1951年以来中国无霜期的变化趋势   总被引：6，自引：0，他引：6  

宁晓菊  张丽君  杨群涛  秦耀辰 《地理学报》2015,70(11):1811-1822

准确界定无霜期及初、终霜日的时空变化是减少气候变化对农业生产的危害、有效提升农业适应性的重要内容。根据1951年以来国内824个气象站点日最低气温资料,分析初、终霜日和无霜期在全国的分布特征,采用累积距平和线性倾向估计模拟三者的变化趋势,并对无霜期进行突变检验。结果显示：① 中国无霜期随纬度增加或海拔升高而减少,无霜期的年际波动幅度随纬度增加或随海拔降低而减少。② 中国80%以上区域呈现初霜日推后、终霜日提前和无霜期延长的趋势,且三者的变化幅度均是北方大于南方、东部大于西部。③ 中国多数农区无霜期延长是初霜日推后和终霜日提前共同影响,而西南区和长江中下游区部分地区无霜期延长是初霜日的推后幅度大于终霜日的推后幅度或终霜日的提前幅度大于初霜日的提前幅度。④ 中国过半区域无霜期在1980s和1990s发生突变。突变集中分布在东北区中西部、内蒙及长城沿线区、黄淮海区、青藏区和甘新区;突变时间上,东部农区和西部农区无霜期分别在1980s和1990s突变。  相似文献   

The boreal spring stratospheric final warming and its interannual and interdecadal variability     

HU JingGao  REN RongCai  YU YueYue & XU HaiMing 《中国科学:地球科学(英文版)》2014,57(4):710-718

Based on the daily NCEP/DOE reanalysis II data,dates of the boreal spring Stratospheric Final Warming(SFW) events during 1979–2010 are defined as the time when the zonal-mean zonal wind at the central latitudes(65°–75°N) of the westerly polar jet drops below zero and never recovers until the subsequent autumn.It is found that the SFW events occur successively from the mid to the lower stratosphere and averagely from the mid to late April with a temporal lag of about 13 days from 10 to 50 hPa.Over the past 32 years,the earliest SFW occurs in mid March whereas the latest SFW happens in late May,showing a clear interannual variability of the time of SFW.Accompanying the SFW onset,the stratospheric circulation transits from a winter dynamical regime to a summertime state,and the maximum negative tendency of zonal wind and the strongest convergence of planetary-wave are observed.Composite results show that the early/late SFW events in boreal spring correspond to a quicker/slower transition of the stratospheric circulation,with the zonal-mean zonal wind reducing about 20/5 m s-1 at 30 hPa within 10 days around the onset date.Meanwhile,the planetary wave activities are relatively strong/weak associating with an out-of-/in-phase circumpolar circulation anomaly before and after the SFW events in the stratosphere.All these results indicate that,the earlier breakdown of the stratospheric polar vortex(SPV),as for the winter stratospheric sudden warming(SSW) events is driven mainly by wave forcing;and in contrast,the later breakdown of the SPV exhibits more characteristics of its seasonal evolution.Nevertheless,after the breakdown of SPV,the polar temperature anomalies always exhibit an out-of-phase relationship between the stratosphere and the troposphere for both the early and late SFW events,which implies an intimate stratosphere–troposphere dynamical coupling in spring.In addition,there exists a remarkable interdecadal change of the onset time of SFW in the mid 1990s.On average,the SFW onset time before the mid 1990s is 11 days earlier than that afterwards,corresponding to the increased/decreased planetary wave activities in late winter-early spring before/after the 1990s.  相似文献   

黑龙江省43a初霜冻时空特征分析及对主要作物安全成熟的影响   总被引：2，自引：0，他引：2  

高永刚  王育光  温秀卿  于成龙 《黑龙江气象》2005,(4):4-6

本文对黑龙江省近43a初霜冻趋势时空特征进行了分析，在空间上，全省平均每10a向北推移1-2d：在时间上，年变化推迟0．094d，43a来平均推迟约4d。根据黑龙江省各主要作物成熟期的时空分布情况，讨论了初霜冻对主要作物安全成熟的影响。  相似文献   

Basalt and tonalite from the Amami Plateau, northern West Philippine Basin: New Early Cretaceous ages and geochemical results, and their petrologic and tectonic implications   总被引：3，自引：0，他引：3  

