1998年秋到1999年春华南特大干旱气候成因   总被引：1，自引：2，他引：1       下载免费PDF全文

陆丹 《气象》2001,27(1):48-52

利用奇异值分解 (SVD) ,配合统计相关技术的应用 ,研究了广西秋季到第 2年 3月降水与 5 0 0 h Pa高度场和热带、北太平洋海温场的时间和空间结构及其相互关系。结果表明 ,第一耦合场明显反映了 ENSO信息 ,具有很高的相关 ;而海气配对的第二耦合场反映了作为关键区的日本海域以东的海温与 1 0 0°E以东 5 0 0 h Pa高度有较好的负相关。分析 1 998年以来海气场的变化 ,高度场上北太平洋中高纬 5 0 0 h Pa高度明显偏低 ,亚洲大陆和北太平洋中低纬高度偏高 ,因此其间冷空气明显偏弱 ,路径偏东 ;而海温场上 ENSO的变化 ,L ANina的发展过程与第一耦合场的海温变化模态一致 ;后期海、气关键区变化与第二耦合场相符。因此 ENSO的变化 ,日本海域以东升温造成了环流形势的异常 ,这是华南特大干旱的原因。利用时间系数互为因子法对广西 1 998年 8月到 1 999年 3月逐月降水作 SVD定量预报 ,预报降水持续偏少 ,1 999年春季干旱将非常严重。  相似文献   

参数估计的统一模型——广义Gauss-Markov模型     

陶本藻  刘大杰 《武汉大学学报(信息科学版)》1990,(4)

设计矩阵可以是秩亏阵,观测值的协方差阵可以是奇异阵的广义 Gauss-Markov模型(简称广义G-M模型),它是一种形式简单的统一模型。本文从最小二乘估计V~TQ~-V=min 出发,研究广义G-M 模型的参数估计理论和方法。说明了V~TQV~-=min与 Rao及Bjeharmmar等的平差原则一致。并对广义 G-M模型之解及其性质进行了系统讨论。  相似文献   

重磁联合广义反演磁、密度界面     

Wang Xichen 《吉林大学学报(地球科学版)》1990,(1)

本文利用广义线性反演技术,讨论了综合重磁两种地球物理资料集,联合反演磁、密度界面的方法及效果,所做的模型实验证明了重磁联合反演方法在削减解的非唯一性,提高解的可信度方面,是一种有前途的综合反演方法。  相似文献   

奇异值分解(SVD)在位场数据去噪中的应用     

邢琮琮  吴燕冈  赵昕  赵国兴  李朝辉  孙帮民 《世界地质》2016,35(4):1119-1126

根据奇异值分解原理,分析其在位场去噪中的可行性,提出了一种判断有效阶次k的方法。对多边形厚板模型的重力异常进行奇异值分解去噪和小波去噪效果的对比,证明了奇异值分解去噪的有效性和优势。将其应用于实测重力数据的处理中,取得较好的效果。理论模型和实测资料的处理结果表明:基于奇异值分解的去噪方法可以有效地去除随机噪声,提高数据处理和解释的精度。  相似文献   

Impact of Planetary Wave Reflection on Tropospheric Blocking over the Urals–Siberia Region in January 2008   总被引：1，自引：0，他引：1  

Debashis Nath  Wen Chen 《大气科学进展》2016,33(3):309-318

Planetary wave reflection from the stratosphere played a significant role in changing the tropospheric circulation pattern over Eurasia in mid-January 2008. We studied the 2008 event and compared with composite analysis(winters of 2002/2003,2004/2005, 2006/2007, 2007/2008, 2010/2011 and 2011/2012), when the downward coupling was stronger, by employing time-lagged singular value decomposition analysis on the geopotential height field. In the Northern Hemisphere, the geopotential fields were decomposed into zonal mean and wave components to compare the relative covariance patterns. It was found that the wavenumber 1(WN1) component was dominant compared with the wavenumber 2(WN2) component and zonal mean process. For the WN1 field, the covariance was much higher(lower) for the negative(positive) lag, with a prominent peak around +15 days when the leading stratosphere coupled strongly with the troposphere. It contributed to the downward coupling due to reflection, when the stratosphere exhibited a partially reflective background state. We also analyzed the evolution of the WN1 anomaly and heat flux anomaly, both in the troposphere and stratosphere, during January–March 2008. The amplitude of the tropospheric WN1 pattern reached a maximum and was consistent with a downward wave coupling event influenced by the stratospheric WN1 anomaly at 10 h Pa. This was consistent with the reflection of the WN1 component over Eurasia, which triggered an anomalous blocking high in the Urals–Siberia region. We further clarified the impact of reflection on the tropospheric WN1 field and hence the tropospheric circulation pattern by changing the propagation direction during and after the event.  相似文献   

