单侧控制条件下SPOT5 HRG影像的定向试验     

王铁军  孙洪双  马治  郑福海 《测绘软科学研究》2010,(6):62-65

高分辨率卫星影像已经成为获取地理信息的重要数据源,而其定向是一项关键技术。本文利用单侧不同数量及分布的控制点对SPOT5 HRG影像进行了定向试验,探讨了在单侧控制条件下SPOT5 HRG影像的定向精度情况,为地面控制点获取较困难地区的影像定向提供了一条参考途径。  相似文献   

Integrating downscaled CMIP5 data with a physically based hydrologic model to estimate potential climate change impacts on streamflow processes in a mixed‐use watershed          下载免费PDF全文

Michael G. Sunde  Hong S. He  Jason A. Hubbart  Michael A. Urban 《水文研究》2017,31(9):1790-1803

Climatic changes have altered surface water regimes worldwide, and climate projections suggest that such alterations will continue. To inform management decisions, climate projections must be paired with hydrologic models to develop quantitative estimates of watershed scale water regime changes. Such modeling approaches often involve downscaling climate model outputs, which are generally presented at coarse spatial scales. In this study, Coupled Model Intercomparison Project Phase 5 climate model projections were analyzed to determine models representing severe and conservative climate scenarios for the study watershed. Based on temperature and precipitation projections, output from GFDL‐ESM2G (representative concentration pathway 2.6) and MIROC‐ESM (representative concentration pathway 8.5) were selected to represent conservative (Δ_C) and severe (Δ_S) change scenarios, respectively. Climate data were used as forcing for the soil and water assessment tool to analyze the potential effects of climate change on hydrologic processes in a mixed‐use watershed in central Missouri, USA. Results showed annual streamflow decreases ranging from ?5.9% to ?26.8% and evapotranspiration (ET) increases ranging from +7.2% to +19.4%. During the mid‐21st century, sizeable decreases to summer streamflow were observed under both scenarios, along with large increases of fall, spring, and summer ET under Δ_S. During the late 21st century period, large decreases of summer streamflow under both scenarios, and large increases to spring (Δ_S), fall (Δ_S) and summer (Δ_C) ET were observed. This study demonstrated the sensitivity of a Midwestern watershed to future climatic changes utilizing projections from Coupled Model Intercomparison Project Phase 5 models and presented an approach that used multiple climate model outputs to characterize potential watershed scale climate impacts.  相似文献   

雨生红球藻中crtO基因存在3个5’上游侧翼序列     

高政权  孟春晓  叶乃好 《海洋通报(英文版)》2010,12(1):59-64

在本研究中，我们首次通过基因组上游第一次步移克隆到了雨生红球藻中crtO基因的3个不同大小的5’上游侧翼序列1．1kb，1．9kb和2．2kb。利用生物信息学方法分别预测并比较了这3个不同大小的5’上游侧翼序列，结果发现，三者具有与高等植物相类似的顺式作用元件，如脱落酸反应元件（ABRE）、干燥或低温反应元件（DRE／C-repeat）、几种光反应元件（G1-box,GAG-motif，l-boxand ATC—motif）、热激反应元件（HSE）、机械伤害反应元件（WUN-motif）、生长素反应元件（TGA-element）、茉莉酸甲酯反应元件（TGACG-element）和反式作用因子MYB蛋白的结合位点（MBSandMRE）等等，但是三者并不具有典型的TATA框和CCAAT框。上述研究预示了雨生红球藻虾青素合成中crtO基因调控方式的多样化。  相似文献   

A study of variability of annual river flow of the southern African region     

BERHANU FANTA  B. T. ZAAKE  R. K. KACHROO 《水文科学杂志》2013,58(4):513-524

Abstract

Variability of river flow is investigated in 502 river flow gauging stations in nine countries of the southern African region with a view to document the spatial variability of the river flow regimes. Those regions where there is strong evidence of declining or increasing trend in annual runoff have been identified. The study has shown that runoff in the region ranges from over 320 mm year^?1 in the Lower Zambezi and the highlands of Tanzania to less than 10 mm year^?1 in the deserts of Namibia and the Kalahari. There is also evidence of declining runoff in parts of Zambia, Angola, Mozambique and the High Veld in South Africa. The recent decline seems to have started from around 1975.  相似文献   

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

Asnor Muizan Ishak  Michaela Bray  Renji Remesan  Dawei Han 《水文研究》2012,26(7):1062-1078

