城市气象研究动向的思考

基于近年来城市气象观测与模拟研究的最新进展,展望了城市气象未来的发展方向和重点研究领域,主要包括以下六个方面：城市气象数值模拟、新观测技术及同化应用、观测与数值模拟互动、城市化对天气气候影响机理、城市气候资源利用与热岛效应减缓措施,以及城市化对大气环境及人体健康的影响。指出了城市冠层模式发展、城市水文过程及城市降水、城市边界层及其他模式物理过程和模式评估等方面亟需解决的关键科学问题。     

Advances in Urban Meteorological Research in China

Over the past decades, a large number of studies have been carried out in the field of urban meteorology in China. This paper summarizes the main progress in urban meteorology research from four aspects: urban meteorological observation network and field campaign, multi-scale model of urban meteorology, interaction between urban meteorology and atmospheric environment, and the impacts of urbanization on weather and climate. Major advances are as follows. China’s major cities have established or are improving comprehensive urban meteorological observation networks characterized by multi-platform, multi-variable, multi-scale, multi-link, and multi-function. Beijing, Nanjing, Shanghai, and other cities carried out urban meteorological field campaigns, which were included in the WMO research demonstration project. Wind tunnel experiments and scale-model outdoor experiments were successfully conducted. Multi-scale urban meteorological and air quality prediction numerical model systems have been developed and put into operational use. The urban heat island effect; urban impacts on precipitation, regional climate, and air quality; urban planning; and interaction between urban meteorology and atmospheric environment are extensively investigated. Finally, efforts to improve observational technology, data assimilation, and urban system modeling, to explore the impacts of urbanization on environment and human health, and to provide integrated urban hydro-meteorological climate and environmental services are planned ahead.     

城市气象研究进展

中国数十年来在城市气象研究这一新兴学科领域开展了大量研究并获得了多方面的丰硕成果。文中从城市气象观测网与观测试验、城市气象多尺度模式、城市气象与大气环境相互影响、城市化对天气气候的影响等4个方面论述了城市气象的主要研究进展:中国各大城市已建立或正在完善具有多平台、多变量、多尺度、多重链接、多功能等特点的城市气象综合观测网;北京、南京、上海等地开展了大型城市气象观测科学试验,被世界气象组织列入研究示范项目;成功开展了风洞实验、缩尺度外场实验研究;建立了多尺度城市气象和空气质量预报数值模式,并应用于业务;在城市热岛效应、城市对降水影响、城市气象与城市规划、城市化对区域气候及空气质量的影响、城市气象与大气环境相互作用等研究领域取得长足进展。最后指出,未来需要重点从新观测技术及观测资料同化应用、城市系统模式研究、城市化对天气气候的影响机理、城市化对大气环境和人体健康的影响、城市水文气象气候与环境综合服务等方面开展科学研究与应用,为中国城市化、生态文明建设、防灾减灾和应对气候变化等国家需求提供科技支撑。      

大气科学的世纪进展与未来展望

今天的大气科学已从20世纪初经验的阐述转变为既有理论基础又有客观定量化的一门数理学科,其发展步伐在近50年来不断加快。文章回顾了近百年来大气科学在探测、数值天气预报和气候研究3方面所取得的主要成就,并对大气科学在21世纪的潜在发展作一展望。大气探测、计算能力和信息输送方面的技术进步无疑是近代和未来大气科学迅速发展的巨大动力。这些技术进步促使数值模式分辨率在不断提高,越来越多的实测和卫星等遥感资料在通过反演和同化进入模式初始条件和全球气象分析场,模式物理过程和参数化逐步趋向现实,从而使全球和区域数值预报水平持续提高。同时对大量观测资料的统计分析和许多气候子系统耦合模式的若干试验,大大提高了对造成气候变化和影响的物理、动力机制的认识;特别是对全球气温变暖,其中人类活动的影响,以及ENSO的发生、发展和消亡的机制和过程的认识。近期数值天气预报则趋向于模式发展的统一、预报时效的增加和对有足够成员且有代表性的集合预报的日益重视。气候研究将致力于减少各物理和化学过程参数化、分辨率等因素在模式中的不确定性,逐步达到跨月、季节直至年代际气候变化的合理预测。可以预言在不久的将来,地球-空间系统各变量的观测和预报将逐步数字化、自动化,人们可提前3~5 d得知灾害性天气发生时间和地点的概率,人工影响天气等学科在21世纪将会有突破。同时,可以看到世界各国共同协作建立地球-空间综合观测系统,发展能“包罗万象”的地球-空间-减灾的统一模式。然后综合利用大量观测和模式资料,及时掌握地球-空间系统中的各尺度变化规律,以确保人类社会的持续发展。     

