基于决策树分类的大屯矿区地物信息提取及矿区污染分析     

于海若  燕琴  董春  战丽丽 《测绘与空间地理信息》2016,(4):67-69,72

本文在对国内外遥感图像分类方法充分研究分析的基础上,选择决策树分类法对大屯矿区的Landsat 8遥感图像进行分类研究。选取样本提取并分析研究区典型地类光谱特征曲线,依据光谱曲线特征和归一化植被指数建立了土地利用分类决策树模型,通过反复试验和修正,筛选出适宜大屯矿区地物分类的决策树最优阈值,对研究区进行分类和精度评价,最后通过分类结果对研究区的水体污染状况进行简要分析。  相似文献   

Geocrowdsourcing and accessibility for dynamic environments     

Han Qin  Rebecca M. Rice  Sven Fuhrmann  Matthew T. Rice  Kevin M. Curtin  Eric Ong 《GeoJournal》2016,81(5):699-716

  相似文献   

Possible sources of forecast errors generated by the global/regional assimilation and prediction system for landfalling tropical cyclones. Part I: Initial uncertainties     

Feifan Zhou  Munehiko Yamaguchi  Xiaohao Qin 《大气科学进展》2016,33(7):841-851

This paper investigates the possible sources of errors associated with tropical cyclone (TC) tracks forecasted using the Global/Regional Assimilation and Prediction System (GRAPES). The GRAPES forecasts were made for 16 landfalling TCs in the western North Pacific basin during the 2008 and 2009 seasons, with a forecast length of 72 hours, and using the default initial conditions (“initials”, hereafter), which are from the NCEP-FNL dataset, as well as ECMWF initials. The forecasts are compared with ECMWF forecasts. The results show that in most TCs, the GRAPES forecasts are improved when using the ECMWF initials compared with the default initials. Compared with the ECMWF initials, the default initials produce lower intensity TCs and a lower intensity subtropical high, but a higher intensity South Asia high and monsoon trough, as well as a higher temperature but lower specific humidity at the TC center. Replacement of the geopotential height and wind fields with the ECMWF initials in and around the TC center at the initial time was found to be the most efficient way to improve the forecasts. In addition, TCs that showed the greatest improvement in forecast accuracy usually had the largest initial uncertainties in TC intensity and were usually in the intensifying phase. The results demonstrate the importance of the initial intensity for TC track forecasts made using GRAPES, and indicate the model is better in describing the intensifying phase than the decaying phase of TCs. Finally, the limit of the improvement indicates that the model error associated with GRAPES forecasts may be the main cause of poor forecasts of landfalling TCs. Thus, further examinations of the model errors are required.  相似文献   

TRMM-observed summer warm rain over the tropical and subtropical Pacific Ocean: Characteristics and regional differences   总被引：1，自引：0，他引：1  

秦放  傅云飞 《Acta Meteorologica Sinica》2016,30(3):371-385

Based on the merged measurements from the TRMM Precipitation Radar and Visible and Infrared Scanner, refined characteristics (intensity, frequency, vertical structure, and diurnal variation) and regional differences of the warm rain over the tropical and subtropical Pacific Ocean (40ffiS-40ffiN, 120ffiE-70ffiW) in boreal summer are investigated for the period 1998-2012. The results reveal that three warm rain types (phased, pure, and mixed) exist over these regions. The phased warm rain, which occurs during the developing or declining stage of precipitation weather systems, is located over the central to western Intertropical Convergence Zone, South Pacific Convergence Zone, and Northwest Pacific. Its occurrence frequency peaks at midnight and minimizes during daytime with a 5.5-km maximum echo top. The frequency of this warm rain type is about 2.2%, and it contributes to 40% of the regional total rainfall. The pure warm rain is characterized by typical stable precipitation with an echo top lower than 4 km, and mostly occurs in Southeast Pacific. Although its frequency is less than 1.3%, this type of warm rain accounts for 95% of the regional total rainfall. Its occurrence peaks before dawn and it usually disappears in the afternoon. For the mixed warm rain, some may develop into deep convective precipitation, while most are similar to those of the pure type. The mixed warm rain is mainly located over the ocean east of Hawaii. Its frequency is 1.2%, but this type of warm rain could contribute to 80% of the regional total rainfall. The results also uncover that the mixed and pure types occur over the regions where SST ranges from 295 to 299 K, accompanied by relatively strong downdrafts at 500 hPa. Both the mixed and pure warm rains happen in a more unstable atmosphere, compared with the phased warm rain.  相似文献   

