Identification of trends in annual maximum sea levels using robust locally weighted regression     

A.T. Walden  P. Prescott 《Estuarine, Coastal and Shelf Science》1983,16(1):17-26

Estimates of the frequency of occurrence of extreme high sea levels may be obtained from a sample of annual maxima. However, the presence of a secular trend may lead to serious doubts about the validity of analysing these annual maxima as if they were a random sample from an extreme-value distribution. Robust locally weighted regression, employing a simple model, is used to illustrate how any secular trend may be estimated. The annual maxima may then be adjusted for this trend and more reliable estimates of the frequencies of occurrence of extreme sea levels determined.  相似文献   

中国七大地区“气候变化—作物产量—经济影响”综合评价     

刘远  王芳  张正涛  黄承芳  陈曦  李宁 《气候变化研究进展》2021,17(4):455-465

农业作为响应气候变化最敏感的领域之一,未来作物产量可能受到深刻影响。量化气候变化冲击作物产量导致的最终经济影响,需要综合“气候变化—作物产量—经济影响”开展链式研究。文中采用系统回顾和Meta回归分析方法整合了55篇文献的667项研究结果,推导出我国七大地区主要作物（水稻、玉米、小麦）产量与地区内未来温度和降水变化的定量关系,并将其作为农业部门的损失量代入改进的多区域投入产出模型,量化七大地区内与地区间遭受的经济波及影响（ERE)。结果显示：(1)气候变化对我国作物产量的影响主要体现在温度升高上,每升温1℃减产2.6%~12.7%,东北和西北地区作物受升温影响最显著;(2) 气候变化导致的作物减产将对经济产生更严重的波及影响,GDP因作物减产每下降1%将额外产生17.8%的波及影响;(3) 21世纪末,若不考虑CO₂肥效作用,作物减产导致的ERE将占GDP的-0.1%~13.6%（负值表示收益),最悲观情况下ERE与当前我国农业总产值相当（2012年为基准年);(4)不同地区受ERE影响程度的差异较大,因各区之间产业结构、贸易联系及经济发展程度存在差异,西南地区遭受本区及来自其他地区的ERE比华东地区高2.8~8.5倍。  相似文献   

Retrieval of Sea Surface Wind Speed by One-Dimensional Synthetic Aperture Microwave Radiometer     

艾未华  冯梦延  陆文  马烁  陈冠宇 《热带气象学报(英文版)》2021,27(1):62-69

One-dimensional synthetic aperture microwave radiometers have higher spatial resolution and record measurements at multiple incidence angles. In this paper, we propose a multiple linear regression method to retrieve sea surface wind speed at an incidence angle between 0° ~65°. We assume that a one-dimensional synthetic aperture microwave radiometer operates at frequencies of 6.9, 10.65, 18.7, 23.8 and 36.5 GHz. Then, the microwave radiative transfer forward model is used to simulate the measured brightness temperatures. The sensitivity of the brightness temperatures at 0°~65° to the sea surface wind speed is calculated. Then, vertical polarization channels(VR), horizontal polarization channels(HR) and all channels(AR) are used to retrieve the sea surface wind speed via a multiple linear regression algorithm at 0° ~65°, and the relationship between the retrieval error and incidence angle is obtained. The results are as follows:(1) The sensitivity of the vertical polarization brightness temperature to the sea surface wind speed is smaller than that of the horizontal polarization.(2) The retrieval error increases with Gaussian noise. The retrieval error of VR first increases and then decreases with increasing incidence angle, the retrieval error of HR gradually decreases with increasing incidence angle, and the retrieval error of AR first decreases and then increases with increasing incidence angle.(3) The retrieval error of AR is the lowest and it is necessary to retrieve the sea surface wind speed at a larger incidence angle for AR.  相似文献   

