2006年度干旱气候变化与减灾学术研讨会技术总结

引言2007年1月16-17日,由中国气象局兰州干旱气象研究所、甘肃省干旱气候变化与减灾重点实验室、中国气象局干旱气候变化与减灾重点开放实验室和中国气象学会干旱气象学委员会主办的“2006年度干旱气候变化与减灾学术研讨会”在兰州召开。来自中国科学院青藏高原研究所、寒区旱     

极端事件对人类系统的影响

在IPCC特别报告《管理极端事件和灾害风险,推进气候变化适应》中,极端天气气候事件对人类系统的影响是最重要的影响评估内容之一,其评估结果为：极端影响可能缘于极端天气气候事件,但也可能并非极端事件的后果。暴露度和脆弱性是灾害风险的重要决定因素;极端和非极端天气气候事件的严重程度和影响在很大程度上取决于对这些事件的脆弱性和暴露度水平;人居模式、城市化和社会经济状况的变化已经影响观测到的脆弱性和暴露度的变化趋势;无论在发达国家还是发展中国家,沿海人居环境均暴露于极端事件,并受其影响,如小岛屿国家和亚洲大三角洲地区;脆弱人口还包括难民、国内流离失所的人和那些生活在边远地区的人;极端事件将极大地影响与气候联系密切的部门,如水、农业、食物安全、健康和旅游业。     

7个IPCC AR4模式对中国地区极端降水指数模拟能力的评估及其未来情景预估

利用中国区域550个站点1961～2000年日降水量资料, 考察参与政府间气候变化委员会(IPCC)第四次评估报告的7个新一代全球模式及多模式集合对现代气候情景下(20C3M)5个极端降水指数的模拟能力, 同时进行中国区域未来不同排放情形下极端降水事件变化的预估, 结果表明: 最新全球模式能较好地模拟出极端降水指数气候场的空间分布及其中国区域的线性趋势, 且模式集合模拟能力优于大部分单个模式, 但在青藏高原东侧、 高原南部存在虚假的极端降水高值区, 模拟的东部季风区的极端降水强度系统性偏低, 区域平均序列年际变率的模拟能力也较低。中国地区21世纪与降水有关的事件都有趋于极端化的趋势, 极端降水强度可能增强, 干旱也将加重, 且变化幅度与排放强度成正比。     

极端天气和气候事件的变化

自1950年以来的观测证据表明,有些极端天气和气候事件已经发生了变化。全球尺度上,人为影响可能已经导致极端日最低和最高温度升高;由于平均海平面上升,人类活动可能已对沿海极端高水位事件的增加产生了影响;具有中等信度的是,人为影响已导致全球强降水增加;由于热带气旋历史记录的不确定性、缺乏对热带气旋与气候变化之间关联的物理机制的完整认识及热带气旋自然变率的程度,将可检测到的热带气旋活动变化归因于人为影响仅具有低信度。将单一的极端事件变化归因于人为气候变化具有挑战性。对极端事件变化预估的信度取决于事件的类型、区域和季节、观测资料的数量和质量、基本物理过程的认知水平及模式对其模拟的可靠性。     

世界气象组织气候资源技术会简介

由世界气象组织(WMO)主办,中国气象局承办的WMO气候资源技术会于2005年11月1～2日在北京举行。共有来自71个国家的122名代表参加了此次会议,另外WTO和WHO也派员参加了此次会议。中国气象局局长,世界气象组织中国常任代表秦大河院士与世界气象组织秘书长雅罗先生出席开幕式并致辞。     

Reducing Vulnerability of Agriculture and Forestry to Climate Variability and Change: Workshop Summary and Recommendations

