影响青藏高原植被生理过程与大气C02浓度及气候变化的相互作用

利用一陆面过程模式,初步模拟研究了青藏高原夏季风盛行期植被生理过程与大气CO2浓度及气候变化的相互作用.结果表明,气候以及大气CO2浓度变化对青藏高原地区的植被生理过程有较明显的影响,高温、高湿和高CO2浓度将加强高原植被的光合作用和呼吸作用,有利于植被生长.高原植被也可通过生理过程,产生净C02吸收,降低大气C02含量,起到调整温室效应的作用,从而影响全球气候变化;当气温升高、大气C02增加时,这种作用更加有效.青藏高原地区大气C02浓度加倍,对高原地区气候的直接影响不明显.植被的存在也会影响区域气候变化,并可通过改变高原热源,进而影响高原及其周边地区气候变化.文中还归纳出了植被生理与气候相互作用的简单概念模型.     

青藏高原大气一植被相互作用的模拟试验Ⅰ.物理通量和参数

在原大气-植被相互作用模式AVIM的基础上作了改进,包括对植被生理过程,如(1)光合作用;(2)呼吸;(3)分配和(4)物候等新的描述方法.对青藏高原上30个站点进行模拟计算,给出了高原上地表辐射及水热物理通量以及地表拖曳系数和地面反照率的分布特征.模拟结果表明净辐射和感热通量由东南向西北增加,高原西北部地表反照率较高,东南部地表反照率较低.     

青藏高原大气—植被相互作用的模拟试验——Ⅰ.物理通量和参数

在原大气-植被相互作用模式AVIM的基础上作了改进,包括对值被生理过程,如（1）光合作用：（2）呼吸;（3）分配和（4）物候等新的描述方法。对青藏高原上30个站点进行模拟计算,给出了高压上地表辐射及水热物理通量以及地表拖曳系数和地面反照率的分布特征。模拟结果表明净辐射和感热通量由东南和西北增加,高原西北部地表反照率较高,东南部地表反照率较低。     

大气CO2浓度升高及气候变化对作物冠层光合影响的数值模拟

利用美国Licor-6200光合作用测定仪,对黄淮海地区代表性冬小麦品种鲁麦23号叶片光合作用速率进行了较为全面的测定,分别确定了冬小麦叶片光-光合作用响应曲线和CO2-光合作用响应曲线,在此基础上,建立了叶片光合作用模式,并进而建立了一个具有瞬时时间尺度,空间积分为叶片尺度的冬小麦冠层模式,利用模式分别分析了大气中CO2浓度升高和温度变化对冠层光合作用的不同影响,并在此基础上进一步进行了综合数值分析.单因子分析表明晴天状况下,冠层光合速率随CO2浓度升高而上升,当CO2浓度由330×10-6上升至660×10-6时,冠层光合日总量可增加19.7 %;冠层光合速率随辐射增加而增大,辐射量增加10.0 %,冠层光合日总量可增加6.7 %;冠层光合速率随温度升高而下降,温度升高1 ℃,冠层光合日总量减少2.9 %.多因子综合数值分析表明在辐射量较大的气候背景下,冠层光合日总量对温度和CO2变化响应更加敏感.本文的实测数据为研究气候变化对中国农业影响提供了最基本的可靠模型参数,冠层光合模型为未来改进作物模型提供了理论基础.     