区域气候模拟研究及其应用进展

区域气候模拟研究在过去十几年里取得了显著的进步。经过广泛的发展和不断的检验,区域气候模式现在已经成为气候研究和业务预报的重要工具。目前已经发表了很多令人鼓舞的结果,其中包括过去极端气候事件的模拟,当前气候发展演变和未来气候变化的预测,特别是对月和季节尺度气候的模拟与预测。通过对高分辨率和动力连续的区域气候模式结果的分析,人们对于周-季节时间尺度的各种物理过程,包括陆面和水文过程、边界层、云和降水、云-辐射相互作用的认识也在不断的深入。然而,区域气候是多尺度扰动(如中尺度、天气尺度、行星尺度扰动)和多圈层系统(如大气圈、生物圈、水圈、冰雪圈、陆面)相互作用的结果,同时物理过程本身具有不确定性,人们对一些复杂的物理过程,特别是土壤湿度作用以及云-气候反馈过程也缺乏深刻的理解,因此该领域的研究还面临着很多挑战。作者重点总结并评述了区域气候模式对现在和未来区域气候模拟、极端天气和气候事件模拟、物理过程研究、短期气候预测几方面应用的研究进展,最后讨论了区域气候模式发展在上述各方面,特别是周-次季节时间尺度区域天气和气候的模拟与预测所面临的挑战和应用前景。     

Urbanization Impact on Regional Climate and Extreme Weather: Current Understanding,Uncertainties, and Future Research Directions

Urban environments lie at the confluence of social,cultural,and economic activities and have unique biophysical characteristics due to continued infrastructure development that generally replaces natural landscapes with built-up structures.The vast majority of studies on urban perturbation of local weather and climate have been centered on the urban heat island(UHI)effect,referring to the higher temperature in cities compared to their natural surroundings.Besides the UHI effect and heat waves,urbanization also impacts atmospheric moisture,wind,boundary layer structure,cloud formation,dispersion of air pollutants,precipitation,and storms.In this review article,we first introduce the datasets and methods used in studying urban areas and their impacts through both observation and modeling and then summarize the scientific insights on the impact of urbanization on various aspects of regional climate and extreme weather based on more than 500 studies.We also highlight the major research gaps and challenges in our understanding of the impacts of urbanization and provide our perspective and recommendations for future research priorities and directions.     

Multivariate and multiscale dependence in the global climate system revealed through complex networks

A systematic characterization of multivariate dependence at multiple spatio-temporal scales is critical to understanding climate system dynamics and improving predictive ability from models and data. However, dependence structures in climate are complex due to nonlinear dynamical generating processes, long-range spatial and long-memory temporal relationships, as well as low-frequency variability. Here we utilize complex networks to explore dependence in climate data. Specifically, networks constructed from reanalysis-based atmospheric variables over oceans and partitioned with community detection methods demonstrate the potential to capture regional and global dependence structures within and among climate variables. Proximity-based dependence as well as long-range spatial relationships are examined along with their evolution over time, yielding new insights on ocean meteorology. The tools are implicitly validated by confirming conceptual understanding about aggregate correlations and teleconnections. Our results also suggest a close similarity of observed dependence patterns in relative humidity and horizontal wind speed over oceans. In addition, updraft velocity, which relates to convective activity over the oceans, exhibits short spatiotemporal decorrelation scales but long-range dependence over time. The multivariate and multi-scale dependence patterns broadly persist over multiple time windows. Our findings motivate further investigations of dependence structures among observations, reanalysis and model-simulated data to enhance process understanding, assess model reliability and improve regional climate predictions.     

