小兴安岭东部9.0 ka B.P.以来沼泽发育与古环境演变研究

对迄今为止所发现的小兴安岭东部全新世最早发育的沼泽剖面进行14 C测年、孢粉分析、粘土矿物分析、泥炭植物残体鉴定 ,根据获得的信息 ,综合分析 ,相互印证 ,研究了 9.0kaB .P .以来沼泽发育、植被演替、气候变化与古地理环境演变过程。结果表明 ,本区植被演替经历五个阶段 ,即针叶林 (90 0 0aB .P .～ 830 0aB .P .)→针阔混交林 (830 0aB .P .～ 6 80 0aB .P .)→以栎、榆、胡桃为主阔叶林 (6 80 0aB .P .～ 30 5 0aB .P .)→以桦为主阔叶林 (30 5 0aB .P .～ 2 35 0aB .P .)→以松为主的针阔混交林 (2 35 0aB .P .～ 0aB .P .)。与之相对应 ,气候变化序列为 :寒冷较湿→温和略湿→温暖湿润→温凉较湿→冷凉湿润 ;沼泽发育也相应地可划分为五个时期 :沼泽孕育期 ,富营养沼泽萌发期 ,富营养沼泽旺盛发育期和中营养沼泽孕育期 ,沼泽进一步扩大发育期和中营养沼泽形成期 ,沼泽继续扩大发育期和贫营养沼泽形成期。沼泽最早开始发育始于年代为 70 95± 90aB .P .。汤洪岭 12支线沼泽剖面可作为该区全新统的标准剖面     

Pre-summer Persistent Heavy Rain over Southern China and Its Relationship with Intra-seasonal Oscillation of Tropical Atmosphere

Based on daily precipitation data supplied by the Chinese meteorological administration, hourly reanalysis datasets provided by the ECMWF and daily outgoing long wave radiation supplied by the NOAA, the evolution regularity of continuous heavy precipitation over Southern China(SC) from April to June in 1979-2020 was systematically analyzed. The interaction between specific humidity and circulation field at the background-scale, the intra-seasonal-scale and the synoptic-scale, and its influence o...     

含煤岩系沉积学研究的几点思考

根据沉积学和煤地质学的理论和方法 ,对聚煤作用、聚煤中心、煤层在地层格架中的分布、煤的前身--泥炭和成煤基地--沼泽地 ,以及煤和煤系中的矿物组分--高岭石进行了介绍、分析、论述 ,并再次提出华北晚古生代海侵问题。     

Linking physiography and evaporation using the isotopic composition of river water in 16 Canadian boreal catchments

Highly seasonal boreal catchments are hydrologically complex and generally data poor and, hence, are ripe for investigation using tracer‐aided hydrologic models. The influence of physiography on isotopic metrics was assessed to identify the catchment characteristics dominating evaporative enrichment. A multiyear stable isotope of water dataset was collected at the outlets of 16 boreal catchments in central Canada ranging in area from 12 to 15,282 km². Physiographic characteristics were obtained through raster analysis of freely available land cover images, stream networks, and digital elevation models. Correlation analysis indicated that as the percentage coverage of open water increased, so too did the evaporative effects observed at the catchment outlet. Correlation to wetland metrics indicated that increasing the percentage coverage of wetlands can reduce or increase evaporative effects observed, depending on the isotopic metric used and the corresponding drainage density, catchment slope, and presence of headwater lakes. The slopes of river evaporative‐mixing lines appear to reflect multifaceted relationships, strongest between catchment slope, headwater lakes, and connected wetlands, whereas mean line‐conditioned excess is more directly linked to physiographic variables. Hence, the slopes of river evaporative‐mixing lines and mean line‐conditioned excess are not interchangeable metrics of evaporative enrichment in a catchment. Relationships identified appear to be independent of catchment scale. These results suggest that adequate inclusion of the distribution of open water throughout a catchment, adequate representation of wetland processes, catchment slope, and drainage density are critical characteristics to include in tracer‐aided hydrologic models in boreal environments in order to minimize structural uncertainty.     

The boreal summer intraseasonal oscillation simulated by four Chinese AGCMs participating in the CMIP5 project

The performances of four Chinese AGCMs participating in the Coupled Model Intercomparison Project Phase 5 （CMIP5） in the simulation of the boreal summer intraseasonal oscillation （BSISO） are assessed. The authors focus on the major characteristics of BSISO： the intensity, significant period, and propagation. The results show that the four AGCMs can reproduce boreal summer intraseasonal signals of precipitation; however their limitations are also evident. Compared with the Climate Prediction Center Merged Analysis of Precipitation （CMAP） data, the models underestimate the strength of the intraseasonal oscillation （ISO） over the eastern equatorial Indian Ocean （IO） during the boreal summer （May to October）, but overestimate the intraseasonal variability over the western Pacific （WP）. In the model results, the westward propagation dominates, whereas the eastward propagation dominates in the CMAP data. The northward propagation in these models is tilted southwest-northeast, which is also different from the CMAP result. Thus, there is not a northeast-southwest tilted rain belt revolution off the equator during the BSISO＇s eastward journey in the models. The biases of the BSISO are consistent with the summer mean state, especially the vertical shear. Analysis also shows that there is a positive feedback between the intraseasonal precipitation and the summer mean precipitation. The positive feedback processes may amplify the models＇ biases in the BSISO simulation.     

