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随着气象事业的发展和制作精细化预报的需求,气象业务系统对时间的要求及时间概念的重要性愈来愈被认识。统一气象业务系统的时间,对提高观测数据质量起到十分重要的作用。GPS-Net授时系统是采用GPS时间源及系统接收软件技术,对计算机进行授时服务。通过Network网络授时发布软件和Network用户终端接收软件技术,将标准的时间经过网络传递给若干用户,同时还要充分考虑GPS系统安全和网络安全。结果表明:GPS-Net授时系统能准确地获取GPS时间源信息,并通过网络技术发布到用户终端上,使气象业务系统获得标准的时间误差小于1秒。由于采用网络发布式和气象内网限制方式,有效地减少了服务器和用户终端的负担,防止了外网病毒与黑客的侵入。GPS-Net授时系统为气象装备和气象业务系统,提供了快捷、准确、自动的授时解决方案。 相似文献
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利用2017—2018年GRAPES-GFS模式预报资料和广西区域自动站逐时气温观测资料,分析模式预报偏差特征,发现GRAPES-GFS模式对广西区域2m温度的预报系统性偏低,随着预报时效增加,预报偏差增大,系统性偏差主要出现在桂北山区、左右江河谷及沿海;春夏秋三季的午后气温预报偏差有明显的系统性,冬季午后气温和四季凌晨气温预报偏差的随机性较大。为了确定滑动订正的最优时窗,通过活动时窗长度的方法,设计不同的滑动订正方案,制定最优时窗滑动订正方案,并进一步利用2020年最优时窗滑动订正业务试验产品,对比验证了该方案的订正效果。结果表明:分别采用固定时窗、季节最优时窗、月份最优时窗等滑动平均订正方案进行订正,春夏秋3季的订正效果明显好于冬季、午后订正技巧高于夜间,其中固定时窗滑动平均方案中的长时窗(15～60d)订正、季节最优时窗滑动订正以及月份最优时窗滑动订正这几种方式订正效果最优;所制定的最优时窗滑动平均订正方案,可以在不同滑动方案的基础上稳定地提高预报准确率,达到最优时窗滑动的目的。 相似文献
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G. A. Meehl R. Lukas G. N. Kiladis K. M. Weickmann A. J. Matthews M. Wheeler 《Climate Dynamics》2001,17(10):753-775
Interactions involving various time and space scales, both within the tropics and between the tropics and midlatitudes, are
ubiquitous in the climate system. We propose a conceptual framework for understanding such interactions whereby longer time
scales and larger space scales set the base state for processes on shorter time scales and smaller space scales, which in
turn have an influence back on the longer time scales and larger space scales in a continuum of process-related interactions.
Though not intended to be comprehensive, we do cite examples from the literature to provide evidence for the validity of this
framework. Decadal time scale base states of the coupled climate system set the context for the manifestation of interannual
time scales (El Nino/Southern Oscillation, ENSO and tropospheric biennial oscillation, TBO) which are influenced by and interact
with the annual cycle and seasonal time scales. Those base states in turn influence the large-scale coupled processes involved
with intraseasonal and submonthly time scales, tied to interactions within the tropics and extratropics, and tropical–midlatitude
teleconnections. All of these set the base state for processes on the synoptic and mesoscale and regional/local space scales.
Events at those relatively short time scales and small space scales may then affect the longer time scale and larger space
scale processes in turn, reaching back out to submonthly, intraseasonal, seasonal, annual, TBO, ENSO and decadal. Global coupled
models can capture some elements of the decadal, ENSO, TBO, annual and seasonal time scales with the associated global space
scales. However, coupled models are less successful at simulating phenomena at subseasonal and shorter time scales with hemispheric
and smaller space scales. In the context of the proposed conceptual framework, the synergistic interactions of the time and
space scales suggest that a high priority must be placed on improved simulations of all of the time and space scales in the
climate system. This is particularly important for the subseasonal time scales and hemispheric and smaller space scales, which
are not well simulated at present, to improve the prospects of successfully forecasting phenomena beyond the synoptic scales.
