太平洋大尺度环流数值模拟 II:长期平均环流   总被引：2，自引：2，他引：2       下载免费PDF全文

张荣华  曾庆存  张学洪 《大气科学》1991,15(5):51-64

用本文第Ⅰ部分所给出的四层太平洋环流模式,模拟在定常年平均大气强迫场驱动下太平洋长期平均环流。所进行的53年数值积分表明,模式成功地模拟出观测到的太平洋大尺度环流基本特征,特别是能直接计算出在海洋动力学和大尺度海气相互作用研究中有重要应用的海面起伏,对表层流场的模拟也明显优于具有同等分辨率的其他模式的结果;对气候有重要影响的SST形势的模拟结果同观测也较为一致。本文还用第53年数值积分资料进行了扰动压力场、斜压扰动压力场和海表热通量等的诊断计算和分析。文中还对模拟结果进行了物理和动力学的分析和解释。  相似文献   

应用气象卫星NOAA-AVHRR图像进行植被研究的多时相途径     

朱启疆 《遥感学报》1991,(2)

本文讨论了应用NOAA-AVHRR数字图像研究植被季相变化和进行植被分类的多时相方法。对生长季节的各时相植被指数VI图像进行图像分割,可揭示植被绿锋的进退和季相变化及其在空间上的表现。对多时相的植被指数VI图像进行主成分变换,据第一主成分的直方图各特征峰的形状和位置进行图像分割,可获得植被景观图,这一结果与现行的植被分布图相当一致。  相似文献   

Caledonian terranes along the southwestern border of the East European platform — Evidence,speculation and open questions     

Dietrich Franke 《Studia Geophysica et Geodaetica》1995,39(3):241-256

Summary According to the terrane model used for the interpretation of the heterogeneities in the Lower Palaeozoic development along the southwestern border of the East European platform (Baltica) several suspect terranes have been accreted to the passive platform margin during the closure of the postulated Tornquist Sea in Ordovician and Silurian times. Their final docking and partly overthrusting onto the platform are of Scandian (Early Devonian) age. A matter of dispute is the provenance of the various terranes. There are lithofacies, structural, palaeobiogeographical and palaeomagnetic constraints for relations both to Baltica and East Avalonia. Specific similarities can be observed between the Southern Jylland, Pomerania, ysogóry (including Radom-Krasik), and Rawa Russkaja terranes. After their accretion and amalgamation they may form a more or less continuous Caledonian marginal thrust belt along the platform border. On the other hand, more significant differences exist between the latter and the so far recognized Southern North Sea, Maopolska, Cracovides, Upper Silesian, Sudeten, Kochanowka, and Dobrogean terranes. The position of any Tornquist Sea suture zone(s) is still completely enigmatic.  相似文献   

黑潮延伸体海表温度锋位置的变化特征   总被引：2，自引：1，他引：1  

王焱鑫  杨小怡  胡建宇 《海洋学报(英文版)》2016,35(7):30-35

High spatial resolution sea surface temperature(SST) data from 1993 to 2013 are used to detect the position of the Kuroshio Extension sea surface temperature front(KEF) from 141°E to 158°E,and the seasonal,monthly and interannual-to-decadal variations of the KEF position are investigated.The latitudinal position of the KEF varies with longitudes:the westernmost part of the KEF from 141°E to 144°E is relatively stable,whereas the easternmost part from 153°E to 158°E exhibits the largest amplitude of its north-south displacement.In the light of the magnitudes of the standard deviations at longitudes,then the KEF is divided into three sections:western part of the KEF(KEFw,141°–144°E),central part of the KEF(KEFc,144°–153°E) and eastern part of the KEF(KEFe,153°–158°E).Further analysis reveals that the KEFw position is dominated by the decadal variability,while the KEFc and KEFe positions change significantly both on interannual and decadal time scales.In addition,the KEFw position is well correlated with the KEF path length.The possible mode leading to the decadal oscillation of the KEFw is further discussed.The KEFw position exhibits significant connections with the Pacific decadal oscillation(PDO) index and the north Pacific gyre oscillation(NPGO) index with a time lag of 40 and 33 months,respectively.  相似文献   

