Direct Climatic Effect of Aerosols and Interdecadal Variations over East Asia Investigated by a Regional Coupled Climate-Chemistry/Aerosol Model

The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/ aerosol model, which includes major anthropogenic aerosols （sulfate, black carbon, and organic carbon） and natural aerosols （soil dust and sea salt）. Anthropogenic emissions used in model simulation are from a global emission inventory prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report （IPCC AR5）, whereas natural aerosols are calculated online in the model. The simulated 20-year average direct solar radiative effect due to aerosols at the surface was estimated to be in a range of-9- -33 W m-2 over most areas of China, with maxima over the Gobi desert of West China, and-12 W m-2 to -24 W m-2 over the Sichuan Basin, the middle and lower reaches of the Yellow River and the Yangtze River. Aerosols caused surface cooling in most areas of East Asia, with maxima of-0.8℃ to -1.6℃ over the deserts of West China, the Sichuan Basin, portions of central China, and the middle reaches of the Yangtze River. Aerosols induced a precipitation decrease over almost the entire East China, with maxima of-90 mm/year to -150 mm/year over the Sichuan Basin, the middle reaches of the Yangtze River and the lower reaches of the Yellow River. Interdecadal variation of the climate response to the aerosol direct radiative effect is evident, indicating larger decrease in surface air temperature and stronger per- turbation to precipitation in the 1990s than that in the 1980s, which could be due to the interdecadal variation of anthropogenic emissions.

Effect of Landform on Seasonal Temperature Structures across China in the Past 52 Years

The data of 16o national meteorological observatory stations including the long-term monthly temperature data in China were analyzed to study the seasonal variation of the spatial temperature structures across China in the past half century. It is found that temperature structures differ between seasons： a latitude temperature pattern in winter and a landform temperature pattern in summer, which indicate that the effect of landform on temperature structure is much stronger in summer than that in winter and the effect of latitudinal temperature is much stronger in winter than that in summer. The mechanisms of the seasonal difference in temperature structures are also discussed in this paper.

Dynamics and Responses of Vegetation to Climatic Variations in Ziya- Daqing Basins, China

Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging Spectroradiometer(MODIS) Normalized Difference Vegetation Index(NDVI) data and meteorological data(temperature and precipitation) from 2001 to 2012, the trend of vegetation dynamics were examined in the Ziya-Daqing basins, China. The path analysis was used to obtain the information on the relationships among climatic factors and their effects on vegetation growth. It was found that the trends of growing season NDVI were insignificant in most plain dry land, while the upward trends were significant in forest, grass and dry land in Taihang Mountains. According to the path analysis, in 23% of the basins the inter-annual NDVI variation was dominated by the direct effect of precipitation, in 5% by the direct effects of precipitation and temperature, and in less than 1% by the direct effect of temperature or indirect effects of these two climatic factors. It indicated that precipitation significantly affected the vegetation growth in the whole basins, and this effect was not regulated by temperature. Precipitation increase(especially in July, August and September) was favorable to greenness enhancement. Summer temperature rising showed negative effect on plant productivity enhancement, but temperature rise in April was beneficial for the vegetation growth. When April temperature increases by 1℃, the onset date of greenness for natural vegetation will be 2 days in advance. There was a lag-time effect of precipitation or temperature on monthly NDVI for all land use types except grass.

Characteristics of gravity signal and loading effect in China

The complex geographical environment in China makes its gravity signals miscellaneous.This work gives a comprehensive representation and explanation in secular trend of gravity change in different regions,the key features of which include positive trend in inner Tibet Plateau and South China and negative trend in North China plain and high mountain Asia（HMA）.We also present the patterns of amplitudes and phases of annual and semiannual change.The mechanism underlying the semiannual period is explicitly discussed.The displacement in three directions expressed in terms of geo-potential spherical coefficients and load Love numbers are given.A case study applied with these equations is presented.The results show that Global Positioning System（GPS） observations can be used to compare with Gravity Recovery and Climate Experiment（GRACE） derived displacement and the vertical direction has a signal-noise-ratio of about one order of magnitude larger than the horizontal directions.

