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1.
采用集合经验模态分解(EEMD)和滑动傅里叶分析方法,建立了非线性气候序列的统计预测模型。针对气候要素距平场,对EOF分解得到的各模态时间系数进行EEMD分解,对得到的各IMF分量构建滑动傅里叶(Fourier)分析预报模型,提取出控制当前复杂气候信号的主要傅里叶频谱组合作为IMF分量的主要成分,即确定当前信号的主要波内频率,再将各个IMF分量和剩余项预测结果重构得到各模态时间序列的预测结果,最终通过时空重构得到预测场。将上述思想方法应用于新疆地区风场的预测试验,并采用距平相关系数(ACC),预报技巧(SS)和同号率(R)进行评估,结果表明对于区域性的风速预报,基于上述思想的算法模型能够较好地把握当前气候信号的主要变化频率,较为理想地预测了气候要素时间系数,对新疆地区风速变化的形态分布有较好的估计,使其预报时效在40侯以内均拥有一定的预报技巧,平均SS在0.5以上,36侯以内平均ACC达到0.4以上。  相似文献   

2.
基于EOF分解的中期平均气温距平客观预报方法   总被引:1,自引:0,他引:1  
本文通过将500 hPa高度、850 hPa温度、海平面气压的预报与历史要素场进行EOF分解,并假定EOF分解空间函数(即特征向量)是基本稳定的,建立以EOF分解主分量系列的时间系数、预报站点附近基本要素值的时间序列与预报站点平均气温距平的多元线性逐步回归预报方程,结合ECMWF集合预报数值产品,生成全国范围未来10 d平均气温距平客观预报产品投入业务应用,并采用同号率方法检验。结果表明,客观预报产品在检验时段内,同号率平均值为0.77,明显高于ECMWF集合预报模式2 m温度直接计算得出的同类产品同号率0.63;该客观预报产品不仅在分布范围上,同时在距平幅度上预报效果均较好。此外,相关分析也证明同号率方法在检验中期时效气温距平预报中有其合理性。  相似文献   

3.
利用2005年7月—2009年12月阿勒泰地区7个气象观测站逐月和旬的降水和温度实况资料、国家气候中心制作的月动力延伸预测模式的图形资料,采用预报评分法(P)和距平符号异同评分法对内插预测结果进行检验。结果表明:月动力延伸预报产品对各月温度距平同号率要明显高于降水距平百分率预报与实况同号率,对各月温度距平的预报评分比较稳定,而对各月降水距平百分率的预报评分差异较大。  相似文献   

4.
海洋表面温度(Sea Surface Temperature,SST)具有非平稳、非线性的特征,直接将处理平稳数据序列的方法应用到非平稳非线性特征明显的序列上显然是不合适的,预测的误差将会很大。为了提高预测精度,更好地解决非平稳非线性序列预测的问题,本文以东北部太平洋(40°N~50°N、150°W~135°W)区域的月平均海洋表面距平温度为例,首先分别应用集合经验模态分解(EEMD)和互补集合经验模态分解(CEEMD)方法将SST分解为不同尺度的一系列模态分量(IMF),再运用BP(Back Propagation)神经网络模型对每一个模态分量进行分析预测,最后将各IMF预测结果进行重构得到SST的预测值。数值试验的结果表明,CEEMD分解精度比EEMD分解精度高,CEEMD提高了基于BP神经网络的预测精度。系列试验统计分析说明应用这种方法对SST的1年预测是有效的。  相似文献   

5.
基于站点资料、再分析数据和动力气候模式回报数据,利用经验正交函数分解(EOF,Empirical Orthogonal Function)迭代和年际增量方法,探讨了长江流域年尺度降水异常的动力-统计降尺度预测方法及其应用效果。结果表明,基于再分析数据的年尺度环流场,建立的长江流域年尺度降水异常增量的统计降尺度预测方案,其26 a回报检验的距平相关系数(ACC)平均达0.6,证明该方案具有较高的可预报性。进一步利用模式预测的年尺度环流场,建立了年降水异常增量的动力-统计降尺度预测方案,其ACC平均为0.42,显示了较高的回报技巧,远优于模式直接输出的年降水动力预报结果。通过分析调制年降水预报技巧高低的因素发现,赤道中东太平洋年平均海温距平为负值时,预报技巧更高,ACC平均达0.5以上。在拉尼娜发展年或拉尼娜持续年的冷水背景下,利用EOF迭代选取的特征向量偏多时,多尺度的大气环流信息被纳入预测模型中作为预测信号,预测技巧得到了提高。  相似文献   

6.
短期气候预测的多时间序列相空间相似模型   总被引:3,自引:0,他引:3  
为了充分利用对气候系统进行定时观测而积累的关于它过去和现在情况的大量数据,本文提出了短期气候预测的一种多时间序列相空间相似模型,并从与云南气候变化有某种物理关系的20多个时间序列出发,建立了一个云南短期气候变化的年度预测模型。模型对云南80个气象观测站点1991~1998年的5月雨量距平和5月气温距平预测检验的距平同号率分别达到424/640= 66.3% 和426/640= 66.6% ;对云南1990~1997年的6~8月雨量距平、6~8月气温距平、年雨量距平和年气温距平预测检验的距平同号率则可分别达到404/640= 63.1% 、463/640= 72.3% 、456/640= 71.3% 和455/640= 71.1% 。  相似文献   

