Extreme hot and dry climate anomalies occurred in central-eastern China during the summer of 2022,w hich had a significant impact on the economy,agriculture,and human community. This paper review s the spatiotemporal characteristics and causes of this hot and dry event occurrence.During the summer of 2022,the areal mean extreme high temperature frequency,monthly mean daily maximum temperature,and high temperature days reached their highest values since 1979,w hile the areal mean monthly mean precipitation over central-eastern China reached its low est since 1979.These climate anomalies are caused by the combined effects of several factors,including anomalous strong w estern Pacific subtropical highs,increased disturbances in mid-latitude w esterlies,and tropical sea surface temperature anomalies. In addition,the paper explores the influence of global w arming trend on this extreme event,As w ell as the future changes in extreme heat and drought in China.

基于2017-2018年中国气象局高分辨率数值预报产品、甘肃实时城镇预报产品和国家级地面观测站数据,利用小波分析、滑动训练、最优融合等技术,研发出甘肃省智能网格高低温客观订正产品.检验分析表明:城镇预报产品、滑动训练订正产品、最优融合产品3种订正产品对CMA预报均有订正能力,3种客观订正产品的最高气温订正能力强于最低气温订正能力;滑动训练法与最优融合法产生的高低温订正产品,在系统误差明显地区(甘南、陇南等)的预报结果要好于模式客观预报,而高低温城镇预报产品在气温局地性强或者模式客观预报能力差的区域有优势;最优融合预报方法生成的高低温产品预报能力略高于滑动训练订正产品且与现有预报员制作城镇预报产品基本持平,初步具备了替代主观预报的能力.

利用1951-2010年中国160站气温、降水资料,分析中国代表性台站冬季和夏季气温、降水的气候值及气候变率在前后30 a的差异,并对结果使用不同方法进行显著性检验.结果 表明,季气温气候平均值的变化总体与全球增暖一致,以升温为主,但夏季在秦岭以南及长江中游地区出现显著局部变冷现象;季气温气候变率的变化相对较小,冬季总体不显著,夏季仅有少数台站显著.降水的气候变化总体不明显,季降水气候值变化的空间分布复杂,冬季南方地区、夏季东部地区总体增加,冬、夏季降水气候变率的变化均不显著.理论检验方法(t检验、F检验)与随机模拟方法(EMC法)的显著性检验结果,对气温的差别较小、对降水的差别较大,这与样本距平序列是否服从正态分布有关.EMC法可在确保样本统计特征不变的情况下,通过多次随机模拟,无需考虑其理论统计分布特征,使检验结果更为可靠.

基于中国气象局(China Meterological Administration,CMA)高分辨率数值预报产品、欧洲中期数值预报中心(the European Center for Medium-range Weather Forecast,ECMWF)精细化数值预报产品和国家级地面观测站数据,采用小波分析方法及滑动训练、最优融合等技术对模式误差序列进行时频处理,实现了对模式系统误差和局地误差的订正,发展了西北区智能网格气温客观预报方法(northwest intelligent gridtemperature objective prediction method,NWTM).以2017年3月-2018年2月数据作为训练样本,对2018年3月-2019年1月西北区239个国家基本站进行检验.结果 表明:1)NWTM对CMA和ECMWF两种模式产品的气温预报能力有显著的提升;随着预报时效增长,两种模式订正产品的误差增大.2)NWTM对ECMWF西北区最高气温的订正效果要明显优于CMA,但就最低气温而言,NWTM对CMA的订正效果更为显著.其中,就24 h最高气温而言,ECMWF在宁夏的订正效果最好,CMA在青海的订正效果最好;而对于24 h最低气温的预报,CMA在西北4省的订正效果相差不大,EC-MWF在陕西的订正效果最好.3)空间误差检验表明:针对最高气温的预报,ECMWF订正产品的订正能力明显优于CMA,特别是在甘肃河西走廊和中东部、陕西北部和南部、宁夏中南部及青海大部.就最低气温的预报而言,ECMWF和CMA对甘肃河东和陕西南部的订正能力较好;ECMWF订正产品在宁夏中南部及青海南部的订正能力高于CMA,而CMA订正产品在陕西中部的订正能力更优.