极地大气科学与全球变化研究进展

南极和北极是地球上的气候敏感地区, 也是多个国际科学计划研究全球气候变化的关键地区。极地大气科学考察与研究是极地科学研究的重要组成部分。中国气象科学研究院的极地大气科学考察与研究始于20世纪80年代, 25年来有较大进展。中国气象科学研究院参加了我国组织的23次南极考察、2次北冰洋考察和3次北极考察; 承担了南极长城站和中山站、北极黄河站气象业务建设和维持, 以及中-澳合作南极冰盖3个无人自动气象站工作; 进行了常规地面气象、Brewer大气臭氧、近地面物理、冰雪和大气化学等观测, 获得了较为系统的极地大气环境资料。开展了有关极地大气科学与全球变化的研究, 在极地天气气候特征及气候变化时空多样性、极地海冰变化和南极海冰涛动、极地近地面物理特征和海-冰-气相互作用、中山站臭氧变化特征及南极臭氧洞和大气化学、气候代用资料获取和古气候环境以及极地大气环境变化对东亚环流和中国天气气候影响等方面的研究取得了新进展。中国极地大气科学正积极通过多学科交叉、走国际合作道路, 努力提高对极地在全球变化中作用的认识水平, 并积极探索极地变化对我国气候、环境的影响。     

Impacts of Oceanic Fronts and Eddies in the Kuroshio-Oyashio Extension Region on the Atmospheric General Circulation and Storm Track

This paper reviews the progress in our understanding of the atmospheric response to midlatitude oceanic fronts and eddies,emphasizing the Kuroshio-Oyashio Extension(KOE)region.Oceanic perturbations of interest consist of sharp oceanic fronts,temperature anomalies associated with mesoscale eddies,and to some extent even higher-frequency submesoscale variability.The focus is on the free atmosphere above the boundary layer.As the midlatitude atmosphere is dominated by vigorous transient eddy activity in the storm track,the response of both the time-mean flow and the storm track is assessed.The storm track response arguably overwhelms the mean-flow response and makes the latter hard to detect from observations.Oceanic frontal impacts on the mesoscale structures of individual synoptic storms are discussed,followed by the role of oceanic fronts in maintaining the storm track as a whole.KOE fronts exhibit significant decadal variability and can therefore presumably modulate the storm track.Relevant studies are summarized and intercompared.Current understanding has advanced greatly but is still subject to large uncertainties arising from inadequate data resolution and other factors.Recent modeling studies highlighted the importance of mesoscale eddies and probably even submesoscale processes in maintaining the storm track but confirmation and validation are still needed.Moreover,the atmospheric response can potentially provide a feedback mechanism for the North Pacific climate.By reviewing the above aspects,we envision that future research shall focus more upon the interaction between smaller-scale oceanic processes(fronts,eddies,submesoscale features)and atmospheric processes(fronts,extratropical cyclones etc.),in an integrated way,within the context of different climate background states.     

上对流层-下平流层交换过程研究的进展与展望

上对流层和下平流层(UTLS)区域的高度范围大致为5～20 km.UTLS区域大气成分的分布及变化对于认识气候长期变化也极为重要,因为该区域的臭氧是一种有效的温室气体,其中的水汽、卷云和气溶胶对太阳短波辐射和地球长波辐射有很强的调制作用,因而对于天气和气候变化产生不可忽略的辐射强迫作用; UTLS区域中,还有航空业的飞机排放,强对流云云中与云上闪电产生相当量的NOx,这些都对UTLS区域乃至更高及更低层大气的化学成分与分布产生重大影响.该文介绍上对流层和下平流层区域的交换过程研究的意义和手段,同时介绍有关研究的进展,重点回顾近年来国内一些学者开展的工作.另外,还列举一些研究问题和方向,最后重点展望青藏高原上空上对流层-下平流层区域的研究,因为该地区UTLS交换过程不仅具有显著区域特征,而且在全球平流层-对流层交换中可能有重要贡献.     

Postprocessing of simulated precipitation for impact research in West Africa. Part I: model output statistics for monthly data

Rainfall represents an important factor in agriculture and food security, particularly, in the low latitudes. Climatological and hydrological studies which attempt to diagnose the hydrological cycle, require high-quality precipitation data. In West Africa, like in many parts of the world, the density of observational data is low and climate models are needed in order to perform homogeneous and complete data sets. However, climate models tend to produce systematic errors, especially, in terms of rainfall and cloud processes, which are usually approximated by physical parameterizations. In this study, a 25-year climatology of monthly precipitation in West Africa is presented, derived from a regional climate model simulation, and evaluated with respect to observational data. It is found that the model systematically underestimates the rainfall amount and variability and does not capture some details of the seasonal cycle in sub-Saharan West Africa. Thus, in its present form the precipitation climatology is not appropriate to draw a realistic picture of the hydrological cycle in West Africa nor to serve as input data for impact research. Therefore, a statistical model is developed in order to adjust the simulated rainfall data to the characteristics of observed precipitation. Assuming that the regional climate model is much more reliable in terms of atmospheric circulation and thermodynamics, model output statistics is used to correct simulated rainfall by means of other simulated parameters of the near-surface climate like temperature, sea level pressure and wind components. Monthly data is adjusted by a cross-validated multiple regression model. The resulting adjusted rainfall climatology reveals a substantial improvement in terms of the model deficiencies mentioned above. In part II of this publication, the characteristics of simulated daily precipitation is adapted to station data by applying a weather generator. Once the postprocessing approach is trained, it can be extrapolated to simulation periods, for which observational data do not exist like for instance future climate.     

