Influence of the NAO on Wintertime Surface Air Temperature over East Asia: Multidecadal Variability and Decadal Prediction

In this paper,we investigate the influence of the winter NAO on the multidecadal variability of winter East Asian surface air temperature(EASAT)and EASAT decadal prediction.The observational analysis shows that the winter EASAT and East Asian minimum SAT(EAmSAT)display strong in-phase fluctuations and a significant 60-80-year multidecadal variability,apart from a long-term warming trend.The winter EASAT experienced a decreasing trend in the last two decades,which is consistent with the occurrence of extremely cold events in East Asia winters in recent years.The winter NAO leads the detrended winter EASAT by 12-18 years with the greatest significant positive correlation at the lead time of 15 years.Further analysis shows that ENSO may affect winter EASAT interannual variability,but does not affect the robust lead relationship between the winter NAO and EASAT.We present the coupled oceanic-atmospheric bridge(COAB)mechanism of the NAO influences on winter EASAT multidecadal variability through its accumulated delayed effect of~15 years on the Atlantic Multidecadal Oscillation(AMO)and Africa-Asia multidecadal teleconnection(AAMT)pattern.An NAO-based linear model for predicting winter decadal EASAT is constructed on the principle of the COAB mechanism,with good hindcast performance.The winter EASAT for 2020-34 is predicted to keep on fluctuating downward until~2025,implying a high probability of occurrence of extremely cold events in coming winters in East Asia,followed by a sudden turn towards sharp warming.The predicted 2020/21 winter EASAT is almost the same as the 2019/20 winter.     

Recent Progress in Studies of the Variabilities and Mechanisms of the East Asian Monsoon in a Changing Climate

Located in a monsoon domain,East Asia suffers devastating natural hazards induced by anomalous monsoon behaviors.East Asian monsoon(EAM)research has traditionally been a high priority for the Chinese climate community and is particularly challenging in a changing climate where the global mean temperature has been rising.Recent advances in studies of the variabilities and mechanisms of the EAM are reviewed in this paper,focusing on the interannual to interdecadal time scales.Some new results have been achieved in understanding the behaviors of the EAM,such as the evolution of the East Asian summer monsoon(EASM),including both its onset and withdrawal over the South China Sea,the changes in the northern boundary activity of the EASM,or the transitional climate zone in East Asia,and the cycle of the EASM and the East Asian winter monsoon and their linkages.In addition,understanding of the mechanism of the EAM variability has improved in several aspects,including the impacts of different types of ENSO on the EAM,the impacts from the Indian Ocean and Atlantic Ocean,and the roles of mid-to high-latitude processes.Finally,some scientific issues regarding our understanding of the EAM are proposed for future investigation.     

Extreme Cold Events from East Asia to North America in Winter 2020/21: Comparisons,Causes, and Future Implications

Three striking and impactful extreme cold weather events successively occurred across East Asia and North America during the mid-winter of 2020/21.These events open a new window to detect possible underlying physical processes.The analysis here indicates that the occurrences of the three events resulted from integrated effects of a concurrence of anomalous thermal conditions in three oceans and interactive Arctic-lower latitude atmospheric circulation processes,which were linked and influenced by one major sudden stratospheric warming(SSW).The North Atlantic warm blob initiated an increased poleward transient eddy heat flux,reducing the Barents-Kara seas sea ice over a warmed ocean and disrupting the stratospheric polar vortex(SPV)to induce the major SSW.The Rossby wave trains excited by the North Atlantic warm blob and the tropical Pacific La Nina interacted with the Arctic tropospheric circulation anomalies or the tropospheric polar vortex to provide dynamic settings,steering cold polar air outbreaks.The long memory of the retreated sea ice with the underlying warm ocean and the amplified tropospheric blocking highs from the midlatitudes to the Arctic intermittently fueled the increased transient eddy heat flux to sustain the SSW over a long time period.The displaced or split SPV centers associated with the SSW played crucial roles in substantially intensifying the tropospheric circulation anomalies and moving the jet stream to the far south to cause cold air outbreaks to a rarely observed extreme state.The results have significant implications for increasing prediction skill and improving policy decision making to enhance resilience in“One Health,One Future”.     