7.
应用MJO制作长江流域月降水预测的试验研究   总被引:1,自引:0,他引:1  
张礼平  张乐飞 《气象》2013,39(9):1217-1220
用MJO指数RMM1、RMM2、振幅 1—25日平均代替月平均,用上月月平均RMM1和RMM2、振幅构造为右场,下月长江流域降水场为左场,SVD分析两场的关联,借助最优化技术,在降水场预测距平与实况距平同号总站数最大意义下确定系数,建立估计公式,由右场时间系数估计左场时间系数,最后反演降水场。尽管多数的月第一模态相关并不显著,但实际预测效果较好。  相似文献   

8.
中国夏季降水异常EOF模态的时间稳定性分析   总被引:4,自引:1,他引:3  
庞轶舒  祝从文  刘凯 《大气科学》2014,38(6):1137-1146
本文基于1980~2012年中国160个台站降水资料,利用滑动交叉检验等方法讨论了中国夏季降水距平和距平百分率EOF各模态的时间稳定性,在此基础上探讨了EOF方法在中国夏季降水短期气候预测中的应用条件和潜在能力。研究表明,随机剔除一年样本,中国夏季降水距平场前四个EOF模态表现出显著的稳定性。若时间系数完全预测准确,则潜在的可预测站点主要位于黄河以南地区,理想预测与原始降水的距平相关系数为0.6左右。相对而言,降水距平百分率各模态的时间稳定性易受极端降水事件的影响,当人为削弱这种影响后,随机剔除一年样本,其前三个模态的稳定性得到提高,潜在的可预测站点均匀分布,理想预测与原始降水的距平相关系数为0.48。但是,伴随着预报时效的增加,降水距平和距平百分率后三个EOF模态的时间稳定性下降,预示着EOF方法对未来两年以上降水的预测能力将会明显下降。  相似文献   

9.
T63模式月动力延伸预报高度场的改进实验   总被引:3,自引:1,他引:2       下载免费PDF全文
为克服T63模式月动力延伸预报中纬向平均环流的系统性误差较大的情形,文章利用NCEP/NCAR逐候再分析500 hPa高度场资料和非线性时空序列预测理论的局域近似法进行逐候纬向平均高度距平场预报.近30组个例的预报效果分析表明,就1~3旬总体而言,非线性时空序列预测方法对纬向平均高度距平场的预报优于持续性预报和模式动力延伸预报,体现了改善纬向平均高度场的能力.尤其是第3旬的预报,当持续性预报偏差与实况偏差明显增大、动力预报技巧相对于第1旬和第2旬降低时,相空间重构结果仍然保持一定的优势.  相似文献   

10.
针对东北地区53站的降水距平百分率和温度距平这两个基本业务要素,运用李维京等在1999年提出来的动力统计相结合和典型相关回归这两种方案,对国家气候中心T63动力延伸集合预报的500hPa月平均高度距平进行释用,对释用结果采用PS评分和同号率进行预测效果评估.结果表明:这两种方法有较好的应用价值。  相似文献   

11.
The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics.  相似文献   

12.
Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms.  相似文献   

13.
Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d.  相似文献   

14.
Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region.  相似文献   

15.
正The Taal Volcano in Luzon is one of the most active and dangerous volcanoes of the Philippines. A recent eruption occurred on 12 January 2020(Fig. 1a), and this volcano is still active with the occurrence of volcanic earthquakes. The eruption has become a deep concern worldwide, not only for its damage on local society, but also for potential hazardous consequences on the Earth's climate and environment.  相似文献   

16.
正While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly, aerosol ammonium nitrate remains high in East China. As the high nitrate abundances are strongly linked with ammonia, reducing ammonia emissions is becoming increasingly important to improve the air quality of China. Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions, long-term surface observation of ammonia concentrations are sparse. In addition, there is still no consensus on  相似文献   

17.
Using the International Comprehensive Ocean-Atmosphere Data Set(ICOADS) and ERA-Interim data, spatial distributions of air-sea temperature difference(ASTD) in the South China Sea(SCS) for the past 35 years are compared,and variations of spatial and temporal distributions of ASTD in this region are addressed using empirical orthogonal function decomposition and wavelet analysis methods. The results indicate that both ICOADS and ERA-Interim data can reflect actual distribution characteristics of ASTD in the SCS, but values of ASTD from the ERA-Interim data are smaller than those of the ICOADS data in the same region. In addition, the ASTD characteristics from the ERA-Interim data are not obvious inshore. A seesaw-type, north-south distribution of ASTD is dominant in the SCS; i.e., a positive peak in the south is associated with a negative peak in the north in November, and a negative peak in the south is accompanied by a positive peak in the north during April and May. Interannual ASTD variations in summer or autumn are decreasing. There is a seesaw-type distribution of ASTD between Beibu Bay and most of the SCS in summer, and the center of large values is in the Nansha Islands area in autumn. The ASTD in the SCS has a strong quasi-3a oscillation period in all seasons, and a quasi-11 a period in winter and spring. The ASTD is positively correlated with the Nio3.4 index in summer and autumn but negatively correlated in spring and winter.  相似文献   

18.
正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.SUBMISSIONAll submitted  相似文献   

19.
20.
《大气和海洋科学快报》2014,(5):F0003-F0003
AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) pub- lishes short research letters on all disciplines of the atmos- phere sciences and physical oceanography. Contributions from all over the world are welcome.  相似文献   

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