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991.
992.
A STUDY OF MICROWAVE RADIATION TRANSFER CHARACTERISTICS IN STRATIFIED PRECIPITATION CLOUDS BY COMBINING STRATIFIED CLOUD MODEL WITH MICROWAVE RADIATION TRANSFER MODEL 下载免费PDF全文
In this paper,the effect of precipitation particles on microwave radiation transfer characteristics in stratified clouds over the ocean is studied by combining stratified cloud model with microwave radiation transfer model.By comparing the calculated results with the true data,it is found that precipitation particle distribution and water shell around ice phase particle strongly affect the upwelling radiation.Therefore,the precipitation particle distribution and water shellaround ice phase particle must be considered when a calculating scheme is designed for retrieving precipitation in stratified clouds by the use of microwave radiation transfer model. 相似文献
993.
Terrain revised model for air temperature in mountainous area based on DEMs: A case study in Yaoxian county 总被引:1,自引:0,他引:1
YANG Xin TANG Guoan XIAO Chenchao DENG Fengdong 《地理学报(英文版)》2007,17(4):399-408
In mountainous area, spatial interpolation is the traditional method to calculate air temperature by use of observed temperature data. Due to lack of sufficient observation data in mountainous areas many precise interpolation methods could give only coarse result which could not meet the demand of precision agriculture and local climate exploration. Based on DEMs of 25 m resolution, a reversed model is constructed, with which temperature is simulated to the corresponding slope unit from the solar radiation. Taking Yaoxian county as a test area, and mean monthly temperature data as basic information sources, which are collected from 15 weather stations around Yaoxian county in Shaanxi province from the year of 1970 to 2000, a simulation for the solar radiation cell by cell is completed. By simulating solar radiation at each slope and flat cell unit, the terrain revised temperature model could be realized. A comparison between the simulated temperature and the radiation temperature from TM6 thermal infrared image shows that the terrain improved model gets a finer temperature distribution at local level. The accuracy of simulated temperature in mountainous area is higher than it is in flat area. 相似文献
994.
岩石破裂电磁辐射现象是客观存在的物理现象.随着电磁辐射观测技术在地震研究、冲击矿压预测等领域的应用,极大地推动了岩石破裂电磁辐射的实验研究.本文对岩石破裂电磁辐射的影响因素以及相伴生的现象,以及有关的物理解释进行了概括介绍.由于不同研究者使用实验设计、实验参数、实验条件的不同,使得观测和研究结果同样难以统一认识.不同的研究者根据各自的试验提出了不同的物理机制.同时对已发现现象的重复性、证实性研究岩石试验缺乏.严重匮乏利用数值模拟以及建立模型定量研究岩石破裂的电磁辐射.此外,岩样实验系统不同于实际的地震系统,进行模拟震源环境的实验研究,发展大尺度的标本和原岩现场实验的基础上,如何建立室内室外岩石实验与地震观测事实之间的联系是问题的关键. 相似文献
995.
乌鲁木齐市近30a太阳辐射变化及其成因初探 总被引:1,自引:0,他引:1
利用乌鲁木齐市气象站1976—2005年太阳辐射和气象观测资料,分析乌鲁木齐市太阳辐射的变化及其成因。结果是:1990年以前总辐射、直接辐射是减少的,以后是增加的;而散射辐射在1986年之前递增、之后递减。初步认定总云量的减少、低云量的增加以及相对湿度的缓慢下降对太阳辐射变化有重要影响;从太阳辐射变化间接得出:近30a乌鲁木齐市空气污染总体有所减轻。 相似文献
996.
比较Morcrette辐射方案和Fu_Liou辐射方案对NCC/IAP T63海气耦合模式云和辐射模拟的影响, 结果表明:两种方案模拟的大气顶入射辐射存在明显的差异; 晴空大气Fu_Liou方案的短波吸收能力在全球普遍较Morcrette方案低; 在60°S~60°N之间, Fu_Liou方案模拟的行星反照率更接近于ERBE卫星观测; 在对大气顶净辐射的模拟上, 除了冬季的太平洋和大西洋东岸云量明显减少的部分地区外, Fu_Liou方案对大气顶净辐射的模拟总体上较Morcrette方案有了较为明显的改善; Fu_Liou方案模拟的海洋低层云显著减少, 而热带地区高云的模拟明显增加; 由于采用了“二元云量”算法, 尽管云量有所减少, Fu_Liou方案模拟的云短波吸收作用仍有所增强, 一定程度上改进了Morcrette方案云的短波吸收作用偏弱的现象。 相似文献
997.