贵州省地表反照率变化及其对气候变化的响应

在全球气候变化背景下,地表反照率作为地表辐射平衡和气候研究的重要参数之一,在低纬度喀斯特地区开展地表反照率变化对气候要素的响应研究对理解低纬度喀斯特地区地表反照率的气候效应和区域生态环境保护具有重要意义。以贵州省为例,基于MCD43A3反照率数据、MOD15A2H LAI数据、气温和降水数据,使用Theil-Sen斜率估计和Mann-Kendall趋势检验分析、偏相关分析、滞后相关系数分析法,分析了贵州省地表反照率时空变化特征及与气候要素的时滞效应。结果表明:①贵州省2001-2022年地表反照率整体偏低,年际变化呈缓慢波动上升,年内变化呈先上升后下降;不同季节平均地表反照率比较为夏>秋>春>冬,年际变化趋势在空间上呈西升东降,在时间上为春夏上升,秋冬下降;②夏季地表反照率变化与温度、降水、叶面积指数(LAI)正负相关共存,温度对地表反照率负相关面积较大,降水和LAI则与温度相反,贵州西部毕节地区地表反照率对气候变化更为敏感;③在夏季地表反照率与温度、降水、LAI的响应中,贵州省80%以上区域表现出时滞效应。

城市化对山东省和福建省气温变化影响的对比分析

以山东和福建为研究区,基于气象站气候观测数据及ERA5-land再分析数据,采用变化趋势分析、观测减再分析(Observation Minus Reanalysis,OMR)和对比分析等方法,在区域尺度上探讨不同气候背景下城市化引起的局地升温差异。结果表明,1987—2017年山东省台站年平均气温平均变化率略高于福建省,分别为0.38℃·(10a)^(-1)和0.33℃·(10a)^(-1),但两省各季节气温变化趋势存在很大差异。城市化对山东省年和各季节T_(mean)变化的影响均大于福建省,北方相对干旱且较长的日照时间更利于城市热岛形成,这是导致上述差异的重要原因。此外,城市化对两省秋、冬季节T_(mean)变化的影响较春、夏季节更大,这与秋、冬季节相对干旱且静稳的气候特征有关。山东省城市化升温幅度的季节性差异较福建省大,可能与北方地区季节气候波动更大有关。

Altitude Effects of Climatic Variation on Tibetan Plateau and Its Vicinities

High topographies, such as the Tibetan plateau （TP） in China, have been considered as the sensitive areas in response to global climate change. By analyzing the relationship between warming structure and altitude （1 000-5 000 m） in the TP and its vicinities using the 46-year January mean observed temperature data, we found that there was a significant altitude effect of temperature warming onset time （mutation time） on the plateau and the neighboring regions： the higher the altitude, the later the climate warming happens, and vice versa. There also seems a slight altitude effect on warming magnitude： the higher the altitude, the less the warming magnitude. Therefore, the temperature warming in the high altitude area of the TP （below 5 000 m） responds to global warming less sensitively than the low-altitude neighboring areas both in onset time and magnitude, which may be mainly caused by high albedo and large thermal capacity of the ice/snow cover on the higher part of the plateau and possible heat island effect in the lower part of the plateau.

西南高山亚高山区植被活动变化的气候驱动效应与可持续性

[目的]探究西南高山亚高山区植被活动变化的驱动因素及可持续性,可为其生态系统管理提供一定的科学依据。[方法]基于2001-2018年MODIS NDVI数据和气象数据,用线性回归、Hurst指数、相关分析等方法分析了西南高山亚高山地区植被活动的时空变化特征、植被活动的稳定性和可持续性及对气候变化的响应。[结果](1)研究区以NDVI为代表的植被活动整体上显著增强,其中相对稳定的区域占63.69%,显著增强的区域占25.06%,显著降低的区域占2.73%。在植被类型中,落叶阔叶林的显著绿化趋势最强,而灌木的显著褐化趋势最强,草地对气候变化的敏感性高于林地。植被活动显著增加的区域主要分布在区域东北部的嘉陵江和岷江等地。(2)变异系数(CV)表明NDVI整体稳定性较强,从植被类型看,阔叶林和混交林的稳定性较高,农田的稳定性最低。(3) Hurst指数分析表明,植被活动趋势呈反持续的比例为69.47%,植被活动趋势呈可持续的比例为29.88%,研究区植被总体出现弱反持续性特征,在未来,植被活动增强的趋势有降低或反转的风险;(4)气候驱动因子分析表明,西南高山亚高山区温度对植被的影响占主导,即温度既是驱动植被绿化的关键因子,同样也是植被褐化的关键因子。在植被发生显著绿化的区域,常绿阔叶林和常绿针叶林的温度驱动效应低于落叶阔叶林和针阔混交林;而在植被显著褐化的区域,前两者的温度驱动效应却显著高于后两者。[结论]气温是植被活动变化的主要气候驱动因子,未来植被活动有弱反持续性的特征。