西北太平洋海洋温度锋生与锋消机制的初步研究     

赵宁  韩震  刘贤博 《海洋科学》2016,40(1):123-131

海洋锋面区域对气候变化以及海气耦合作用的影响非常显著,通过分析其形成机制,可以帮助进一步了解海洋与大气的相互作用过程以及其物理过程。利用Argo数据、NCEP/NCAR再分析数据和遥感风场数据对西北太平洋的混合层温度与温度锋面的变化机制进行了研究。基于海洋混合层的热量收支模型,发现在北太平洋区域的海洋混合层温度主要受到净热通量控制,同时还存在一个季节变化明显的温度锋面。9~2月为温度锋面加强时期,3~4月温度锋面变化不明显,而5~8月温度锋面则迅速减弱。根据研究,该温度锋面的加强与减弱主要是由于净热通量的南北差异造成的,而在净热通量中则以短波辐射通量与潜热通量为主要影响因子。  相似文献   

一次黑潮海洋锋强迫下的蒸发波导突变性与非均匀性的观测与模拟研究     

丁菊丽  梁志超  费建芳  吕庆平  赵小峰 《气象学报》2021,79(6):1049-1062

蒸发波导是影响海上雷达系统探测性能的主导机制,海表温度（SST）锋带来的蒸发波导非均匀性和突变性具有重要的研究价值。2018年春季航次“海气相互作用观测试验”,曾两次穿越黑潮海域获取了珍贵的观测资料。在此基础上,结合欧洲中期天气预报中心（ECMWF）再分析资料（ERA-Interim）和HYSPLIT（Hybrid Single Particle Lagrangian Integrated Trajectories）气块轨迹溯源,分离出两个重要的走航观测时段。S1段（持续约21 h）气流从暖海水区吹向冷海水区,以稳定层结为主,其间因黑潮海洋锋的存在,气流由黑潮主体的暖水区吹向大陆冷海区时,形成具有强逆温层的海洋边界层,并伴随海雾的生成,导致此处蒸发波导高度突降为0。此后为持续近66 h的S2段,气流由冷海水区吹向暖海水区,以近中性弱不稳定层结为主,蒸发波导高度基本维持在12 m高度。数值模拟结果表明,模拟时段内的黑潮海洋锋区,蒸发波导高度突变性和非均匀性始终存在,且伴随暖海水吹向冷海水的锋区突变性更强。黑潮海洋锋对蒸发波导的这种天气尺度强迫作用的加强与层结稳定度的突变和海雾的生成有关。   相似文献   

持续性冷涡暖锋暴雨成因及特征分析     

任丽  栾晨  王晓雪  张月 《气象与环境学报》2022,38(3):37-44

利用常规观测资料、自动气象站降水量以及NCEP FNL再分析资料,对2019年8月6—8日一次持续性东北冷涡暴雨过程成因及特征进行诊断分析。结果表明:暖锋稳定维持在同一区域且不断锋生造成持续性暴雨。强降水出现在850 hPa锋区南侧,呈东西带状分布,暴雨与最大锋生区相对应。大气中层为弱对流不稳定,有利于强降水的维持。高层正位涡大值区向下层扩展,促使中低层涡度增加,在暖锋前形成正涡柱结构,在地面锋区上诱发出气旋性环流,有低压新生。锋区低层的强辐合区位于迎风坡,锋面辐合抬升和地形强迫抬升的共同作用,使低层强辐合区持续3 d维持在同一区域。冷涡东移减弱阶段,台风携带大量暖湿空气北上促使锋区北抬,强降水维持。冷涡新生和维持阶段,T_(850-500)≥25℃,K≥35℃,且有一定的对流有效位能,对暴雨的出现有较好的指示意义。暴雨区东边界的水汽输入最为关键,占到整个水汽输入总量的一半,尽管南边界的总水汽输入量不大,但集中出现在第一个暴雨日,是6日暴雨过程主要水汽贡献者。  相似文献   

