Estimation of the Land Surface Emissivity in the Hinterland of Taklimakan Desert   总被引：3，自引：2，他引：1  

LIU Yong-qiang  Ali MAMTIMIN  HUO Wen  YANG Xing-hua  LIU Xin-chun  MENG Xian-yong  HE Qing 《山地科学学报》2014,(6):1543-1551

An accurate accounting of land surface emissivity(ε) is important both for the retrieval of surface temperatures and the calculation of the longwave surface energy budgets.Since ε is one of the important parameterizations in land surface models(LSMs),accurate accounting also improves the accuracy of surface temperatures and sensible heat fluxes simulated by LSMs.In order to obtain an accurate emissivity,this paper focuses on estimating ε from data collected in the hinterland of Taklimakan Desert by two different methods.In the first method,ε was derived from the surface broadband emissivity in the 8–14 μm thermal infrared atmospheric window,which was determined from spectral radiances observed by field measurements using a portable Fourier transform infrared spectrometer,the mean ε being 0.9051.The second method compared the observed and calculated heat fluxes under nearneutral atmospheric stability and estimated ε indirectly by minimizing the root-mean-square difference between them.The result of the second method found a mean value of 0.9042,which is consistent with the result by the first method.Although the two methods recover ε from different field experiments and data,the difference of meanvalues is 0.0009.The first method is superior to the indirect method,and is also more convenient.  相似文献   

基于HJ-1B的城市热岛季节变化研究——以北京市为例   总被引：3，自引：1，他引：2  

刘帅  李琦  朱亚杰 《地理科学》2014,(1)

基于中国的HJ-1B卫星反演地表温度,通过建立一种2.5维高斯表面模型来对北京城市热岛建模,定量描述热岛的位置、形状和大小,并用这种模型来描述城市热环境及其季节变化。研究发现,北京市热岛效应季节变化明显,夏季市中心形成热岛且强度和范围最大,冬季城区中心变成冷岛。在2009年夏季,北京市热岛区域东西横跨33.92 km,南北横跨40.92 km,面积约为1 090.14 km2。相对的,在冬季,北京市区温度比郊区低,从而形成一个冷岛。研究表明HJ-1B卫星是城市热环境监测中的一个良好的数据源。  相似文献   

高中地理教学中“举三反一”的应用     

胡永泉 《地理教学》2014,(15):57-58

英国学者R.J.约翰斯顿在《哲学与人文地理学》中说：＂科学的功能……就是建立普遍规律来概括所论科学关注的经验事件或客体的行为,从而使我们将关于孤立的已知事件的知识联系起来,并对未知做出可靠的预测。＂地理科学一个重要的功能就是对地球表面的地理事实、地理现象,进行分析、概括,归纳、分析其中蕴含的地理原理、地理规律,并运用地理原理和地理规律做出科学的预测。因此,归纳推理是地理科学的重要研究方法。  相似文献   

Greenland Ice Sheet surface melt: A review     

Kang Yang  ManChun Li 《寒旱区科学》2014,6(2):0099-0106

Surface melt has great impacts on the Greenland Ice Sheet （GrlS） mass balance and thereby has become the focus of significant GrlS research in recent years. The production, transport, and release processes of surface meltwater are the keys to understanding the poten- tial impacts of the GrlS surface melt. These hydrological processes can elucidate the following scientific questions： How much melt- water is produced atop the GrlS？ What are the characteristics of the meltwater-formed supraglacial hydrological system？ How does the meltwater influence the GrlS motion？ The GrlS supraglacial hydrology has a number of key roles and yet continues to be poorly understood or documented. This paper summarizes the current understanding of the GrlS surface melt, emphasizing the three essential supraglacial hydrological processes： （1） meltwater production： surface melt modeling is an important approach to acquire surface melt information, and areas, depths, and volumes of supraglacial lakes extracted from remotely sensed imagery can also provide surface melt information; （2） meltwater transport： the spatial distributions of supraglacial lakes, supraglacial sarams, moulins, and crevasses demonstrate the characteristics of the supraglacial hydrological system, revealing the meltwater transport process; and （3） meltwater release： the release of meltwater into the englacial and the subglacial ice sheet has important but undetermined impacts on the GrlS motion. The correlation between surface runoff and the GrlS motion speed is employed to understand these influences.  相似文献   

作者更正     

杨晓彤 《海洋湖沼通报》2014,(2)

<正>由于本人的疏忽,在《海洋湖沼通报》2014年第一期~页刊登的论文《反映台湾以东黑潮流量变化的海表面高度关键区域的确定》中的摘要部分和结论部分中"黑潮流量的变化滞后该区域海表面高度1个月左右",均为"海表面高度的变化滞后黑潮流量变化1个月左右"的误写,在此予以更正。对此前文中的失误给读者带来的误导深表歉意。  相似文献   

海底电缆表面多次波衰减方法     

王兆旗  周芳明  庄锡进  陈见伟  黄鋆 《海洋地质前沿》2014,30(8)

海底电缆多次波衰减是国外地球物理研究的热点之一,国内研究关注相对较少,相应理论和实验研究相对匮乏。介绍了OBC多次波的压制方法,对上下行波场反褶积衰减海底电缆表面多次波方法理论及相应技术流程做出了详尽阐述。该方法不需要震源信息、不需要去掉直达波和鬼波,即可达到衰减表面相关多次波的目的,通过理论模型和实际资料的验证,取得了理想的效果。  相似文献   