The International Workshop on Reducing Vulnerability of Agriculture and Forestry to Climate Variability and Climate Change held in Ljubljana, Solvenia, from 7 to 9 October 2002 addressed a range of important issues relating to climate variability, climate change, agriculture, and forestry including the state of agriculture and forestry and agrometeological information, and potential adaptation strategies for agriculture and forestry to changing climate conditions and other pressures. There is evidence that global warming over the last millennium has already resulted in increased global average annual temperature and changes in rainfall, with the 1990s being likely the warmest decade in the Northern Hemisphere at least. During the past century, changes in temperature patterns have, for example, had a direct impact on the number of frost days and the length of growing seasons with significant implications for agriculture and forestry. Land cover changes, changes in global ocean circulation and sea surface temperature patterns, and changes in the composition of the global atmosphere are leading to changes in rainfall. These changes may be more pronounced in the tropics. For example, crop varieties grown in the Sahel may not be able to withstand the projected warming trends and will certainly be at risk due to projected lower amounts of rainfall as well. Seasonal to interannual climate forecasts will definitely improve in the future with a better understanding of dynamic relationships. However, the main issue at present is how to make better use of the existing information and dispersion of knowledge to the farm level. Direct participation by the farming communities in pilot projects on agrometeorological services will be essential to determine the actual value of forecasts and to better identify the specific user needs. Old (visits, extension radio) and new (internet) communication techniques, when adapted to local applications, may assist in the dissemination of useful information to the farmers and decision makers. Some farming systems with an inherent resilience may adapt more readily to climate pressures, making long-term adjustments to varying and changing conditions. Other systems will need interventions for adaptation that should be more strongly supported by agrometeorological services for agricultural producers. This applies, among others, to systems where pests and diseases play an important role. Scientists have to guide policy makers in fostering an environment in which adaptation strategies can be effected. There is a clear need for integrating preparedness for climate variability and climate change. In developed countries, a trend of higher yields, but with greater annual fluctuations and changes in cropping patterns and crop calendars can be expected with changing climate scenarios. Shifts in projected cropping patterns can be disruptive to rural societies in general. However, developed countries have the technology to adapt more readily to the projected climate changes. In many developing countries, the present conditions of agriculture and forestry are already marginal, due to degradation of natural resources, the use of inappropriate technologies and other stresses. For these reasons, the ability to adapt will be more difficult in the tropics and subtropics and in countries in transition. Food security will remain a problem in many developing countries. Nevertheless, there are many examples of traditional knowledge, indigenous technologies and local innovations that can be used effectively as a foundation for improved farming systems. Before developing adaptation strategies, it is essential to learn from the actual difficulties faced by farmers to cope with risk management at the farm level. Agrometeorologists must play an important role in assisting farmers with the development of feasible strategies to adapt to climate variability and climate change. Agrometeorologists should also advise national policy makers on the urgent need to cope with the vulnerabilities of agriculture and forestry to climate variability and climate change. The workshop recommendations were largely limited to adaptation. Adaptation to the adverse effects of climate variability and climate change is of high priority for nearly all countries, but developing countries are particularly vulnerable. Effective measures to cope with vulnerability and adaptation need to be developed at all levels. Capacity building must be integrated into adaptation measures for sustainable agricultural development strategies. Consequently, nations must develop strategies that effectively focus on specific regional issues to promote sustainable development.     

Impacts of Multi-Scale Solar Activity on Climate. Part I: Atmospheric Circulation Patterns and Climate Extremes

The impacts of solar activity on climate are explored in this two-part study.Based on the principles of atmospheric dynamics,Part I propose an amplifying mechanism of solar impacts on winter climate extremes through changing the atmospheric circulation patterns.This mechanism is supported by data analysis of the sunspot number up to the predicted Solar Cycle 24,the historical surface temperature data,and atmospheric variables of NCEP/NCAR Reanalysis up to the February 2011 for the Northern Hemisphere winters.For low solar activity,the thermal contrast between the low-and high-latitudes is enhanced,so as the mid-latitude baroclinic ultra-long wave activity.The land-ocean thermal contrast is also enhanced,which amplifies the topographic waves.The enhanced mid-latitude waves in turn enhance the meridional heat transport from the low to high latitudes,making the atmospheric "heat engine" more efficient than normal.The jets shift southward and the polar vortex is weakened.The Northern Annular Mode(NAM) index tends to be negative.The mid-latitude surface exhibits large-scale convergence and updrafts,which favor extreme weather/climate events to occur.The thermally driven Siberian high is enhanced,which enhances the East Asian winter monsoon(EAWM).For high solar activity,the mid-latitude circulation patterns are less wavy with less meridional transport.The NAM tends to be positive,and the Siberian high and the EAWM tend to be weaker than normal.Thus the extreme weather/climate events for high solar activity occur in different regions with different severity from those for low solar activity.The solar influence on the midto high-latitude surface temperature and circulations can stand out after removing the influence from the El Nin o-Southern Oscillation.The atmospheric amplifying mechanism indicates that the solar impacts on climate should not be simply estimated by the magnitude of the change in the solar radiation over solar cycles when it is compared with other external radiative forcings that do not influence the climate in the same way as the sun does.     