天气预报是指一周内至两周时间尺度的气象预报,而月季及以上时间尺度的预报则属于气候预测范畴.中国的气候预测起步很早,无论在研究工作中还是在业务应用上都取得了显著成就.文中扼要回顾了这些研究和业务发展成就,重点包括:对于季风和梅雨、寒潮的早期认知和后期研究发现、早期气候预测业务发展概况、动力气候预测的早期探索、动力-统计气候预测方法的研制和应用、气候预测模式的发展以及初始化和多模式集合预测、东亚气候系统变异的全方位探索、气候预测范畴的不断拓展和气候预测研究的不断创新.也对未来气候预测研究和业务发展提出了几个重大挑战性课题,涉及不同时间尺度气候变异过程之间的相互作用、季节内至年代际气候预测、气候系统模式及初始化、动力-统计相结合的气候预测方法等方面.

“一带一路”区域国家经济、政治发展极不平衡,随着全球气候变暖,区域内的自然环境、气候资源、水资源等都将面临着显著而复杂的变化,并且干旱、洪涝等多种气候灾害是“一带一路”区域可持续发展和重大基础设施建设面临的重大威胁之一.目前,“一带一路”倡议已经进入实质性建设阶段,沿线地区的气候变化及其灾害风险关乎“一带一路”倡议能否顺利实施及亚投行的投资安全.在此背景下,2016-2018年中国科学院地球科学学部实施了“‘一带一路’区域气候变化问题”咨询评议项目,项目针对该区域气候变化的事实、未来变化预估、气候变化的可能影响以及带来的潜在风险等问题进行了系统的调研,并开展了若干分析和研究.经过两年的努力,项目组完成了有关进展报告四份,包括一份总报告和三份分报告.本文扼要地概括和介绍了项目取得的主要成果.

外强迫随时间的变化对于非平稳系统的影响十分重要,如何从该系统中重构或提取外强迫信息则成为研究其中动力学特征的关键所在.本文基于慢特征分析方法(Slow Feature Analysis,SFA)以连续系统(改变的Lorenz系统)为参考模型,分别讨论在周期型强迫、减弱的周期型强迫、指数衰减型强迫、伴随指数衰减的周期型强迫等条件下,SFA方法对模型中不同强迫信号的提取能力.结果显示,SFA方法能够提取作用于连续系统中的外强迫信息,其提取效果与外强迫的强度、噪声以及嵌入维数m有关:对于越弱的外强迫或者存在越强的噪声干扰,提取效果越差,提取信号中将出现虚假的高频波动;嵌入维数m的增大能在一定程度上提高外强迫信号的提取效果.试验还表明,作用在单一变量上的外强迫会将其驱动信息嵌入于系统中,因此,可以通过SFA分析方法从其他变量中提取其外强迫信号.

采用卡尔曼滤波类型自适应误差订正法和滑动自适应权重法,对2012年夏季ECMWF 10 m全风速场集合预报结果进行偏差订正,对订正前后的预报结果进行评估,并通过Jumpiness指数对预报结果订正前后的预报不一致性特征进行分析.结果 表明,卡尔曼滤波类型自适应误差订正法能有效降低集合预报的均方根误差,且当起报时刻为00时对中低纬度地区的订正效果更显著,当起报时刻为12时对中高纬度地区的订正效果更明显;卡尔曼滤波类型自适应误差订正法能有效改善Talagrand的U型或L型分布;由均方根误差分析结果知道,ECMWF 10 m全风速场集合预报本身存在较大的预报不一致性,经过卡尔曼滤波类型自适应误差订正后,集合预报的预报不一致性明显降低,偏差订正可有效改善集合预报的预报不一致性,且随着预报时效的延长,卡尔曼滤波误差法对预报不一致性的改善效果更加明显;从预报不一致性的发生次数特征来看,单点跳跃出现的次数最多,异号三点跳跃的次数最少;经过卡尔曼滤波类型自适应误差订正后,单点跳跃、异号两点跳跃、异号三点跳跃次数都有所下降.