平流层大气动力学及其与对流层大气相互作用的研究:进展与问题

本文综述了近年来关于平流层大气动力学及其与对流层大气相互作用动力过程的研究进展,特别是回顾了近年来关于平流层大气环流和行星波动力学、热带平流层大气波动及其与基本气流相互作用、平流层大气环流变异对对流层环流和气候变异的影响及其动力过程、平流层大气数值模拟以及在全球变暖背景下平流层大气的长期演变趋势预估等的研究进展。最近的研究揭示了大气准定常行星波传播波导的振荡现象、重力波在热带平流层准两年振荡和全球物质输送中的作用、平流层长期的变冷趋势变化、平流层在对流层天气和气候变化中的作用等现象,表明了平流层大气动力学研究的重要性。平流层大气动力学的深入研究,以及对数值模式中平流层模拟性能的提高,最终都会推动整个大气科学和气候变化研究的进一步发展。     

极端降水特性分析研究进展

极端降水是极端天气气候变化的重要指标,研究其时空分布特征对于正确认识全球气候变暖背景下的极端天气气候过程具有重要意义。就近年来国内外极端降水的特征及其与大气、海洋异常的关系研究进行简要的回顾,最好提出了其存在的不足方面。     

全球变暖与城市效应共同作用下的极端天气气候事件变化的最新认知

近年来,城市气候变化问题引起高度关注。综合IPCC第一工作组第六次评估报告(IPCC AR6)关于气候变暖背景下城市对极端天气气候事件影响的评估,本文得到以下科学认识：城市化加剧了局部气候变暖,全球许多城市都面临更多更强的高温热浪事件;城市化使得诸多城市区域及其下风向极端降水增加,地表径流加强;沿海城市受到日益加剧的与海平面上升有关的复合型洪水的影响;城市污染物排放和不利通风的建筑结构加剧了区域污染,同时增加了地表的臭氧含量。预计未来城市极端高温、极端降水及有关洪水事件将更为频发,空气污染形势更为严峻,气候变化风险进一步加大。中国城镇化进程迅速,需要进一步加强气候变化背景下城市极端事件的观测、形成机理和数值模拟研究,以提升城市极端事件风险认识水平和应对能力。     

Progress in the Study of Nonlinear Atmospheric Dynamics and Predictability of Weather and Climate in China (2007--2011)

Recent progress in the study of nonlinear atmospheric dynamics and related predictability of weather and climate in China (2007-2011) are briefly introduced in this article. Major achievements in the study of nonlinear atmospheric dynamics have been classified into two types:(1) progress based on the analysis of solutions of simplified control equations, such as the dynamics of NAO, the optimal precursors for blocking onset, and the behavior of nonlinear waves, and (2) progress based on data analyses, such as the nonlinear analyses of fluctuations and recording-breaking temperature events, the long-range correlation of extreme events, and new methods of detecting abrupt dynamical change. Major achievements in the study of predictability include the following:(1) the application of nonlinear local Lyapunov exponents (NLLE) to weather and climate predictability; (2) the application of condition nonlinear optimal perturbation (CNOP) to the studies of El Nin o-Southern Oscillation (ENSO) predictions, ensemble forecasting, targeted observation, and sensitivity analysis of the ecosystem; and (3) new strategies proposed for predictability studies. The results of these studies have provided greater understanding of the dynamics and nonlinear mechanisms of atmospheric motion, and they represent new ideas for developing numerical models and improving the forecast skill of weather and climate events.     