全球大气CO2浓度变化特点简析

研究表明，全球CO2浓度变化有二大特点，一是北半球具有明显的季节变化，而南半球由于各纬度上的浓度变化很小，没有明显的季节变化。二是两个半球又有一个相同的特点，那就是都有较大的逐年增高的趋势，各地的平均年增长率在1．4至1．7ppmv/a之间。南北两半球相比，北半球的年平均浓度要高出4ppmv，年平均增长率也要略高一些。研究表明，大气CO2浓度的变化还具有10年左右的周期，而且与厄尔尼诺年的关系比较密切。     

改则地区气候变化对植被生理过程的影响及反馈效应的模拟研究

利用1997年10月1日至1998年9月30日设置在青藏高原西部改则的自动气象站观测资料作为强迫场,采用大气-植被相互作用模式(AVIM)对改则地区气候变化对植被生长过程的影响及反馈效应进行了模拟研究。结果表明,AVIM模式对青藏高原西部陆面过程具有一定模拟能力,能够较真实地模拟出地表特征量的变化特点。通过敏感性试验发现,青藏高原气候变化对植被生理生长过程有明显影响:降水增加有利于植被生长,尤其在雨季最为明显,其他季节无太大变化;气候变暖对植被生理过程的综合作用是植被净光合作用的变化,即春季增强,夏季减弱,秋季和冬季变化不大;暖湿化对高原植被生态系统的影响主要是春季和夏季植被活动增强,尤其春季最为明显。植被物理特性参数可以在相当大程度上改变陆面过程,进而导致高原热源发生变化,因此,为准确估计地表能量收支,对模式陆面参数进行深入研究是必要的。     

大气长波辐射计算中的温度订正和CO2浓度效应

本文对长波辐射平均面透射率的计算方法和温度效应作了一系列试验。试验表明,在计算中可以采用制表和插值节省计算时间,并保证计算精度。温度效应较明显,在计算大气长波辐射变温率时,应予以考虑。最后还对CO_2浓度变化所引起的变温效应进行了计算,得出了一些有意义的结果。     

青藏高原植被下垫面对东亚大气环流影响的数值试验

采用Ｊ．Ｗ．Ｄｅａｒｄｏｒｆｆ（１）地表植被参数化方案，利用Ｐ－ａ原始方程５层模式（２），分析了青藏高原有植被和无植被两种不同下垫面情况下的大气响应，结果表明有植被下垫面通过增加向大气输送潜热通量，加强了高原上空的热低压，增强了高原北部的热成风，加强了高原南侧的季风环流，使青藏高原及我国东南地区的降水增多。     

郑州城区大气CO2浓度变化特征及影响因素分析

郑州城区大气CO2浓度日变化比较强烈,变化幅度在26.24 ～ 64.34 μmol·mol-1,全天最低值出现在15时前后,最高值则出现在夜间至清晨.从季节来看,夏、秋两季的日变化幅度比冬、春两季的大.其中,1月份平均浓度达到最高,为455.80 μmol·mol-1;7月份平均浓度则最低,为369.25 μmol·mol-1.影响郑州城区大气CO2浓度变化的原因是人为取暖活动及植被的季节变化,另外一些气象因素也对CO2浓度有一定的影响.     

景德镇地区大气CO2浓度变化特征

利用景德镇温室气体监测站CO_2观测数据,分析了景德镇地区2017年12月—2018年11月大气CO_2浓度变化特征,同时对其浓度进行了筛分,以剔除污染数据,使其更具区域代表性。研究表明:景德镇地区大气CO_2浓度昼降夜升,早上最高,傍晚最低;春季最高,秋季最低;春、夏季NNE、NE、ENE风向,秋季NE、ENE风向以及冬季W、WSW、SW、SSW、S风向上CO_2浓度较高。同时,春、夏和秋季大气CO_2浓度大致随风速的增加而不断降低,冬季风速对大气CO_2浓度无明显影响。筛分后数据显示景德镇地区年均大气CO_2浓度为422.1×10~(-6),浓度日均值年振幅73.96×10~(-6),夏半年CO_2浓度低于冬半年。     