Received: 3 April 2000/ Accepted: 6 November 2000 相似文献
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Influence of Precipitation on the Determination of Proper Time for Soil Resistivity Measurement 
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下载免费PDF全文 In order to obtain reliable and effective upland soil resistivity measurements,it is necessary to know how much time after the rain stops is required before making soil resistivity observations so that the influence of precipitation on the measurements can be eliminated.Based on the soil resistivity monitoring data at different depths obtained from the soil conductance automatic monitoring system using the triple-electrode method,and the precipitation data from the synchronous and automatic observing system in Hechuan County of Chongqing,this paper analyzed the effect of rain on the determination of upland soil resistivity measurement time.The results showed that the required interval time between the measurement and the termination of rain should be as follows: if the rainfall was less than 0.1 mm,the interval time was zero;the interval time was 24 h if the precipitation time was less than 1 h or the rainfall was 0.1-2.0 mm; the interval time was 72 h if the precipitation time was 2-10 h or the rainfall was within 2.1-5.0 mm; and the interval time of 72 232 h was observed when the precipitation time was 10-25 h or longer or the rainfall was 5.0 10.1 mm or larger.Relevant observations showed that the above conclusions were on the whole valid for different soil depths.On the other hand,the results indicated that the maximum variance ratio for the influence of precipitation on resistivity measurement was about 28.9%,and the average variance was about 3.9%.Moreover,a preliminary analysis also showed that the precipitation process time might play a more crucial role in the resistivity recovery time than the precipitation amount.It is also found that it is practically better to use the rank correlation method than the numerical correlation analysis method to determine the time break between the stop of rain and the time to carry out the soil resistivity measurement. 相似文献
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Water stored as part of the land surface is lost to evapotranspiration and runoff on different time scales,and the partitioning between these time scales is important for modeling soil water in a climate model.Different time scales are imposed on evapotranspiration primarily because it is derived from different reservoirs with different storage capacities, from the very rapid evaporation of canopy stores to the slow removal by transpiration of rooting zone soil moisture. Runoff likewise ranges in time scale from rapid surface terms to the slower base-flow. The longest time scale losses of water determine the slow variation of soil moisture and hence the longer time scale effects of soil moisture on precipitation. This paper shows with a simple analysis how shifting the partitioning of evapotranspiration between the different reservoirs affects the variability of soil moisture and precipitation. In particular, it is concluded that a shift to shorter time scale reservoirs shifts the variance of precipitation from that which is potentially predictable to unpredictable. 相似文献
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塔克拉玛干沙漠腹地近地层春季铅直湍流的小波分析 总被引：1，自引：1，他引：0
利用塔克拉玛干沙漠腹地近地层10m高度处快速响应探测系统的湍流资料,对春季晴天和沙尘暴天气下不同稳定层结的铅直湍流脉动进行小波变化及其方差分析,以期了解铅直湍流的尺度结构特征。结果表明,不稳定层结条件下,春季晴天近地层的铅直湍流脉动以12—17S的周期为主,最小周期为1-1．5s;春季沙尘暴时最主要的周期则为6-10s,最小周期为0．4—0．6s。沙尘暴时不稳定层结的湍流尺度总体上小于晴天,较小尺度波动振荡更加明显,湍流运动比晴天更加频繁。稳定层结条件下,春季晴天以10—16S的周期振荡为主,最小周期为1．3-1．8s;春季沙尘暴则以11—20s的周期振荡为主,最小周期为0．5—0．8s。晴天稳定层结时的铅直脉动比沙尘暴时周期小,小周期的湍流运动更明显一些,但周期更小的波动在沙尘暴天气时则多一些。 相似文献
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河湟谷地暴雨频率的研究 总被引：2，自引：0，他引：2
利用青海（黄）河湟（水）谷地12个气象台站1980～2002年自记降水资料,分析了该流域不同历时暴雨的时空特征及其不稳定性,统计了不同历时、不同频率的设计暴雨。研究表明：河湟谷地不同历时的最大暴雨均呈现出增多趋势,且随着降水历时的延长和降水量的增大,其倾向率在不断增大,年际变化的阶段性波动逐步趋缓,各时段最大暴雨的平均值的空间分布特征逐步与年降水量的空间分布趋于接近,地形对暴雨的空间分布影响明显;30分钟的最大暴雨最为不稳定,同时随着降水时段的延长,最大暴雨的稳定性逐步增大;各时段最大暴雨的分布为正偏态;各时段不同频率的最大暴雨的空间分布总体上与实测值有很好的一致性,但较之于实测值则具有较大的不稳定性。 相似文献