热带气旋各个要素对于海表面降温的影响   总被引：1，自引：0，他引：1  

梁朋  管守德  赵玮  张军 《中国海洋大学学报(自然科学版)》2014,44(8):11-17

热带气旋的经过会引起海洋内部强烈的剪切,由剪切不稳定触发的强混合可以将温跃层的冷水卷挟上来,导致海洋混合层加深和海表面温度的下降。本文利用3-Dimensional Price Weller and Pinkel(3DPWP)模式模拟了不同热带气旋下的海表面降温,分别研究了热带气旋各个要素(气旋的强度,最大风速半径和移动速度)对于海表面降温的影响。模拟结果表明,海表面降温的空间分布主要受到气旋移动速度的影响,移动速度越快的降温,右偏现象越明显。海表面降温的幅度以及降温的区域随着气旋强度和最大风速半径的增大而单调递增,随移动速度增加而单调递减。海表面降温与热带气旋3个要素的拟合结果表明,气旋各个要素对于海表面降温影响作用的大小不同:在气旋移动速度较慢(小于4.5m/s)时,海表面降温主要受到气旋级别和移动速度的影响,在气旋移动速度较快(大于4.5m/s)时,气旋移动速度的影响作用减弱,海表面降温主要受气旋级别的影响。气旋最大风速半径的影响作用始终较小。  相似文献   

Results of a CLM4 Land Surface Simulation over China Using a Multisource Integrated Land Cover Dataset          下载免费PDF全文

YU Yan  XIE Zheng-Hui  WANG Yuan-Yuan  CHEN Feng 《大气和海洋科学快报》2014,(4):279-285

In this study, the high-accuracy multisource integrated Chinese land cover （MICLCover） dataset was used in version 4 of the Community Land Model （CLM4） to assess how the new land cover information affected land surface simulation over China. Compared to the default land cover dataset in CLM4, the MICL data indicated lower values for bare soil （14.6% reduction）, nee- dleleaf tree （3.6%）, and broadleaf tree （1.9%）; higher values for shrub cover （1.8% increase）, grassland （9.9%）, cropland （5.0%）, glaciers （0.5%）, lakes （1.6%）, and wetland （1.1%）; and unchanged for urban areas. Two comparative CLM4 simulations were conducted for the 33-yr period from 1972 to 2004, one using the MICL dataset and the other using the default dataset. The results revealed that the MICL data produced a 0.3% lower mean annual surface albedo over China than the original data. The largest contributor to the reduced value was semiarid regions （2.1% reduction）. The MICL-data albedo value agreed more closely with observations （MODIS broad- band black-sky albedo products） over arid and semiarid regions than for the original data to some extent. The simulated average sensible heat flux over China increased by only 0.1 W m 2 owing to the reduced values in arid and semiarid regions, as opposed to increases in humid and semihumid regions, while an increased latent heat flux of I W m-2 was reflected in almost identical changes over the whole region. In addition, the mean annual runoff simulated by CLM4 using MICL data decreased by 6.8 mm yr-1, primarily due to large simulated decreases in humid regions.  相似文献   

Application of a Coupled Land Surface-Hydrological Model to Flood Simulation in the Huaihe River Basin of China   总被引：1，自引：0，他引：1       下载免费PDF全文

LI Min  LIN Zhao-Hui  YANG Chuan-Guo  SHAO Quan-Xi 《大气和海洋科学快报》2014,7(6):493-498

A hydrological simulation in the Huaihe River Basin（HRB） was investigated using two different models： a coupled land surface hydrological model（CLHMS）, and a large-scale hydrological model（LSX-HMS）. The NCEP-NCAR reanalysis dataset and observed precipitation data were used as meteorological inputs. The simulation results from both models were compared in terms of flood processes forecasting during high flow periods in the summers of 2003 and 2007, and partial high flow periods in 2000. The comparison results showed that the simulated streamflow by CLHMS model agreed well with the observations with Nash-Sutcliffe coefficients larger than 0.76, in both periods of 2000 at Lutaizi and Bengbu stations in the HRB, while the skill of the LSX-HMS model was relatively poor. The simulation results for the high flow periods in 2003 and 2007 suggested that the CLHMS model can simulate both the peak time and intensity of the hydrological processes, while the LSX-HMS model provides a delayed flood peak. These results demonstrated the importance of considering the coupling between the land surface and hydrological module in achieving better predictions for hydrological processes, and CLHMS was proven to be a promising model for future applications in flood simulation and forecasting.  相似文献   

Numerical simulation and experimental research on hydrodynamic performance of propeller with varying shaft depths   总被引：2，自引：0，他引：2  

郭春雨  赵大刚  孙瑜 《中国海洋工程》2014,28(2):271-282

In order to study hydrodynamic performance of a propeller in the free surface, the numerical simulation and open-water experiments are carried out with varying shaft depths of propeller. The influences of shaft depths of a propeller on thrust and torque coefficient in calm water are mainly studied. Meanwhile, this paper also studies the propeller air-ingestion under special working conditions by experiment and theoretical calculation method, and compares the calculation results and experimental results. The results prove that the theoretical calculation model used in this paper can imitate the propeller air-ingestion successfully. The successful phenomenon simulation provides an essential theoretical basis to understand the physical essence of the propeller air-ingestion.  相似文献