植被退化对青藏高原冬夏季气候影响的模拟研究

利用区域气候模式RegCM3,模拟分析了青藏高原地区植被退化对自身及周边地区气候产生的影响。结果表明：植被退化后,在退化区域冬夏季地表温度明显升高,最大增值2℃,而外围则温度降低,量值为-0.5℃～-1℃。夏季气温的变化趋势与地表温度类似,但量值较小,冬季退化区气温增加范围较大。夏季退化区湿度和降水增大,增加值分别达到0.6g/kg和35mm/month;退化区外围降水减少,外围西部及北部地区湿度减小,中心值为-0.4 g/kg。在冬季,湿度稍有减小,主要分布在西藏地区和青海、四川的交界处。     

Interannual Variability of the Normalized Difference Vegetation Index on the Tibetan Plateau and Its Relationship with Climate Change

The Qinghai-Xizang Plateau, or Tibetan Plateau, is a sensitive region for climate change, where the manifestation of global warming is particularly noticeable. The wide climate variability in this region significantly affects the local land ecosystem and could consequently lead to notable vegetation changes. In this paper, the interannual variations of the plateau vegetation are investigated using a 21-year normalized difference vegetation index （NDVI） dataset to quantify the consequences of climate warming for the regional ecosystem and its interactions. The results show that vegetation coverage is best in the eastern and southern plateau regions and deteriorates toward the west and north. On the whole, vegetation activity demonstrates a gradual enhancement in an oscillatory manner during 1982-2002. The temporal variation also exhibits striking regional differences： an increasing trend is most apparent in the west, south, north and southeast, whereas a decreasing trend is present along the southern plateau boundary and in the central-east region. Covariance analysis between the NDVI and surface temperature/precipitation suggests that vegetation change is closely related to climate change. However, the controlling physical processes vary geographically. In the west and east, vegetation variability is found to be driven predominantly by temperature, with the impact of precipitation being of secondary importance. In the central plateau, however, temperature and precipitation factors are equally important in modulating the interannual vegetation variability.     

基于MODIS NDVI和气候信息的草原植被变化监测

对植被的动态监测可以从一定程度上反映气候变化趋势。该文利用2000—2005年MODIS NDVI数据对锡林郭勒盟典型草原植被变化进行动态监测,在此基础上,以降水量、水汽压、平均气温、最高气温、最低气温、日照时数作为气候指标,分析锡林郭勒盟典型草原和荒漠草原MODIS NDVI与同期及前期气候因子的相关性,探讨草原植被变化的气候驱动因子。结果表明:2000—2005年锡林郭勒盟植被改善面积大于退化面积,植被退化面积最大的区域为荒漠草原,占全盟面积的12.84%,植被改善面积最大的区域为典型草原,占全盟面积29.09%。4类草原改善趋势由强到弱的顺序为草甸草原、典型草原、沙地草原、荒漠草原。对于典型草原,其NDVI与最高气温关系最密切,其次为水汽压;对于荒漠草原,其NDVI与最高气温关系最为密切,其次为最低气温。此外,NDVI对气候因子的响应表现出明显的时滞效应。     

The Soil Moisture and Net Primary Production Affected by CO_2 and Climate Change Using a Coupled Model

In this paper, a coupled model was used to estimate the responses of soil moisture and net primary production of vegetation （NPP） to increasing atmospheric CO2 concentration and climate change. The analysis uses three experiments simulated by the second-generation Earth System Model （CanESM2） of the Canadian Centre for Climate Modelling and Analysis （CCCma）, which are part of the phase 5 of the Coupled Model Intercomparison Project （CMIP5）. The authors focus on the magnitude and evolution of responses in soil moisture and NPP using simulations modeled by CanESM, in which the individual effects of increasing CO2 concentration and climate change and their combined effect are separately accounted for. When considering only the single effect of climate change, the soil moisture and NPP have a linear trend of 0.03 kg m^-2 yr^-1 and-0.14 gC m^- 2 yr^-2, respec- tively. However, such a reduction in the global NPP results from the decrease of NPP at lower latitudes and in the Southern Hemisphere, although increased NPP has been shown in high northern latitudes. The largest negative trend is located in the Amazon basin at -1.79 gC m^-2 yr^-2. For the individual effect of increasing CO2 concentration, both soil moisture and NPP show increases, with an elevated linear trend of 0.02 kg m^-2 yr^-1 and 0.84 gC m^-2 yr^-2, respectively. Most regions show an increasing NPP, except Alaska. For the combined effect of increasing atmospheric CO2 and climate change, the increased soil moisture and NPP exhibit a linear trend of 0.04 kg m^2 yr^-1 and 0.83 gC m^2 yr^-2 at a global scale. In the Amazon basin, the higher reduction in soil moisture is illustrated by the model, with a linear trend of-0.39 kg m^-2 yr^-1, for the combined effect. Such a change in soil moisture is caused by a weakened Walker circulation simulated by this coupled model, compared with the single effect of increasing CO2 concentration （experiment M2）, and a consequence of the reduction in NPP is also shown in this area, with a linear trend of-     