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1979~2013年西北太平洋地区海平面气压场季节转换时间的变化分析 总被引：1，自引：0，他引：1
采用1979~2013年NCEP/NCAR再分析资料,借助线性趋势、距平、累积距平、Mann-Kendall突变检验及Morlet小波等方法分析了西北太平洋地区海平面气压场季节转换时间的长期趋势和多尺度周期变化特征。结果表明:海平面气压场一年中存在两次季节转变,20°N~50°N海平面气压场冬夏季节转变的时间在第20候左右,而夏冬季节转变发生在第51候。并且海平面气压场的季节转换时间存在纬度差异与经度差异。通过趋势分析,发现海平面气压场由冬季型转变到夏季型的时间存在显著的趋势变化,并且在近35年内是趋于提前,其气候倾向率为-0.33候/10 a;夏季型转换为冬季型的时间趋于延后,气候倾向率为0.25候/10 a。季节转换时间的Mann-Kendall突变检测结果表明,海平面气压场由冬向夏的转换时间在1997~1998年间发生了突变;夏季型转换为冬季型的时间尚未发现显著突变。最后通过对季节转换时间的小波分析与小波功率谱的显著性检验得出,冬夏季节转换的时间具有显著的15 a周期变化;夏冬季节转换时间8 a周期振荡最为剧烈。 相似文献
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Record-breaking extreme temperatures have been measured in the last two decades all over Turkey, with recent studies detecting positive trends in extreme temperature time series. In this study, nonstationary extreme value analysis was performed on extreme temperature time series obtained from fifty stations scattered over the seven geographical regions of Turkey. Basic characterization of the data set was defined through outlier detection, homogeneity, trend detection, and stationarity tests. Trend-including non-stationary extreme temperature time series were analyzed with non-stationary Generalized Extreme Value distribution. Three main physical drivers were considered as the leading causes that trigger the observed trends in extreme temperatures over Turkey: time, teleconnection patterns of the Arctic Oscillations, and those of the North Atlantic Oscillations. The results showed that most of the absolute annual minimum and maximum temperature time series are inhomogeneous while the possible breakpoints date back to the1970s and 1990s, respectively. More than half of the absolute annual maximum time series (26/50 and many of the absolute annual minimum time series (21/50) showed a positive trend. No negative trend was detected in the extreme temperature time series. Based on the frequency analysis of the 21 annual maximum time series, the non-stationary estimations of 50-year return levels were detected to be higher than in the stationary model (between 0.44 °C and 3.73 °C). The return levels in 15 of the 20 minimum temperature time series increased from 0.11 °C up to 12.28 °C. Elevation increases the nonstationarity impact on absolute minimum temperatures and decreases it on absolute maximums. The findings in this study indicate that the consideration of non-stationarity in extreme temperature time series is a necessity during return level estimations over the study area. 相似文献
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异地气象卫星地面站的时间同步方案及误差分析 总被引：4，自引：0，他引：4
时间统一是跨区域多个气象卫星地面站顺利完成卫星数据接收任务及全系统业务正常运行和控制的重要要素。时间的标准有世界时、原子时及世界协调时等，提供时间标准的源有专用时统设备、全球定位系统（GPS）授时设备、天文台短波广播接收设备等。系统内的时间差异将使系统不能协调工作，导致接收任务的部分失败或完全失败。首先介绍了时间标准，和时间在业务系统中传输的常用方法，然后介绍一种利用GPS授时设备提供时码源，实现全系统时间统一的解决方案，最后讨论了采用该方法给系统授时的时间误差分析方法。该方案在气象卫星地面应用系统中成功应用，并可靠工作。此方案在多雷达组成的探测网，自动气象站网及其他气象业务网络中也将有广泛的应用前景。 相似文献
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广州中尺度模式局地要素预报性能分析 总被引：7，自引：2，他引：7
该文简要介绍了华南中尺度模式的地表要素的预报诊断方案, 站点要素时间序列预报情况.用适合站点要素时间序列预报的检验方法, 检验并分析了各要素时间序列预报的性能.表明该中尺度模式的地表要素时间序列预报方案是有效的, 预报具有较高的准确性和应用价值. 相似文献
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采用哈密1951—2004年逐日平均气温资料,对近54年来哈密四季开始时间和季节跨度的年际、年代际变化、气候趋势和周期特征进行了分析。结果表明:哈密冬、夏季比春、秋季长,春、秋季有延长趋势,冬季逐渐缩短,夏季变化不大,但整体前移。 相似文献
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通过分析L波段高空探测系统的时序设计原理,进行GTS1型探空仪与RS92型探空仪的同球比对施放试验验证,确定了由L波段高空探测系统的时序设计造成的测量元件感应气象要素至地面设备计算机软件赋时之间的时间差,会造成测量结果的随机波动。L波段探空系统总体时差对气压测量影响较大,对温度的影响较小,对湿度的影响较为复杂;由此造成的气压不确定性,将影响探空应用文件的准确性。相对于测量元件的感应时间总是延迟的,其总体散布中心为测量元件感应气象要素后1.2s,时差散布的扩展不确定度为0.98s,气压误差最大可达0.86hPa。北斗-GPS双模式导航测风探空仪的设计中采用了消除时差的方法,大大减小了测量结果的随机误差,并且在2013年12月中国气象局阳江试验中效果良好,为该问题提出了改进方法。 相似文献
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内蒙古地区农业干旱检索查询及旱情实时监测系统 总被引：3，自引：1，他引：3
针对内蒙古地区农业干旱的特点和旱灾发生频繁的现状，以及干旱对当地农业生产所造成的严重影响，利用地理信息系统(GIS)、Visual Basic和Access等技术方法，编制了内蒙古农业干旱检索查询及旱情实时监测系统。该系统建立了历史上农区干旱信息、农区干旱指标和作物生长季(4～9月)的基本气象资料、干旱实时监测信息等数据库，实现了历史上农区干旱信息(干旱出现年份、发生季节、出现强度、出现区域、受损情况等)的综合检索查询和实时气象资料的自动采集，具有监测信息的统计、检索、旱情分析评估等功能，能实时有效地监测干旱灾害的发生、发展，并提供逐月旱情评估、任意时段旱情分析和不同年份旱情的比较分析，可为相关部门抗旱决策提供可靠的数据资源。 相似文献