从“气候”到“全球气候系统”概念的发展

气候学中从“气候”的概念发展为“全球气候系统”标志着科学的发展.从现代气候学的观点看,气候是全球气候系统的特征,而不是局地的温、湿、压.科学技术进步是全球气候系统概念建立的基础,这主要指:高速电子计算机的制造,全球观测系统的建立,及气候模式的发展.气候科学的发展同社会发展的关系越来越密切.     

气候观测系统及其相关的关键问题

地球系统中的大气圈、水圈、冰雪圈、岩石圈和生物圈构成了气候系统, 气候系统中不同圈层之间的相互作用决定了气候的自然变化。由于人类活动的日益加剧, 对气候系统已经产生了显著影响。气候的自然变化和人类活动导致的气候变化对社会经济的发展以及人民生活的影响日益加大, 并涉及到国家安全、环境外交和可持续发展等一系列重大问题。要认识气候变化及其强迫因素、预测未来气候变化, 最基础的工作是建立针对气候目的涉及到气候系统五大圈层的综合气候观测系统, 以获取所需的高质量资料和相关产品, 提供气候系统变化的详细信息。该文回顾了气候观测系统设计在中国的发展以及中国气象科学研究院在组织设计中国气候观测系统中的作用, 并指出了在建立我国气候观测系统中存在的一些需要改进的方面。在对气候观测系统进行分析的基础上, 指出了与建立气候观测系统相关的10个方面的关键问题, 这些问题包括:气候观测系统的科学需求、气候观测系统的代表性、全面性、规范性、对气候预测和预估及模式发展的支撑性、多学科应用性、社会经济性、资料开放共享性以及气候系统资料的同化再分析和历史资料的抢救。     

贵州气候业务现状与发展趋势分析

气候轨道业务包括月、季、年和年际尺度的气候系统监测与诊断、短期气候预测、气候系统影响评价、气候应用与服务、气候资源开发利用等。通过对贵州省气候轨道业务现状的分析,介绍了目前贵州气候轨道工作存在和需要解决的若干问题,展望了今后的发展目标。     

气候系统及模式中反馈机制研究 I.概念和方法

气候系统中存在着各种各样的气候反馈机制,而气候模式对这些反馈机制描述的差异,正是造成不同模式对同一直接辐射强迫（如二氧化碳加倍）的响应不同的主要原因。因此,只有正确描述气候系统中的各种反馈作用,气候模式才可能用来对未来的气候变化进行预测。为此,本文首先介绍了气候系统及模式反馈机制分析研究时所常用的一些概念,如气候敏感性参数、云辐射强迫等,随后概述了气候模式反馈机制比较分析时常用的各种方法,并指出了这些方法各自的优缺点。而详细的有关气候系统及模式中反馈作用及其机制的分析则在文章的第ＩＩ部分给出。     

气候系统及模式中反馈机制研究 Ⅰ.研究和方法

气候系统中存在着各种各样的气候反馈机制,而气候模式对这些反馈机制描述的差异,正是造成不同模式对同一直接辐射强迫（如二氧化碳加倍）的响应不同的主要原因。因此,只有正确描述气候系统中的各种反馈作用,气候模式才可能用来对未来的气候变化进行预测。为此,本文首先介绍了气候系统及模式反馈机制分析研究时所常用的一些概念,如气候敏感性参数、云辐射强迫等,随后概述了气候模式反馈机制比较分析时常用的各种方法,并指出了这些方法各自的优缺点。而详细的有关气候系统及模式中反馈作用及其机制的分析则在文章的第II部分给出。     

气侯层次和分数维

本文应用非线性理论分析了多层次的气候系统,指出分数维是气候系统结构的特征,是气候系统中尺度变换后的不变量。分数维可用于平滑气候资料,滤掉尺度较小的振动,形成较高的气候层次。平滑前后的气候层次结构已不相同。低层次气候变化的规律很不确定,在高层次上看就比较确定了。高、低层次之间存在非线性的相互作用。以上是气候研究中的一些基本问题,本文用我国的气候资料对此作了初步的探讨。     