Characterizing the Winter Concurrent Variation Patterns of the Subtropical and Polar-Front Jets over East Asia

In this study, the concurrent variation relationships between the East Asian subtropical jet （EASJ） and polar-front jet （PFJ） over the East Asian land mass in the winter season on different timescales are identified and the impacts of the jet concurrent variation patterns on the atmospheric circulation in mid-high latitude regions and climate ano- malies in China are examined, using NCEP-NCAR reanalysis data and observational data. The major variability modes of the winter upper-level wind field on interannual timescales are characterized by the meridional shift of the PFJ and out-of-phase variation in the intensity of the subtropical jet and PFJ. On subseasonal and synoptic timescales, the concurrent variation relationships can be categorized into four configuration patterns： a strong （weak） subtropical jet accompanied by a weak （strong） PFJ, or a strong （weak） subtropical jet with a strong （weak） PFJ. The out-of- phase variation [i.e., a stronger （weaker） EASJ and weaker （stronger） PFJ] is found to be more common than the in- phase variation [i.e., a stronger （weaker） EASJ and stronger （weaker） PF J]. These concurrent variation relationships repre- sent the integral structure and variation features of the atmospheric general circulation over East Asia, and have signi- ficant impacts on the weather and climate. The strong subtropical jet/weak PFJ （weak subtropical jet/strong PFJ） pat- tern leads to anomalous negative （positive） geopotential height in midlatitude regions and favors cold （warm） condi- tions, and positive （negative） rainfall anomalies in southern China. For both strong jet configurations, the geopoten- tial height anomaly in the mid-high latitudes shows a northwest-southeast tilted dipole pattern, resulting in northern warm-southern cold temperature anomalies, and positive rainfall anomalies in southern China. For both weak jet situations, positive geopotential height anomalies dominate the East Asian area, and warm conditions occur over most areas in China, corresponding to less negative rainfall anomalies in southern China. The complicated rainfall and temperature anomaly patterns in China can be explained by the concurrent variation relationships between the two jets. A close relationship may exist between the synoptic-scale transient eddy activity （STEA） and the intensity of jet streams, especially for the PFJ. Significantly reduced （strengthened） STEA over the polar-front area is intim- ately associated with a decreased （increased） intensity of the PFJ.

去区域气候变异的农业水资源利用效率研究

农业水资源利用效率可用作物耗水量与总供水量(包括灌溉输水量和降水量)的比值表示。气象因子直接影响着作物耗水量和总供水量,但是气象因子对两者的影响程度不同,因此区域的气候差异造成的作物耗水量和总供水量的差异,在一定程度上影响着农业水资源利用效率。提出了一种去区域气候变异的农业水资源利用效率指标,以2004年为基准年,计算了全国的农业水资源利用效率,并分析了其主要影响因素。研究结果显示全国的水资源利用效率总体上从北至南呈下降的趋势。水资源利用效率随着农业水资源亏缺度和节水灌溉面积的增加而增加,随着灌溉水量的增加而降低。

中国近百年气温场变化成因的统计诊断分析

利用ＢＰ－ＣＣＡ方法，诊断中国近百年（１８８１～１９９２年）气温场变化之成因．结果表明：（１）ＣＯ２浓度增加所导致的温室效应的加剧，与中国近百年增暖趋势的关系最为密切；（２）８０年代后，温室效应加剧所起的主导作用更加明显，相应敏感区位于华北北部、东北、西北西部及长江中下游地区；（３）火山活动对气温变化的长期趋势所叠加的波动变化起主要作用，敏感区主要在３５°Ｎ以南，中心位于西南地区；（４）２０年代至４０年代增暖可能是温室效应、火山活动和太阳活动多种因素综合作用的结果。

西安市气候变暖与城市热岛效应问题研究

选取1961—2003年西安站和周围4站月平均气温资料,利用西安站与周围4站气温距平滑动平均变化趋势的差异,发现该站平均气温有两个明显的上升期,热岛效应使西安站平均升温1.07℃,并建立了西安市城市热岛效应模型。在此基础上分离了气候变暖过程中由于城市热岛效应引起的增温作用。

