SIMULATION OF TROPICAL CYCLONES OVER THE WESTERN NORTH PACIFIC AND LANDFALLING IN CHINA BY REGCM4     

吴婕  高学杰 《热带气象学报(英文版)》2019,25(4):437-447

This study evaluates the performance of the regional climate model RegCM4 in simulating tropical cyclone (TC) activities over the Western North Pacific (WNP) and their landfalling in China. The model is driven by ERA-Interim boundary conditions at a grid spacing of 25 km, with the simulation period as 1991–2010. Results show that RegCM4 performs well in capturing the main structural features of observed TCs, and in simulating the genesis number and annual cycle of the genesis. The model reproduces the general pattern of the observed TC tracks and occurrence frequency. However, significant underestimation of the occurrence frequency as well as the TC intensity is found. Number of the landfalling TCs over China is also much less than the observed. Bias of the model in reproducing the large-scale circulation pattern and steering flow may contribute to the underestimated landfalling TC numbers.  相似文献   

Seesaw Pattern of Rainfall Anomalies between the Tropical Western North Pacific and Central Southern China during Late Summer     

Xinyu LI  Riyu LU 《大气科学进展》2019,36(3):261-270

It is well known that suppressed convection in the tropical western North Pacific(WNP) induces an anticyclonic anomaly,and this anticyclonic anomaly results in more rainfall along the East Asian rain band through more water vapor transport during summer, as well as early and middle summer. However, the present results indicate that during late summer(from mid-August to the beginning of September), the anomalous anticyclone leads to more rainfall over central southern China(CSC), a region quite different from preceding periods. The uniqueness of late summer is found to be related to the dramatic change in climatological monsoon flows: southerlies over southern China during early and middle summer but easterlies during late summer. Therefore, the anomalous anticyclone, which shows a southerly anomaly over southern China, enhances monsoonal southerlies and induces more rainfall along the rain band during early and middle summer. During late summer,however, the anomalous anticyclone reflects a complicated change in monsoon flows: it changes the path, rather than the intensity, of monsoon flows. Specifically, during late summers of suppressed convection in the tropical WNP, southerlies dominate from the South China Sea to southern China, and during late summers of enhanced convection, northeasterlies dominate from the East China Sea to southern China, causing more and less rainfall in CSC, respectively.  相似文献   

From pollen percentage to vegetation cover: evaluation of the Landscape Reconstruction Algorithm in western Norway   总被引：1，自引：0，他引：1       下载免费PDF全文

KARI LOE HJELLE  INGVILD KRISTINE MEHL  SHINYA SUGITA  GIDSKE LEKNÆS ANDERSEN 《第四纪科学杂志》2015,30(4):312-324

The Landscape Reconstruction Algorithm (LRA) with the two models REVEALS and LOVE is developed to transform pollen percentage data to vegetation cover. This paper presents the first study to evaluate LRA in a region with large topographic variations within a short distances. The REVEALS model estimates regional vegetation abundance based on pollen assemblages from large lakes (100–500 ha). Pollen surface samples from one large and 28 small lakes are used together with a combination of regionally derived pollen productivity estimates and available estimates from other regions of Europe. The results show a good relationship between REVEALS‐estimated forest cover and vegetation abundance based on the CORINE land‐cover data. The REVEALS results using various sets of pollen assemblages from small lakes were comparable to those using one large lake. Local vegetation abundance using the LOVE model was estimated around 26 lakes. For common taxa, such as Pinus and Poaceae, the LOVE‐based estimates of plant abundance match well with the distance‐weighted plant abundances based on vegetation maps. Our results indicate that the LRA approach is effective for reconstruction of long‐term vegetation changes in western Norway and other regions with high topographic relief when no major gradients exist in the pollen data.  相似文献   

CORRELATION ANALYSIS OF THE WESTERN PACIFIC SUBTROPICAL HIGH AND EASTERN ASIAN SUMMER MONSOON SYSTEM BASED ON FUZZY SYSTEMS AND DYNAMICAL MODEL INVERSION FORECAST     

