黑云杉林大气CO2稳定同位素组成δ13C,δ18O的分析

研究CO₂稳定同位素特征可以揭示光合、呼吸作用等众多信息,从而有助于了解生态系统与环境之间的碳循环过程。利用大气CO₂浓度及其稳定同位素的测定资料,分析稳定同位素比δ¹³C、δ¹⁸O,发现两者具有相似的时空分布特征。主要表现在δ¹³C和δ¹⁸O在冠层内具有明显的垂直变化趋势,冠层上部重同位素含量较高,而底部含量较低。从时间变化看,δ¹³C和δ¹⁸O在午后到日落具有较高的水平,而凌晨,δ¹³C和δ¹⁸O较低。运用Keeling图法分析δ¹³C、δ¹⁸O和CO2浓度的关系,发现δ¹³C值主要受光合和呼吸作用影响,与CO₂浓度的高低密切相关;而δ¹⁸O的变化比较复杂,因为δ¹⁸O除受光合、呼吸强度影响外,还取决于环境空气湿度。     

云南一次持续性暴雨过程的非地转湿Q*

应用非地转湿Q^*,对2001年5月31日至6月2日发生在云南的持续性暴雨天气过程进行诊断分析。结果表明,非地转湿Q矢量辐合区是暴雨发生的有利区域;非地转湿Q矢量的垂直分布反映了次级环流的方向和强弱,云南的暴雨落区位于次级环流的上升支附近。     

逐对剔除的相关系数检验方法及应用

为了定量考察样本相关系数的真实性和稳定性,基于χ²检验方法,通过逐对剔除样本中的元素并构造相关系数组的方式,提出了逐对剔除的相关系数检验方法,并用理想数据样本和真实气候数据验证了该方法的正确性和可行性。结果表明,此方法可以客观、定量地找出样本中影响相关系数真实性和稳定性的极端值,这些极端值的存在会使样本的相关系数发生较大变化。本方法的检验过程简单、物理意义清楚,并且,检验过程被定量化,克服了传统方法(散点图、滑动相关等)的一些不足。     

S2MP结构分析

S²MP是SGI刚刚推出的新一代体系结构,既具有MPP的可扩展性,又具有SMP的可编程性,将两者的优势集于一身。将S²MP与历史上曾经出现的两种多机结构进行比较,指出了S²MP结构的特点。分析结果认为,S²MP是当代MIMD机器最具代表性的结构。     

锡林浩特草原CO2通量特征及其影响因素分析

利用锡林浩特国家气候观象台开路涡度相关系统、辐射土壤观测系统,测得的长期连续通量观测数据,对锡林浩特草原2009—2011年期间的CO₂通量观测特征进行了分析。结果表明:CO₂通量存在明显的年际、季节和日变化特征。3 a中NEE年际变率达到200 g·m^-2,季节变率最大达到460 g·m^-2,日变化幅度生长季最大达到0.25 mg·m^-2·s^-1。通过不同时间尺度碳通量与温度、水分、辐射等环境因子的分析,认为CO₂通量日变化主要受温度和光合有效辐射影响,而季节变化和年变化主要受降水和土壤含水量的影响。降水强度及时间分布是制约牧草CO₂吸收的关键因素,大于15%的土壤含水量有利于促进牧草生长。     

2014—2019年北京和南京地区PM2.5和臭氧质量浓度相关性研究

自2014年以来,中国细颗粒物（PM_2.5）浓度大幅度下降,但臭氧（O₃）浓度逐年缓慢上升,厘清PM_2.5和O₃（P-O）相关性尤为关键.在本研究中,2014—2019年北京和南京PM_2.5年均质量浓度下降幅度分别为-6.86和-6.15 μg·m^-3·a^-1;而日最大8小时平均O₃质量浓度（MDA8 O₃）年均增长幅度为1.50和1.75 μg·m^-3·a^-1.研究期间,北京地区MDA8 O₃质量浓度小于100 μg·m^-3,P-O呈负相关;而当质量浓度大于100 μg·m^-3时,P-O为正相关.通过Pearson相关系数研究P-O两者相关性.在两个城市每月相关性分析中,在每日时间尺度5—9月为强的正相关;而小时时间尺度11月至次年2月趋于负相关.在北京,P-O每月和季节相关性变化大于南京.在日变化中,夏季在16时为强的正相关,春秋两季在13—17时为弱的正相关,而在春、秋和冬季8时,却为强的负相关.     

