超出了历史记录;1998年太阳活动处在上升期……会议认为,1998年前期海洋、大气环流、降水、气温和天文背景都出现了极端异常现象,这些异常事件和现象将不可避免地会给黄、海河流域汛期带来重大影响作     

珠江三角洲地区极端降水时空演变特征

研究区域极端降水演变对科学应对变化环境下区域水资源利用及防灾减灾具有重要意义。选取气候变化检测指数专家组（ETCCDI）定义的6个极端降水指数（最大持续干旱日数、最大持续降水日数、极端降水日数、极端降水总量、最大日降水量和日降水强度）,采用线性趋势法和克里金插值法对珠江三角洲地区极端降水变化进行时空演变分析,并采用交叉小波识别大气环流异常因子（厄尔尼诺-南方涛动、北大西洋涛动、太平洋年代际振荡和印度洋偶极子）与极端降水的相关关系。结果显示:（1）除最大持续降水日数外,各极端降水指数均有不同程度增加,表明珠江三角洲地区极端降水正在增加,但变化不显著;（2）极端降水增加的站点主要集中在区域中部和北部,其中变化显著站点主要位于珠江口北部和区域北部;（3）不同气候态下各极端降水指数总体空间分布相似,但变化趋势空间差异较大,且变化幅度有所增加,表明随着年代际的推移极端降水越来越明显;（4）印度洋偶极子对最大持续干旱日数的影响最显著,而厄尔尼诺-南方涛动对其他极端降水指标的影响最显著。     

气候变化对黄河径流的影响

讨论了自然气候变化和人类活动产生的未来气候变化对黄河区域水情的影响。通过比较不同区域气候模式如厄尔尼诺（其概念采用Trenberth的定义，即“在Nino3和4区域海平面气温在6个月或更长时间内的5个月的滑动平均异常升高值为0．4℃”）、拉尼娜（热带太平洋海域变冷，是厄尔尼诺的对立事件）及南方涛动等来研究自然气候变化对径流的影响；通过观测数据和Arc GIS地理统计分析工具获得的径流、降水和温度的关系，评估未来气候变化对区域水情的影响。结果显示：①人类活动是导致过去50年中黄河流域水资源危机的首要因子；②除了人类活动，气候变化也是黄河流域径流减少的主要因子；③黄河流域的降水和径流显示了与厄尔尼诺或拉尼娜气候变化的有显著的响应，同时该响应也具有空间上的差异；④运用41年的观测资料建立了降水-径流-气温的关系，结果显示径流对降水和气温同样具有敏感性；⑤在研究基于观测资料的气候变化对区域水情的影响中，ArcGIS地理统计分析软件是一个有用的工具。     

EI NIO PHENOMENON AND EXTENDED ASSOCIATE PATTERN ANALYSIS

1 .　INTRODUCTIONIntroductionEINi noPhenomenon ,thelargestinterannualclimatesignal ,isthefirstclimatephe nomenonshowntodependessentiallyuponcoupledair seainteractionsinthePacificregions .In pastdecadesmanyeffortshavebeenmadeinunder standingandpredictingENSO :suchasthehypoth esisofBjerknes[1] thatENSOarisesasaself sus tainedcycleinwhichSSTAinthePacificcausethetradewindstostrengthenorslackenandthatthisinturndrivestheoceancirculationchangesthatproduceSSTA ;Wyrtki’srelaxationtheory[…     

THE RESPONSES OF THE THIRD GENERATION OF IAP/LASG OCEANIC GCM TO DIFFERENT EXTERNAL FORCING

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅａｎｎｕａｌｍｅａｎｃｌｉｍａｔｏｌｏｇｙ ,ｓｅａｓｏｎａｌｃｙｃｌｅａｎｄｉｎｔｅｒａｎｎｕａｌｖａｒｉｅｔｉｅｓｃｈａｒａｃｔｅｒｉｓｔｉｃｏｆｓｅａｓｕｒｆａｃｅｔｅｍｐｅｒａｔｕｒｅ (ＳＳＴ)ａｎｄｕｐｐｅｒ ｏｃｅａｎｈｅａｔｃｏｎｔｅｎｔａｓｗｅｌｌａｓｔｈｅｉｒｒｅｌａｔｉｏｎｓｈｉｐｉｎＬ30Ｔ63,ｔｈｅｔｈｉｒｄｇｅｎ ｅｒａｔｉｏｎｏｆｔｈｅｏｃｅａｎｉｃ ｇｅｎｅｒａｌｃｉｒｃｕｌａｔｉｏｎｍｏｄｅｌ(ＧＣＭ )ｄｅｖｅｌｏｐｅｄｉｎｔｈｅＳｔａｔ…     

Sea level variability in East China Sea and its response to ENSO

Sea level variability in the East China Sea (ECS) was examined based primarily on the analysis of TOPEX/Poseidon altimetry data and tide gauge data as well as numerical simulation with the Princeton ocean model (POM). It is concluded that the inter-annual sea level variation in the ECS is negatively correlated with the ENSO index, and that the impact is more apparent in the southern area than in the northern area. Both data analysis and numerical model results also show that the sea level was lower during the typical El Nio period of 1997 to 1998. El Nio also causes the decrease of the annual sea level variation range in the ECS. This phenomenon is especially evident in the southern ECS. The impacts of wind stress and ocean circulation on the sea level variation in the ECS are also discussed in this paper. It is found that the wind stress most strongly affecting the sea level was in the directions of 70o and 20o south of east, respectively, over the northern and southern areas of the ECS. The northwest wind is particularly strong when El Nio occurs, and sea water is transported southeastward, which lowers the sea level in the southern ECS. The sea level variation in the southern ECS is also significantly affected by the strengthening of the Kuroshio. During the strengthening period of the Kuroshio, the sea level in the ECS usually drops, while the sea level rises when the Kuroshio weakens.     