近些年,中国东部经历了严重的霾污染,对人体健康、交通安全、生态系统以及社会经济有巨大的危害.在1周以内的霾污染预报之外,季节尺度的霾污染预测可以给减排治污措施的制定提供更长时间尺度的科学支撑.本文以年际增量为预测对象,选取前期外强迫因子为自变量,分别针对京津冀和长三角区域建立逐月的冬季霾日数季节尺度预测模型,并开展了实时的季节预测.总体来看,京津冀和长三角区域预测模型的性能大体处于相似的水平,均方根误差在2d左右,对距平符号的捕捉率在80％以上,对霾日数变化的长期趋势具有很好的再现能力.在2016/2017年冬季京津冀霾日数实时预测中,模型预测的结果相对于常年值的定性结论全部准确,相对于前一年污染状况的结论大多数准确.在2017/2018年冬季长三角霾日数实时预测中,12月和1月的预测误差较小,2月的预测误差在2d左右.

利用1979-2016年ERA-interim逐日再分析资料,定义了青藏高原臭氧谷(Ozone Valley over the Tibetan Plateau,OVTP)极端和普通强(弱)事件,并讨论了其特征.结果表明:1)OVTP极端强事件在夏秋季节多发,10月最多,频率达2.0％;OVTP普通强事件在春夏季多发,7月最多,频率达1.7％.OVTP极端弱事件在秋冬季多发,12月最多,频率达3.8％;OVTP普通弱事件在冬季多发,1月最多,频率达2.0％.2) OVTP极端强事件出现频率显著增加(0.004％·a-1),极端弱事件出现频率显著减少(-0.015％·a-1).OVTP普通事件的变化均不显著.3)OVTP极端强事件的面积和强度均在秋季最大,10月达到最大值,面积为4.3×105 km2,强度为1.5×05 t;OVTP普通强事件的面积和强度均在夏季最大,7月达到峰值,面积为1.7×105 km2,强度为4.1×103t.OVTP极端弱事件的面积和强度在春夏较小,4月达到最小值,面积为3.2×104 km2,强度为1.1×102 t;OVTP普通弱事件的面积和强度在春夏秋均较小,4月和10月达到极小值,4月面积为2.5× 104km2,强度为68 t,10月面积为2.2× 104km2,强度为97 t.4) OVTP极端和普通强事件的面积(强度)均呈显著增大(增强)趋势,极端强事件的面积达2.5×102 km2·a-1,强度达2.5×102 t·a-1,普通强事件的面积达4.5×102km2·a-1,强度达4.5t.a-1.极端和普通弱事件的面积(强度)均呈显著减小(减弱)趋势,极端弱事件的面积达-1.7×104 km2·a-1,强度达-7.0× 103 t·a-1,普通弱事件的面积达-2.3×103 km2·a-1,强度达-2.7×102 t·a-1.

The inconsistency of the forecast reflects evolution characteristics with time of the prediction error of continuous multiple prediction at a fixed time in the future.In order to explore the inconsistency of fore-casting products in operational numerical forecasting applications,12 h precipitation and 2 m ground tem-perature,which are predicted by three numerical models GQEC,T639 and GQJP from November 2015 to October 2016 are analyzed.Quantitative calculation method of Jumpiness index is adopted by considering the sensitivity of the index to the target region. The inconsistency of the numerical model in three different regions is studied by means of statistical a-nalysis and typical case study.Results show that for statistical average,the inconsistency of the numerical models increases with the extension of the forecast time.Long time prediction inconsistency is greater. Jumpiness index of precipitation and temperature is related to the magnitude of the change,and Jumpiness index of precipitation is larger than that of temperature.It also shows that results of two consecutive tem-perature forecast are more consistent.The temperature prediction ability of the model is better than that of precipitation forecast.The comparison of different numerical models shows that GQEC has obvious advan-tages in many aspects.Although Jumpiness index of GQJP is less than T639,its jumping frequency is greater,indicating its prediction consistency is inferior to T639.There are seasonal differences in jumping frequency of model products.Both the jump frequency of precipitation and temperature is the highest in summer and the lowest in winter.The inconsistency test of two typical cases of rainstorm and cold air cooling process further corroborates statistical analysis results.Results also show that the forecast incon-sistency of the numerical model is not only related to the geographical position,but also to the selected are-a size.The larger the region is,the smaller Jumpiness index becomes,and vice versa.In addition,the spatial distribution of Jumpiness index in the region is related to geographical location and topography.In general,where elements change bigger,Jumpiness index becomes greater there.The regional distribution of Jumpiness index of different meteorological elements is different.The index value of Jumpiness index of 12 h precipitation forecast increases gradually from north to south in region Ⅰ.While 2 m ground tempera-ture prediction,Jumpiness index from north to south in region Ⅰ gradually decreases.