我国现代气候业务现状及未来发展趋势

从气候监测诊断、气候预测、气候系统模式、气候评价与灾害风险管理、气候变化业务和气候业务平台等角度,系统概述了我国现代气候业务现状。提出了以气候监测和动力学诊断为基础,以提升气候服务、气候风险管理和应对气候变化能力为目标,以发展客观化气候预测技术和定量化气候评估方法为核心的现代气候业务概念。分析了国际气候业务发展趋势及我国气候业务的差距,明确了加强气候系统基本变量监测、提高气候系统模式分辨率和改进物理过程、发展第2代短期气候预测系统、研发气象灾害风险评估方法并建立中国气候服务系统 (CFCS) 等发展任务。     

气候动力学与气候预测理论的研究

主要概述了中国科学院大气物理研究所近些年来在气候动力学与气候预测理论研究领域的若干重要研究进展.通过对气候系统变化多尺度特征及其动力学的分析和研究,提出了一系列气候系统动力学理论,并在此基础上提出了适合于我国季风气候特点的气候预测理论和方法,在国际上率先开展了跨季度数值气候预测,进一步建立了先进、完善的短期数值气候预测系统,并应用于我国夏季旱涝预测业务.这些工作既带有极大的基础性意义,同时也具有巨大的应用价值,为我国大气科学及气候科学乃至环境科学的研究提供了重要工具.     

小参数气候模式

本文提出了海洋-大气-冰气候系统的综合模式,它由描述海面平均温度变化和海冰扩展边界变化的两个非线性预报方程所组成.在该模式描述的气候系统内会产生自振动状态.研究了系统对地球轨道参数扰动所造成的日射率变化的响应.已经证明,为了正确地描述气候的长周期振动,必须考虑世纪间的气候变率,根据模式,这种气候变率对气候振动谱有重大影响.本文还模拟了气候系统从非周期状态到周期状态的转变(从上新世到更新世的转变).     

中国气候系统复杂性及其地域差异

气候系统是一个非线性复杂系统,对其复杂性进行度量有助于认识气候变化的内在本质.通过对全国648个台站1961～1990年30年日气温和日降水距平系列的近似熵分析,发现该指数可以有效地度量气候系统的复杂性.气温日变化系列的近似熵高值带出现在大陆性过渡性气候和海洋性过渡性气候带,而在海洋性气候或大陆性气候单一气候类型控制的区域近似熵值普遍较低,这反映了两种或两种气候类型交互地带气候特征较为复杂;降水日变化的高值区出现在海拔较高、地表起伏较大的区域,反映了地形条件是塑造降水系列复杂性的重要因素.     

Deriving and Applying Response Surface Diagrams for Evaluating Climate Change Impacts on Crop Production

This paper presents the method to develop response surface diagrams (RSD) suitable to evaluate the impacts of climate change on potential crop production and crop area. The diagrams depict the response of different agricultural crops to average long-term changes in ambient temperature and precipitation on a country basis. They take into account the spatial and seasonal variability of climate, and differences in the climate response of important crops. RSDs for Germany and the Democratic Republic of Congo illustrate that countries and crop types differ greatly in their sensitivity to unit changes in long-term average climate. In comparing the area-weighted RSDs for Germany and Democratic Republic of Congo, it was found that the potential production in Germany of a weighted aggregation of crops is mainly sensitive to changes in temperature, whereas the potential crop production in the Democratic Republic of Congo mainly responds to changes in precipitation (over the specified ranges of climate variables). The RSDs can provide a visual overview of these varying sensitivities, and are a convenient and simple-to-understand method to summarize crop responses to climate change in a particular country.     