自动气象站出现故障编发报文的几种方法

1引言伊春自动气象站是国家基本站(现改为一级站),每天担负8次天气报,资料参加全球交换。当计算机出现故障时,天气报是否能在规定的时间内准确的编发出是至关重要的。出现故障时,在短时间内准确的手工编发出报文难度很大,容易出现错情或造成迟报等重大错情。为了避免这种情况的发生,总结了以下几种方法进行编发报,降低了出错的几率。     

Forecasting Quasi-stationary Front Rainstorm in Southeast China Using Synthetically Multilevel Analog Forecast Technology

The authors use numerical model integral products in a third level forecast of synthetically multi-level analog forecast technology.This is one of the strongest points of this study,which also includes the re-ducing mean vacant-forecast rate method,which pos-sesses many advantages with regard to filtering the analog term.Moreover,the similitude degree between samples is assessed using a combination of meteorological elements,which works better than that described using a single element in earlier analog forecast studies.Based on these techniques,the authors apply the model output,air sounding,surface observation and weather map data from 1990 to 2002 to perform an analog experiment of the quasi-stationary front rainstorm.The most important re-sults are as follows:(1) The forecast successful index is 0.36,and was improved after the forecast model was re-vised.(2) The forecast precise rate (0.59) and the lost-forecast rate (0.33) are also better than those of other methods.(3) Based on the model output data,the syn-thetically multilevel analog forecast technology can pro-duce more accurate forecasts of a quasi-stationary front rainstorm.(4) Optimal analog elements reveal that trig-gering mechanisms are located in the lower troposphere while upper level systems are more important in main-taining the phase of the rainstorm.These variables should be first taken into account in operational forecasts of the quasi-stationary front rainstorm.(5) In addition,experi-ments reveal that the position of the key zone is mainly decided by the position of the system causing the heavy rainfall.     

巧修虹吸雨量计浮子

地面气象常规仪器的零配件近年来十分紧缺,特别是虹吸雨量计的浮子。浮子是虹吸雨量计中最重要的零件,而浮子又最容易冻坏。例如,牡丹江地区2005年5月6～9日4d内,先是下了雨,后又转雨加雪、雪,绥芬河站的降水量近30mm。温度最低降到1.6℃,虹吸雨量计的安装时间和拆卸时间很难掌握,安装太迟或拆卸太早都可能影响到年度15个时段最大降水量的挑选。由于气候变化和人为因素造成浮子冻坏的现象屡见不鲜,一旦浮子底部冻裂而又没有备份浮子,为了气象资料的完整性可采取巧焊浮子的方法,焊好待用,有了新的浮子再更新。     

江西省2006年1-12月自然灾害公报(摘录)

受气候异常影响,2006年江西自然灾害总体发生水平与常年相比,属偏重发生年份。全省自然灾害主要以台风、暴雨洪涝、雷电、地质灾害、农林生物灾害为主。其中风雹、雷电灾害频繁,雷电死亡人数     

The Sensitive Regions Identified by CNOPs of Three Typhoon Events

In this paper, several sets of observing system simulation experiments (OSSEs) were designed for three typhoon cases to determine whether or not the additional observation data in the sensitive regions identified by conditional nonlinear optimal perturbations (CNOPs) could improve the short-range forecast of typhoons. The results show that the CNOPs capture the sensitive regions for typhoon forecasts, which implies that conducting additional observation in these specific regions and eliminating initial errors could reduce forecast errors. It is inferred from the results that dropping sondes in the CNOP sensitive regions could lead to improvements in typhoon forecasts.     