东营凹陷红层地球物理特征分析及有利储层预测     

张军华  刘震  李琴  任雄风  赵杰 《吉林大学学报(地球科学版)》2021,51(4):1256-1267

东营凹陷深部储层是干燥沉积环境下的一套红层,其中的孔一中储层厚度大、钻遇井少,具有较大勘探潜力。但目标区地层结构复杂,埋深从南到北逐渐变大,井震关系一致性不好,储层预测有很大难度。通过综合分析井震特征、优选地震属性、建立井震厚度关系,使用单一最佳属性法、多元线性回归法、基于学习型的非线性储层预测法,得出以下认识与结论：1）研究区红层具有薄互层典型特征,频率较上覆和下伏地层高,地震反射具有中振、低连、低信噪比特征;2）新研发的基于优势频率的流度因子具有最好的厚度相关性,最大振幅、均方根振幅、过零点数、能量半时也较好;3）无论是多元线性回归还是非线性支持向量机,优化的五属性储层预测效果要好于七属性;4）基于交叉验证的支持向量机方法十分适合深部储层小样本储层厚度预测,效果好于单一最佳属性法和多元线性回归法。  相似文献   

贵阳市空气质量预报方法与效果检验     

宋丹  夏晓玲  何玉龙  张蕾  杜正静 《气象与环境科学》2019,42(1):93-100

2012年环境保护部发布的《环境空气质量标准》实施后,贵阳市空气质量状况发生了变化。利用贵阳市空气质量指数和常规气象要素等资料,分析空气质量特征及其与气象要素的关系,通过多元线性逐步回归和BP神经网络方法,分季节建立空气质量指数预报模型,并同CUACE模式进行对比检验。结果表明:近3年贵阳市空气质量状况良好,优良天数增多,污染天数减少且污染天气多出现在冬季,首要污染物为PM_2.5、PM₁₀和O_3;各季相关因子不同,但主要与相对湿度和风速有关;两种模型预报效果均表现为夏季评价最高,等级TS评分超过85%,指数准确率近99%,冬季预报效果相对最差,TS评分接近或达到70%,指数准确率超过或接近80%,而春、秋季效果指标差距不大;对2015—2016年AQI的预报效果回归模型的优于CUACE模式的,TS评分和预报准确率分别相差16.2%和20.0%。  相似文献   

Application of Partial Least Squares Regression in Multimodal Integrated Forecasting of Water Vapor and Surface Air Temperature   总被引：1，自引：1，他引：0  

Jiangfeng Li  Xiaojun Cai  Wen Wang  Qianwen Li  Yansen Lei 《地球科学进展》2018,33(4):404-415

The use of a new multi model integration method of Partial Least Squares regression (PLS) can completely eliminate the multicollinearity features to improve multi model’s integrated forecasting results of the humidity and temperature. Based on the four centers’ ensemble forecast results, namely, the European Center for Medium-Range Weather Forecasts (ECMWF), Chinese Meteorological Administration (CMA), the Japan Meteorological Agency (JMA) and the UK Met Office (UKMO), we built a 2012 multi mode (25°~60°N, 60°~150°E) 24 ~168 hours forecast time (interval 24 hours) multi model for humidity and temperature and used the four methods, like ensemble average (BREM) for eliminating the deviation, a simple set of average (EMN), Super Ensemble (SUP) and Partial Least Squares regression (PLS) for ground temperature multi model integration. We used the Root-Mean-Square Error (RMSE) and anomaly correlation coefficient (cor) to determine the effect of more modes of integration and to predict a short course of cold. The two prediction results showed that the Partial Least Squares regression (PLS) was the best multi model integrated method, more superior than the other three single modes and compared with the other three methods, it showed better prediction performance, which has certain value and application prospect.  相似文献   

基于多元回归模型的斜坡影响因子分析          下载免费PDF全文

覃强  董建辉 《探矿工程》2018,45(8):102-106

目前,对斜坡影响因子进行量化的评价方法均有各自的局限性。在基于监测数据的基础上提出多元回归模型进行量化斜坡影响因子的方法。通过将确定的斜坡影响因子与回归模型的融合,在一定程度解决了斜坡稳定性评价过程中影响因子的选择和量化的问题,有利于以后对斜坡的认识,建立准确的斜坡稳定性分析模型。最后,将模型应用于某水电站水库堆积体斜坡,对该斜坡的影响因子进行量化,最后分析汶川地震前后的影响因子变化。  相似文献   

