临安冬夏季SO2、NO2和O3体积分数特征及与气象条件的关系

对临安大气本底站2003-2004年冬、夏季二氧化氮(NO2)、二氧化硫(SO2)、臭氧(O3)进行了分析.结果表明:冬季NO2和SO2平均体积分数分别为19.48×10-9和35.74 x10-9,而夏季的平均体积分数分别为4.81×10-9和8.12×10-9,冬季高于夏季;O3在夏季的平均体积分数为33.55×10-9,略高于冬季的25.44×10-9;夜间NO2和SO2体积分数比白天高,并且NO2呈明显的单峰单谷型分布,O3也呈单峰型但峰值出现在白天.NO2、SO2体积分数存在着明显的“假日效应”,假日比非假日低,周五高于假日和非假日;但O3体积分数没有明显的假日效应.降水对SO2有明显的清除作用,但对NO2的清除作用不明显.与风向对比发现,夏季高体积分数的NO2、SO2都受到NW、WNW风的影响,冬季则分别受NE和SW、SSW风的影响;而O3受风向的影响较复杂,与局地光化学反应有关.     

O3,CO2浓度及太阳光谱变化对作物光合作用影响的数值模拟研究

对光合作用 蒸腾作用 气孔调节进行耦合 ,从生物化学尺度扩展至冠层尺度 ,发展了一个冬小麦冠层光合作用生态动力模式 ,模式考虑了O3,CO2 和光谱变化对作物光合的综合影响。利用美国光合作用实测资料对模式进行验证 ,叶片模式通过了相关显著性检验并具有较高的准确度。数值分析表明 :当O3 浓度由 0× 10 -9V/V上升至2 0 0× 10 -9V/V时 ,冠层光合速率下降 2 9%左右 ;当CO2 浓度由 330× 10 -6V/V上升至 6 6 0× 10 -6V/V时 ,冠层光合速率增加大约 37% ;当光谱比例系数由目前的 0 .5下降至 0 .4时 ,冠层光合速率将下降 2 7%左右。对于污染严重、易发生光化学烟雾的城郊附近 ,在阳光强烈的典型晴天 ,中午O3 浓度达到 2 0 0× 10 -9V/V时 ,即使气候条件不发生改变 ,CO2 浓度对作物光合作用的正效应也不足以弥补O3 浓度升高所造成的负效应 ,冠层光合速率将比目前干洁地区略有下降 ,如果进一步考虑光合作用有效辐射光谱成分下降至 0 .4左右 ,冠层光合作用将比目前的BASE值下降 35 %左右。     

简单生物圈模式 (SiB2) 中湍流能量通量对近地层两类阻抗系数的敏感性研究

陆—气之间的能量交换是通过近地层湍流热量和水汽通量来实现的.以往的研究表明近地层阻抗对湍流能量通量有着不同程度的影响,但是关于陆面模式中阻抗系数的取值范围却始终没有统一的标准.为了深入了解简单生物圈模式 (SiB₂) 中近地层阻抗系数取值变化对湍流能量通量的影响,我们以那曲站为例,分别采用传统的逐个因子分析法和考虑参数间相互作用的部分因子分析法定量地研究了夏季该观测站近地层湍流能量通量分别对冠层阻抗系数C₁和地表阻抗系数C₂的敏感性响应.结果表明,感热通量对地表阻抗系数C₂更为敏感,而潜热通量则对冠层阻抗系数C₁较为敏感;感热通量随C₁增加而增大,随C₂增加而减小,而潜热通量则随C₁或C₂的增加而减小;不管是感热通量还是潜热通量,它们对阻抗系数的敏感度随阻抗系数的增大而减小,而对阻抗系数的相对敏感度则随阻抗系数的增大而增大.最后,结合那曲站夏季下垫面稀疏短草的分布特点分析了造成感热通量和潜热通量敏感变化各异的原因.     

厌氧条件下土壤反硝化气体(N2、N2O、NO)和CO2排放——氦环境培养—气体同步直接测定法的应用初探

反硝化过程是维系闭合氮循环所必需的氮素形态转化环节。土壤反硝化过程速率及产物比的直接测定是研究氮循环过程机理的基础,但却是一个难题。为解决此难题,德国卡尔斯鲁厄技术研究所与中国科学院大气物理研究所最近合作新建了一套通过氦环境培养-气体同步直接测定土壤反硝化气体--氮气（N2）、氧化亚氮（N2O）、一氧化氮（NO）和二氧化碳（CO2）排放的系统和与之配套的三阶段培养方法。为检验该新建系统和配套方法测定土壤反硝化过程的准确性和可靠性,以华北地区广泛分布的盐碱地农田土壤（采自山西运城）为研究对象开展实验室培养试验,在初始可溶性有机碳（DOC）供应比较充足约300 mgC kg–1干土（d.s.）的条件下,测试了不同初始土壤硝态氮含量水平（10、100 mgN kg–1d.s.左右,分别表示为10N和100N）的反硝化气体和CO2排放过程。结果显示：100N的反硝化速率（定义为N2、N2O 和NO 排放速率之和）显著高于10N 处理（统计检验显著水平p＜0.01）;两个处理的反硝化产物均以N2为主（质量比分别占77%和75%）,产物的NO/N2O摩尔比分别为1.2和1.5,N2O/N2摩尔比均为0.19;土壤反硝化气体动态排放速率及相关指标的测定结果表明,培养土壤中消失的硝态氮被回收81%～87%,培养前后的氮平衡率达92%～95%。因此,该新建方法测定土壤反硝化速率和产物比的结果具有很好的可靠性,为定量研究土壤反硝化过程提供了有效的直接测定手段。研究中检测到的土壤反硝化产物NO/N2O摩尔比大于1,不同于以往用液体培养基纯培养反硝化细菌得出的NO/N2O摩尔比远小于1的结论。这意味着,不能用NO/N2O摩尔比小于1与否来推断土壤排放的N2O和NO是主要来源于反硝化作用还是硝化作用。     

