广东省群发性高温事件的气候特征研究     

李芷卉  胡娅敏 《热带气象学报》2023,(1):37-46

基于1961—2020年广东省86个国家自动气象站的日最高气温数据,采用一种客观识别方法,对广东省群发性高温事件进行回算识别,结果得到广东省群发性高温事件呈显著增长趋势,且在1990年代发生一次年代际突变,群发性高温事件主要发生在4—10月,其频次、强度、持续时间和空间影响范围等特征参数均呈现以7月为最盛期的类单峰式分布。值得关注的是,近60年来广东群发性短历时高温事件呈略微减少趋势,而长历时(≥6天)的事件数呈现显著增加趋势,这给政府的防灾减灾造成更大的难度。  相似文献   

太阳轨迹空间连续性的日照分析算法优化     

张驰  李佳  周侗  陶菲 《测绘科学》2017,42(9)

针对日照分析模拟必须考虑众多真三维地形/地物的遮挡因素,传统的日照分析方法难以在现实世界的复杂地理场景中得出高效、准确分析结果的问题展开研究,基于太阳运行轨迹的空间连续性,利用数据缓存方法对遮挡图元进行预判,实现了日照分析算法的优化。应用实例表明,将该方法与空间划分方法配合使用,可以在保证运算结果正确的基础上,进一步提高日照分析的计算效率,从而实现复杂地理场景中准确、快速的日照分析计算。  相似文献   

乌鲁木齐市北部农区近53 a来日照时数变化分析     

郑玉萍 《沙漠与绿洲气象(新疆气象)》2017,11(6):40-45

摘要：基于1964-2016年乌鲁木齐市米东区日照时数资料,使用线性回归方法,分析乌鲁木齐市北部农区日照时数的时空变化特征,并用偏最小二乘法（PLS）分析日照时数与各气象要素之间的相关性。结果表明:（1）年日照时数平均每10a递减95.5h,1998年后日照时数急剧减少,连续19a均呈负距平。（2）3-10月日照时数变化不明显,11月至次年2月日照时数显著减少。（3）4—10月大田作物生长季光照条件稳定,冬季设施农业生产季11月至次年3月的日照时数显著减少、寡照日数增多,光照不足严重影响设施农业生产。（4）近53a雾日增加、低能见度发生频率增大、低云量增多、冬季降雪量增加等是造成米东区日照时数剧烈减少的主要气象原因,米东区和主城区相比,局地气候特征更为突出。  相似文献   

Observed advantage for negative binomial over Poisson distribution in partial duration series     

A. Ben-Zvi 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(2):135-146

The goodness of fit of the negative binomial and the Poisson distributions to partial duration series of runoff events is tested. The data have been recorded by eight hydrometric stations located on ephemeral rivers in Isreal. For each station, a number of threshold discharges are considered, by that series of nested subsamples are formed. Owing to size limitations, a Chi-square test is conducted on samples associated with low to moderate threshold discharges. Positive results, at a 5% significance level, are obtained in 30 out of the 53 tests of the Poisson distribution, and in 22 out of the 28 tests of the negative binomial distribution. The fit of the Poisson distribution to samples of conventionally recommended sizes (of 2 to 3 events per year) is found positive for five rivers and negative for the three other rivers The fit of the negative binomial distribution to these samples is found positive for six rivers, inconclusive for one river and short of data for the eighth river. Mixed results are obtained as the threshold level is raised. Therefore, no direct extrapolation is possible to samples associated with high thresholds.An indirect extrapolation is drawn through a comparison of the actual properties of the samples with those expected under a perfect fit of the distribution functions. Ranges of such properties are defined with respect to the properties of the tested samples and to the test results. The actual properties of nine of the eleven samples associated with high thresholds (i.e. mean number of events <-0.1year ^–1) are found within these ranges. This provides a hint for a probable good fit of either distribution, and particularly the negative binomial, to the occurrence frequency of high events.  相似文献   

Amplitude domain analysis for the 30 August 1986 Vrancea intermediate earthquake     

Luminiţa Ardeleanu  Victoria Oancea 《Natural Hazards》1990,3(3):305-314

The amplitude domain analysis applied to the major Vrancea (Romania) earthquake of 30 August 1986 leads to the determination of some parameters characterizing the amplitude and the time duration of the signal.Digital three-component acceleration data, obtained at 10 Romanian seismic stations with epicentral distances between 40 and 200 km, are used. The results are compared with those obtained by Schenk for strong Californian earthquakes.Paper presented in the 21st General Assembly of the European Seismological Commission, Sofia, 1988.  相似文献   

