玉树隆宝2014年冬季冻土积雪对陆气通量关键参数的影响分析

利用玉树隆宝湿地的观测资料,分析了未冻结、冻结和冻结有积雪覆盖三种情况下动量通量和感热通量的日变化情况,计算了三种情况下动量总体输送系数、感热总体输送系数、动力学粗糙度和热力学粗糙度,分析了附加阻尼和粗糙度雷诺数的关系,并将三种附加阻尼的参数化方案进行了比较,结果表明:冻结状态下动量通量和感热通量的日变化幅度最大,冻结有积雪覆盖时,动量通量和感热通量的日变化幅度最小。动量总体输送系数C_D和感热总体输送系数C_H的值在冻结时最大,冻结有积雪覆盖时最小,动力学粗糙度和热力学粗糙度在冻结状况下最小,冻结有积雪覆盖时最大。未冻结、冻结和冻结有积雪覆盖状态下,三种附加阻尼kB~(-1)参数化方案中,幂函数型方案较为合适。     

基于不同分辨率和参数化方案的新疆区域数值模式性能初步评估

基于中尺度数值模式WRF,选取新疆两次强降水过程,设计3个试验方案,其中试验1为控制试验,试验2提高分辨率,试验3提高分辨率并调整物理参数化方案,初步评估不同分辨率和参数化方案对新疆区域2m温度、10m风速、降水预报的影响。结果表明:(1)提高分辨率对2m温度、10m风速模拟精度均有提高,2m温度预报精度提高约0.5℃,降低了日间温度模拟冷偏差;10m风速预报精度提高约0.5m/s,降低了风速模拟正偏差;但提高分辨率后,模式出现虚假降水预报的情况。(2)提高分辨率并调整物理参数化方案后,2m温度模拟误差略有减小,模拟偏差减小约0.2℃;10m风速模拟误差增大约0.5m/s,模拟偏差增大超过0.5m/s;对降水落区、量级的模拟精度显著提高,减小了降水中心的模拟强度,对虚假降水预报有一定修正。     

边界层参数化对海南岛海风环流结构模拟的影响

利用WRF V3.7详细分析了应用8种边界层参数化方案（YSU、MYNN2.5、MYNN3、ACM2、BouLac、UW、SH、GBM）所模拟的2014年5月25日海南岛海风环流结构的差异,其中YSU、ACM2和SH为非局地闭合方案,MYNN2.5、MYNN3、BouLac、UW和GBM为局地闭合方案。结果表明:对于海风环流水平结构的模拟,15时,YSU、ACM2、BouLac、UW和SH模拟的北部海风较强,SH和GBM的内陆风速偏大。温度与海风发展强度相对应,MYNN2.5与MYNN3模拟的岛屿温度偏低,海陆温差小,海风相对较弱。对于海风环流垂直结构的模拟,09时海风开始,但强度较小,且存在残余陆风,向内陆传播距离较短,YSU、MYNN2.5和SH方案的海风相对较强。12时,海风已呈现出较为清晰的环流结构,YSU和ACM2的海风厚度及向内陆传播距离相对强于其它方案,MYNN3的环流结构则不太明显,且向内陆推进距离短,海风相对较弱。15时,海风发展强盛,MYNN2.5和MYNN3方案模拟的海风垂直强度较小,ACM2方案的海风垂直环流特征最为明显。18时,海风的强度和扰动均有所减弱,ACM2、BouLac和UW的整体海风相对强于其它方案。21时海风已基本转为陆风,BouLac与UW的陆风环流结构最为清晰。位温、水汽及海风垂直环流强度的发展变化与海风的演变过程基本一致。造成ACM2模拟海风偏强的原因是其边界层垂直混合偏强,形成了足够的湍流混合强度所致。对于边界层高度的模拟,ACM2的边界层顶最高,这与此方案所模拟的海风强度偏大相吻合,其它方案的边界层高度与海风强度并不完全一致。      

Seasonal evaluation of rainfall estimation by four cumulus parameterization schemes and their sensitivity analysis