秋天

风就那么轻轻地扇了一下,整个荒原就着了火,不停奔忙的救火人却面带微笑。站在垄上,我的心在随着他们的韵律激动地博跳。金黄色玉米,黄金样水稻,所有的稼禾都积极地     

INVESTIGATION OF THE SPATIAL AND TEMPORAL DISTRIBUTION OF EXTREME HIGH TEMPERATURE IN CHINA WITH DETRENDED FLUCTUATION AND PERMUTATION ENTROPY

With temperatures increasing as a result of global warming,extreme high temperatures are becoming more intense and more frequent on larger scale during summer in China.In recent years,a variety of researches have examined the high temperature distribution in China.However,it hardly considers the variation of temperature data and systems when defining the threshold of extreme high temperature.In order to discern the spatio-temporal distribution of extreme heat in China,we examined the daily maximum temperature data of 83 observation stations in China from 1950 to 2008.The objective of this study was to understand the distribution characteristics of extreme high temperature events defined by Detrended Fluctuation Analysis(DFA).The statistical methods of Permutation Entropy(PE)were also used in this study to analyze the temporal distribution.The results showed that the frequency of extreme high temperature events in China presented 3 periods of 7,10—13 and 16—20 years,respectively.The abrupt changes generally happened in the 1960s,the end of 1970s and early 1980s.It was also found that the maximum frequency occurred in the early 1950s,and the frequency decreased sharply until the late 1980s when an evidently increasing trend emerged.Furthermore,the annual averaged frequency of extreme high temperature events reveals a decreasing-increasing-decreasing trend from southwest to northeast China,but an increasing-decreasing trend from southeast to northwest China.And the frequency was higher in southern region than that in northern region.Besides,the maximum and minimum of frequencies were relatively concentrated spatially.Our results also shed light on the reasons for the periods and abrupt changes of the frequency of extreme high temperature events in China.     

Ocean Response to a Climate Change Heat-Flux Perturbation in an Ocean Model and Its Corresponding Coupled Model

State-of-the-art coupled general circulation models(CGCMs)are used to predict ocean heat uptake(OHU)and sealevel change under global warming.However,the projections of different models vary,resulting in high uncertainty.Much of the inter-model spread is driven by responses to surface heat perturbations.This study mainly focuses on the response of the ocean to a surface heat flux perturbation F,as prescribed by the Flux-Anomaly-Forced Model Intercomparison Project(FAFMIP).The results of ocean model were compared with those of a CGCM with the same ocean component.On the global scale,the changes in global mean temperature,ocean heat content(OHC),and steric sea level(SSL)simulated in the OGCM are generally consistent with CGCM simulations.Differences in changes in ocean temperature,OHC,and SSL between the two models primarily occur in the Arctic and Atlantic Oceans(AA)and the Southern Ocean(SO)basins.In addition to the differences in surface heat flux anomalies between the two models,differences in heat exchange between basins also play an important role in the inconsistencies in ocean climate changes in the AA and SO basins.These discrepancies are largely due to both the larger initial value and the greater weakening change of the Atlantic meridional overturning circulation(AMOC)in CGCM.The greater weakening of the AMOC in the CGCM is associated with the atmosphere–ocean feedback and the lack of a restoring salinity boundary condition.Furthermore,differences in surface salinity boundary conditions between the two models contribute to discrepancies in SSL changes.     

自动站大风报警程序设计

1引言在自动站投入使用前绝大多数气象站使用的是EL型风向风速计,其瞬间风速是通过风速指示计人工测得的,人为因素大,精度不够,但人工测量给大风重要天气报、大风危险和解除报提供了依据,不会出现大风记录和报文之间的矛盾现象,而自动站的大风记录却不一样,其记录的大风的起止时间,极大风速及出现的时间是非常精确的,要求值班员实时注意查看自动站的大风记录,避免漏报、错报。由于自动站采集控制软件SAWSS在处理大风记录时存在不足,当大风达到不同的发报标准时不能及时报警,以提醒值班人员作出相应的处理,所以极易造成过时报,甚至漏报。     

