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841.
842.
提升小波:可用于重磁资料处理的新方法 总被引:10,自引:5,他引:5
小波变换在重磁资料处理中得到了广泛应用.通过提升结构构造的二代小波继承了一代小波的优良属性,并且具有灵活性、适应性、易于快速实现等优点.二代小波比一代小波有很多优点和好的属性,其应用范围更为广泛.本文介绍了提升结构构造二代小波的思想,并讨论了其在重磁资料处理中的应用前景. 相似文献
843.
基于有限体积方法和结构化网格,建立了海底滑坡引起的波浪传播数值模型。模型控制方程为考虑了海床随时间变化的二维浅水方程。采用中心迎风格式计算控制体界面数值通量,采用线性重构技术、局部海床高程处理技术和全隐式离散底摩阻项,保证了格式的和谐性、守恒性和水深非负性,有效处理了海岸动边界问题。时间积分采用具有强稳定性质的二阶龙格-库塔方法(ssp RK)。针对滑坡体兴波经典算例开展数值模拟,将计算结果与解析解、实验结果及其他模型计算结果进行比较和分析。结果表明,对于所考虑的计算工况,模型能较合理地模拟滑坡兴波的产生、传播和爬高过程。 相似文献
844.
A depth-integrated, non-hydrostatic model with hybrid finite difference and finite volume numerical algorithm is proposed in this paper. By utilizing a fraction step method, the governing equations are decomposed into hydrostatic and non-hydrostatic parts. The first part is solved by using the finite volume conservative discretization method, whilst the latter is considered by solving discretized Poisson-type equations with the finite difference method. The second-order accuracy, both in time and space, of the finite volume scheme is achieved by using an explicit predictor-correction step and linear construction of variable state in cells. The fluxes across the cell faces are computed in a Godunov-based manner by using MUSTA scheme. Slope and flux limiting technique is used to equip the algorithm with total variation dimensioning property for shock capturing purpose. Wave breaking is treated as a shock by switching off the non-hydrostatic pressure in the steep wave front locally. The model deals with moving wet/dry front in a simple way. Numerical experiments are conducted to verify the proposed model. 相似文献
845.
Improving and validating land surface models based on integrated observations in deserts is one of the challenges in land modeling. Particularly, key parameters and parameterization schemes in desert regions need to be evaluated in-situ to improve the models. In this study, we calibrated the land-surface key parameters and evaluated several formulations or schemes for thermal roughness length (z 0h ) in the common land model (CoLM). Our parameter calibration and scheme evaluation were based on the observed data during a torrid summer (29 July to 11 September 2009) over the Taklimakan Desert hinterland. First, the importance of the key parameters in the experiment was evaluated based on their physics principles and the significance of these key parameters were further validated using sensitivity test. Second, difference schemes (or physics-based formulas) of z 0h were adopted to simulate the variations of energy-related variables (e.g., sensible heat flux and surface skin temperature) and the simulated variations were then compared with the observed data. Third, the z 0h scheme that performed best (i.e., Y07) was then selected to replace the defaulted one (i.e., Z98); the revised scheme and the superiority of Y07 over Z98 was further demonstrated by comparing the simulated results with the observed data. Admittedly, the revised model did a relatively poor job of simulating the diurnal variations of surface soil heat flux, and nighttime soil temperature was also underestimated, calling for further improvement of the model for desert regions. 相似文献
846.
周立平 《沙漠与绿洲气象(新疆气象)》2012,6(6):51-54
为了探讨膜下滴灌棉花水肥耦合效应,于2003-2004年在新疆北疆雨水较少地区开展不同水氮条件对棉花产量效应的大田试验研究。结果表明,在该试验条件下,土壤水分对产量的作用最大,氮肥次之;水氮耦合的产量效应表现为适宜土壤水分中施肥量效果最高,高土壤水分中施肥量次之,低土壤水分低施氮量最低;水氮交互大小的顺序是水氮耦合>土壤水分>施氮量;获得最高籽棉产量5253kg/hm2的灌水量为4190m3/hm2,施氮量为276kg/hm2。 相似文献
847.
EVALUATION OF CONVECTIVE-STRATIFORM RAINFALL SEPARATION SCHEMES BY PRECIPITATION AND CLOUD STATISTICS 总被引:1,自引:1,他引:0
In this study,two convective-stratiform rainfall partitioning schemes are evaluated using precipitation and cloud statistics for different rainfall types categorized by applying surface rainfall equation on grid-scale data from a two-dimensional cloud-resolving model simulation.One scheme is based on surface rainfall intensity whereas the other is based on cloud content information.The model is largely forced by the large-scale vertical velocity derived from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment(TOGA COARE).The results reveal that over 40% of convective rainfall is associated with water vapor divergence,which primarily comes from the rainfall type with local atmospheric drying and water hydrometeor loss/convergence,caused by precipitation and evaporation of rain.More than 40% of stratiform rainfall is related to water vapor convergence,which largely comes from the rainfall type with local atmospheric moistening and hydrometeor loss/convergence attributable to water clouds through precipitation and the evaporation of rain and ice clouds through the conversion from ice hydrometeor to water hydrometeor.This implies that the separation methods based on surface rainfall and cloud content may not clearly separate convective and stratiform rainfall. 相似文献
848.
849.
850.
EXPERIMENTAL STUDY ON A DYNAMIC ASYMMETRICAL TYPHOON INITIALIZATION SCHEME BASED ON 4D-VAR 总被引:1,自引:1,他引:0
Axisymmetric bogus vortexes at sea level are usually used in the traditional bogus data
assimilation (BDA) scheme. In the traditional scheme, the vortex could not accurately describe the specific
characteristics of a typhoon, and the evolving real typhoon is forced to unreasonably adapt to this
changeless vortex. For this reason, an asymmetrical typhoon bogus method with information blended from
the analysis and the observation is put forward in this paper, in which the impact of the Subtropical High is
also taken into consideration. With the fifth-generation Penn State/NCAR Mesoscale Model (MM5) and its
adjoint model, a four-dimensional variational data assimilation (4D-Var) technique is employed to build a
dynamic asymmetrical BDA scheme to assimilate different asymmetrical bogus vortexes at different time.
The track and intensity of six summer typhoons much influenced by the Subtropical High are simulated
and the results are compared. It is shown that the improvement in track simulation in the new scheme is
more significant than that in the traditional scheme. Moreover, the periods for which the track cannot be
simulated well by the traditional scheme can be improved with the new scheme. The results also reveal
that although the simulated typhoon intensity in the new scheme is generally weaker than that in the
traditional scheme, this trend enables the new scheme to simulate, in the later period, closer-to-observation
intensity than the traditional scheme. However, despite the fact that the observed intensity has been largely
weakened, the simulated intensity at later periods of the BDA schemes is still very intensive, resulting in
overly development of the typhoon during the simulation. The limitation to the simulation effect of the
BDA scheme due to this condition needs to be further studied. 相似文献