Temperature and precipitation long-term trends and variations in the Ili-Balkhash Basin

This study analyzed the long-term trends and variations of temperature and precipitation on annual timescale in the Ili-Balkhash Basin (IBB), Kazakhstan. Some statistical tools were employed to detect any climate variations at four stations in the IBB during the period between 1936 and 2005. These methods included the Mann–Kendall trend test, the Theil–Sen approach, and the sequential Mann–Kendall test. The results showed that in temporal scale, the climate in the IBB has been becoming warmer and wetter in the past several decades as a whole. The annual mean temperature and the annual precipitation in the IBB showed an increasing trend since the 1970s and the 1940s, respectively. The significance of the annual mean temperature and annual precipitation trends in the IBB was tested at >95 % confidence level. The slope of the increasing trend of annual mean temperature ranges from 0.019 to 0.029 °C/year, and that of the annual precipitation ranges from 0.654 to 2.179 mm/year. In spatial scale, the multiyear mean values of temperature and precipitation are greater in the southern mountain region than those in the northern plain and hilly land area of the basin. The multiyear mean temperature decreases with the increasing latitudes, while increases with the increasing altitudes except for Karaganda; the multiyear mean precipitation increase with the increasing altitudes, while decreases centered with the Lake Balkhash from the surrounding area. The results may provide climatic backgrounds for solving the problems related to water sources of the IBB.     

Performance of Regional Integrated Environment Modeling System (RIEMS) in precipitation simulations over East Asia

Regional climate models (RCMs) can provide much more precise information on surface characteristics and mesoscale circulation than general circulation models. This potential for obtaining more detailed model results has motivated to a significant focus on RCMs development in East Asia. The Regional Integrated Environment Modeling System, version 2.0 (RIEMS2.0) has been developed from an earlier RCM, RIEMS1.0, at the Key Laboratory of Regional Climate-Environment for East Asia and Nanjing University. To test the ability of RIEMS2.0 to simulate long-term climate and climate changes in East Asia and to provide a basis for further development and applications, we compare simulated precipitation from 1979 to 2008 (simulation duration from 1 January 1978 to 31 December 2008) to observed meteorological data. The results show that RIEMS2.0 reproduces the spatial distribution of precipitation in East Asia but that the simulation overestimates precipitation. The simulated 30-year precipitation average is 26 % greater than the observed precipitation. Simulated upper and root soil water correlate well with remote sensing derived soil moisture. Annual and interannual variation in the average precipitation and their anomalies are both well reproduced by the model. A further analysis of three subregions representing different latitude ranges shows that there is good correlation and consistency between the simulated results and the observed data. Annual variation, interannual variation of average precipitation, and the anomalies in the three sub-regions are also well captured by the model. The model’s performance on atmospheric circulation and moisture transport simulations is discussed to explore the bias between the simulation and observations. In summary, RIEMS2.0 shows stability and does well in both simulating long-term climate and climate changes in East Asia and in describing subregional characteristics.     

Error characteristics of high resolution regional climate models over the Alpine area

This study describes typical error ranges of high resolution regional climate models operated over complex orography and investigates the scale-dependence of these error ranges. The results are valid primarily for the European Alpine region, but to some extent they can also be transferred to other orographically complex regions of the world. We investigate the model errors by evaluating a set of 62 one-year hindcast experiments for the year 1999 with four different regional climate models. The analysis is conducted for the parameters mean sea level pressure, air temperature (mean, minimum and maximum) and precipitation (mean, frequency and intensity), both as an area average over the whole modeled domain (the “Greater Alpine Region”, GAR) and in six subregions. The subregional seasonal error ranges, defined as the interval between the 2.5th percentile and the 97.5th percentile, lie between ?3.2 and +2.0 K for temperature and between ?2.0 and +3.1 mm/day (?45.7 and +94.7%) for precipitation, respectively. While the temperature error ranges are hardly broadened at smaller scales, the precipitation error ranges increase by 28%. These results demonstrate that high resolution RCMs are applicable in relatively small scale climate impact studies with a comparable quality as on well investigated larger scales as far as temperature is concerned. For precipitation, which is a much more demanding parameter, the quality is moderately degraded on smaller scales.     