5—6月东北冷涡持续活动及强度特征          下载免费PDF全文

刘刚  王宁  秦玉琳  曹玲  褚曲成  姚瑶 《应用气象学报》2016,27(1):47-55

利用1960—2012年5—6月NCEP/NCAR逐日再分析资料,基于冷涡经典定义,采取客观识别方法检索东北冷涡活动过程,根据东北冷涡活动时空变化特征给出东北冷涡持续活动过程标准, 通过冷涡强度指数进行定量化分析,该指数对冷涡持续活动过程具有较好表征意义。冷涡活动强对应5月乌拉尔山阻塞高压、贝加尔湖阻塞高压和6月鄂霍次克海阻塞高压活动频繁。通过强弱指数年合成,得到6月强指数年冷涡系统较深厚,集中于对流层中高层,冷心结构明显,具有一定大气斜压特征; 高层存在冷中心,低层有冷空气活动,中高层西风带呈明显的上游分流和下游汇合特征,分汇流之间呈东北高、西南低的偶极子阻塞形势;弱指数年冷涡系统较浅薄,主要集中在对流层中低层,冷心结构不明显,不存在阻塞形势。  相似文献   

新疆哈密地区近54a日照时数的均一性分析及其影响因素     

杨艳玲  秦榕  卢新玉  杨红艳  何亚平 《沙漠与绿洲气象(新疆气象)》2016,10(3):72-76

以新疆哈密地区1961-2014年6个气象观测站地面气象观测资料为依据,利用线性趋势分析、相关性分析、M-K突变检验分析等方法,对哈密地区近54a四季及年平均日照时数的变化趋势、异常年份、突变检验及影响因子进行分析,得出以下结论：近54a哈密地区春季与年平均日照时数均呈上升趋势,而夏、秋、冬季变化比较平稳;年日照时数异常偏少出现在1998年,但从未出现过异常偏多年;年日照时数在1973年和2008年发生两次突变,减少、增加趋势不显著;年、春季日照时数增加与低云量的减少关系密切。  相似文献   

利用双线偏振雷达分析人工防雹作业效果     

陈羿辰  张龙斌  金永利  马建立  嵇磊  秦睿 《气象科技》2016,44(3):479-488

以北京市平谷区2011年6月11日防雹作业为例,利用双线偏振雷达资料,选取与作业区条件十分接近的云块为对比区,根据回波移动方向和速度,跟踪分析在不同高度上防雹作业前后云体宏观结构特征和粒子相态等微物理变化过程。作业后云体所呈现特征为:1作业区的云顶高度、强回波中心高度迅速下降,对比区变化不明显;2作业区水平反射率Zh减小,差分反射率Zdr、零相关系数ρhv增大,单位差分传播相移Kdp小范围内波动,对比区Zh、Zdr、Kdp变化不明显;ρhv增大;3作业区对流减弱,高层较大冰雹粒子、大雨滴下沉明显,最终以霰粒子为主;而对比区域则对流仍然旺盛,冰雹粒子有增多趋势。以上特征表明防雹作业可有效抑制冰雹胚胎成长为冰雹的过程,通过偏振雷达观测参量可对防雹作业效果进行较好的验证。  相似文献   