1993年夏季低温及其对农业的影响   总被引：2，自引：0，他引：2  

吴金栋  太华杰 《气象》1995,21(2):19-22

从农业气候学和农业气象学基本原理出发,通过对１９９３年夏季气候特点的分析,试述“凉夏”天气对农业生产不利影响的一面,以期今后深入研究,达到减灾的目的。  相似文献   

Determination of source duration and moment of earthquakes in the Indian Peninsula using love waveforms     

S. N. Bhattacharya 《Pure and Applied Geophysics》1996,147(3):497-514

Love waves recorded by a long-period seismograph at New Delhi (NDI) from seven earthquakes of magnitude 4.3 to 5.2 in Koyna and Bhatsa on the western coast and one earthquake in Ongole on the eastern coast of the Indian Peninsula have been used to determine the seismic moment for each of the earthquakes by waveform modeling. Transverse component of the synthetic seismogram shows that the maximum amplitude of waveform decreases with an increase of source duration. Thus for an evaluation of the seismic moment by equating the amplitude level of the observed and synthetic waveforms, we must know the source duration. The synthetic seismogram also indicates that a short source duration gives rise to a small but sharp pulse and this pulse is interpreted as anLg wave. Comparison of the observed and synthetic waveforms has been used for a simultaneous evaluation of the source duration and seismic moment. The source durations are found to vary between 2.2 and 4.4 s; for earthquakes with a magnitude range between 4.3 and 5.2 these durations are slightly higher than normal. We obtain moment (M ₀) of Ongole earthquake (M _L =5.1)as 1.7×10²⁴ dyne-cm; moments of Koyna and Bhatsa earthquakes (4.3M _L 5.2) on the western coast lie between 0.7×10²³ and 3.6×10²³ dyne-cm. Moment (M ₀)-magnitude (M _L ) relation logM ₀=1.5M _L +16.0 for the western United States region agrees as well, in general, with the results for the earthquakes in the Indian Peninsula.  相似文献   

喀什市降水日变化特征分析     

赵克明 《沙漠与绿洲气象(新疆气象)》2016,10(2):31-35

利用1994～2013年5～9月喀什市气象站逐小时降水资料,分析喀什近20a降水日变化特征。研究表明,20时至翌日06时为降水量的高值阶段,最大值出现在01时,07时至19时为降水量的低值时段,最小值出现在16时。降水频次的高值区为00时至07时,降水最不易产生的时间为17时。降水强度最高值在20时,次高值为01时,也是累积降水量较大时刻,降水强度最低值出现在15时也是累积降水量的低值区。喀什的降水主要以短时性降水（1～3h）为主,多发生在傍晚至夜间,1h降水频次最多的是量级≤1mm的降水,但1.1mm≤R1≤3.0mm量级的降水贡献率最高。小雨、中雨及大雨降水过程最易发生时段均为前半夜,下午为各量级降水过程发生最少的时段。  相似文献   

塔克拉玛干沙漠腹地区域性与局地性沙尘暴特征分析——以塔中为例     

马建勇  何清  杨兴华  霍文  杨帆 《沙漠与绿洲气象(新疆气象)》2016,10(2):36-42

塔克拉玛干沙漠近几年来沙尘暴发生频率增加,强度增大,为了研究不同尺度沙尘暴的规律,利用2005-2014年塔克拉玛干沙漠腹地塔中及周边14个气象台站沙尘暴资料,给出塔克拉玛干沙漠腹地塔中区域性与局地性沙尘暴天气过程的定义,从区域性与局地性沙尘暴持续时间,能见度,类型,时间变化等特征进行分析。研究结果表明：(1)10塔中发生沙尘暴170d比沙漠南缘和北缘高,比肖塘少,其中区域性沙尘暴80d,局地性沙尘暴90d,天气过程区域性64次,局地性80次;(2)塔中区域性沙尘暴不论是持续时间还是能见度总体上比局地性沙尘暴持续时间长,能见度低;(3)区域与局地沙尘暴可以按主导风向分为5类,但各类沙尘暴在区域性与局地性沙尘暴中表现出季节分布;(4)区域性与局地性沙尘暴10a波动增长,区域性沙尘暴多发生在春季,局地性沙尘暴多发生在夏季,区域性沙尘暴年际和年内变差系数都小于局地沙尘暴,一日中区域性与沙尘暴白天多于夜晚。  相似文献   

The importance of heating duration for Raman CM thermometry: evidence from contact metamorphism around the Great Whin Sill intrusion,UK          下载免费PDF全文

H. Mori  N. Mori  S. Wallis  R. Westaway  C. Annen 《Journal of Metamorphic Geology》2017,35(2):165-180

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