辽河流域气候变化及对径流影响预估与评估分析

辽河流域属于气候变暖较为显著区域,增温幅度比全球和全国的增温幅度都要高。同时辽河流域也是水资源较为匮乏且需求量大的地区,因此气候变化对水资源影响问题也更值得关注。基于长期历史观测气象水文数据和未来不同情景下气候变化预估资料,建立评估气候变化与径流量的关系,预估未来气候变化对径流量的可能影响,为辽河流域应对气候变化决策提供科学依据。结果表明:1961—2020年,辽河流域气温为持续上升趋势,降水没有明显的增减趋势,但存在阶段性变化;辽河流域降水量与径流量有较好的相关关系,具有较为一致的长期变化趋势与特征,年降水量与径流量相关数达到0.6以上。日降水量与径流量相关分析表明,降水发生后次日且为大雨降水等级(即日降水量≥25 mm)时,两者相关系数可高达0.85;敏感性试验和模式模拟试验表明,径流量对气候变化有明显的响应,降水增加(减少)、气温降低(升高),则径流量增加(减少);在未来RCP8.5排放情景下气温升高趋势最为明显,未来径流量也为显著增加趋势;RCP2.6排放情景下气温增加的幅度最小,未来径流量也表现为无明显增减趋势;RCP4.5情景下,气温增加的幅度居中,未来径流量则为减少趋势。     

Hedonic Pricing of Climate Change Impacts to Households in Great Britain

This study investigates the amenity value of climate to British households. By using the hedonic price approach, the marginal willingness to pay for small changes in climate variables is derived. Various indices of temperature and precipitation are used including means, ranges, extremes and January and July averages. We specify one hedonic regression including information on house prices and wage data for 755 Posttowns and found the model containing January and July averages of temperature and precipitation most appropriate. The estimates suggest that British people would typically prefer higher temperatures in January. Increased precipitation in January is likely to reduce welfare. Changes in temperature and precipitation in July are not significant. Limited global warming, with a more pronounced effect of temperature increases compared to higher precipitation levels during winter months, might thus benefit British households.     

Scaling behaviors of precipitation over China

Scaling behaviors in the precipitation time series derived from 1951 to 2009 over China are investigated by detrended fluctuation analysis (DFA) method. The results show that there exists long-term memory for the precipitation time series in some stations, where the values of the scaling exponent α are less than 0.62, implying weak persistence characteristics. The values of scaling exponent in other stations indicate random behaviors. In addition, the scaling exponent α in precipitation records varies from station to station over China. A numerical test is made to verify the significance in DFA exponents by shuffling the data records many times. We think it is significant when the values of scaling exponent before shuffled precipitation records are larger than the interval threshold for 95 % confidence level after shuffling precipitation records many times. By comparison, the daily precipitation records exhibit weak positively long-range correlation in a power law fashion mainly at the stations taking on zonal distributions in south China, upper and middle reaches of the Yellow River, northern part of northeast China. This may be related to the subtropical high. Furthermore, the values of scaling exponent which cannot pass the significance test do not show a clear distribution pattern. It seems that the stations are mainly distributed in coastal areas, southwest China, and southern part of north China. In fact, many complicated factors may affect the scaling behaviors of precipitation such as the system of the east and south Asian monsoon, the interaction between sea and land, and the big landform of the Tibetan Plateau. These results may provide a better prerequisite to long-term predictor of precipitation time series for different regions over China.     