Impact of ENSO on River Flows in Guyana

The El Niño Southern Oscillation (ENSO) phenomenon is a natural part of the global climate system resulting from the interactions between large-scale ocean atmospheric circulation processes in the equatorial Pacific and Indian Oceans. In Guyana, for all the adverse weather and extreme hydrological events, the blame goes to El Niño or La Niña. This paper investigates the relationship between ENSO and three Guyanese river flows; the Demarara, Essequibo and Mazaruni. This work sheds some light on the effects of this phenomenon on these river flows which may be useful for the adaptation policies dealing with the impacts of ENSO.     

BIFURCATION OF THE NORTH EQUATORIAL CURRENT DERIVED FROM ALTIMETRY IN THE PACIFIC OCEAN

1. INTRODUCTION In the western North Pacific, the North Equatorial Current (NEC) bifurcates into the northward flowing Kuroshio and the southward flowing Mindanao Current as it encounters the Philippine coast[1-3]. The bifurcation latitude has direct infl…     

Sea level change under IPCC-A2 scenario in Bohai,Yellow, and East China Seas

Because of the environmental and socioeconomic impacts of anthropogenic sea level rise （SLR）, it is very important to understand the processes leading to past and present SLRs towards more reliable future SLR projections. A regional ocean general circulation model （ROGCM）, with a grid refinement in the Bohai, Yellow, and East China Seas （BYECSs）, was set up to project SLR induced by the ocean dynamic change in the 21st century. The model does not consider the contributions from ice sheets and glacier melting. Data of all forcing terms required in the model came from the simulation of the Community Climate System Model version 3.0 （CCSM3） under the International Panel on Climate Change （IPCC）-A2 scenario. Simulation results show that at the end of the 21st century, the sea level in the BYECSs will rise about 0.12 to 0.20 m. The SLR in the BYECSs during the 21st century is mainly caused by the ocean mass redistribution due to the ocean dynamic change of the Pacific Ocean, which means that water in the Pacific Ocean tends to move to the continental shelves of the BYECSs, although the local steric sea level change is another factor.     

基于ARGO浮标资料的太平洋三维流场估算

针对实际海洋中三维海流观测困难和流场资料欠缺的问题,通过ARGO浮标观测资料与WOA09背景场资料进行最优插值融合,得到较精细的温盐网格化资料,并在此基础之上通过引入P矢量方法,对太平洋海区的三维流场进行了诊断推算。分析表明:ARGO浮标再分析融合数据能够较好表现太平洋温盐场分布结构,在此基础之上诊断推算的三维流场能够合理刻画太平洋流场的基本特征,为获取大尺度海洋三维流场信息提供了有效的途径。     

A STUDY ON VARIABILITY OF SEA SURFACE TEMPERATURE IN TROPICAL PACIFIC, INDIAN OCEAN AND RELATED AIR CIRCULATION

1 .　INTRODUCTIONOceanscover 71%oftheearth’ssurface ,ab sorb 70 %ofthesolarradiationenergy ,85 %ofwhichisstoredintheoceanicsurfacelayerasaheatsourcedrivingair seamotion ,andsuppy 86%ofthemoistureintheair .Thethermalanddy namicinertiamakestheoceanhavespecial“re membrance”and“low passfilter”roleforatmo sphericvariation .Therefore ,thevariabilityofoceanicthermalsituationandair seainteractionareoneoftheimportantfactorscausingtheshortrangeclimaticchanges[1] .Namias ( 195 9) putfor wardthe…     

El Niño–Southern Oscillation Link to South Florida Hydrology and Water Management Applications

This study evaluates the relationships between El Niño–Southern Oscillation (ENSO) indices and South Florida hydrology and proposes applications to water management decision making. ENSO relations to the Upper Kissimmee Basin rainfall, watershed for Lake Okeechobee, and cumulative sea surface temperature (SST) anomalies at Niño 3.4 were evaluated. Additionally, relationship between ENSO and Lake Okeechobee inflows, Arbuckle Creek and Josephine Creek flows were analyzed. Hydrology of the northern watersheds of the South Florida water management system is linked to ENSO events. Dry season (November–May) rainfall and flows are higher than average during El Niño years and lower during La Niña years, at the 90% confidence level or higher. The relationship is strongest when the ENSO event is strong as shown with analysis of correlation. ENSO prediction has more certainty than hydrologic prediction for a region. Identifying ENSO and hydrologic relationships can aid water management decision making by providing a lead-time of months to mitigate drought or flood impacts. The ENSO tracking method, which was published in a previous study, is presented to track ENSO strength and event type to provide supplemental outlook on dry season rainfall for Lake Okeechobee operations. Lake Okeechobee, which is the main storage in the South Florida water management system, is regulated by a schedule with a limited band of stage fluctuation because of susceptibility of the Herbert Hoover Dike to wave erosion and seepage at high stages. An early decision making approach to storage management with respect to ENSO related hydrology, is presented based on tracking the strength of ENSO events.