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.  相似文献   

SPOT5遥感影像在土地调查中的应用     

郎刚  王鹤 《北京测绘》2010,(1):41-43

本文结合SPOT5卫星影像在某地区土地利用调查中的应用,介绍了利用SPOT5卫星遥感影像进行室内判读、结合外业调查建立土地利用数据库,进行土地利用调查的技术方法和工作流程。  相似文献   

GPS第三频载波及民用码的信号质量分析     

吴继忠  杨荣华 《测绘信息与工程》2010,35(5):22-24

介绍了L5载波的特点,分析了L5载波对GPS测量的影响,用实测数据分析了三频载波的信噪比及各个民用码的噪声水平。  相似文献   

Variation and pattern in the responses of mammal faunas to Late Pleistocene climatic change in southeastern South Australia     

Amy C. Macken  Gavin J. Prideaux  Elizabeth H. Reed 《第四纪科学杂志》2012,27(4):415-424

We examined mammal occurrence and variability through the Late Pleistocene vertebrate fossil deposit of Grant Hall in Victoria Fossil Cave, Naracoorte, South Australia. To determine long‐term patterns of change, we compared the composition and relative abundance trends of the assemblage with a nearby Middle Pleistocene deposit in Cathedral Cave. Total species richness did not change through the Grant Hall sequence, dated from 93 ± 8 to 70 ± 5 ka. However, species relative abundances varied between ecologically divergent species, and in some cases between species that demonstrate similar environmental preferences. For some species this variation is comparable to that recorded in Cathedral Cave. Of those showing similar trends between the two deposits, the forest inhabitant, Pseudomys fumeus, recorded an 8.6% decline through Grant Hall, coincident with a 9.7% increase in the dry heath/mallee dweller Pseudomys apodemoides. These patterns indicate that climatic transition from relatively warm, moist to cooler, drier conditions impacted some species in similar ways through climatic cycles of the past. However, the majority of the fauna demonstrated complex responses that are individual and variable through time. Statistical tests of species trends from the Grant Hall assemblage caution that large fossil samples are required to validate patterns observed. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

基于稀少控制点的SPOT5卫星立体条带影像的生产应用研究     

郑福海  王铁军  袁晓宏 《测绘软科学研究》2010,(1):84-87

随着相关技术的发展，高分辨率卫星遥感影像在测绘产品生产中的应用越来越广泛和深入。本文主要通过西部无图区测图的应用实践，讨论利用有理多项式方法、基于稀少控制点纠正的SPOT5HRS立体条带影像的测图生产情况，并对DLG、DEM等产品进行精度检测；同时与传统的航摄方法进行对比，分析其生产效率等情况。  相似文献   

三峡建库后东洞庭湖适宜生态水位需求分析   总被引：1，自引：0，他引：1  

黄宇云  余明辉  陆晶  孙昭华  田浩永 《湖泊科学》2020,32(2):417-427

三峡水库的修建改变了水库下游的水沙条件,影响了洞庭湖湖区的生态平衡,进而引发相关生态问题本文以城陵矶站水位代表东洞庭湖水位,基于其1953 2018年的逐日水位资料,采用滑动t检验法对年平均水位序列进行突变检验,发现因强人类活动导致城陵矶水位发生突变的时间为2004年,考虑为三峡蓄水的影响借鉴IHA(Indicators of Hydrological Alteration,水文变化指标)及RVA(Range of Variability Approach,变化范围法)方法提出了一种同时考虑年内月平均水位过程、水位波动范围、高低水位发生情况以及水位涨落情况的适宜生态水位计算指标体系,能够直观和全面地描述生态系统健康发展对水位的要求,包括1 12月水位分别为:17.07～18.34、17.15～18.89、17.65～22.23、20.25～22.15、22.85～24.90、24.31～26.44、26.88～29.16、25.79～28.32、25.12～27.56、23.59～25.88、20.65～22.81、18.58～19.88 m;年最低水位:16.21～17.86 m,发生时间为第16～51天(年积日);年最高水位:28.54～31.48 m,发生时间为第187～211天(年积日);高水位平均持续时间为32.62～81.32 d/次,低水位平均持续时间为52.13～107.65 d/次;涨水次数为21.9～26.45次,涨水速率为0.17～0.21 m/d;落水次数为23.17～27.6次,落水速率为0.12～0.14 m/d基于上述结果分析三峡建库后城陵矶水位发现,其在1、2月月平均水位分别较适宜生态水位需求高0.83、0.27 m; 10月月平均水位较需求低0.83 m;年最低水位高出需求0.39 m,发生时间先于需求6天;涨水次数高于阈值要求4次,涨水速率低于阈值要求0.01 m/d;落水次数高于阈值要求2次研究成果可为三峡及上游梯级水库群联合调度提供依据.  相似文献