青藏高原小嵩草高寒草甸返青期遥感识别方法筛选

小嵩草高寒草甸是青藏高原的主要植被类型,研究其返青期识别方法对于模拟及预测青藏高原植被物候变化具有重要意义。常用的植被返青期遥感识别方法主要是先对遥感植被指数原始时序数据进行拟合去噪声再求取返青期,各种方法对研究区域、研究经验、参数设置、函数初值设置等有很强的依赖性。为避免返青期识别方法在曲线拟合时对参数初值的依赖性和陷入局部最优解,本文引入了模拟退火算法对双高斯和双逻辑斯蒂函数进行参数优化,并分别对基于以上两种函数及多项式拟合的植被指数时序曲线进行对比,从而选出最佳拟合方法,最后采用最大斜率阈值法、动态阈值法和曲率法识别返青期。利用青藏高原小嵩草高寒草甸34个样本点的返青期地面观测数据及相应的8 km分辨率的NOAA归一化差值植被指数(NDVI)时序数据对以上各种组合的返青期遥感识别方案进行了测试,并选取了153个遥感实验点求取了近30年(1982年—2011年)青藏高原小嵩草高寒草甸的返青期,结果表明:采用双高斯函数拟合的NDVI曲线与原始NDVI时序数据最为接近,在此基础上采用最大斜率阈值法识别的小嵩草高寒草甸返青期及其变化趋势与地面物候观测结果最为一致;同时发现近30年青藏高原小嵩草高寒草甸的平均返青期主要集中在每年的第120—140天,并且呈逐年提前趋势,30年来提前了7天。     

公开版地图数据库的快速更新方法研究

以福建省公开版地图数据库快速更新为例,研究公开版地图数据库快速更新的方法。针对数据精度没有基础地理信息数据库的数据精度高的特点,通过地图服务反馈、各类影像数据、车载导航数据采集等方法和渠道获取变化信息,建立"动态实时更新"的技术流程,同时通过DATE属性提取增量变化信息实现多级比例尺的联动更新。该方法已应用于福建省公开版地图数据库的快速更新,极大地提高了福建省公开版地图数据的现势性与准确性,应急保障出图能力也大大提升,可为其他省提供参考。     

近55年来河西地区季节开始日及长短变化特征

利用河西地区15个气象站点1955～2009年日平均气温资料,采用5d滑动平均、气候倾向率、Mann-Kendall和滑动t检验,ArcGIS中的反距离加权插值等方法分析河西地区四季开始日及其长短变化特征,以揭示气候季节变化对全球气候变暖的响应.结果表明:近55年来,河西地区四季开始日主要表现为春、夏和秋季提早,冬季推...     

Variations in the starting date of the pre-summer rainy season in South China, 1736-2010

The starting dates of the pre-summer rainy season during historical times (1736-1911) in Fuzhou and Guangzhou of South China, were determined and reconstructed on the basis of historical documents in the Yu-Xue-Fen-Cun archive, together with observed features of precipitation during the pre-summer rainy season. In addition, starting dates of the pre-summer rainy season from 1953 in Fuzhou and from 1952 in Guangzhou were reconstructed for the instrumental period. These data allowed for analyses of inter-annual and inter-decadal changes in the starting dates of the pre-summer rainy season in South China over the past 300 years. Results show that the mean starting date of the pre-summer rainy season in South China was the first pentad of May; in addition, periodicities in the starting dates of 2-3 years, 10 years, and 40 years were detected during the period 1736-1911, and of 2-3 years, 10 years, and 22 years during the instrumental period. From 1736 to 1911, the earliest starting dates at Fuzhou and Guangzhou both occurred at the fourth pentad of April, while the latest starting dates were at the sixth pentad of May in Fuzhou and the first pentad of June in Guangzhou. During the instrumental period, the earliest and latest starting dates were at the fourth pentad of April and the first pentad of June, respectively, in both Fuzhou during 1953-2010 and Guangzhou during 1952-2010. The maximum difference between neighboring decades during 1736-1911 was 2.2 and 1.6 pentads in Fuzhou and Guangzhou, respectively, and during the instrumental period it was 2.5 and 2.4 pentads in Fuzhou and Guangzhou, respectively.     

内蒙古地区历史地面基础气象资料专项质量检查综述

文章利用气候要素允许范围检查、内部一致性等气象资料质量控制方法对内蒙古地区历史气象数据进行了质量控制。经质量控制后,极大提高数据的准确性。     

科技论文中“候”的规范表达

"候"作为时间单位,在科技论文中时常出现,但关于"候"的表达存在不规范现象,本文以GB3101—1993和GB/T 7408—1994为依据,给出了有关"候"的规范表达。作为时间的单位,"候"应与天(d)等一样使用,图表中标目为"时间/候"或"t/候";作为日期,"候"可参照年份、月份等使用,图表中标目为"候序数";文中第1次出现日期"候"时,应交待"候"的日期范围。     

红河州区域气象观测站监测预警系统设计与开发

利用云南省红河州所建设的各市县区域气象观测站探测到的降雨、温度、风速、风向等气象要素,结合各气象要素相应的预警标准,根据红河州气象防灾、减灾工作的需要,应用计算机技术与Windows资源研制、开发成智能化气象监测预警软件系统。系统基于WEB方式运行,适宜社会各界使用,且监测预警及时、准确。     

山东省春季植被指数变化的遥感监测分析

主要利用 1 991～ 2 0 0 1年极轨气象卫星遥感资料 ,计算了全省历年 3～ 5月的植被指数 ,分析了我省不同年份春季植被指数的变化以及地域间的变化 ,并结合气象资料 ,分析了这些变化的主要原因     

用颗粒锆石分层蒸发确定云开群罗罅组的时代

用颗粒锆石分层蒸发法对开云群罗罅组变英安斑岩及变流纹斑岩中不同成因锆石分别进行年龄测定，获得该火山岩之形成年龄922-940Ma；后期地质事件年龄427-473Ma、643-716Ma及物源区的年龄1616-2084Ma。     

The phenology of Namaqualand ephemeral species: the effect of sowing date

In all five species examined, seeds sown in autumn (April) produced the tallest plants. Later sowing resulted in early rapid stem elongation and the initiation of flowers/inflorescences in developmentally younger plants (fewer leaves on the main stem) and anthesis at a younger age. Plants from the early sowing produced more open inflorescences at peak flowering than those of later sowing dates. It is therefore concluded that early autumn rain results in the establishment of taller plants which take a longer time to reach anthesis and peak flowering, but at their peak these plants will produce more inflorescences and consequently a more spectacular show than plants that establish later in the season.