天目山柳杉树轮δ13C对华东地区降水序列的重建

对采自天目山的柳杉树轮进行交叉定年后,得到树轮的δ¹³C年序列。将δ¹³C年序列去除大气CO₂的影响,保留其高频振荡部分。利用华东地区部分气象站的降水资料,通过主成份分析,分析了降水与树轮δ¹³C之间的关系。考虑滞后效应,利用回归方法重建了过去一百多年来的华东地区不同时段的降水序列,并分析其变化特征。     

湖北省PM2.5质量浓度遥感估算与时空分布特征

针对地面站点稀疏不足以提供高空间覆盖、高空间分辨率的面域PM_2.5数据支撑区域细颗粒物污染防治的问题,以湖北地区2015-2017年的MODIS卫星遥感气溶胶光学厚度（AOD）产品数据为主预测量,结合温度、湿度、风速、压强等气象参数和植被指数数据等辅助预测量,建立了AOD-PM_2.5关系逐日变化的线性混合效应（LME）模型,用于估算湖北地区的PM_2.5浓度水平.利用十折交叉验证方法进行了模型精度评估.结果表明：1）2015-2017年的交叉验证R²分别达到0.89、0.85和0.88,利用MODIS AOD数据反演近地面PM_2.5质量浓度的线性混合效应模型能很好地用于区域细颗粒物遥感监测;2）省内PM_2.5质量浓度空间差异显著,鄂东、鄂南和鄂北高,鄂西北和鄂东南低;3）全省PM_2.5估算时空数据年均值呈下降态势,分别为65.6±39.8、57.1±34.1和48.1±28.3 μg/m³,各市除随州、咸宁2016、2017年年均值持平外,都呈下降趋势.     

四川盆地与关中盆地春夏季大气降水氧同位素特征及意义

利用四川、关中盆地大气降水稳定同位素观测资料,通过计算、对比分析了两盆地内部降水稳定同位素春夏季节的变化特征.结果表明:两地降水稳定同位素在季节尺度上都具有显著的季节性变化;大气降水δ¹⁸O值与温度、降水量的相关性及变化趋势表明温度及降水量都不是两盆地内春、夏季上控制降水中稳定同位素变化的主要因素;两地春夏季大气降水线及其斜率、截距的异同,可以反映出两地局地气候特点及降水水汽来源的不同.降水水汽的来源是影响两盆地大气降水稳定同位素变化的主要因素,同时地理因素在季节上对地区降水水汽输送路径的影响改变了局地降水稳定同位素的组成.     

江淮之间夏季雨滴谱特征分析

分析了2011—2013年夏季(6—8月)滁州地基雨滴谱观测资料,根据雨强及其随时间的变化将降水分成对流降水和层云降水,分析不同降水类型的雨滴谱特征。结果表明:滁州地区对流降水的质量加权直径D_m和标准化参数lgN_w的平均值分别为1.67 mm和3.91 mm^-1·m^-3,层云降水D_m和lgN_w的平均值分别为1.18 mm和3.57 mm^-1·m^-3,对流降水雨滴平均尺度更大。N_w相比Γ分布参数N₀能更好地反映总数浓度N_t的大小。Γ分布3参数均随雨强的增大而减小,当雨强增长到一定程度时,μ(谱型)和Λ(斜率)趋于常数。研究了μ-Λ关系和Z(反射率因子)-R(雨强)关系。对流降水和层云降水的Z-R关系分别为Z=408R^1.20和Z=301R^1.21。新的Z-R关系和经典Z-R关系(Z=300R^1.40)反演的雨强相比实际观测值均偏小,但新的Z-R关系反演的雨强与实际观测值更接近。     