中国1∶400万沼泽图的编制研究

中国 1∶4 0 0万沼泽图是我国第一幅大范围的沼泽图件。本图及其附图以地图图像的形式 ,形象地、系统地总结和反映了我国有关单位近 4 0年来在沼泽方面的研究成果 ,表现了我国及主要典型区的沼泽及诏泽化土地的类型、特征、形成及其分布规律。重点反映适合我国沼泽特点并具有新观点的分类体系和分区体系。全国沼泽分类体系被分为四级 :类 (第一级 )、亚类 (第二级 )、型 (第三级 )、组 (第四级 )。全国沼泽化土地的分类系统也相应分为四级。主图表示沼泽和沼泽化土地的前三级类型 ,在作为插图 (2幅 )和附图 (4幅 )的典型区沼泽图 (1∶2 0万～ 1∶15 0万 )上侧重表示第四级类型。另一幅插图为《中国沼泽分区图》(1∶2 5 0 0万 ) ,全国被分为 8个沼泽区和 4 0个沼泽亚区。中国 1∶4 0 0万沼泽图采用综合图型 ,范围法与符号法 (分级定位符号 )相结合的表现方法 ,室内制图资料综合分析利用与野外验正和缩编相结合的编绘方法。     

Energy balance above a boreal coniferous forest: a difference in turbulent fluxes between snow‐covered and snow‐free canopies

To evaluate the interactive effects of snow and forest on turbulent fluxes between the forest surface and the atmosphere, the surface energy balance above a forest was measured by the eddy correlation method during the winter of 1995–1996. The forest was a young coniferous plantation comprised of spruce and fir. The study site, in Sapporo, northern Japan, had heavy and frequent snowfalls and the canopy was frequently covered with snow during the study period. A comparison of the observed energy balance above the forest for periods with and without a snow‐covered canopy and an analysis using a single‐source model gave the following results: during daytime when the canopy was covered with snow, the upward latent heat flux was large, about 80% of the net radiation, and the sensible heat flux was positive but small. On the other hand, during daytime when the canopy was dry and free from snow, the sensible heat flux was dominant and the latent heat flux was minor, about 10% of the net radiation. To explain this difference of energy partition between snow‐covered and snow‐free conditions, not only differences in temperature but also differences in the bulk transfer coefficients for latent heat flux were necessary in the model. Therefore, the high evaporation rate from the snow‐covered canopy can be attributed largely to the high moisture availability of the canopy surface. Evaporation from the forest during a 60‐day period in midwinter was estimated on a daily basis as net radiation minus sensible heat flux. The overall average evaporation during the 60‐day period was 0·6 mm day⁻¹, which is larger than that from open snow fields. Copyright © 1999 John Wiley & Sons, Ltd.     

INTERDECADAL CHANGE OF DIABATIC FORCING OVER KEY REGION OF THE MARITIME CONTINENT AND ITS POSSIBLE RELATIONS WITH THE EAST ASIAN SUMMER MONSOON ANOMALIES

The Maritime Continent(MC) is an important region where the Tropical Pacific and the Indian Ocean interact with each other via "the atmospheric bridge" and a key region for the interaction between the Asian and Australian monsoons. Using the NCEP/NCAR and CMAP monthly mean reanalysis over the period of 1979-2012, the interdecadal variations of diabatic forcing over the key region of the Maritime Continent and its possible relations with the East Asian summer monsoon have been investigated in the present paper. Our results show that climate variations in the Maritime Continent is particularly significant in the area of 95-145°E, 10°S-10°N, which is thus defined as the key area of the MC(i.e., KMC area). Without the input of latent heat release in the atmosphere, distinct interdecadal change of diabatic heating is found to exist from 1979 to 2012; it intensified before 1980 s and peaked in the late 1980 s and weakened after this period. By analyzing each individual component that contributes to the diabatic heating in the KMC area, surface latent heat flux and net long-wave radiation in the atmosphere are found to be the two dominant components. With negative diabatic heating anomalies over KMC, there will be more precipitation on islands and less precipitation over sea, and more rainfall around the equator, which is in correspondence with the convergence center around the equator in the KMC area. Along the meridional-vertical section averaged between 115-120 ° E, the well-defined vertical circulation anomalies are observed with the ascending branches over KMC and the area around 30°N respectively, and the descending branch over the South China Sea. Water vapor transports from the Bay of Bengal and South China Sea to eastern China to benefit the positive precipitation anomalies. The meridional-vertical circulation in East Asia plays a critical role in linking the interdecadal variability of diabatic heating over the KMC and East Asian summer monsoon anomalies.