Atmospheric Rivers and Mei-yu Rainfall in China:A Case Study of Summer 2020※     

Ting WANG  Ke WEI  Jiao MA 《大气科学进展》2021,38(12):2137-2152

Atmospheric rivers (ARs) are long, narrow, and transient filaments of strong horizontal water vapor transport that can lead to extreme precipitation. To investigate the relationship between ARs and mei-yu rainfall in China, the mei-yu season of 2020 in the Yangtze-Huaihe River basin is taken as an example. An adjusted AR-detection algorithm is applied on integrated water vapor transport (IVT) of the ERA5 reanalysis. The JRA-55 reanalysis and the data from Integrated Multi-satellite Retrievals for GPM (IMERG) are also utilized to study the impacts of ARs on mei-yu rainfall in 2020. The results reveal that ARs in East Asia have an average length of 5400 km, a width of 600 km, a length/width ratio of 9.3, and a northeastward orientation of 30°. ARs are modulated by the western North Pacific subtropical high. The IVT core is located at the south side of low pressure systems, moving eastward with a speed of 10° d^?1. For the cross sections of ARs in the Yangtze-Huaihe River basin, 75% of the total flux is concentrated below 4 km with low-level jets near AR cores. Moreover, ARs occur mainly in the mei-yu period with a frequency of 20%–60%. The intensity of AR-related precipitation is 6–12 times that of AR-unrelated precipitation, and AR-related precipitation contributes about 50%–80% to total mei-yu precipitation. As shown in this case study of summer 2020, ARs are an essential part of the mei-yu system and have great impacts on mei-yu rainfall. Thus, ARs should receive more attention in research and weather forecast practices.  相似文献   

渤海北部东岸海风锋活动及其触发对流特征分析     

张晶  姚文  陈海涛  何晓东  张运芝  李黎  赵晓川 《气象与环境学报》2021,37(2):33-40

利用常规观测、雷达、卫星及加密自动气象站等资料,对2015年、2018年和2019年渤海北部东岸海风锋活动及其触发的对流特征进行统计分析。结果表明：不同年份渤海北部东岸海风锋活动的差异较大,海风锋主要出现在6—8月,其中7月最多;海风锋可分为沿山型、北部沿海型和混合型3种,其中沿山型占比70%以上,海风锋东移到达沿山地区后维持加强,北部可伸展到沈阳地区;海风锋在雷达反射率图上表现为窄带回波,强度一般小于27 dBz,在速度图上表现为风向的辐合或风速的大值区,但在相关系数、差分反射率等雷达双偏振产品上没有可明显识别的特征;在各种天气背景下均能发生海风锋,其中在高空脊控制下最多,且可触发午后热对流,多为弱对流;在副热带高压后部、高空槽、冷涡背景下的海风锋容易触发强对流天气,带来冰雹、短时强降水、雷雨大风等灾害。  相似文献   

Aptian and Albian atmospheric CO2 changes during oceanic anoxic events: Evidence from fossil Ginkgo cuticles in Jilin Province,Northeast China     

《Cretaceous Research》2016

The Early Cretaceous was a time with super-greenhouse conditions and episodic global oceanic anoxic events. However, relative timing of atmospheric CO₂ emissions and oceanic anoxic events, and their causal relationships remain matters of debate. Using the stomatal index approach, well-preserved fossil cuticles of Ginkgo from the Lower Cretaceous Changcai Formation, eastern Jilin, and from the Lower Cretaceous Yingcheng Formation, central Jilin, Northeast China, were investigated to reconstruct atmospheric CO₂ concentrations during the Aptian and earliest Albian (Early Cretaceous). The results indicate that the CO₂ concentrations reached 1098–1142 ppmv (Carboniferous standardization) or 970–1305 ppmv (regression function) during the Aptian and earliest Albian. Our estimates of palaeoatmospheric CO₂ concentrations during the earliest Albian (OAE 1b) are slightly higher than the data between the early Aptian Selli (OAE 1a) and the middle Aptian Fallot OAEs; this may indicate the absence of any great emissions of CO₂ during the latest Aptian and earliest Albian.  相似文献