Cosmic rays and the electric field of thunderclouds: Evidence for acceleration of particles (runaway electrons)

We present the data on correlations of the intensity of the soft component of cosmic rays with the local electric field of the near-earth atmosphere during thunderstorm periods at the Baksan Valley (North Caucasus, 1700 m a.s.l.). The large-area array for studying the extensive air showers of cosmic rays is used as a particle detector. An electric field meter of the ‘electric mill’ type (rain-protected) is mounted on the roof of the building in the center of this array. The data were obtained in the summer seasons of 2000–2002. We observe strong enhancements of the soft component intensity before some lightning strokes. At the same time, the analysis of the regression curve ‘intensity versus field’ discovers a bump at the field sign that is opposite to the field sign corresponding to acceleration of electrons. It is interpreted as a signature of runaway electrons from the region of the strong field (with opposite sign) overhead.     

Concentrations of 222 Rn, Its Short-Lived Daughters And 212 Pb And Their Ratios Under Complex Atmospheric Conditions And Topography

Atmospheric activity concentrations of ²¹²Pb and short-lived ²²²Rndaughters, together with meteorological elements, have been observed continuously atthree sites at Kamisaibara Village in Japan. In addition, atmospheric activity concentrationof ²²²Rn, equilibrium-equivalent concentration of ²²²Rn and conditionsof the lower atmosphere were observed for three intensive observation periods at Akawase,one of the three sites in Kamisaibara Village. The equilibrium-equivalent concentration of²²²Rn is almost the same as the atmospheric activity concentration of short-lived²²²Rn daughters.The activity concentrations of ²¹²Pb and the short-lived ²²²Rn daughtersand their ratio were low in the daytime owing to convective mixing, and high at nightowing to the surface-based inversion during periods of no precipitation. Their variationshave several patterns corresponding to the scale of the drainage wind or weak mixing.Mechanical mixing due to strong winds through both day and night during the first andsecond observation periods made the atmospheric activity concentrations of ²¹²Pb and the short-lived ²²²Rn daughters continuously low. However, their ratios werecontinuously high during the first period yet continuously low during the second period.This difference can be explained by the effect ofextraction of ²²⁰Rn and ²²²Rndue to strong winds and snow cover. There were also cases in which the ratio of theatmospheric activity concentration of ²¹²Pb to that of the short-lived ²²²Rndaughters at night was equal to or less than the ratio in the daytime. Thisinverse trend, asin the periods of no precipitation mentioned above, is considered to be due to near-neutralconditions on these nights.We find a difference in the ratio of the equilibrium-equivalent concentration of²²²Rn (the activity concentration of short-lived ²²²Rn daughters) tothe activity concentration of ²²²Rn during the first observation period and thatduring the second. The difference can be explained by snow cover on the ground. Wealso find differences among the ratios of the activity concentration of the short-lived²²²Rn daughters to that of ²²²Rn during the three observation periods.These differences can be explained by the submergence of paddy fields.     

冰芯中所记录的气候异常与ENSO事件

通过对３００ＢＰ以来记录于中国古里雅冰芯中的降水和δ１８Ｏ等环境气候信息记录及ＥＮ－ＳＯ事件的分析,发现ＥＮＳＯ的发生与古里雅降水异常显著相关。在厄尔尼诺年,古里雅冰芯中的降水与δ１８Ｏ均负异常,即ＥＮＳＯ与古里雅的降水偏少,温度偏低相联系。     