气候变化对黄河唐乃亥以上地区径流量的影响

根据黄河上游唐乃亥以上气候资料,统计分析了近50年气候变化特点,并以其与唐乃亥站径流关系为依据,建立天然径流量计算公式,计算分析了气候变化对唐乃亥站径流量的影响,结果表明:①近50年降水呈递减趋势,气温表现为显著升高特点;②20世纪90年代以来年平均气温较常年偏高0.5℃左右,而比前期升温达0.7℃～0.8℃;③近期降水量不仅较常年偏少,且比前期显著减少,尤其玛曲一带减少幅度达15.8%,并在时间上以6～9月最甚;④20世纪90年代以来天然年径流量与前期相比,减少了43.7亿m3,气候变化所引起的减幅达20.2%。

影响关中东部冬季日光温室生产的气候变化特点

采用陕西省关中东部1961-2003年的气候资料,对设施农业主要生产阶段(11月-次年3月)的极端最低气温、大雾、连阴天等气候限制因子的时空分布特点分析表明:极端最低气温整体上呈上升趋势,对设施农业生产是有利的;但大雾及连阴天日数大部分为增加趋势,对设施农业生产不利。针对大荔、渭河以南诸县和渭北山区等地不同的气候变化趋势,提出了发展壮大大荔县绿色瓜果菜设施农业基地、适当调减沿渭河各县的设施农业面积、有设施农业发展潜力的北部县应重点解决好温室灌溉和冻害防御问题等建议。

论青藏高原隆起作用于大气的临界高度

在以前工作〔１０〕的基础上，从大气动力学、热力学及气候学的角度，进一步论证了在青藏高原隆起过程中存在一个临界高度ｈｃ〗（～１．５—２ｋｍ）。当高原隆起突破这一临界高度时才开始对大气产生强烈的作用，从而造成大气环流、大气热力结构、亚洲区域以及全球气候等一系列巨大转变。

气候与森林植被变化对水文影响的定量研究进展

如何科学定量地界定气候与森林植被变化对河川径流影响的贡献率,不仅是气候变化影响研究领域中的科学问题,而且也是目前流域管理者所关注和面临的难题。为了给森林植被削洪减灾的作用大小和影响程度提供一个科学的量化依据,在论述森林植被的水文作用及其局限性的基础上,阐述了气候与森林植被变化对流域水文影响贡献率的国内外研究进展。结果显示,由于研究方法的差异以及研究流域和尺度的不同,研究结果存在较大差异,有关的普遍规律研究仍在探索之中。

降水气候变化对人工降水效果评价的影响

采用不同的统计分析方案分析福建省降水气候变化对人工降水效果评价结果的影响。分析结果表明：在福建省降水偏多年份开展人工降水使效果评价结果产生“正噪声”，在降水偏少年份开展人工降水使效果评价结果产生“负噪声”。不同试验方案对降水气候变化的反应有明显的差异，序列试验反应最为明显，历史回归试验次之，多因子分层回归试验产生的“噪声”最小。此外，还对不同试验方案效果显著的临界值进行了估算。

汾河流域气候变化及其对径流影响探讨

在分析汾河径流量变化趋势、20世纪70年代以来断流气候背景,以及气温、降水变化与径流趋势联系和80年代中期以来气候变化特点基础上,建立了河津站天然年径流量计算公式,探讨了气候变化对径流的影响。结果表明:①自20世纪50、60年代丰水期之后径流量总体呈递减趋势;②20世纪70年代以来汾河水量偏枯和断流趋势发展乃是以北半球增暖效应为背景;③20世纪80年代中期以来气候较前期变化有气温升高、尤其冬季最甚,降水减少、特别是汛期及夏、秋季最显著之特点;④气候变化引起径流量平均每年减少5.67亿m3(24.9%),其中气温影响8.6%,降水影响16.3%。因此,汾河流域气候变化及其对径流的影响较为显著。

短期气候异常对我国水资源的影响评估——国家“九五”重中之重科技项目96-908-03-02专题简介

在论述气候异常对我国水资源及国民经济影响的基础上,简要介绍了国家"九五"重中之重科技项目96-908-03-02专题:"气候异常对我国水资源及水分循环影响的评估模型研究"的攻关目标、研究内容及其内部逻辑关系等。

全球气候变化问题

全珠气候变化是世人关注的一个热点问题．地球自其形成以来就存在不同时间尺度的气候变化．可能引起气候变化的那些因素是不确定的，并且所影响的时间尺度可能亦是极不相同的．目前，气候变暖是百年尺度内气候变化的主要趋势．其变化原由尚不能确定是人类温室效应抑或是自然变化，或二者共同影响的结果．文中最后讨论了全球气候变暖有可能引起的主要问题，