A sensitivity-based approach to evaluating future changes in Colorado River discharge

Projections of a drier, warmer climate in the U.S. Southwest would complicate management of the Colorado River system—yet these projections, often based on coarse resolution global climate models, are quite uncertain. We present an approach to understanding future Colorado River discharge based on land surface characterizations that map the Colorado River basin’s hydrologic sensitivities (e.g., changes in streamflow magnitude) to annual and seasonal temperature and precipitation changes. The approach uses a process-based macroscale land surface model (LSM; in this case, the Variable Infiltration Capacity hydrologic model, although methods are applicable to any LSM) to develop sensitivity maps (equivalent to a simple empirical model), and uses these maps to evaluate long-term annual streamflow responses to future precipitation and temperature change. We show that global climate model projections combined with estimates of hydrologic sensitivities, estimated for different seasons and at different change increments, can provide a basis for approximating cumulative distribution functions of streamflow changes similar to more common, computationally intensive full-simulation approaches that force the hydrologic model with downscaled future climate scenarios. For purposes of assessing risk, we argue that the sensitivity-based approach produces viable first-order estimates that can be easily applied to newly released climate information to assess underlying drivers of change and bound, at least approximately, the range of future streamflow uncertainties for water resource planners.     

Multi-year variability or unidirectional trends? Mapping long-term precipitation and temperature changes in continental Southeast Asia using PRECIS regional climate model

The subject of change detection in climate time series has recently received greater interest as the perception of a human-induced change in the climate is now widely accepted. However, changes in regional precipitation and temperature remain uncertain. This study characterizes projected fine-scale changes in precipitation and temperature in continental Southeast Asia over the period 1960?C2049. Twenty four annual variables were derived from grid-based daily precipitation and temperature produced by the PRECIS regional climate model under A2 and B2 scenarios. These time series, capturing precipitation intensities (classified as low, medium and high), seasonality and extremes in precipitation and temperature, were subjected to the modified Mann-Kendall trend detection test accounting for long-term persistence. The results indicate that temperature increases over the whole region with steeper trends in higher latitudes. Increases in annual precipitation, mainly restricted to Myanmar and the Gulf of Thailand, result from increases in high precipitation during the wet season. Decreases are observed mainly over the sea and caused by a reduction of low precipitation. Changes in the occurrence of the monsoon affect the low-latitude sea areas only. By showing that significant precipitation change are minor over land areas, these results challenge most of the previous studies that suggested significant precipitation changes over Southeast Asia, often mixing up multi-decadal variability and long-term unidirectional trends. Significant changes in precipitation and temperature may induce higher agricultural yields as steepest temperature and precipitation increases will predominantly affect the coldest and driest land areas of the region.     

Seasonal to yearly assessment of temperature and precipitation trends in the North Western Mediterranean Basin by dynamical downscaling of climate scenarios at high resolution (1971–2050)

The complex topography and high climatic variability of the North Western Mediterranean Basin (NWMB) require a detailed assessment of climate change projections at high resolution. ECHAM5/MPIOM global climate projections for mid-21st century and three different emission scenarios are downscaled at 10 km resolution over the NWMB, using the WRF-ARW regional model. High resolution improves the spatial distribution of temperature and precipitation climatologies, with Pearson's correlation against observation being higher for WRF-ARW (0.98 for temperature and 0.81 for precipitation) when compared to the ERA40 reanalysis (0.69 and 0.53, respectively). However, downscaled results slightly underestimate mean temperature (≈1.3 K) and overestimate the precipitation field (≈400 mm/year). Temperature is expected to raise in the NWMB in all considered scenarios (up to 1.4 K for the annual mean), and particularly during summertime and at high altitude areas. Annual mean precipitation is likely to decrease (around ?5 % to ?13 % for the most extreme scenarios). The climate signal for seasonal precipitation is not so clear, as it is highly influenced by the driving GCM simulation. All scenarios suggest statistically significant decreases of precipitation for mountain ranges in winter and autumn. High resolution simulations of regional climate are potentially useful to decision makers. Nevertheless, uncertainties related to seasonal precipitation projections still persist and have to be addressed.