Characteristics of ionic components in precipitation in Kitakyushu City,Japan

Precipitation samples were collected by filtrating bulk sampler in Kitakyushu City, Japan, from January 1988 to December 1990. Volume weighted annual mean of pH was 4.93, but the pH distribution indicated that most probable value lay in the range pH 6.0–6.4. Volume weighted annual mean concentrations of major ionic components were as follows; SO ₄ ^2– : 84.2, NO ₃ ^– : 28.1, Cl^–: 86.3, NH ₄ ⁺ : 45.5, Ca²⁺: 63.3, Mg²⁺: 27.0, K⁺: 3.4, Na⁺: 69.0 µ eq l^–1. The highest concentrations of these ionic components were observed in winter and the lowest occurred in the rainy season. The ratio of ex-SO ₄ ^2– /NO ₃ ^– exhibited the lowest ratio in summer, and the highest ratio in winter. Good correlations were obtained between Cl^– and Na⁺, ex-SO ₄ ²⁺ and ex-Ca²⁺, NO ₃ ^– and ex-Ca²⁺, and NH ₄ ⁺ and ex-SO ₄ ^2– , respectively. However, no correlation between Cl^– and Na⁺ with Ca²⁺ was observed. The relationship of H⁺ with (ex-SO ₄ ^2– + NO ₃ ^– ) - (ex-Ca²⁺ + NH ₄ ⁺ ) indicated positive correlation.     

Relationship between Solar Wind-Magnetosphere Energy and Eurasian Winter Cold Events

The profound impact of solar irradiance variations on the decadal variability of Earth' s climate has been investigated by previous studies.However,it remains a challenge to quantify the energetic particle precipitation(EPP) influence on the surface climate,which is an emerging research topic.The solar wind is a source of magnetospheric EPP,and the total energy input from the solar wind into Earth' s magnetosphere(E_(in)) shows remarkable interdecadal and interannual variability.B ased on the new E_(in) index,this study reveals a significant interannual relationship between the annual mean E_(in)and Eurasian cold extremes in the subsequent winter.Less frequent cold events are observed over Eurasia(primarily north of 50°N) following the higher-than-normal E_(in) activity in the previous year,accompanied by more frequent cold events over northern Africa,and vice versa.This response pattern shows great resemblance to the first empirical orthogonal function of the variability of cold extremes over Eurasia,with a spatial correlation coefficient of 0.79.The pronounced intensification of the positive North Atlantic Oscillation events and poleward shift of the North Atlantic storm track associated with the anomalously higher E_(in) favor the anomalous extreme atmospheric circulation events,and thus less frequent extreme cold temperatures over northern Eurasia on the interannual time scale.It is further hypothesized that the wave-mean flow interaction in the stratosphere and troposphere is favorable for the connection of E_(in) signals to tropospheric circulation and climate in the following winter.     

The effects of the Arctic haze as determined from airborne radiometric measurements during AGASP II

The interaction of the Aretic winter aerosol (Arctic haze) with solar radiation produces changes in the radiation field that result in the enhancement of scattering and absorption processes which alter the energy balance and solar energy distribution in the Arctic atmosphere-surface system. During the second Arctic Gas and Aerosols Sampling Project (AGASP II) field experiment, we measured radiation parameters using the NOAA WP-3D research aircraft as a platform. State-of-the-art instrumentation was used to measure in situ the absorption of solar radiation by the Arctic atmosphere during severe haze events. Simultaneously with the absorption measurements, we determined optical depths, and total, direct, and scattered radiation fields. All optical measurements were made at spectral bands centered at 412, 500, 675, and 778 nm and with a bandpass of 10 nm. With this selection of spectral regions we concentrated on the measurement of the radiative effects of the aerosol excluding most of the contributions by the gaseous components of the atmosphere. An additional measurement performed during these experiments was the determination of total solar spectrum fluxes. The experimentally determined parameters were used to define an aerosol model that was employed to deduce the absorption by the aerosols over the full solar spectrum and to calculate atmospheric heating rate profiles. The analyses summarized above allowed us to deduce the magnitude of the change in some important parameters. For example, we found changes in instantaneous heating rate of up to about 0.6 K/day. Besides the increased absorption (30 to 40%) and scattering of radiation by the atmosphere, the haze reduces the surface absorption of solar energy by 6 to 10% and the effective planetary albedo over ice surfaces by 3 to 6%. The vertical distribution of the absorbing aerosol is inferred from the flux measurements. Values for the specific absorption of carbon are found to be around 6 m²/g for externally mixed aerosol and about 11.7 m²/g for internally mixed aerosol. A complete study of the radiative effects of the Arctic haze should include infrared measurements and calculations as well as physics of the ice, snow, and water surfaces.     