气象水文灾害的防灾减灾教育培训新进展

简要综述了第十届世界气象组织教育与培训大会的主题报告内容.本次大会主要讨论防灾减灾的气象水文教育与培训等问题,集中讨论了"备灾-预防和早期预警"、"减灾-应急、救援和重建"和"跨学科培训"等3个主题,强调集合数值预报系统对于估计出现极端天气事件的风险非常重要,同时必须培训气象、水文工作者使用集合预报中的概率预报信息.中国气象灾害监测、预测和预警已经从单纯提供一般意义上的气象灾害信息提升到有利于社会经济发展的气象灾害服务,既考虑自然因子也考虑经济发展的影响.在跨学科培训方面,将管理知识和气象知识结合起来,可以取得非常好的效果.大会建议提高世界气象组织区域培训中心以及各国气象水文部门培训单位的培训能力,主要通过提供防灾减灾的专门培训单元,对自然灾害风险管理短期课程进行指导,重视各国气象水文部门对于管理和传播领域培训的需求.     

中国雷雨之分布

中国幅员辽阔,地形复杂,而测候事业历史甚短,纪录为数既少,年代复长短不齐,观测又精粗不一,欲持此以论雷雨之分布,诚非易事;然若先就以往之纪录,加以整理,虽云疏陋,要亦可藉以略知其梗概。本文纪录,多取自南京气象研究所出版之月刊与年报,     

The Linkage between Two Types of El Ni?o Events and Summer Streamflow over the Yellow and Yangtze River Basins

It is generally agreed that El Nino can be classified into East Pacific(EP)and Central Pacific(CP)types.Nevertheless,little is known about the relationship between these two types of El Ni?o and land surface climate elements.This study investigates the linkage between EP/CP El Ni?o and summer streamflow over the Yellow and Yangtze River basins and their possible mechanisms.Over the Yellow River basin,the anomalous streamflow always manifests as positive(negative)in EP(CP)years,with a correlation coefficient of 0.39(-0.37);while over the Yangtze River basin,the anomalous streamflow shows as positive in both EP and CP years,with correlation coefficients of 0.72 and 0.48,respectively.Analyses of the surface hydrological cycle indicate that the streamflow is more influenced by local evapotranspiration(ET)than precipitation over the Yellow River basin,while it is dominantly affected by precipitation over the Yangtze River basin.The different features over these two river basins can be explained by the anomalous atmospheric circulation,which is cyclonic(anticyclonic)north(south)of 30°N over East Asia.EP years are dominated by two anticyclones,which bring strong water vapor convergence and induce more precipitation but less ET,and subsequently increase streamflow and flooding risks.In CP years,especially over the Yellow River basin,two cyclones dominate and lead to water vapor divergence and reduce moisture arriving.Meanwhile,the ET enhances mainly due to local high surface air temperature,which further evaporates water from the soil.As a result,the streamflow decreases,which will then increase the drought risk.     

Current Status and Future Challenges of Weather Radar Polarimetry: Bridging the Gap between Radar Meteorology/Hydrology/Engineering and Numerical Weather Prediction

After decades of research and development, the WSR-88 D(NEXRAD) network in the United States was upgraded with dual-polarization capability, providing polarimetric radar data(PRD) that have the potential to improve weather observations,quantification, forecasting, and warnings. The weather radar networks in China and other countries are also being upgraded with dual-polarization capability. Now, with radar polarimetry technology having matured, and PRD available both nationally and globally, it is important to understand the current status and future challenges and opportunities. The potential impact of PRD has been limited by their oftentimes subjective and empirical use. More importantly, the community has not begun to regularly derive from PRD the state parameters, such as water mixing ratios and number concentrations, used in numerical weather prediction(NWP) models.In this review, we summarize the current status of weather radar polarimetry, discuss the issues and limitations of PRD usage, and explore potential approaches to more efficiently use PRD for quantitative precipitation estimation and forecasting based on statistical retrieval with physical constraints where prior information is used and observation error is included. This approach aligns the observation-based retrievals favored by the radar meteorology community with the model-based analysis of the NWP community. We also examine the challenges and opportunities of polarimetric phased array radar research and development for future weather observation.     

