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太阳活动11年周期对东亚冬季风与随后东亚夏季风关系的影响及其过程 总被引:2,自引:0,他引:2
利用长时间再分析资料和台站观测资料以及反映太阳周期活动的太阳黑子数资料,研究了太阳活动11年周期对东亚冬季风与随后夏季风关系的影响和过程。结果表明,弱(强)的东亚冬季风后的次年春、夏季在西北太平洋上空往往出现反气旋(气旋)式环流异常。通过将东亚冬季风指数分解为与ENSO有关的部分以及与ENSO无关的部分,进一步证实东亚冬、夏季风之间的联系主要来自于与ENSO有关的东亚冬季风异常。在此基础上着重分析了太阳活动对东亚冬、夏季风关系的影响和过程。研究表明,太阳活动显著影响了东亚冬季风与ENSO的关系,在太阳活动偏低年ENSO与东亚冬季风的关系更为密切。并且,对应与ENSO有关的东亚冬季风异常,当太阳活动偏低(LS)时西北太平洋附近的异常反气旋明显增强,范围扩大,其西北侧的西南气流强度偏强并向北延伸,从而使春季多雨地区绵延到内蒙古乃至西北地区;而夏季降水主要集中在长江流域中游,表明是一个强的夏季风年。然而,在太阳活动偏高(HS)年的次年春、夏季,不论是环流异常还是降水场的异常都明显偏弱。这说明东亚冬季风与随后夏季风的关系在LS年要比HS年更紧密。对海温异常的分析则进一步表明,LS(HS)年从冬季至夏季与ENSO有关的东亚冬季风异常相联系的印度洋及热带西太平洋海温正相关范围明显偏大(小);而赤道东太平洋的显著正海温异常衰减迅速(缓慢)。上述海温异常的差异是西北太平洋反气旋能否从冬季持续到夏季的重要原因,并可以很好地解释太阳活动对东亚冬、夏季风关系的影响。 相似文献
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春季北大西洋涛动与夏季西北太平洋热带气旋生成频数关系的年代际变化 总被引:1,自引:0,他引:1
The present study reveals the fact that the relationship between the spring(April–May) North Atlantic Oscillation(NAO) and the following summer(June–September) tropical cyclone(TC) genesis frequency over the western North Pacific(WNP) during the period of 1950–2018 was not stationary. It is shown that the relationship between the two has experienced a pronounced interdecadal shift, being weak and insignificant before yet strong and statistically significant after the early 1980 s. Next we compare the spring NAO associated dynamic and thermodynamic conditions, sea surface temperature(SST) anomalies, and atmospheric circulation processes between the two subperiods of 1954–1976 and 1996–2018, so as to illucidate the possible mechanism for this interdecadal variation in the NAO-TC connection. During the latter epoch, when the spring NAO was positive,enhanced low-level vorticity, reduced vertical zonal wind shear, intensified vertical velocity and increased middle-level relative humidity were present over the WNP in the summer, which is conducive to the genesis of WNP TCs. When the spring NAO is negative, the dynamic and thermodynamic factors are disadvantageous for the summertime TC formation and development over the WNP. The results of further analysis indicate that the persistence of North Atlantic tri-pole SST anomalies from spring to the subsequent summer induced by the spring NAO plays a fundamental role in the linkage between the spring NAO and summer atmospheric circulation.During the period of 1996–2018, a remarkable eastward propagating wave-train occurred across the northern Eurasian continent, forced by the anomalous SST tri-pole in the North Atlantic. The East Asian jet flow became greatly intensified, and the deep convection in the tropics was further enhanced via the changes of the local Hadley circulation, corresponding to a positive spring NAO. During the former epoch, the spring NAO-induced tri-pole SST anomalies in the North Atlantic were non-existent, and the related atmospheric circulation anomalies were extremely weak, thereby leading to the linkage between spring NAO and WNP TC genesis frequency in the following summer being insignificant. 相似文献
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城市土地储备制度是指由城市政府委托的机构,通过征用、收购、置换、到期收回、土地整理等方式,从分散的土地使用者手中将土地集中起来,并由政府或政府委托的机构组织进行土地整治与开发,在完成了房屋拆迁、土地平整等一系列前期开发工作后,再根据城市土地年度供应计 相似文献
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Modulation of the Arctic Oscillation and the East Asian winter climate relationships by the 11-year solar cycle 总被引:2,自引:0,他引:2
The modulation of the relationship between the Arctic Oscillation (AO) and the East Asian winter climate by the 11-year solar cycle was investigated.During winters with high solar activity (HS),robust ... 相似文献
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资源三号卫星全色与多光谱影像融合方法 总被引:1,自引:0,他引:1
在处理新型高分辨率遥感卫星影像时,传统的像素级融合方法会引起绿色植被区域较大的光谱扭曲.本文提出一种适合资源三号卫星影像的融合新方法,可以很好地解决此问题.首先对全色图像进行低通滤波并下采样得到退化后的图像HP,利用回归方法建立多光谱影像与图像HP的方程求解回归系数,考虑到绿色植被颜色失真严重,采用NDVI进行分类,分别求取绿地和非绿地的回归系数进行分类融合.试验结果证明,该方法在提高多光谱影像分辨率的同时,尽可能多地保持了光谱信息,特别是绿色植被区域,融合效果要好于其他方法. 相似文献
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利用美国气象环境预报中心和美国国家大气研究中心(NCEP/NCAR)再分析资料以及中国气象局发布的热带气旋(TC)最佳路径数据集,本文探讨了1950–2018年期间晚春(5月)北极涛动(AO)与随后夏季(6–9月)西北太平洋上空热带气旋生成频数的关系.研究表明,晚春AO对夏季西北太平洋TC生成有明显的预报指示意义,二者... 相似文献