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   

中国东部夏季降水与气温的联合EOF分析     

郑金新  黎洛丝  郑嘉雯  郑菲菲 《广东气象》2019,41(2):9-14

采用JEOF等方法分析中国东部夏季降水和气温的协同变化时空分布特征,结果表明:当时间系数为正时,第1典型场降水型态从北向南(下同)呈"++-"分布,气温表现为冷异常,500 hPa回归场在中纬度地区呈显著低压异常,SST回归场表现为太平洋海域呈西北-东南的分布;第2典型场降水呈"+-"分布,气温则呈"-+"分布;第3典型场降水分布呈中间型,气温场呈"-+"分布。  相似文献   

河源市秋季暴雨的时空分布和环流特征     

段海花  侯学源  贺发胜 《广东气象》2019,(1):5-9

利用1964—2013年河源市5个国家气象站日降水量、NCEP/NCAR逐月2.5°×2.5°再分析资料,分析河源市秋季暴雨的时空分布特征和同期环流特征。结果表明:(1)河源市秋季暴雨日数在空间分布上自南向北逐渐减少,9月的分布特征与秋季一致,11月的分布型与9月完全相反;秋季暴雨日数呈弱增长的气候变化趋势,且存在明显的阶段性变化。(2)南海到西北太平洋地区纬向风垂直切变偏小和南方涛动处在正位相时,对应有利9和10月热带气旋的生成、发展,副热带高压偏西偏北、强度偏强,有利于热带气旋趋向广东,而来自该区的强东南季风,给河源带来充沛的水汽,为暴雨的发生提供了有利的水汽条件。另外,活跃的南支槽也是造成10月暴雨的重要影响系统之一。(3)热带气旋对11月暴雨日数的贡献较小,南支槽和东移南下的高原短波槽是造成该月暴雨的重要影响系统。西太平洋副热带高压偏西偏南、强度偏强,河源受其西侧的异常西南风影响,获得充足的水汽供应,有利于暴雨的发生。(4)秋季华南地区海平面气压偏低或冷空气活动偏弱时,有利于河源暴雨天气的发生。  相似文献   

亚印太交汇区海表温度的分布和变化特征及其对中国降水的影响     

卢峰  郑彬 《海洋学报》2011,33(5):39-46

利用1967-2009年的逐月海表温度(Sea Surface Temperature,SST)资料和降水资料,以及经验正交函数(Empirical Orthogonal Function,EOF)和相关分析方法,探讨了亚印太交汇区(Joining Area of Asia and Indian-Pacific Oce...  相似文献   

安徽宣城红土微生物GDGTs分布特征及其古环境意义   总被引：1，自引：0，他引：1       下载免费PDF全文

马瑞元  彭红霞  张林  顾延生  胡圣虹 《地球科学》2015,40(5):863-869

中国南方更新世红土是古气候环境变化研究非常重要的载体之一,红土微生物类脂分子是其古气候环境研究的有效指标,但其在红土中的古气候意义需要更进一步的挖掘和明确.选取处于气候变化敏感地带并且已有很好年代学基础的安徽宣城红土剖面进行详细的野外调查和系统的样品采集,利用改善后的碱式水解法提取红土微生物类脂分子,通过对比分析、比较印证等方法对其中的甘油二烷基链甘油四醚(glycerol dialkyl glycerol tetraethers,简称GDGTs)进行系统研究.宣城剖面GDGTs分布特征显示:剖面下部各指标呈旋回性变化、而上部相对稳定,表明形成初期环境比较动荡,而后期成土环境相对稳定;土壤pH为7.0~8.0,推测其物源主要来源于北方干旱区或长江中下游干涸河滩沉积;BIT指标反映宣城地区在130 ka BP左右气候极为干旱.结果表明,红土中微生物类脂物GDGTs能够定量、高分辨率地重建安徽宣城的古气候环境,具有重要的研究意义.   相似文献   