洪梅  张韧  阎恒乾  葛晶晶 《热带气象学报(英文版)》2015,21(S1):34-45

Based on the adaptive network fuzzy inference system (ANFIS), methods to filter out the noise of impact factors from the main signal are discussed. Focusing on the abnormal weather conditions in 2010, we use the delay-relevant method to analyze the five members of the summer monsoon system that had the largest effect on the subtropical high anomalies from the observational data. ANFIS is suitable for research and simulation of subtropical highs that are difficult to describe accurately with dynamics, allowing the effect of five factors on the subtropical high anomalies to be examined. Our results show that the Mascarene cold high, the Indian monsoon latent heat flux, and the South China Sea monsoon trough had the largest effect on the subtropical high anomalies. Diagnostic analysis, with genetic algorithms (GA) and dynamical reconstruction theory, reconstructed the nonlinear dynamical model of the subtropical high and its main factors objectively and accurately from the sequence of observations in 2010. Furthermore, a dynamically extended forecast experiment is performed. The forecasts for the subtropical high area index, the Mascarene cold high index, the Indian monsoon latent heat flux, and the South China Sea monsoon trough index all show a strong short-term effect over less than 25 days. The forecasting trend is accurate, and the error rate is no more than 7%. Our results provide new insight and methods for research on the association between the western Pacific subtropical high and the East Asian summer monsoon system, and for the prediction of the western Pacific subtropical high index.  相似文献   

The Asymmetry of Subsurface Temperature Anomalies Associated with ENSO in the Equatorial Western Pacific          下载免费PDF全文

HUA Li-Juan  YU Yong-Qiang 《大气和海洋科学快报》2015,8(1):23-28

The phenomenon of ENSO asymmetry has been recognized for many years, but most studies have focused on the asymmetry of surface temperature anomalies in the equatorial eastern Pacific. Here, the authors investigate the temperature asymmetry associated with ENSO in the subsurface of the western Pacific through analysis of observations and numerical experiments with an ocean GCM. Both the observation and simulation exhibit significant ENSO asymmetry, characterized by negative temperature skewness in the equatorial western Pacific and positive skewness in the eastern Pacific. Heat budget analysis reveals that nonlinear dynamical heating results in the positive temperature asymmetry in the equatorial eastern Pacific, but tends to weaken the negative temperature asymmetry in the equatorial western Pacific. The climatological meridional current transports the temperature anomalies and corresponding negative asymmetry from the off-equator region to the equator in the subsurface of the western Pacific. Through a sensitivity experiment with reversed wind stress forcing, the authors suggest that the skewness of the wind stress anomalies does not contribute to the negative temperature asymmetry in the western Pacific in the first-order approximation, while the internal nonlinear dynamics does play a key role. The study suggests that, as a result of nonlinear processes, the oceanic responses to anomalous wind stress are nonlinear and asymmetric in the tropical Pacific.  相似文献   

冬季西太平洋暖池与华南降水关系的年代际变化   总被引：1，自引：1，他引：0       下载免费PDF全文

何金海  袁良  祁莉 《大气科学学报》2015,38(6):721-730

利用1951-2010年全国台站冬季降水观测资料、Hadley环流中心逐月海表温度资料以及NCEP/NCAR再分析月平均资料,探讨了西太平洋暖池与我国华南地区冬季降水的关系。结果表明,西太平洋暖池与我国华南冬季降水的年际关系在1972年发生了明显的年代际转折,20世纪70年代前两者弱的负相关未通过信度检验,而70年代后两者相关系数达到-0.5~-0.6。回归分析显示,70年代前,暖池对产生华南冬季降水的水汽条件以及动力条件等的影响不显著,因此其与华南冬季降水的关系不明显。70年代后,暖池偏暖时,在菲律宾海区域激发出一个显著的气旋性环流,该环流西北侧的偏北风不利于南海地区水汽向我国华南地区输送,华南地区水汽辐散增强,而且南支槽地区对流减弱,南支扰动不活跃且扰动不能向下游地区传播,华南地区扰动活动减弱,此外暖池偏暖使北半球经向环流显著增强,且下沉支位于我国华南地区,加强了华南地区的下沉运动,因而华南地区冬季降水显著偏少;暖池偏冷时,情况相反。  相似文献   