Sustainable water resources management require scientifically sound information on precipitation, as it plays a key role in hydrological responses in a catchment. In recent years, mesoscale weather models in conjunction with hydrological models have gained great attention as they can provide high‐resolution downscaled weather variables. Many cumulus parameterization schemes (CPSs) have been developed and incorporated into three‐dimensional Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model 5 (MM5). This study has performed a comprehensive evaluation of four CPSs (the Anthes–Kuo, Grell, Betts–Miller and Kain–Fritsch93 schemes) to identify how their inclusion influences the mesoscale model's precipitation estimation capabilities. The study has also compared these four CPSs in terms of variability in rainfall estimation at various horizontal and vertical levels. For this purpose, the MM5 was nested down to resolution of 81 km for Domain 1 (domain span 21 × 81 km) and 3 km for Domain 4 (domain span 16 × 3 km), respectively, with vertical resolutions at 23, 40 and 53 vertical levels. The study was carried out at the Brue catchment in Southwest England using both the ERA‐40 reanalysis data and the land‐based observation data. The performances of four CPs were evaluated in terms of their ability to simulate the amount of cumulative rainfall in 4 months in 1995 representing the four seasonal months, namely, January (winter), March (spring), July (summer) and October (autumn). It is observed that the Anthes–Kuo scheme has produced inferior precipitation values during spring and autumn seasons while simulations during winter and summer were consistently good. The Betts–Miller scheme has produced some reasonable results, particularly at the small‐scale domain (3 km grid size) during winter and summer. The KF2 scheme was the best scheme for the larger‐scale (81 km grid size) domain during winter season at both 23 and 53 vertical levels. This scheme tended to underestimate rainfall for other seasons including the small‐scale domain (3 km grid size) in the mesoscale. The Grell scheme was the best scheme in simulating rainfall rates, and was found to be superior to other three schemes with consistently better results in all four seasons and in different domain scales. Copyright © 2011 John Wiley & Sons, Ltd.     

Introducing a transferable fishing day management regime for Pacific Island countries

On 1 December 2007, eight ‘Small Island Developing States’ in the Western and Central Pacific Ocean implemented a management regime restricting the total number of days fished by tuna purse seine vessels within their waters, commonly referred to as the Vessel Day Scheme (VDS). The VDS is seen as one component of management arrangements to reduce fishing mortality on bigeye and yellowfin tuna, constrain fishing effort, and increase the rate of return from access fees by Distant Water Fishing Nations.     

Abrupt behaviours of streamflow and sediment load variations of the Yangtze River basin,China

Monthly sediment load and streamflow series spanning 1963–2004 from four hydrological stations situation in the main stem of the Yangtze River, China, are analysed using scanning t‐test and the simple two‐phase linear regression scheme. Results indicate significant changes in the sediment load and streamflow from the upper reach to the lower reach of the Yangtze River. Relatively consistent positive coherency relations can be detected between streamflow and sediment load in the upper reach and negative coherency in the middle and lower reaches. Interestingly, negative coherency is found mainly for larger time scales. Changes in sediment load are the result mainly of human influence; specifically, the construction of water reservoirs may be the major cause of negative coherency. Accentuating the human influence from the upper to the lower reach results in inconsistent correlations between sediment load and streamflow. Decreasing sediment load being observed in recent years has the potential to alter the topographical properties of the river channel and the consequent development and recession of the Yangtze Delta. Results of this study are of practical significance for river channel management and evaluation of the influence of human activities on the hydrological regimes of large rivers. Copyright © 2012 John Wiley & Sons, Ltd.     

Compact and tunable mid-infrared source based on a 2 μm dual-wavelength KTiOPO4 intracavity optical parametric oscillator

Using a double resonant KTiOPO₄ (KTP) intracavity optical parametric oscillator operating at degenerated point of 2 μm, we demonstrate a unique mid-infrared source based on difference frequency generation in GaSe crystal. The output tuning range is 8.42-19.52 μm, and a peak power of 834 W for type-I phase matching scheme and 730 W for type-II phase matching scheme are achieved. Experimental results show that this oscillator is a good alternative to the generator of a compact and tabletop mid-infrared radiation with a widely tunable range.     

Some remarks on cumulus parameterization

A simple parameterization of cumulonimbus convective heating is presented. The model is primarily based on preserving a moisture budget and on detraining cloud air at levels corresponding to the neutral buoyancy of the air converged at low levels. Results are compared with data from the western Pacific and GATE. Agreement is good. Suggestions are offered for improving the model and extending it to other regions.     

勘探工程地质统计信息法

勘探工程地质统计信息法试图运用定量评价准则研究勘探工程,而定量评价准则是建立在矿体数学模型基础上。本文在最优勘探方案和最优工程位置选择方面作了一些研究。     

云和辐射 （II）:环流模式中的云和云辐射参数化

这一部分论述了在环流模式中应用的各种云参数化和云辐射参数化方案。云参数化分为云的诊断和预报二大类，云辐射参数化则包活云光学性质的参数化和云整体辐射性质（反射率、透过率、吸收率和发射率）的参数化。