省级气象广域网网络优化的设计与应用     

许玮  王迎迎  秦运龙  杨维发  李鑫 《气象科技》2016,44(3):358-362

目前湖北省气象地面宽带网省—地—县3级结构中,省局与各市(州)局间采用单条专线连接,手动VPN(Virtual Private Network)拨号线路备份的传输方式,这种传输方式不足以保证数据传输的可靠性。现设计新增一条专线,实现省到地的双线路备份。同时,增加一台省端网络互联交换机,升级地市端的网络互联路由器硬件,将数据划分为业务数据和视频会商两类,定义不同的传输方式。业务数据采用OSPF(Open Shortest Path First)动态路由方式进行传输,视频会商通过配置静态路由BFD(Bidirectional Forwarding Detection)联动的路由方式进行传输,并通过QoS(Quality of Service)保证其4 Mb/s的带宽,从而实现省到地数据业务更合理可靠地传输。  相似文献   

一次东北冷涡暴雨过程成因分析     

斯琴  荀学义  王佳津 《气象科技》2016,44(6):1016-1023

利用常规气象观测资料、NCEP 1°×1°逐6h的再分析资料和FY-2E红外云图、TBB等资料,对2014年7月7—8日由东北冷涡引发内蒙古东北部的暴雨过程形成原因进行了天气学诊断分析,结果表明:1低空急流是主要水汽来源,不同地区出现暴雨的机制不同,兴安盟东部、呼伦贝尔市东南部由于槽前、切变南缘地面暖锋附近,中低空急流汇合处,强辐合抬升触发不稳定能量释放导致强天气的发生,而呼伦贝尔市西南部暴雨跟中上层冷涡的生成发展与对应的地面低压逐步耦合的动力作用相关;2湿位涡的分布对暴雨的发生、落区有较强的指示性作用,700hPa正负值区过度带的配置是暴雨发生发展的有利潜势,暴雨发生在700hPa等值线密集带和850hPa MPV2大于等于0的叠加区域内,700hPa正负过渡带附近,偏向于正值一侧;3最大降水量的雨强落后于云团TBB最低值1~2h,并不是强TBB与最强降水同步出现。  相似文献   

硫酸参与的长江流域岩石化学风化速率与大气CO2消耗   总被引：4，自引：0，他引：4  

张连凯  覃小群  刘朋雨  黄奇波 《地质学报》2016,90(8):1933-1943

流域的岩石化学风化过程是全球碳循环中的重要环节。以往的流域水化学碳汇通量估算大多是基于碳酸的风化作用。而实际上,硫酸和碳酸一样,也参与了流域碳元素的地球化学循环,从而对全球碳循环过程产生影响。长江流域水体近几年出现酸化现象,大部分河段SO42-和Ca2+含量增高,其对应的岩石风化过程和大气CO2消耗速率也发生变化。文章对长江干流及主要支流2013年不同季节的离子组成进行监测,利用水化学平衡法和Galy估算模型,对长江流域岩石化学风化速率和CO2消耗通量进行了估算,对硫酸参与下的长江流域岩石风化和碳循环过程进行了分析。结果表明,长江流域水体离子主要来源于硅酸盐岩风化和碳酸盐岩风化。其中碳酸盐岩风化对河水离子贡献率为92%。在硅酸盐岩广泛分布的赣江流域,碳酸盐岩风化离子贡献也达85%。分析表明,硫酸参与了长江流域的岩石风化过程,对水体中离子产生一定影响。硫酸的参与加快了碳酸盐岩的化学风化速率,平均提高约30%,但是使流域大气CO2消耗速率降低。在不考虑蒸发岩溶蚀作用下,平均从516×103 mol/km2·a降至356×103 mol/km2·a,降低约31%。在各支流中,硫酸对乌江流域碳酸盐岩的风化和碳循环的影响最大,而对雅砻江的影响最小,这与乌江流域的含煤地层、矿床硫化物及大气酸沉降有关。  相似文献