Searching for Added Value in Simulating Climate Extremes with a High-Resolution Regional Climate Model over Western Canada

We evaluate the capacity of a regional climate model to represent observed extreme temperature and precipitation events and also examine the impact of increased resolution, in an effort to identify added value in this respect. Two climate simulations of western Canada (WCan) were conducted with the Canadian Regional Climate Model (version 4) at 15 (CRCM15) and 45?km (CRCM45) horizontal resolution driven at the lateral boundaries by data from the European Centre for Medium-range Weather Forecasts (ECMWF) 40-year Reanalysis (ERA-40) for the period 1973–1995. The simulations were evaluated using the spline-interpolated dataset ANUSPLIN, a daily observational gridded surface temperature and precipitation product with a nominal resolution of approximately 10?km. We examine a range of climate extremes, comprising the 10th and 90th percentiles of daily maximum (TX) and minimum (TN) temperatures, the 90th percentile of daily precipitation (PR90), and the 27 core Climate Daily Extremes (CLIMDEX) indices.

Both simulations exhibit cold biases compared with observations over WCan, with the bias exacerbated at higher resolution, suggesting little added value for temperature overall. There are instances, however, of regional improvement in the spatial pattern of temperature extremes at the higher resolution of CRCM15 (e.g., the CLIMDEX index for the annual number of days when TX?>?25°C). The high-resolution simulations also reveal similarly localized features in precipitation (e.g., rain shadows) that are not resolved at the 45?km resolution. With regard to precipitation extremes, although both simulations generally display wet biases, CRCM15 features a reduced bias in PR90 in all seasons except winter. This improvement occurs despite the fact that spatial and interannual variability of PR90 in CRCM15 is significantly overestimated relative to both CRCM45 and ANUSPLIN. We posit that these characteristics are the result of demonstrable differences between corresponding topographical datasets used in the gridded observations and CRCM, the resulting errors propagated to physical variables tied to elevation and the beneficial effect of subsequent spatial averaging. Because topographical input is often discordant between simulations and gridded observations, it is argued that a limited form of spatial averaging may contribute added value beyond that which has already been noted in previous studies with respect to small-scale climate variability.     

菏泽市气候极值的统计分布和再现期研究

科学合理地估算某地区的气候极值再现期是气象科技服务的重要内容,对当地经济建设具有重要意义。对菏泽市35种气候极值,分别都用皮尔逊Ⅲ型（Pearson Ⅲ）、对数正态（log normal）、耿贝尔（Gumbel）、韦伯（Weibull）分布函数进行拟合,用χ2检验选出最优者。使用选出的最优分布函数,用多个再现期算出再现期极值,列成表格以备气象服务中使用。通过最优分布函数的选取,对哪个类型的气候要素较多服从于哪个分布函数问题进行了研究。研究结果发现极端气温类型的极值和日数类型的极值较多服从于皮尔逊Ⅲ型分布,降水和其他类型的极值较多服从于耿贝尔分布。简要介绍了计算中使用Excel的技巧。     

Indicators of Climate Change for the Russian Federation

Observed climate changes over the Russian Federation (RF) territory are considered. Several indicators based on monthly mean temperature and precipitation station data are used to quantify regional climate changes. Some of these are the components of two aggregated indices of climate change, suggested by Karl et al. (1996): the Climate Extremes Index (CEI) and the Greenhouse Climate Response Index (GCRI). For the RF territory as a whole, and for its western part, the "Russian Permafrost Free (RPF) territory" in particular, changes in surface air temperature are investigated, together with changes in precipitation and drought indices, and also the fraction of the Russian territory experiencing climatic anomalies below and/or above certain specified percentiles. Composite indices CEI-3 and GCRI-3 based on three parameters (air temperature, precipitation and drought indices) are examined, as well as the Climate Anomaly Index (CAI), known in Russia as Bagrov's coefficient of "anomality".It is shown, that over the area of the RPF as a whole, air temperature and the occurrence of drought has increased somewhat during the 20th century, while precipitation has decreased; these changes were non-uniform in space. The linear trend accounts for only a small fraction of the total variability, but the role of climate variations on decadal scales seems more substantial. The CEI, determined as the percentage of the area experiencing extreme anomalies (with a 10% or less frequency of occurrence) of either sign, increased for mean annual temperature, decreased for total precipitation and increased slightly for the occurrence of drought conditions; the aggregated index based on all three of these quantities increased slightly. There was also an increase in the GCRI-3 index, which is indicative of an agreement between the observed climate changes and the changes owing to the greenhouse effect as predicted by climatic models.The observed climate changes are too small to enable us confidently to reject a hypothesis that they are a reflection of the natural variability of climatic parameters within the context of a stationary climate. However, there is no doubt about the reality and importance of the observed changes.     