An Improved Atmospheric Vector Radiative Transfer Model Incorporating Rough Ocean Boundaries

The radiative transfer model (RT3), a vector radiative transfer (VRT) scheme in a plane-parallel atmosphere, was bounded by a rough ocean surface in this study. The boundary problem was solved using a Fourier series decomposition of the radiation field as a function of the azimuth. For the case of a rough ocean surface, the decomposition was obtained by developing both the Fresnel reflection matrix and the probability distribution of the water facet orientation as Fourier series. The effect of shadowing by ocean surface waves was also considered in the boundary condition. The VRT model can compute the intensity and degree of polarization of the light at the top of the atmosphere (TOA), the ocean surface, and any level of the atmosphere in the ocean-atmosphere system. The results obtained by our model are in good agreement with those computed by Ahmad’s model. The simulated results showed that the shadow effects of wave facets on the intensity and the degree of polarization are negligible except at the ocean surface near the grazing angle, possibly because we did not consider the effect of white caps.     

POSSIBLE RELATIONSHIP BETWEEN THE INTERANNUAL ANOMALY OF THE TROPICAL PACIFIC SEA SURFACE HEIGHT AND SUMMER PRECIPITATION IN CHINA

By using NCEP GODAS monthly sea surface height(SSH) and 160-station monthly precipitation data in China,the seasonal and interannual characteristics of SSH are analyzed over the tropical Pacific,and correlations between SSH and summer rainfall are discussed.The results are shown as follows:(1) The tropical Pacific SSH takes on a "V" pattern in the climatic field with an eastward opening,and it is higher in the western part(in the northwestern part) than in the eastern part(in the southwestern part).The high-value areas are more stable in the northwest,and the value range(greater than 0.8 m) is larger in spring and summer than in autumn and winter.The high-value area in the southwestern part is the largest(smallest) and more northerly(southerly) in spring(summer).SSH is higher in spring and autumn than in summer and winter over the equatorial zone.(2) The interannual anomalies of the SSH are the strongest over the tropical western and southwestern Pacific and are stronger in winter and spring than in summer and autumn.The interannual anomalies are also strong over the equatorial middle and eastern Pacific.The distribution ranges are larger and the intensities are stronger in the autumn and winter.There is a close relationship between the SSH interannual anomalies and ENSO events in autumn,winter and spring.(3) When ENSO events take place in winter,according to the simultaneous relationship among the tropic Pacific SSH,850 hPa wind fields and the summer precipitation of China,it can be predicted that the precipitation will be significantly more than normal over the south of the Yangtze River,especially over Dongting Lake and Poyang Lake region,eastern Qinghai-Tibet Plateau,Yangtze-Huai River Valley,eastern part of Inner Mongolia and less than normal over the area of Great Band of Yellow River,North China and South China in successive summers.     

Re-Assessing Climatic Warming in China since 1900

The regional mean surface air temperature(SAT)in China has risen with a rate of 1.3–1.7℃(100 yr)^-1 since 1900,based on the recently developed homogenized observations.This estimate is larger than those[0.5–0.8℃(100 yr)^-1]adopted in the early National Reports of Climate Change in China.The present paper reviews the studies of the longterm SAT series of China,highlighting the homogenization of station observations as the key progress.The SAT series of China in early studies showed a prominent warm peak in the 1940s,mainly due to inhomogeneous records associated with site-moves of a number of stations from urban to outskirts in the early 1950s,thus leading to underestimates of the centennial warming trend.Parts of China were relatively warm around the 1940s but with differentphase interdecadal variations,while some parts were even relatively cool.This fact is supported by proxy data and could partly be explained by interdecadal changes in large-scale circulation.The effect of urbanization should have a minor contribution to the observed warming in China,although the estimates of such contributions for individual urban stations remain controversial.Further studies relevant to the present topic are discussed.