土地利用变化对我国区域气候影响的数值试验

使用RegCM2区域气候模式单向嵌套澳大利亚CSIRO R21L9全球海-气耦合模式,通过将中国区域植被覆盖由理想状况改变为实际状况的数值试验对比分析,探讨了当代中国土地利用变化对中国区域气候的影响,并对结果进行了统计显著性检验。研究表明,土地利用的变化,会导致我国西北等地区年平均降水减少,导致年平均气温在内陆部分地区升高和在沿海个别地区降低,引起许多地方夏季日平均最高气温升高,而冬季日平均最低气温则在我国东部部分地区降低的同时在西北地区升高,土壤湿度的变化表现为大范围的降低。研究同时表明,相同的土地变化在不同的地理环境下引起的气候要素变化有一定的不一致性。     

对气候变化背景下中欧易北河流域可用水的评估

The Elbe region is representative of humid to semi-humid landscapes in Central Europe,where water availability during the summer season is the limiting factor for plant growth and crop yields.especially in the loess areas with high crop productivity having annual precipitation lower than 500 mm.This paper summarizes the results of the first phase of the GLOWA(GLObal WAter)-Elbe project and tries to assess the reliability of water supply in the German part of the Elbe river basin for the next 50 years,a time scale relevant for the implementation of water and land use management plans.One focus of the study was developing scenarios which are consistent with climate and land use changes considering possible uncertainties.The concluding result of the study is that nature and communities in parts of Central Europe will have to deal with considerably lower water resources under scenario conditions.     

Preliminary Assessment of the Common Land Model Coupled with the IAP Dynamic Global Vegetation Model

The Common Land Model（CoLM） was coupled with the IAP Dynamic Global Vegetation Model（IAPDGVM）, and the performance of this combined CoLMIAP model was evaluated. Offline simulations using both the original Common Land Model（CoLM-LPJ） and CoLM-IAP were conducted. The CoLM-IAP coupled model showed a significant improvement over CoLMLPJ, as the deciduous tree distribution decreased over temperate and boreal regions, while the distribution of evergreen trees increased over the tropics. Some biases in CoLM-LPJ were preserved, including the overestimation of evergreen trees in tropical savanna, the underestimation of boreal evergreen trees, and the absence of boreal shrubs. However, most of these biases did not exist in a further coupled simulation of IAP-DGVM with the Community Land Model（CLM）, for which the parameters of IAP-DGVM were optimized. This implies that further improvement is needed to deal with the differences between CoLM and CLM in parameterizations of landbased physical and biochemical processes.     

