Improvement of mono-window algorithm for retrieving land surface temperature from HJ-1B satellite data   总被引：2，自引：0，他引：2  

Ji Zhou  Wenfeng Zhan  Deyong Hu  Xiang Zhao 《中国地理科学(英文版)》2010,20(2):123-131

The thermal infrared channel (IRS4) of HJ-1B satellite obtains view zenith angles (VZA) up to ±33°. The view angle should be taken into account when retrieving land surface temperature (LST) from IRS4 data. This study aims at improving the mono-window algorithm for retrieving LST from IRS4 data. Based on atmospheric radiative transfer simulations,a model for correcting the VZA effects on atmospheric transmittance is proposed. In addition,a generalized model for calculating the effective mean atmospheric temperature is developed. Validation with the simulated dataset based on standard atmospheric profiles reveals that the improved mono-window algorithm for IRS4 obtains high accuracy for LST retrieval,with the mean absolute error (MAE) and root mean square error (RMSE) being 1.0 K and 1.1 K,respectively. Numerical experiment with the radiosonde profile acquired in Beijing in winter demonstrates that the improved mono-window algorithm exhibits excellent ability for LST retrieval,with MAE and RMSE being 0.6 K and 0.6 K,respectively. Further application in Qinghai Lake and comparison with the Moderate-Resolution Imaging Spectroradiometer (MODIS) LST product suggest that the improved mono-window algorithm is applicable and feasible in actual conditions.  相似文献   

大气气溶胶光学特性与遥感图像光谱相关性分析     

刘海隆  刘洪斌  武伟  杨晓光 《地球信息科学学报》2005,7(3):81-86

大气气溶胶对气候变化有重要的影响,由于观测资料缺乏,遥感成为越来越重要的研究手段。通过对气溶胶粒子的散射和反射特性分析表明,气溶胶的光学特性因气溶胶的成分和入射光波长的不同而不同,利用这些光谱差异,可以通过遥感方法进行光学厚度的反演,进而研究气溶胶的运动及分布、气候效应等特征。气溶胶中不同的粒子尺度及组成使其散射光学特性有较大的差异,2.1μm(或2.2μm)波段处的光谱反射率受尘粒气溶胶的影响较大;气溶胶具有时空变异特征;气溶胶在大气层上界(TDA)的辐射强迫表现为正效应,在单粒子反射率(SSA)的某一区间,其净效应因云状大小、表面反射率以及垂直气溶胶和云的分布的变化而变化,它通过影响云的凝聚核和半向效应而具有间接辐射强迫效应,另外它与臭氧的含量具有密切关系;在气溶胶信息的获取中,太阳光度计观测是一种重要手段,遥感正成为研究气溶胶越来越重要的途径。  相似文献   

开垦对科尔沁沙地土壤团聚体分布及稳定性的影响     

曹立悦  李玉霖  詹瑾  石丽娜 《中国沙漠》2021,41(2):212-220

选取科尔沁地区不同开垦年限玉米田,以沙质草地为对照,采用湿筛法测定了 0-40 cm土壤各粒径团聚体分布状况,以大于0.25 mm水稳性团聚体的含量(W0.25)、平均重量直径(MWD)、几何平均直径(GMD)、分形维数(D)和土壤可蚀性因子(K)为稳定性评价指标,研究随着开垦年限和土层深度变化下土壤水稳性团聚体的含量...  相似文献   

基于自动压缩传输与解压处理的县级台站MICAPS数据资料远程调用方法     

彭兴德  王洪斌  李光芬  池再香 《气象科技》2007,35(4):597-601

针对县级台站的网络现状和气象现代化业务服务需要,提出了一种基于自动压缩、传输、解压、处理的MICAPS数据资料远程调用方法,使基层台站可实现对省级或地(市)级单收站数据资料的共享使用,满足了气象资料的集约化应用需要,对于避免重复建设、减少县级台站维护成本具有积极作用。  相似文献   

Pumping-induced drawdown and stream depletion in a leaky aquifer system     

Butler JJ  Zhan X  Zlotnik VA 《Ground water》2007,45(2):178-186

The impact of ground water pumping on nearby streams is often estimated using analytic models of the interconnected stream-aquifer system. A common assumption of these models is that the pumped aquifer is underlain by an impermeable formation. A new semianalytic solution for drawdown and stream depletion has been developed that does not require this assumption. This solution shows that pumping-induced flow (leakage) through an underlying aquitard can be an important recharge mechanism in many stream-aquifer systems. The relative importance of this source of recharge increases with the distance between the pumping well and the stream. The distance at which leakage becomes the primary component of the pumping-induced recharge depends on the specific properties of the aquifer, aquitard, and streambed. Even when the aquitard is orders of magnitude less transmissive than the aquifer, leakage can be an important recharge mechanism because of the large surface area over which it occurs. Failure to consider aquitard leakage can lead to large overestimations of both the drawdown produced by pumping and the contribution of stream depletion to the pumping-induced recharge. The ramifications for water resources management and water rights adjudication can be significant. A hypothetical example helps illustrate these points and demonstrates that more attention should be given to estimating the properties of aquitards underlying stream-aquifer systems. The solution presented here should serve as a relatively simple but versatile tool for practical assessments of pumping-induced stream-aquifer interactions. However, this solution should not be used for such assessments without site-specific data that indicate pumping has induced leakage through the aquitard.  相似文献   