总体最小二乘曲线曲面模型建立方法比较探究     

郝伟姣  陈慧建 《测绘与空间地理信息》2016,(6):196-198

本文探究了总体最小二乘的3种方法,包括奇异值分解、最小奇异值方法和迭代法,并且对3种方法进行比较。在模型推导的基础上,文中对3种总体最小二乘法在曲线和曲面拟合中求解的参数及其精度进行了比较分析。通过与最小二乘法的比较表明:总体最小二乘法得到的拟合结果更加稳健,并且发现迭代法和奇异值分解方法的结果是一样的;最小奇异值方法的结果欠优。  相似文献   

Autumn atmospheric preconditioning for interannual variability of wintertime sea-ice in the Okhotsk Sea     

Yoshi N. Sasaki  Yurika Katagiri  Shoshiro Minobe  Ignatius G. Rigor 《Journal of Oceanography》2007,63(2):255-265

Relations in year-to-year variability between wintertime Sea-Ice Concentrations (SICs) in the Okhotsk Sea and atmospheric anomalies consisting of zonal and meridional 1000-hPa wind speeds and 850-hPa air temperatures are studied using a singular value decomposition analysis. It is revealed that the late autumn (October–November) atmospheric conditions strongly influence sea-ice variability from the same season (late autumn) through late winter (February—March), in which sea-ice extent is at its maximum. The autumn atmospheric conditions for the positive sea-ice anomalies exhibit cold air temperature anomalies over the Okhotsk Sea and wind anomalies blowing into the Okhotsk Sea from Siberia. These atmospheric conditions yield anomalous ocean-to-atmosphere heat fluxes and cold sea surface temperature anomalies in the Okhotsk Sea. Hence, these results suggest that the atmospheric conditions affect the sea-ice through heat anomalies stored in sea-ice and oceanic fields. The late autumn atmosphere conditions are related to large 700-hPa geopotential height anomalies over the Bering Sea and northern Eurasia, which are related to a stationary Rossby wave propagation over the North Pacific and that from the North Atlantic to Eurasia, respectively. In addition, the late autumn atmospheric preconditioning also plays an important role in the decreasing trend in the Okhotsk sea-ice extent observed from 1980 to the mid-1990s. Based on the lagged sea-ice response to the late autumn atmosphere, a simple seasonal prediction scheme is proposed for the February–March sea-ice extent using four-month leading atmospheric conditions. This scheme explains 45% of the variance of the Okhotsk sea-ice extent.  相似文献   

北太平洋海温与福建后汛期降水量的关系   总被引：1，自引：0，他引：1  

李玲  苏万康 《台湾海峡》2005,24(1):7-14

本文应用奇异值分解方法给出同期和前期北太平洋海温与福建后汛期降水量相互匹配的空间典型分布型．分析结果表明，无论同期还是前期北太平洋海温与福建后汛期降水量之间均存在着清晰的遥相关．同期的赤道中东太平洋海温异常增高、日本以东洋面海温偏低，福建后汛期降水量偏少；另外，闽南地区后汛期降水量与同期NINO西海区和黑潮海区的海温成正相关关系．冬、春季出现厄尔尼诺现象时，次年福建尤其是闽南沿海后汛期降水量将偏少．  相似文献   

基于SSA和AR模型的海面变化预测试验   总被引：1，自引：0，他引：1  

俞肇元  袁林旺  谢志仁  董华军  孙健 《海洋湖沼通报》2007,(4):14-20

以吴淞站1955-2001年月平均潮位序列为基础,采用奇异谱分析(SSA)与自回归模型(AR)相结合的方案(SSA AR),进行了月平均潮位预测试验。基本思路是对SSA分析的结果选择若干有意义的分量进行序列重建,借助于自回归模型进行分量预测,再对它们进行叠加,从而建立预测模型。本文以1955-1996年数据为基础建立模型,1997-2001年数据作为验证,检验结果表明,两种方法的结合使用显示了较好的效果。  相似文献   

线性最小二乘问题的正则化方法     

刘新国 《中国海洋大学学报(自然科学版)》1989,(3)

本文讨论一类求解线性最小二乘问题的正则化方法的可行性。给出两条较为实用的可行性检验准则,推广了经典的Greville定理。  相似文献