植物冠层动量交换特征的实验研究

使用湍流梯度测试资料，对植物冠层动量交换特征进行了详细研究，结果表明:森林冠层内惯性副区能谱曲线仍可用幂指数描述，但斜率比-2/3更负；森林冠层内湍流尺度有变小的趋势；森林上层的耗散系数比下层大；由植被吸收引起动量及动量通量随冠层深度增加而明显减小；冠层下层的动量通量和耗散系数分别与上层的量有好的正相关；森林冠层内耗散系数和动量通量随大气稳定度有明显变化。     

空气动力学方法在湍流通量计算中的误差分析

采用迭代方法检验了在近地面层大气中使用空气动力学方法时，温度、湿度和风速梯度等观测误差对感热和潜热通量计算的相对误差，结果表明，在微风和低温环境中，空气动力学方法的使用受到限制。     

The Footprint for Estimation of Atmosphere-Surface Exchange Fluxes by Profile Techniques

The flux footprint, that is the contribution per unit emission from each element of the upwind surface area to measurement of the vertical flux of a passive scalar, is calculated for fluxes estimated by micrometeorological profile techniques. It is found that the upwind extent of the footprint for concentration-profile flux estimates is similar to that of the footprint for eddy-covariance flux measurements, when the eddy-covariance measurement is made at a height equal to the arithmetic mean of the highest and lowest profile measurement heights for stable stratification or the geometric mean for unstable stratification. The concentration-profile flux footprint depends on the ratio of the highest to the lowest measurement height, but is insensitive to the number of measurement levels. The concentration-profile flux footprint extends closer to the measurement location than does the 'equivalent eddy-covariance flux footprint, and the difference becomes more pronounced as the ratio of the profile measurement heights increases. The flux footprint for the Bowen-ratio technique is identical to that for a two-level profile measurement only for very limited circumstances. In the more general case, a flux footprint cannot be defined for the Bowen-ratio technique and the uniform upwind fetch required for representative flux measurements depends on the specific spatial distribution of surface fluxes.     

塔中地面加热场强度变化特征分析

利用塔克拉玛干沙漠大气环境综合观测试验站塔中西站10 m梯度自动气象站2009年1、4、7、10月观测数据,基于土壤的一维热扩散方程计算四季自然沙地下垫面的地表土壤热通量和地面加热场强度,从而分析沙漠下垫面的地面加热场强度变化特征。结果表明:(1)春季和夏季地表土壤热通量日总量为正值,热通量方向向下,沙层相对大气是热汇,秋季和冬季则相反;日较差最大值出现在秋季,最小值出现在冬季;除冬季以外土壤热通量只占净辐射通量的很小一部分;(2)1、4、7、10月地面加热场强度分别为-33.20～87.39 W/m~2、-36.92～274.16 W/m~2、-7.59～244.78W/m~2、-24.90～170.42 W/m~2,地面加热场强度日平均值均为正值,地面为热源,夏季最强,春季次之,冬季最弱;(3)与大气相较,白天地面为强热源,夜间为弱冷源,春季地面加热场强度峰值出现在12时(地方时),夏季、秋季、冬季均出现在13时(地方时)。因此,塔克拉玛干沙漠腹地地面加热场强度具有独特的日变化和季节变化特征。     

基于RegCM4.6的中国地区云对地表太阳辐射的影响研究

使用RegCM4.6区域气候模式，选取Emanuel和Mix（Grell+Emanuel）两种积云对流参数化方案，以2016年为例，分别对中国地区云短波辐射强迫及其涉及的物理量进行数值模拟，揭示其时空分布特征，并探究两种积云对流参数方案模拟效果的差异及其原因。结果表明：从季节平均来看，全国地表云短波辐射强迫均为负值，云对地表为冷却效应，冬季最小，春夏季较大。塔里木盆地四季均为辐射强迫低值区，夏季冷却效应最弱，辐射强迫绝对值低于40 W·m-2；全天空地表净短波辐射分布也呈显著季节差异，除夏季外均呈由南向北逐渐递减的分布趋势；晴空地表净短波辐射在横断山脉处和塔里木盆地处均比较低，其中春季最为明显；两个方案所得的季节空间分布特征大致相同，但在数值上存在差异。春季时全国大部分地区全天空地表净短波辐射通量差异最大，在55 W·m-2左右，晴空地表净短波辐射通量在青藏高原处差异在60W·m-2左右。     

海表动量和热量通量的数值模拟

本文分析了用IAP两层大气环流模式模拟的海表动量和热量通量,并将其同Han等和Esbensen等的气候资料比较.模拟的热量通量与观测估计值有类似的水平分布和季节变化,但在中低纬地区有偏多的热量由海洋向大气输送,尤其1月北半球中纬大气需要从海洋获得过分多的热量;模拟的海表动量通量和气候估计值也类似,但模拟的北半球冬季中高纬西风动量通量中心位置偏东,赤道中西太平洋和大西洋的东风动量通量偏弱,南半球环绕南极的西风带模拟得过分弱(尤其在7月份).本文还检验了基本变量的日变化和日际变化对计算海表动量和湍流扩散热量通量的影响,结果表明用月平均,日平均和每小时的基本量计算的动量和湍流扩散热量通量依次增大,尤其在中高纬地区更明显.     

中国土壤热通量的气候计算及其分布特征

根据北京等6个热平衡站的资料，通过5种方案计算比较得出土壤热通量Qs动的气候计算方法Qs＝2．826·△θs-20＋0．486·△T－0．777这里△θs-20、△T分别为土中5与20厘米温差和地一气温差．该式相关比为0．897，平均拟合误差1．4wm-2。据此计算全国215站的土中热交换量，并分析其时空变化，得出一些有意义的结果。     

Excessive degassing of Izu-Oshima volcano: magma convection in a conduit

Excess degassing of magmatic H₂O and SO₂ was observed at Izu-Oshima volcano during its latest degassing activity from January 1988 to March 1990. The minimum production rate for degassed magma was calculated to be about 1×10⁴ kg/s using emission rates of magmatic H₂O and SO₂, and H₂O and S contents of the magma. The minimum total volume of magma degassed during the 27-month period is estimated to be 2.6×10⁸ m³. This volume is 20 times larger than that of the magma ejected during the 1986 summit eruption. Convective transport of magma through a conduit is proposed as the mechanism that causes degassing from a magma reservoir at several kilometers depth. The magma transport rate is quantitatively evaluated based on two fluid-dynamic models: Poiseuille flow in a concentric double-walled pipe, and ascent of non-degassed magma spheres through a conduit filled with degassed magma. This process is further tested for an andesitic volcano and is concluded to be a common process for volcanoes that discharge excess volatiles.     

On the coupling of hydrography,phytoplankton, zooplankton,and settling organic particles offshore in the Arabian Sea

Processes and issues related to the connections between hydrography, plankton, and the flux of organic carbon to great depth are reviewed for the offshore Arabian Sea and compared with observations in similar regimes of other seas. The south-north and west-east gradients and seasonality in the Arabian Sea are emphasized, but generalizations about the area as a whole are shunned. New data include regional differences in seasonality of satellite-observed chlorophyll for two years. The rule for the depth dependence of organic flux is unclear, therefore, this should be the first priority for future investigations. While the data for supply of organic carbon by settling and demand for the depth interval 200–1,000 m in the eastern Arabian Sea are in fair agreement, this is not true for the interval between 300 and 400 m. For advancing the understanding of the generation of flux in the upper layers and the consumption at depth, very much needs to be learned about the biology of the principal species of Zooplankton and nekton. To keep the task manageable, further studies of flux should focus on only one or two subdivisions of the Arabian Sea.