Rosemary  Hickey-Vargas 《Island Arc》2005,14(4):653-665

Abstract Basalts and tonalites dredged from the Amami Plateau in the northern West Philippine Basin have the geochemical characteristics of intraoceanic island arc rocks: low ⁸⁷Sr/⁸⁶Sr (0.70297–0.70310), intermediate ¹⁴³Nd/¹⁴⁴Nd (0.51288–0.51292), moderate light rare earth element (LREE) enrichment (La/Yb = 4.1–6.6) and high La/Nb (1.4–4.3). The incremental heating of hornblende from tonalites yielded well‐defined plateaus and ⁴⁰Ar/³⁹Ar isochron ages of 115.8 ± 0.5 Ma and 117.0 ± 1.1 Ma, while plagioclase yielded disturbed Ar release patterns, with ages ranging from 70 to 112 Ma. Taken together, these results show that the Amami Plateau was formed by subduction‐related magmatism in the Early Cretaceous period, earlier than indicated by prior K/Ar results. The results support tectonic models in which the West Philippine Basin was opened within a complex of Jurassic–Paleocene island arc terranes, which are now scattered in the northern West Philippine Basin, the Philippine Islands and Halmahera. The Amami Plateau tonalites and basalts have higher Sr/Y and lower Y and ⁸⁷Sr/⁸⁶Sr compared with younger tonalitic rocks from the northern Kyushu–Palau Ridge and the Tanzawa complex, which were formed by the subduction of the Pacific Plate beneath the Philippine Sea Plate. Based on the geochemical characteristics of the basalts, the Early Cretaceous subduction zone that formed the Amami Plateau may have been the site of slab melting, which suggests that a younger and hotter plate was being subducted at that time. However, the Amami tonalites were probably formed from basaltic magma by fractional crystallization or by partial melting of basaltic arc crust, rather than by melting of the subducted slab.  相似文献   

江苏火电厂循环水冷却塔设计湿球温度稳定性研究     

潘晓春  陈兵  杨杰  程春龙 《气象科学》2018,38(5):666-673

基于现行工业循环水冷却塔设计标准中设计湿球温度计算存在的问题开展针对性研究,根据江苏省13座气象站1961—2013年炎热季逐日气象观测要素,利用傅里叶线谱和小波变换两种周期分析方法,揭示出设计湿球温度具有2 a、6 a、9 a及13 a的年周期性特征;进而通过分析各站不同起算年以及不同样本长度的资料对设计湿球温度计算的影响,探讨了设计湿球温度对资料年限长度的敏感性特征。在此基础上,综合考虑湿球温度的周期性变化与火电厂各代表容量发电机组运行费用,对江苏省境内火电厂不同代表容量机组设计湿球温度计算分别给出了最佳资料年限推荐值。  相似文献   

江南雨季地理区域及起止时间的客观确定   总被引：3，自引：0，他引：3  

詹丰兴  何金海  章毅之  朱志伟 《海洋学报》2015,37(6):1-11

本文基于国家气象信息中心整编的全国1 675个台站观测资料以及NCEP/NCAR的再分析资料,定义了候降水指数,利用旋转正交经验函数分解(REOF)法对全国候降水的季节进程进行了诊断分析,得到了表征气候态降水逐候进程的南、北方模态及各自的时间系数,发现REOF第二模态对应降水季节进程中的江南雨季。综合考虑我国南方(31°N以南、110°E以东区域)气候态降水的候进程、降水季节进程(4-6月降水指数减去6-8月降水指数)年际变率以及雨季(4-6月降水指数)降水年际变率的一致性,客观定义了江南雨季的地理范围。利用客观划定区域内的降水指数、925hPa经向风以及西北太平洋副热带高压500hPa脊线位置3个指标,制定了判定江南雨季起止时间的方法,进而对1961-2012年江南雨季起止时间进行了客观确定,给出了江南雨季起止时间序列。本文旨在为规范江南雨季的监测提供参考和借鉴,并为其预测提供科学基础。  相似文献   

华南前汛期开始日期异常与大气环流和海温变化的关系   总被引：5，自引：1，他引：4  

伍红雨  杨崧  蒋兴文 《气象学报》2015,73(2):319-330

利用1961—2012年美国国家环境预报中心/大气研究中心(NCEP/NCAR)的再分析资料、NOAA海温资料,CMAP降水资料和华南261个测站降水观测资料,首先分析华南前汛期开始日期(以下简称华南开汛)异常的气候特征,然后采用相关分析、合成分析的方法研究华南开汛异常与3—4月大气环流以及海温变化的关系。结果表明,近52 a来华南开汛具有显著的年际变化特征,但变化趋势不明显。开汛最早出现在1983年3月1日,最晚出现在1963年6月1日,1961—2012年华南平均开汛日期是4月6日。华南开汛主要出现在3—4月,占92.3%。华南开汛与3—4月华南降水相关最显著,开汛偏早(晚),对应华南3—4月降水偏多(少)。华南开汛偏早年,在3—4月,对流层高层副热带西风急流偏强,中层西太平洋副热带高压偏强偏西、低层南支槽偏强,华南上空西南气流偏强;华南开汛偏晚年则相反。华南开汛与3—4月中国南海及周边地区海温显著相关,海温偏低(高)对应华南开汛偏晚(早)。华南开汛偏晚年的海温和大气环流异常比早年显著。  相似文献   