The 12th Workshop on Antarctic Meteorology and Climate

正1.Overview The 12th Workshop on Antarctic Meteorology and Climate(WAMC),formerly known as the Antarctic Meteorological Observation,Modeling,and Forecasting(AMOMF)Workshop(AMOMFW),was held at the National Center for Atmospheric Research(NCAR)in Boulder,Colorado,USA on 26–28 June 2017.The annual workshop dates from 2006,and recent meetings have been the 10th AMOMF Workshop held in 2015 in Cambridge,United Kingdom(Colwell et al.,2016)and the     

极值统计理论的进展及其在气候变化研究中的应用

着重论述极值统计分布在极端天气气候事件和重大工程设计中的重要意义,综述该领域国内外研究进展。例如,基于超门限峰值法（POT）的广义帕累托分布（GPD)和基于单元极大值法（BM）的广义极值分布（GEV）及其参数间的理论关系;采用极值分布模型与多状态一阶Markov链相结合构建降尺度模型模拟局地极端降水事件,推算一定重现期的极端降水量的分位数;探讨极值分布模型分位数估计误差问题,多维极值分布理论及其应用等问题。     

Conceptual Framework for Changes of Extremes of the Hydrological Cycle with Climate Change

A physically based conceptual framework is put forward that explains why an increase in heavy precipitation events should be a primary manifestation of the climate change that accompanies increases in greenhouse gases in the atmosphere. Increased concentrations of greenhouse gases in the atmosphere increase downwelling infrared radiation, and this global heating at the surface not only acts to increase temperatures but also increases evaporation which enhances the atmospheric moisture content. Consequently all weather systems, ranging from individual clouds and thunderstorms to extratropical cyclones, which feed on the available moisture through storm-scale moisture convergence, are likely to produce correspondingly enhanced precipitation rates. Increases in heavy rainfall at the expense of more moderate rainfall are the consequence along with increased runoff and risk of flooding. However, because of constraints in the surface energy budget, there are also implications for the frequency and/or efficiency of precipitation. It follows that increased attention should be given to trends in atmospheric moisture content, and datasets on hourly precipitation rates and frequency need to be developed and analyzed as well as total accumulation.     

QM和QDM方法对中国极端气候的高分辨率气候变化模拟的误差订正对比

采用分位数映射（Quantile Mapping, QM）和delta分位数映射（Quantile Delta Mapping, QDM）两种误差订正方法对区域气候模式RegCM4在中国区域内模拟的逐日气温和降水数据进行订正。模式数据是5种不同全球气候模式驱动下的区域模式气候变化模拟结果。计算订正前后的极端气候指数进行对比分析,包括日最高气温极大值（TXx）、日最低气温极小值（TNn）、连续干旱日数（CDD）和最大日降水量（RX1day）。结果表明,5组模拟结果和其集合平均（ensR）都显示气温指数的模拟效果高于降水指数,其中对TXx模拟最好,对CDD的模拟最差;经过订正后,针对不同模式的两种订正结果都能够有效地减小模式与观测的偏差并提高了空间相关系数,且两种方法的订正效果无明显差别。对RCP4.5情景下未来变化的分析中,QM在一定程度上改变了模式模拟的未来变化幅度和空间分布特征,QDM则能够有效地保留所有极端指数的气候变化信号。从全国平均来看,除CDD外,所有指数未来都呈现增加趋势,且QDM订正结果与订正前模式模拟的变化趋势更为接近。建议在气候变化模拟的误差订正中采用QDM方法。     

Changes in Daily Climate Extremes of Observed Temperature and Precipitation in China

Daily precipitation for 1960–2011 and maximum/minimum temperature extremes for 1960–2008 recorded at 549 stations in China are utilized to investigate climate extreme variations.A set of indices is derived and analyzed with a main focus on the trends and variabilities of daily extreme occurrences.Results show significant increases in daily extreme warm temperatures and decreases in daily extreme cold temperatures,defined as the number of days in which daily maximum temperature(Tmax)and daily minimum temperature(Tmin)are greater than the 90th percentile and less than the10th percentile,respectively.Generally,the trend magnitudes are larger in indices derived from Tmin than those from Tmax.Trends of percentile-based precipitation indices show distinct spatial patterns with increases in heavy precipitation events,defined as the top 95th percentile of daily precipitation,in western and northeastern China and in the low reaches of the Yangtze River basin region,and slight decreases in other areas.Light precipitation,defined as the tail of the5th percentile of daily precipitation,however,decreases in most areas.The annual maximum consecutive dry days(CDD)show an increasing trend in southern China and the middle-low reach of the Yellow River basin,while the annual maximum consecutive wet days(CWD)displays a downtrend over most regions except western China.These indices vary significantly with regions and seasons.Overall,occurrences of extreme events in China are more frequent,particularly the night time extreme temperature,and landmasses in China become warmer and wetter.     