为了研究和揭示宁夏南部地气能量传输过程及特点并进一步评估退耕还林还草的生态效应, 利用Landsat-7 ETM+卫星遥感资料所求取的地表特征参数, 将地表分成水体、裸地、半裸地、草地、林地5类地表覆盖类型, 结合常规气象观测资料, 分别计算得出宁夏南部地表辐射和热量平衡各量的区域分布, 并给出各量的分布图和直方图, 分类别讨论了地表辐射和热量平衡各量分布特征, 使得对宁夏南部区域地表辐射和热量平衡区域分布有一个直观、综合的了解和认识。研究表明, 植被分布对地表辐射和热量平衡各量影响很大。 相似文献
998.
Long-term comparisons of net radiation calculation schemes 总被引:1,自引:0,他引:1
J. H. Kjaersgaard R. H. Cuenca F. L. Plauborg S. Hansen 《Boundary-Layer Meteorology》2007,123(3):417-431
Six commonly used models for calculating daily net radiation were tested against measured net radiation. Meteorological data
from 32 and 7 consecutive years obtained at two temperate sites were used. The extensive duration of the datasets ensured
that all weather conditions and extreme events were captured. A set of statistical procedures was used to evaluate the performance
of the models. The mean bias errors ranged from 0.0 W m−2 to 24.8 W m−2 and 0.1–24.7 W m−2 and root mean square error from 11.0 W m−2 to 28.1 W m−2 and 10.0–27.9 W m−2 at the two sites respectively, for days without snow cover on the ground. The best agreement was found when locally calibrated
model coefficients were used. Only negligible differences in model performances were found between the two sites and the differences
were lower than the inaccuracies of the net radiation instruments used. Including days with snow cover in the analysis lead
to a slight increase in the bias and scatter of the predictions. Model performances were in general better during summertime
than wintertime. Altered albedo values during winter caused by generally low sun angles were likely the cause of this. Analysis
showed that at least 5 years of data were needed to obtain stable calibration coefficients for local calibration of the models.
Based on the results from this study, and due to their physical background, two physical based models were recommended for
calculating daily values of net radiation under temperate climate regimes. A simple adjustment of the calibration coefficients
based on climate regime was suggested for these models. 相似文献
999.
1000.
A Matrix Approach Coupled with Monte Carlo Techniques for Solving the Net Radiative Balance of the Urban Block 总被引:2,自引:0,他引:2
Marta J. N. Oliveira Panão Helder J. P. Gonçalves Paulo M. C. Ferrão 《Boundary-Layer Meteorology》2007,122(1):217-241
A new method is developed for solving the shortwave and longwave net radiative balance of a three-dimensional urban structure,
represented by parallelepiped blocks uniformly distributed in each direction. The method is based on a novel approach to determine
the shape factors among surfaces, which are estimated by Monte Carlo techniques due to the complex geometry associated with
the three-dimensional urban structure. Then, a set of linear equations is solved to quantify the radiative balance, in order
to obtain their exact solution, considering all the inter-reflections among surfaces. The comparison between the new and the
ray-tracing tracking methods resulted in a Pearson correlation coefficient of 0.996. However, by integrating the linear equations’
exact solution with Monte Carlo techniques, the new method reduces by a factor of 36 the central processing unit (CPU) time
used to perform the calculations of the ray-tracing tracking method. The use of the model for a sensitivity study allows us
to verify the effective absorptance and emittance increases with the canyon aspect ratio of the urban layout. An urban structure
formed by square cross-sectional blocks absorbs more solar radiation than an urban structure formed by rectangular cross-sectional
blocks. The approximation of a specific geometry for an equivalent bi-dimensional infinite street can be applied for rectangular
cross-sectional blocks, where the width is 11 times or more greater than the depth dimension. 相似文献