Influences of Climate Change on the Uptake and Storage of Anthropogenic CO2 in the Global Ocean

A global ocean general circulation model, called LASG/IAP Climate system ocean model (LICOM), is employed to study the influence of climate change on the uptake and storage of anthropogenic CO 2 in the global ocean. Two simulations were made: the control run (RUN1) with the climatological daily mean forcing data, and the climate change run (RUN2) with the interannually varying daily mean forcing data from the NCEP (National Centers for Environmental Prediction) of the US. The results show that the simulated distributions and storages of anthropogenic dissolved inorganic carbon (anDIC) from both runs are consistent with the data-based results. Compared with the data-based results, the simulations generate higher anDIC concentrations in the upper layer and lower storage amount of anDIC between the subsurface and 1000-m depth, especially in RUN1. A comparison of the two runs shows that the interannually varying forcing can enhance the transport of main water masses, so the rate of interior transport of anDIC is increased. The higher transfer rate of anDIC in RUN2 decreases its high concentration in the upper layer and increases its storage amount below the subsurface, which leads to closer distributions of anDIC in RUN2 to the data-based results than in RUN1. The higher transfer rate in RUN2 also induces larger exchange flux than in RUN1. It is estimated that the global oceanic anthropogenic CO 2 uptake was 1.83 and 2.16 Pg C yr 1 in the two runs in 1995, respectively, and as of 1994, the global ocean contained 99 Pg C in RUN1 and 107 Pg C in RUN2 of anDIC, indicating that the model under the interannually varying forcing could take up 8.1% more anthropogenic carbon than the model under the climatological forcing. These values are within the range of other estimates based on observation and model simulation, while the estimates in RUN1 are near the low bound of other works. It is estimated that the variability of root mean square of the global air-sea anthropogenic carbon flux from the simulated monthly mean results of RUN2 with its seasonal cycle and long-term trend removed is 0.1 Pg C yr 1 . The most distinct anomalies appear to be in the tropical Pacific Ocean and the Southern Ocean.     

植被覆盖异常变化影响陆面状况的数值模拟

利用NCAR最新的公用陆面模式CLM3．0，通过数值模拟初步研究了植被叶面积指数（LAI，leafareaindex）异常变化对陆面状况的可能影响，结果表明，植被LAI的异常变化能够引起地表能量平衡、地表水循环等陆面状况的异常。（1）植被LAI的异常变化主要影响太阳辐射在植被与地表之间的分配，以及地表的感热、潜热通量。植被LAI增大，能够引起植被吸收的太阳辐射增加，而到达土壤表面的太阳辐射减小，并导致植被的蒸发、蒸腾潜热通量增加，造成地表的蒸发潜热和感热通量不同程度的减小。（2）植被LAI增大时，植被对降水的拦截和植被叶面的蒸发增大，植被的蒸腾作用也明显增强；植被LAI增加会使得热带地区各个季节的土壤表面蒸发、地表径流减小，而土壤湿度有所增加；LAI增加造成中高纬度地区土壤蒸发的减少主要出现在夏季；LAI增加还能够引起中高纬地区冬、春积雪深度不同程度的增加，造成春末、夏初地表径流的增加。（3）植被LAI增加能够使得叶面和土壤温度有所下降，但植被LAI的变化对叶面、土壤温度的影响相对较小。     

黄淮海地区植被活动对气候变化的响应特征

基于1982 -2003年GIMMSNDVI遥感数据和气象资料, 综合运用趋势分析、相关分析、奇异值分解等方法, 分析我国黄淮海地区植被活动对气候变化响应的时空特征。结果表明:黄淮海地区整体气候变暖趋势比较明显, 干旱化尚不显著, 年平均植被NDVI表现为略微增加的趋势。在年尺度上, 温度是敏感性最强的气候因子, 全年温度、降水、相对湿度对植被NDVI动态变化具有正效应, 而蒸发量具有负效应; 在季尺度上, 温度、降水的敏感性最强。自然植被对降水的敏感性最强, 其次是温度; 农业植被对温度的敏感性最强, 其次是降水。植被对气候变化响应的空间特征表现为, 植被主要生长季平均NDVI与温度距平场空间结构一致, 与蒸发量距平场反位相对应, 与降水量距平场呈北、南部正负相反分布, 与相对湿度距平场呈南、北向正负相反的空间分布。