极区上行离子对地磁活动和季节变化响应的统计分析

利用DMSP F13卫星离子漂移速度测量数据和Wind卫星行星际磁场测量数据,对极区顶部电离层离子整体上行进行研究,主要考察平静期和磁暴期离子上行强度,以及不同行星际磁场方向和季节对离子上行的影响。研究发现,无论是南半球还是北半球,磁暴期的上行发生率都超过平静期;无论磁暴期还是平静期,南半球在北向行星际磁场时上行发生率高于南向行星际磁场、北半球在南向行星际磁场时上行发生率高于北向行星际磁场,且该结论在磁暴期比平静期更为明显;南半球平静期在北向行星际磁场和南向行星际磁场时冬季的上行发生率都远高于夏季,超过2倍,北半球平静期在北向行星际磁场和南向行星际磁场时夏季的上行发生率高于冬季。     

Regional and Global Tropopause Fold Occurrence and Related Ozone Flux Across the Tropopause

This paper gives a synthesis of three algorithms to detect the presenceof tropopause folds from vertical ozone/radio-sounding profiles and frommeteorological analysis. Also an algorithm to identify injection ofstratospheric air into the lower troposphere fromozone/⁷beryllium time series is presented. Differences in theresults obtained from the algorithms are observed and discussed with respectto the criteria for fold detection and input data used. Spatial gradients inthe obtained folding frequencies are made evident on a global scale from thealgorithm based on meteorological analysis (Q-vector/potential vorticity)and probably also on a regional European scale from algorithms both basedmeteorological analyses and on ozone/PTU soundings. The observed seasonalvariation of folding occurrence is rather flat except during summer whenalso some differences appear between the algorithms. By combining thefolding frequencies with literature estimates of the cross-tropopause ozonetransfer in single folding events, an average stratospheric ozone influxinto the troposphere of 5.7 ± 1.3× 10¹⁰ mol.cm^-2 s^-1 is obtained for the Northern hemisphereand 12± 2.7× 10¹⁰ mol. cm^-2s^-1 for Western Europe. Potential additional contributions dueto other stratosphere-troposphere exchange processes than folds are not yetincluded in these estimates. Finally, the link between statistics fromozone/⁷beryllium data and folding statistics is brieflydiscussed.     

风云二号卫星空间天气监测预警系统开发及其应用

风云二号卫星载有太阳X射线监测仪及空间粒子探测器, 空间粒子探测器实时监测轨道空间的质子、电子及α粒子的能谱及通量变化, 太阳X射线监测仪实时监测太阳软硬X射线暴。这些监测数据直接反映了太阳的活动水平, 可对X射线暴、质子事件及电子事件进行实时监测。同时, 利用风云二号X射线探测器的数据, 可对一些空间环境灾害进行预警。该文介绍了中国气象局“空间天气监测预警系统一期工程”中有关风云二号静止气象卫星 (B星) 空间环境监测资料软件处理系统的设计思路, 以及高能粒子探测器和太阳X射线监测仪的数据处理方法, 并通过一些实例, 介绍了该系统在利用风云二号卫星空间环境监测数据进行空间天气监测预警业务的情况。