PRELIMINARY STUDY OF VARIATION OF SO2 AND AEROSOL PARTICLE BACKGROUND CONCENTRATIONS IN THE EASTERN CHINA

The average concentrations of sulphur dioxide,sulfate aerosol and TSP were about 8-10 ppb,15.08 μg m^-3,and 241.40 μg m^-3 respectively,which were measured at the Lin'an regional background station during August-November,1991.The higher concentrations of SO₂ and SO₄^2- maybe acidify the rainfall.It has a great influence upon the human health and ecosystem.The simulated results indicate that the distributions of SO₂ and SO₄^2- were determined by local emission sources.Average aerosol particle number density was 2.0×10⁴ cm^-3.It shows that social development and human activities strongly affect the atmospheric background level.     

整层大气甲烷总量季节变化的遥测

利用自行研制的一台用于探测大气成分的太阳红外光谱仪 ,在地面连续自动地记录了晴天的太阳红外光谱。用逐线积分法计算了整层大气的吸收 ,发现在 3.42 8μm波段主要是大气甲烷的吸收 ,从记录的该波段的太阳红外光谱中反演出整层大气中甲烷的总含量 ,经过近一年半的观测 ,得到了合肥地区大气甲烷垂直柱含量的季节变化规律。发现其变化规律与北半球背景对流层空气采样分析法测量的甲烷季节变化规律基本相同。文中详细介绍了测量仪器、测量原理和部分测量结果 ,并对结果进行了简单的讨论。     

CHARACTERISTICS OF SEASONAL VARIATION OF RAINFALL OVER THE TIBETAN PLATEAU DURING SUMMER 1998 AND ITS IMPACT ON EAST ASIAN WEATHER*

The seasonal variation of rainy season over the Tibetan Plateau in summer 1998 is analyzed by using daily observational rainfall data for Lhasa from 1955 to 1996,and rainfall data at 70 stations from January to August of 1998 over the Tibetan Plateau (TP) and adjacent regions,as well as TBB data from May to August of 1998.The onset date of rainy season for Lhasa is climatologically 6 June.Among the analyzed years,the earliest onset date is 6 May,while the latest may delay to 2 July.The obvious inter-decadal variation can be found in the series of onset date.The onset date of summer 1998 over middle TP (onset date of Lhasa) is 24 June,which is relatively later than the normal case.The onset for rainy season of 1998 started over southeast and northeast parts of TP and then propagated westward and northward.The convection over east and west parts of TP shows that there is a quasi 12-15 day oscillation.In June,the convection over middle and lower reaches of Yangtze River is formed by the westward propagation of convection over subtropical western Pacific.while in July.it is formed by the eastward propagation of convection over TP.Besides,it is also found that there exists good negative and obvious advance and lag correlation between the convection over the middle and western TP and that over the subtropical western Pacific and southern China.Therefore it can be inferred that a feedback zonal circulation with a quasi two-three week oscillation exists between the ascending region of TP and descending region of subtropical western Pacific,i.e.the convection over TP may affect the subtropical high over western Pacific and vice versa.     

NUMERICAL SIMULATION OF THE INFLUENCE OFO3,CO2 AND SPECTRUM VARIATION ON THE PHOTOSYNTHESIS OF CROP CANOPY*

Coupled the photosynthesis with transpiration and adjustment of stoma,a dynamic ecological model for simulating the canopy photosynthesis of winter wheat was established by scaling up from the biochemical scale to canopy scale,in which the effects of O₃,CO₂ and solar spectrum on crop photosynthesis were fully considered.Validation of the model against the data measured with CI-301PS portable photosynthesis analyzer showed that the leaf photosynthesis model passed the correlation significance test and had a fairly high accuracy.Numerical analysis showed that the canopy photosynthesis rate would be reduced by 29% if the O₃ concentration increases from 0 ppbv to 200 ppbv,whereas the canopy photosynthesis rate would increase by about 37% while the CO₂ concentration increases from 330 ppmv to 660 ppmv,and the canopy photosynthesis rate would be reduced by 27%0 or so under the condition that the spectrum coefficient changed from 0.5 to 0.4.If the O₃ concentration reached 200 ppbv at noon on the typical sunny day with higher radiation,the canopy photosynthesis will be reduced slightly in the suburb area where the pollution is serious and the photochemical fog is easy to be formed,contrast with that in the clear region and regardless of the climate change,due to the fact that the positive effect of CO₂ on crop photosynthesis can not compensate the negative effect of O₃ on crop photosynthesis.The canopy photosynthesis will be reduced by 35% or so than the BASE value at present,when the spectrum of photosynthetic active radiation(PAR) reduces to 0.4 or so.     