To improve the accuracy of the model products for precipitation forecast in flood season,we used the daily precipitation data of 92 observation stations in Jiangxi between March and July from 2015 to 2016 and precipitation forecast produced by the ECMWF (24-72 h),and chose the Gamma function to simulate the probability density distributions of precipitation and to capture the bias information,to match the probability of the model precipitation forecast and observation,and correct the different precipitation levels of model,thus to make a corrected precipitation value over ECMWF for every precipitation levels.The regional distribution characteristics of the model corrected precipitation value and the changes of the forecast scores before and after correction were analyzed.The results showed that:for the precipitation levels larger than 25 mm,the model precipitation forecast was less than the observation;for the low precipitation levels such as light rain,the model precipitation forecast was more than the observation;the model's systematic errors could be effectively corrected after revising.The method of forecast-observation probability matching was effective in improving the quality of precipitation forecast,especially for the heavy precipitation forecast.The shorter the forecast time was,the better the correction would be,and it would have good application effect in business.

This paper defines a group of seasonal and monthly mean new circulation indices of Aleutian low (AL) at 1 000 hPa in winter,including intensity(P),area(S) and central position(λc,(φ)c).The circulation indices are calculated by using the NCEP/NCAR monthly mean height field at 1 000 hPa during 60 winters from 1948/1949 to 2007/2008.The climatological and anomalous characteristics of AL are analyzed by the circulation indices,focused on analyzing the correlation relationships between circulation indices(P and λc) with sea surface temperature(SST) in Pacific,temperatures and precipitation in the Northern Hemisphere during the corresponding period,respectively.Results show that:1)AL is the strongest with the center lying to the south and west of the normal position in January,the weakest with the center lying to the north and east in December,and the middle in February.2) There is a negative correlation between P and λ c,with the center lying to the east of the normal(λ′＞0) in the AL strong years(P′＜0) and to the west in the weak years.On the interdecadal scale,AL has continued to be strong and eastward since 1970s,but there are reversing signs in recent years.3)AL is stronger and lies to the east of the normal in the strong E1 Ni(n)o years,and it is opposite in the strong La Ni(n)a years,which is particularly evident after 1975.There is a significant positive correlation between AL and SST in the mid-latitude Pacific,with AL strengthening and moving eastward in the SST negative anomaly years.4)The significant correlation zones distribute as the great circle wave train of “+-+” signs between AL index(P) and temperature,precipitation over the mid-and high-latitudes in the Northern Hemisphere during the same period,respectively.The correlation centers locate in the mid-latitude North Pacific,northwest and south of North America,close to the PNA (PacificNorth America) teleconnection pattern,whereas there are obvious differences between them in the tropical regions of the Northern Hemisphere.AL and Mongolian high are two adjacent atmosphere activity centers over the midand high-latitudes in the Northern Hemisphere in winter,but their correlation relationships with the El Ni(n)o/La Ni(n)a events,temperature and precipitation in the Northern Hemisphere during the same period are significantly different,which are questions worthy of further study.

Based on the daily mean temperature data of 1960-1999 at 175 meteorological stations over China,this paper firstly analyzes the characteristics of the two climate backgrounds (Climate background A contained the years from 1960 to 1989,while the climate background B contained the years from 1970 to 1999).Monte Carlo significance test method is applied to examine the difference in winter and summer under the two climate backgrounds.Respectively based on the two different climate backgrounds,the study applies climate percentile method to analyze the variation characteristic of the extreme temperature over China from 2000 to 2010.The result showed that the difference of winter average temperature under the two climate backgrounds is more significant than the difference in summer.The extreme low temperature events in winter (summer) happen less frequently than extreme high temperature events in winter(summer) over China.Because the climate background B contained the years from 1980 to 2000 and the global warming was most serious during this period,when we use climate background B as the background during 2000-2010,the extreme low temperature events in winter(summer) happen more frequently than using climate background A as the background.The situation of extreme high temperature in winter(summer) is contrary to the situation of extreme low temperature events in winter(summer) from 2000 to 2010.These results are consistent with the trends of global warming.