中国极端气候变化观测研究回顾与展望

评述、总结了近年有关中国极端气候变化的观测研究成果,讨论了尚未解决的科学问题和今后应重点加强的工作方向。已有研究表明,1951年以来中国大陆地区极端气候事件频率和强度发生了一定变化,但不同类型和不同区域极端气候变化存在明显差异。从全国范围看,与异常偏冷相关的极端事件如寒潮、冷夜和冷昼天数、霜冻日数等,显著减少减弱,偏冷的气候极值减轻;与异常偏暖相关的暖夜、暖昼日数明显增多,暖夜日数增多尤其明显,但高温事件频数和偏热的气候极值未见显著长期趋势;全国平均暴雨和极端强降水事件频率和强度有所增长,特别是长江中下游和东南地区、西部特别是西北地区有较明显增长,而华北、东北中南部和西南部分地区减少减弱;多数地区小雨频数明显下降,偏轻和偏强降水的强度似有增加;全国遭受气象干旱的范围呈较明显增加趋势,其中华北和东北地区增加更为显著;登陆和影响我国的热带气旋、台风频数有所下降,其造成的降水总量有较明显减少;北方地区的沙尘暴事件从总体上看有显著减少减弱趋势;我国东部部分地区夏季雷暴发生频率也存在较明显下降趋势。现有工作表明,在涉及极端气候变化研究的资料处理和分析方法方面还有改进余地。观测资料的非均一性,以及观测环境改变和城市化对地面气候要素变化趋势的影响偏差,需要进行深入评价和客观订正。此外,目前对于区域极端气候变化的综合分析还较薄弱,在极端气候变化机理的研究方面有待加强。     

中国气候变化指数分析

用统计学方法对全国范围内160个测站1951-1996年的46年内气温、降水资料进行分析，得出年平均气温、降水的标准化距平场以及冷、暖季的气温、降水的标准化距平场，干旱指数等一系列表征气候变化的指标，以这些指标为基础得出气候增暖作用指数和气候极值性指数，并得出气候变化趋势是向着干和热的方向发展变化的。     

Simulation of Climate and Weather Extreme Indices with the INM-CM5 Climate Model

The simulation of extreme weather indices with the INM-CM5 and INMCM4 climate models for modern climate which were developed in the Institute of Numerical Mathematics of Russian Academy of Sciences is considered. It is shown that the INM-CM5 model improved the simulation of almost all indices concerning temperature (especially to its minimum values) and precipitation (mean total precipitation, mean precipitation intensity) extremes and concerning consecutive dry days and consecutive wet days. At the same time, the simulation of indices connected with extreme heavy precipitation became worse. It was found that this shortcoming can be minimized by introducing the vertical mixing of horizontal wind for the large-scale condensation and deep convection.     

中国区域气候极值重现水平的非平稳模型及趋势分析

应用基于GEV(Generalized Extreme Value)分布的平稳/非平稳极值概率模型,拟合中国区域489站自建站至2013年极端最高、最低温度和日最大降水量的年极值序列,并导出极值的重现水平及其变率随重现期和时间变化的一般表达式。着重分析了气候极值的"常态"(重现期为2年)与"极端态"(重现期为50年)的变化趋势及其线性变率的空间格局。详细探讨了极值的常态与极端态变化趋势相反的原因以及可能的影响。结果表明,极端最高温度在东部季风区普遍适用平稳模型;在其他地区更适用非平稳模型,其常态和极端态都以增温为主。极端最低温度在全国范围内普遍适用非平稳模型,其常态和极端态也都以增温为主,但在东北局部地区极端态呈现与常态相反的降温趋势。日最大降水量则在全国范围内普遍适用平稳模型。当GEV分布的尺度参数随时间变化时,与极值的常态相比,极端态的变率范围要大得多,并可能导致两者的变率异号的情形;尤其是当气候极值的常态日趋平缓而极端态却日益极端时,可能导致更为剧烈的灾害性天气。