CO2和O3浓度倍增对作物影响的研究进展

文中利用自行设计的OTC - 1型开顶式气室进行了 9a的田间试验 ,取得了一批质量可靠的试验数据 ,分析了CO2 浓度倍增对大豆、冬小麦、棉花、玉米、春小麦和谷子的生物量、产量及品质的影响 ,结果表明CO2 浓度倍增对上述 6种作物的生物量及产量的影响均是正效应 ,对冬小麦、棉花和谷子品质的影响可能是有利的 ,对玉米品质的影响可能是不利的 ,对大豆的影响不大 ;分析了O3 浓度倍增对冬小麦、水稻、油菜和菠菜生物量、产量及品质的影响 ,结果表明O3 浓度倍增对上述 4种作物生物量的影响均是负效应 ,对冬小麦和水稻的产量影响是负效应 ,但是冬小麦和水稻籽粒中粗蛋白和 17种氨基酸含量都有所增加 ;分析了CO2 和O3 浓度复合倍增对大豆生物量、产量及品质的影响 ,结果是生物量和产量呈增加趋势 ,说明了CO2 的正效应大于O3 的负效应。采用作物模型数值模拟方法 ,分析了CO2 和O3 浓度倍增对冬小麦生物量及产量的影响。     

龙凤山大气近地层O3浓度变化及与其它因素的关系

研究首次在龙凤山区域大气本底站测得的地面Ｏ３浓度及其变化的资料表明,中国东北农村地面大气Ｏ３浓度总体水平不很高,但在少数特殊的天气条件下,时均浓度可超过国家二级标准。Ｏ３浓度存在明显的季节和日变化,其月平均浓度１９９５年１月最低（２７．５ｐｐｂ）,１９９４年１１月最高（４３．２ｐｐｂ）。Ｏ３日变化幅度夏季的晴天最大（２８ｐｐｂ）,冬季的阴天最小（８ｐｐｂ）。气象要素（尤其是风速、气温和相对湿度等）和ＮＯｘ与地面Ｏ３浓度有较密切的关系。用多变量分析法探讨了地面Ｏ３各指标随气象因子和ＮＯｘ共同变化的规律,并拟合了寒冷和温暖期里与地面Ｏ３日最高浓度、日最低浓度及日变化幅度有关的方程。     

OBSERVATION AND INVESTIGATION OF VARIABILITIES OF BASELINE CO2 CONCENTRATION OVER WALIGUAN MOUNTAIN IN QINGHAI PROVINCE OF CHINA*

In-situ measurement of atmospheric CO₂ was made at the top of the Waliguan Mountain(36°17'N,100°54'E,3816 m asl).where the air is not directly affected by the local anthropogenic and natural sources,by using a nondispersive infrared(NDIR)analyzer and following the procedures proposed by WMO.The CO₂ in the flask samples collected on the mountain was also analyzed in a laboratory.The measurements uncover the daily,monthly and seasonal variabilities and the baseline level of the CO₂ in the air over the "clean" area of Chinese hinterland.Results suggest that the CO₂ concentration over the East Asia continent has evident periodical variation,similar to that of global distribution.In 1992,an annual mean baseline CO₂ concentration of 356.4 ppm over the continent was obtained.The annual mean value was 357.2 ppm for 1993.Some relationships between the CO₂ concentration at Waliguan and the weather conditions,especially,wind speed and direction are found through the observation.     

MIROC_Hires模式模拟我国极端降水非均匀性在CO2浓度增加下的响应

利用日本东京大学气候系统研究中心、日本环境研究所和日本地球环境研究中心联合研制的全球海气耦合气候系统模式(MIROC_Hires)输出的逐日降水资料,探讨CO2浓度增加下我国极端降水非均匀性的响应及其可能机制。结果表明:(1)就气候平均而言,CO2浓度增加后,我国南部地区极端降水事件的发生更为集中,而北方地区的极端降水事件分布较平均。(2)从年际变率来看,我国南部地区极端降水事件集中度在"A1B试验"中偏小,年际之间的差异不大,而北方地区的极端降水集中度增加,年际之间变化剧烈。(3)CO2浓度增加后,南方和北方地区在水平和垂直上的增温幅度不一致,且整层大气平均的稳定度呈现出南北反相差异。这种不均匀增暖的分布很可能是导致我国极端降水非均匀性在CO2浓度增加后变化的原因。