塔里木克拉通北缘阔克塔格西富碱侵入岩成因及其构造意义——锆石U- Pb年代学、岩石地球化学及Sr- Nd- Hf- O同位素制约     

潘蓓蓓  黄河  张招崇  王涛  吴欢欢  秦切  李海舟 《地质学报》2023,97(7):2195-2221

富碱侵入岩具有深源浅成的属性,是示踪地幔组成的窗口。位于东天山与塔里木克拉通北缘交界处的阔克塔格以西出露一处以正长岩为主体、包含少量中—基性岩石单元的富碱侵入岩。LA- ICP- MS锆石U- Pb测年显示其侵位于227~224 Ma之间,为印支期岩浆作用产物。该岩体具有富碱（Na2O+K2O=7. 93%~ 12. 28%）、富铝（Al2O3=15. 62%~18. 67%）、贫镁（MgO=0. 12%~4. 01%）、贫钛（TiO2=0. 14%~1. 63%）的特征,属于准铝质的（A/CNK=0. 78~1. 00）高钾钙碱性—钾玄岩系列。微量元素表现出高场强元素Nb、Ta、Th、U、Zr、Hf的富集,不相容元素Sr、P、Ti的亏损特征;轻重稀土分馏明显（（La/Yb）N=15. 09~34. 90）,表现为轻稀土强烈富集的右倾型曲线,Eu异常变化较大（δEu=0. 12~1. 72）。在同位素组成上,富碱侵入岩呈现相对宽泛但总体富集的全岩Sr- Nd和锆石Hf同位素特征,(87Sr/86Sr)i=0. 70489~0. 70581,εNd(t)=14. 56~6. 74,εHf(t)=11. 48~+3. 06,锆石δ18O值（5. 49‰~6. 87‰）略高于地幔值（5. 3‰±0. 6‰）。阔克塔格西富碱侵入岩具A1型花岗岩特征,形成于板内伸展构造环境中。基于主、微量元素及Sr- Nd- Hf- O同位素特征,笔者认为该杂岩体为同源岩浆演化产物,源于富集岩石圈地幔的原始岩浆上升并经历AFC（同化混染- 分离结晶）过程。晚三叠世塔里木克拉通北缘—东天山—北山地区处于板内构造体制,A1型花岗岩和正长岩差异化的时空分布特征很可能记录了古亚洲洋自西到东 “剪刀式”的闭合过程。  相似文献   

A New Darwinopterid Pterosaur from the Middle Jurassic of Western Liaoning, Northeastern China and its Ecological Implications   总被引：2，自引：0，他引：2  

Lü Junchang  XU Li  CHANG Huali  ZHANG Xingliao 《《地质学报》英文版》2011,85(3):507-514

A new species of Darwinopterus, D. robustodens sp. nov. is described and named. Based on the new specimen, the diagnostic characters of Darwinopterus are amended and include: rostral dentition composed of well-spaced, spike-like teeth; the longest teeth are confined to the anterior half of the tooth row; tooth alveoli have raised margins; nasoantorbital fenestra confluent; inclined quadrate; elongate cervical vertebrae with low neural spine and reduced or absent ribs; long tail of more than 20 caudals partially enclosed by filiform extensions of the pre- and postzygapophyses; short metacarpus less than 60 per cent length of humerus, fifth toe with two elongate phalanges and curved second pedal phalanx of the fifth toe with the angle between the proximal and distal segments about 130 degrees. The complete specimen of the new pterosaur D. robustodens sp. nov. provides much more osteological information. The differences in tooth morphologies between Darwinopterus modularis and D. robustodens sp. nov. suggest that they filled different ecological niches. The hard integument-bearing Coleoptera may have been the main food source of Darwinopterus robustodens.  相似文献   

Geochronology and Petrogenesis for the Protolith of Biotite Plagioclase Gneiss at Lianghe, Western Yunnan   总被引：5，自引：0，他引：5  

CONG Feng  LIN Shiliang  ZOU Guangfu  XIE Tao  LI Zaihui  TANG Fawei  PENG Zhimin 《《地质学报》英文版》2011,85(4):870-880

In this paper,we report an integrated study of U-Pb age and Hf isotope compositions of zircons from biotite plagioclase gneiss at Lianghe in western Yunnan.The zircons preserved inherited core and rim texture.Igneous zircon grains and rims yielded a weighted mean ~(206)Pb/~(238)U age of 120.4±1.7 Ma,theirε_(Hf)(120 Ma)values were mainly negative ranging from-13.9 to-10.7,with Hf model ages between 1.9 Ga and 2.0 Ga,some zircons had positiveε_(Hf)(120 Ma)values ranging from 0.2 to 2.1.The inherited cores ...  相似文献   

Hybrid Sedimentation in Late Permian-Early Triassic in Western Sichuan Basin,China     

龙胜祥  吴世祥  李宏涛  白振瑞  马金钰  张华 《中国地质大学学报(英文版)》2011,(3)

Mixed carbonate-siliciclastic sedimentation is common in the Upper Permian-Lower Tri-assic in the western Sichuan(四川) basin.The extensional movement was strong in the Late Permian,resulting in differential uplifting of fault blocks.During this period,there was an extensive retrogres-sion.The Kangdian(康滇) ancient land progressive uplifted and enlarged,forming the major prove-nance of terrigenous clastics.In Changxingian age,mixed terrigenous-carbonate sedimentation was dis-tributed in the area between Dafeis...  相似文献