Identification of landslide susceptibility zones in Gish River basin,West Bengal,India     

Tirthankar Basu  Swades Pal 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(1):14-28

The occurrence of landslide in the hilly region of Darjeeling during monsoon season is a matter of serious concern. Every year this natural hazard damages the major roads at several places and thus disrupts the transport and communication system in this region. This paper tries to prepare a landslide susceptibility zone (LSZ) map for the Gish River basin. A total number of 16 spatial parameters have been taken for this study and these are categorised under six factor clusters or groups for example, triggering factors, protective factor, lithological factors, morphometric factors, hydrological factors and anthropogenic factors. The LSZ map is prepared by integrating all the parameters adopting the weighting base as logistic regression. The landslide susceptibility map shows that nearly 9.11% of the area falls under the very high landslide-susceptible zone while 40.28% of the area of the total basin lies under the very low landslide-susceptible zone. The landslide-susceptible model is validated through the receiver operating characteristic curve. This curve shows 86% success rate in defining landslide-susceptible zones and 83.40% prediction rate for the occurrence of landslides. The spatial relationship between the landslide susceptibility model and other factors’ groups shows that the morphometric factors’ cluster (mainly slope) is the focalone for the determination of landslide-susceptible zone.  相似文献   

中国雾霾分布及其组成相关性分析   总被引：1，自引：0，他引：1  

贾艳红  陆赛娣  冯小莉  冒赟  申玲丽 《测绘与空间地理信息》2015,(12):9-12

雾霾天气由于其对人体健康及交通能见度的极大影响而受到广泛关注。在收集相关污染物与气象数据基础上,基于GIS技术及最小二乘法和地理加权回归模型分析了我国2014年1月雾霾空间分布特征及其组成要素的相关性。研究表明,2014年1月我国各省会城市基本都受到雾霾影响,其中华北地区最为显著,华东、华南沿海城市具有一定的相似性;西南部地区大部雾霾污染明显小于其他地区。从雾霾物质组成上看,PM_(2.5)与PM_(10)、CO、NO_2和SO_2之间存在微妙关系,随着其他污染物的增加,PM_(2.5)数值也会随之增大,其中PM_(10)和CO对PM2.5的影响是显著的。从研究方法上看,利用地理加权回归建模方法对雾霾及其组成成份相关性研究的效果(84%)略好于最小二乘法的分析效果(82.59%)。本研究可为了解雾霾空间分布特征及分析其相关影响因素提供参考。  相似文献   

Geographically-weighted regression analysis of percentage of late-stage prostate cancer diagnosis in Florida     

《Applied geography (Sevenoaks, England)》2015

This study assessed spatial context and the local impacts of putative factors on the proportion of prostate cancer diagnosed at late-stages in Florida during the period 2001–2007. A logistic regression was performed aspatially and by geographically-weighted regression (GWR) at the nodes of a 5 km spacing grid overlaid over Florida and using all the cancer cases within a radius of 125 km of each node. Variables associated significantly with high percentages of late-stage prostate cancer included having comorbidities, smoking, being Black and living in census tracts with farmhouses. Having private or public insurance, being married or diagnosed in a for-profit facility, as well as living in census tracts with high household income reduced significantly this likelihood. Geographically-weighted regression allowed the identification of areas where the local odds ratio is significantly different from the ratio estimated using aspatial regression (State-level). For example, the local odds ratios for the comorbidity covariates were significantly smaller than the State-level odds ratio in Tallahassee and Pensacola, while they were significantly larger in Palm Beach. This emphasizes the need for local strategies and cancer control interventions to reduce the percentage of prostate cancer diagnosed at late-stages and ultimately eliminate health disparities.  相似文献