统计方法在数值模式中应用的若干新进展

目前,数值模式的准确性不断提高,天气预报和气候预测越来越依靠数值模式。数值模式不仅仅是求解描述大气运动和热力过程的方程组,其中也大量使用了统计方法,统计方法是数值模式的重要组成部分。本文对统计方法在数值模式中应用的最新进展进行了综述。首先,分析了统计方法在数值模式的资料同化、集合预报、次网格尺度物理过程参数化方案、数值产品统计释用、延伸期预报、模式检验等方面的应用。然后阐述了贝叶斯统计在数值模式中应用的新进展。最后,对统计方法在数值模式中应用的未来发展趋势进行了展望。     

云降水物理与人工影响天气研究进展(2008～2012年)

本文回顾和总结了近5年(2008～2012年)云降水物理与人工影响天气主要研究进展,并讨论了目前存在的主要问题和亟待解决的关键科学问题.内容涉及可分辨云数值模式及模拟研究、云降水的观测与遥感反演研究、气溶胶对云降水的影响及人工影响天气相关的数值模式、观测试验研究等.提高对云降水形成过程、时空结构与演变机理的深入认识,对揭示大气水循环、气候变化过程,提高天气精细化预报、大气云水资源开发利用及气象防灾减灾的能力,具有十分重要的作用.     

A Review of Climate Change Attribution Studies

This paper reviews recent progress in climate change attribution studies. The focus is on the attribution of observed long-term changes in surface temperature, precipitation, circulation, and extremes, as well as that of specific extreme weather and climate events. Based on new methods and better models and observations, the latest studies further verify the conclusions on climate change attribution in the IPCC AR5, and enrich the evidence for anthropogenic influences on weather and climate variables and extremes. The uncertainty of global temperature change attributable to anthropogenic forcings lies in the considerable uncertainty of estimated total radiative forcing due to aerosols, while the uncertainty of precipitation change attribution arises from the limitations of observation and model simulations along with influences from large internal variability. In terms of extreme weather and climate events, it is clear that attribution studies have provided important new insights into the changes in the intensity or frequency of some of these events caused by anthropogenic climate change. The framing of the research question, the methods selected, and the model and statistical methods used all have influences on the results and conclusions drawn in an event attribution study. Overall, attribution studies in China remain inadequate because of limited research focus and the complexity of the monsoon climate in East Asia. Attribution research in China has focused mainly on changes or events related to temperature, such as the attribution of changes in mean and extreme temperature and individual heat wave events. Some progress has also been made regarding the pattern of changes in precipitation and individual extreme rainfall events in China. Nonetheless, gaps remain with respect to the attribution of changes in extreme precipitation, circulation, and drought, as well as to the event attribution such as those related to drought and tropical cyclones. It can be expected that, with the continual development of climate models, ongoing improvements to data, and the introduction of new methods in the future, climate change attribution research will develop accordingly. Additionally, further improvement in climate change attribution will facilitate the development of operational attribution systems for extreme events, as well as attribution studies of climate change impacts.     

Challenges and opportunities for re-framing resource use policy with practice theories: The change points approach

Concerns about the climate crisis and the escalating pace of global consumption are accelerating the pressure on governments to moderate public demand for resources like water, food and energy. Notwithstanding their increasing sophistication, standard behavioural change approaches continue to be criticised for a narrow understanding of what shapes behaviour. One alternative theoretical position comes from practice theories, which draw on interpretive and relational understandings to focus on practices rather than people's behaviour, and hence highlight the complex and distributed set of factors shaping resource use. While practice theories have gained considerable interest from policy institutions within and beyond the UK they so far have had limited impact upon policy. It has even been argued that there are insurmountable challenges in reconciling the ontological commitments of practice theories with the realities of policy processes. This article advances academic and policy debates about the practical implications of practice theories. It works with evidence from transdisciplinary research intended to establish whether and how key distinctive insights from social practice research can usefully be brought to bear on policy. We pursued this through co-productive research with four key UK national policy partners, focusing on effective communication of social practice research evidence on agreed issues. A key outcome of collaboratively negotiating challenging social theory to usefully influence policy processes is the ‘Change Points’ approach, which our partners identified as offering new thinking on initiatives promoting reductions in people's use and disposal of resources. The Change Points approach was developed to enable policy processes to confront the complexities of everyday action, transforming both how problems are framed and how practical initiatives for effecting change are developed. We discuss the case of food waste reduction in order to demonstrate the potential of Change Points to reframe behaviour change policy. We end the paper by addressing the potential and limitations of informing policy with insights from practice theories based upon the successes as well as the challenges we have met. This discussion has broader implications beyond practice theories to other fields of social theory, and to debates on the relations between academic research and policy more broadly. We argue that, through a co-productive approach with policy professionals, and so engagement with the practices of policy making, it is possible to provide a partial and pragmatic but nevertheless effective translation of key distinctive insights from practice theories and related research, to reframe policy problems and hence to identify spaces for effecting change for sustainability.