湖北异常初雪日的成因分析及预测     

张灵  周月华 《气象》2015,41(3):346-352

统计湖北省76站1961/1962—2012/2013共52年大范围初雪偏早/偏晚年份,揭示初雪日异常早/晚年同期环流特征,初雪偏晚当年11月至次年2月海温、高度场及低层风场的典型分布表现为:中高纬的西北太平洋海温及新西兰东侧南太平洋海温异常偏高,有利于乌拉尔山脊减弱、贝加尔湖低压及阿留申地区低压减弱,东亚大槽偏强同时孟加拉湾槽偏弱,对应500 hPa高度距平场上欧亚大陆自北至南呈"—+—"的波列分布,中国大陆地区低层风场被北风距平控制;反之,初雪偏早。2013/2014年关键区海温及环流分布符合典型的初雪偏晚对应特征。利用1961—1992年11月关键区海温首次建立湖北初雪日预测模型,准确预测2013年冬季初雪偏晚,同时针对1993—2012年初雪早晚的回报检验准确率达75%,为预测湖北初雪发生的早晚提供了新方法。  相似文献   

多源地学信息图像复合处理技术在区域成矿统计预测中的应用研究—以冀北张家口金矿集中区为例     

韩先菊 《地质与勘探》2014,50(Z1):1424-1429

本文以冀北金矿集中区为例,利用系列遥感影像图,开展构造、岩性解译和蚀变信息提取;根据航磁△T、甚低频垂直虚分量和航放K/Th彩色密度分割图像,提取与金矿化有关的地球物理成矿预测变量。综合遥感及地质、矿产、物探、化探等图像资料,在区域金矿成矿理论指导下,以数字图像处理技术为手段,进行图像之间的复合处理,开展区域金矿成矿规律分析,提取区域金矿找矿预测评价标志（变量）。采用信息量法、特征分析法和见矿概率回归估计法等方法开展金矿成矿统计预测,圈定13处找矿远景区。  相似文献   

The spatio-temporal variations of frost-free period in China from 1951 to 2012     

Xiaoju Ning  Gangjun Liu  Lijun Zhang  Xiaoyang Qin  Shenghui Zhou  Yaochen Qin 《地理学报(英文版)》2017,27(1):23-42

The frost-free period(FFP)first frost date(FFD) and last frost date(LFD) have been regard as the important climate variables for agricultural production. Understanding the spatio-temporal variations of the FFPFFD and LFD is beneficial to reduce the harmful impacts of climate change on agricultural production and enhance the agricultural adaptation. This study examined daily minimum temperatures for 823 national-level meteorological stationscalculated the values of FFDLFD and FFP for station-specific and region-specific from 1951 to 2012estimated the gradients of linear regression for station-specific moving averages of FFDLFD and FFPand assessed station-specific time series of FFP and detected the abrupt change. The results as follows: at both the station level and the regional levelthe FFP across China decreases with the increase of latitude from south to northand with the increase of altitude from east to west generally. At the station levelthe inter-annual fluctuations of FFDLFD and FFP in south and west agricultural regions are greater than those in north and east. At the regional levelexcluding the QT regiontemporal changes of FFP are relatively small in both the low-latitude and the high-latitude regionsbut for the mid-latitude regions. According to the linear trend gradients of the moving average values of station-specific FFDLFD and FFPFFD was delayedLFD advancedand FFP extended gradually over the 80% of China. Furthermorethe change magnitudes for FFDLFD and FFP in the north and east agricultural regions are higher than that in the southern and western. Among the 659 station-specific time series of FFP examined by the Mann-Kendall test341 stationslocated mainly in the north regionhave one identifiable and significant abrupt change. And at the 341 stations with identified abrupt changesmost(57%) abrupt changes occurred during 1991–2012followed by the periods of 1981–1990(28%)1971–1980(12%)and 1951–1970(3%). The spatio-temporal variations of FFDLFD and FFP would provide important guidance to agricultural practices.  相似文献