利用2011年3月-2013年2月TIGGE资料中ECMWF,NCEP及CMA 3个中心的500 hPa位势高度场、850 hPa温度场和海平面气压场的集合预报资料,采用Jumpiness指数同时结合单点跳跃、异号两点跳跃等预报跳跃相关概念,研究了集合控制预报和集合平均预报的预报跳跃特征问题,并进行对比分析.结果表明:平均而言,短时效预报之间的跳跃性低于长时效预报之间的跳跃性.集合平均预报的结果之间较其相应的控制预报具有更好的一致性.在预报跳跃的频率统计方面,集合平均预报结果总体上明显低于集合控制预报,两者在长时效的预报跳跃情况差别较大.该文研究了预报跳跃对不同区域、时间和变量的敏感性,结果表明:时间平均的预报跳跃性对区域和变量很敏感.不同预报跳跃类型出现的频率及集合控制预报和集合平均预报在预报跳跃性方面的差异对区域、时间和变量的敏感性有限.

During the development of numerical weather prediction, a new notable problem: forecast inconsist⁃ ency, has been investigated in recent years. Forecast inconsistency means the large difference between two consecu⁃ tive forecasts in the successive forecasts. The main issues of forecast inconsistency are systematically presented in this paper, including its concept, methods of quantification analysis, the possible causes and the relationship with forecast error. Results show that there are few methods of quantification analysis, and their applicability and objec⁃ tivity still require further study. In terms of the reasons of forecast inconsistency, present research is limited to a brief analysis of the theory, and the specific roles of the initial error and the model error in the formation of forecast inconsistency are still unclear. Some potential problems and possible research direction of forecast inconsistency are pointed out in the end.

近年来随着数值天气预报的不断发展,数值天气预报中出现了一个新的值得注意的问题:预报不一致性,即连续多次预报中,前后两次预报所做出的预报结果之间差异较大的现象.本文较系统地概述了这一问题,总结了预报不一致性的概念、定量分析方法、产生的可能原因及其与预报误差的关系等方面的研究成果.目前预报不一致性的定量分析方法还较少,其适用性和客观性等还需进一步研究.在预报不一致性产生的原因方面,现有的研究仅限于理论上的简要分析,初始误差和模式误差在预报不一致性形成过程中的具体作用等尚不清楚.最后阐述了在预报不一致性研究中存在的一些问题及可能的研究方向.

以南京信息工程大学“大气科学”和英国雷丁大学“气象学”专业为例，选择有代表性的“数值模拟与预测”课程，对中英两国在大气科学本科教学过程中的课程设置与教学内容、教学模式、教学手段以及评价方法等进行对比分析。在此基础上，有针对性地提出调整培养方案、优化教学环节、转变教学模式、改进教学手段，以及改革评价方法，强化过程管理的具体建议。

针对南京信息工程大学大气科学学院本科教学过程中存在的实际问题,分析大气科学学院实施课程负责人制度的必要性,介绍课程负责人制度的具体规定和管理办法,总结实施课程负责人制度所取得的成效。

Based on the percentile method,a distinction method for the extreme weather events is proposed by the construction of the climatologically equally likely intervals firstly.Then,the corresponding forecasting evaluation on extreme weather events is performed for 500 hPa geopotential height over Eurasian area in summer 2003.The results are as follows：1）In the analyzed period and region,the frequency of the extreme events is slightly higher than the climatological average situation.In NCEP-EPS,the forecast frequency is easy to become higher for the lower extreme events,but relatively reliable,whereas it is decreased with the extension of lead-time for the higher extreme events.When the lead-time is less than 3 d （more than 5 d）,the forecast frequency is higher（lower） with relatively less reliability.2）EV（economic value） analysis shows that the performance of NCEP-EPS probabilistic forecast for the higher（lower） extreme events is better than that for the normal weather events.3）Forecast hit rate analysis shows that the hit rate is lower in the high-probability threshold.Further analysis points out that it is perhaps related with the lower ensemble spread in some cases.With the decrease of probability threshold,the hit rate steadily increases.It means that the spread of ensemble members can make them to cover all possible region of observation value,thereby to get the better forecasting results.