FASTL波段多波束馈源设计的初步分析     

詹德志  金乘进  于金龙  甘恒谦  朱凯  刘鸿飞 《云南天文台台刊》2010,(4):295-302

把抛物面天线的偏焦理论应用于FASTL波段多波束馈源系统的设计,分析了馈源喇叭横向偏焦距离与相应波束偏离角之间的关系,结合多波束射电望远镜扫描方式的要求,给出了FASTL波段多波束馈源的工作带宽、多波束馈源中相邻喇叭的间距以及喇叭口径大小的限制,并对正六边形阵列中处于不同位置的喇叭对应的波束的主瓣情况作了详细计算和分析。由此说明了FASTL波段多波束馈源采用19波束的可行性。另一方面,根据得到的工作频率带宽和喇叭口径大小的情况,对OMT和喇叭类型的选择进行了探讨。本文给出了FASTL波段多波束系统的大概轮廓,为进一步精确设计指明了方向。  相似文献   

Relative phase analyses of long-term hemispheric solar flare activity     

K. J. Li  P. X. Gao  L. S. Zhan  X. J. Shi  W. W. Zhu 《Monthly notices of the Royal Astronomical Society》2010,401(1):342-346

Wavelet transform methods, including the continuous wavelet transform, cross-wavelet transform and wavelet coherence, have been proposed to investigate the phase synchrony of the monthly mean flare indices in the time interval 1966 January–2007 December in the solar northern and southern hemispheres, respectively. The Schwabe cycle is the only period of statistical significance, and its mean value is 10.7 yr for the monthly mean flare indices in the northern hemisphere but slightly smaller, 10.1 yr, in the southern hemisphere – this should lead to phase asynchrony between the two. Both the cross-wavelet transform and wavelet coherence analyses show asynchronous behaviour with strong phase mixing in the high-frequency components of hemispheric flare activity, and strong synchronous behaviour with coherent phase angles in the low-frequency components, corresponding to the period-scales around the Schwabe cycle. The northern flare activity should lead the southern for the low-frequency components.  相似文献   

The north–south asymmetry of filaments in solar cycles 16–21     

K.J. Li  X.H. Liu  P.X. Gao  L.S. Zhan 《New Astronomy》2010,15(4):346-350

In the present study, the north–south asymmetry of filaments in solar cycles 16–21 is investigated with the use of the solar filaments observed at the Observatoire de Paris, Section de Meudon from March 1919 to December 1989. Filament activity is found regularly dominated in each of cycles 16–21 in the same hemisphere as that inferred by sunspot activity, and it is found to run in a different asymmetrical behavior at different latitudinal bands, suggesting that the north–south asymmetry of filament activity should be a function of latitudes. The regularity on the north–south asymmetry of sunspot activity given by Li et al. (2002b) is demonstrated by filament activity. The periods in the north–south asymmetry of solar filament activity are 9.13, and 12.8 years without the solar cycle found.  相似文献   

大别造山带晚造山期花岗岩类     

王超  赵展  焦若鸿  王绪诚  许长海 《华南地质与矿产》2010,(4):8-15

大别造山带存在中侏罗世花岗质岩浆活动,相关花岗岩类在成分上与准铝质岩一致,其锆石U-Pb与全岩Rb-Sr年龄为174~161 Ma。这些岩体主要属于造山带中下地壳深部熔融、侵入之产物,具有晚造山挤压型花岗岩的特点。岩体出露面积与剥露深度的区域变化,主要与后期强烈的热窿伸展差异改造作用有关。大别造山带晚造山期的挤压环境,还控制合肥盆地前陆挤压阶段(中侏罗世–晚侏罗世早期)以及南北两侧逆冲推覆构造的发育。西太平洋汇聚特性的急剧变化(侏罗纪末),是促成大别山造山根突发性拆沉事件以及区域伸展机制取代晚造山期挤压作用的根本原因,推测这种晚造山期挤压环境大致结束于~160Ma,即造山根突发性拆沉作用发生之时。  相似文献   

黔北地区下志留统龙马溪组烃源岩生物标志物          下载免费PDF全文

林家善  谢渊  刘建清  赵瞻  景小燕 《沉积与特提斯地质》2010,30(4):109-112

应用气相色谱和色谱-质谱分析技术,对黔北地区下志留统龙马溪组烃源岩的甾烷和萜烷进行测试分析。结果表明,正构烷烃为后单峰型,主峰碳为C22～C30,Pr/Ph值为0.48～0.64,Pr/nC17为1.35～4.22,Ph/nC18为0.92～0.97。甾烷中,具孕烷系列的异常高值,C27、C28和C29呈规则甾烷"V"字型分布(C27C28C29),具明显的C27优势,甾烷/藿烷比值为0.57～0.71。萜烷类中具三环萜烷高值,低升藿烷,高伽马蜡烷指数特征。成熟度方面,OPE1,Ts/(Ts+Tm)分布在0.42～0.48之间,C3122S/(S+R)值为0.6～0.66,C29ββ/(ββ+αα)在0.56～0.58之间,反映出龙马溪期具明显的水体分层和高还原环境。有机质主要来源于浮游水生生物和藻类,并经历了一定的生物降解过程。烃源岩的热演化已进入高成熟-过成熟阶段。  相似文献