IMPACT OF TROPICAL INTRASEASONAL OSCILLATIONS ON THE PRECIPITATION OF GUANGDONG IN JUNES     

林爱兰  李春晖  谷德军  郑彬 《热带气象学报(英文版)》2015,21(4):326-336

The impact of tropical intraseasonal oscillations on the precipitation of Guangdong in Junes and its physical mechanism are analyzed using 30-yr (1979 to 2008), 86-station observational daily precipitation of Guangdong and daily atmospheric data from NCEP-DOE Reanalysis. It is found that during the annually first rainy season (April to June), the modulating effect of the activity of intraseasonal oscillations propagating eastward along the equator (MJO) on the June precipitation in Guangdong is different from that in other months. The most indicative effect of MJO on positive (negative) anomalous precipitation over the whole or most of the province is phase 3 (phase 6) of strong MJO events in Junes. A Northwest Pacific subtropical high intensifies and extends westward during phase 3. Water vapor transporting along the edge of the subtropical high from Western Pacific enhances significantly the water vapor flux over Guangdong, resulting in the enhancement of the precipitation. The condition is reverse during phase 6. The mechanism for which the subtropical high intensifies and extends westward during phase 3 is related to the atmospheric response to the asymmetric heating over the eastern Indian Ocean. Analyses of two cases of sustained strong rainfall of Guangdong in June 2010 showed that both of them are closely linked with a MJO state which is both strong and in phase 3, besides the effect from a westerly trough. It is argued further that the MJO activity is indicative of strong rainfall of Guangdong in June. The results in the present work are helpful in developing strategies for forecasting severe rainfall in Guangdong and extending, combined with the outputs of dynamic forecast models, the period of forecasting validity.  相似文献   

The Project Siberian High in CMIP5 Models          下载免费PDF全文

LI Fei  GAO Yong-Qi 《大气和海洋科学快报》2015,8(4)

The Siberian high(SH)experienced a decline from the 1970s to 1990s and a recovery in recent years.The evolution of the SH under global warming is unclear.In this study,41 Coupled Model Intercomparison Project Phase 5(CMIP5)climate models are evaluated in terms of their ability to simulate the temporal evolution of the SH in the 19th and 20th centuries and the spatial pattern of the SH during 1981–2005.The results show that 12models can capture the temporal evolution of the SH center intensity(SHCI)for 1872–2005.The linear correlation coefficient between the SHCI from the Twentieth Century Reanalysis and the simulated SHCI from the multi-model ensemble(MME)of the 12 models is 0.3 on annual and inter-annual scales(above the 99%confidence level).On decadal and multi-decadal time scales,the MME also captures the pronounced reduction(between 1981–2000and 1881–1900 period)and the recovery(during1991–2005)of the SH intensity.Finally,the future evolution of the SH is investigated using the MME of the 12models under the+4.5 and+8.5 W m-2 Representative Concentration Pathway(RCP)scenarios(RCP4.5 and RCP8.5).It is shown that the SHCI,similar to the SHCI in the 20th century,has no significant long-term trend in the 21st century under global warming(RCP8.5 scenario).At the end of 21st century(2081–2100),the SH shows stronger interannual variability than the SH at the end of20th century(1981–2000).The increased interannual variability likely favors the increased interannual variability in winter air temperature over midlatitude Eurasia at the end of 21st century.  相似文献   

Analyses of the warm season rainfall climatology of the northeastern US using regional climate model simulations and radar rainfall fields     

June K. Yeung  James A. SmithGabriele Villarini  Alexandros A. NtelekosMary Lynn Baeck  Witold F. Krajewski 《Advances in water resources》2011,34(2):184-204

We examine the warm season (April-September) rainfall climatology of the northeastern US through analyses of high-resolution radar rainfall fields from the Hydro-NEXRAD system and regional climate model simulations using the weather research and forecasting (WRF) model. Analyses center on the 5-year period from 2003 to 2007 and the study area includes the New York-New Jersey metropolitan region covered by radar rainfall fields from the Fort Dix, NJ WSR-88D. The objective of this study is to develop and test tools for examining rainfall climatology, with a special focus on heavy rainfall. An additional emphasis is on rainfall climatology in regions of complex terrain, like the northeastern US, which is characterized by land-water boundaries, large heterogeneity in land use and cover, and mountainous terrain in the western portion of the region. We develop a 5-year record of warm season radar rainfall fields for the study region using the Hydro-NEXRAD system. We perform regional downscaling simulations for the 5-year study period using the WRF model. Radar rainfall fields are used to characterize the interannual, seasonal and diurnal variation of rainfall over the study region and to examine spatial heterogeneity of rainfall. Regional climate model simulations are characterized by a wet bias in the rainfall fields, with the largest bias in the high-elevation regions of the model domain. We show that model simulations capture broad features of the interannual, seasonal, and diurnal variation of rainfall. Model simulations do not capture spatial gradients in radar rainfall fields around the New York metropolitan region and land-water boundaries to the east. The model climatology of convective available potential energy (CAPE) is used to interpret the regional distribution of warm season rainfall and the seasonal and diurnal variability of rainfall. We use hydrologic and meteorological observations from July 2007 to examine the interactions of land surface processes and rainfall from a regional perspective.  相似文献   

Oceanic climatology in the coupled model FGOALS-g2: Improvements and biases   总被引：1，自引：0，他引：1  

林鹏飞  俞永强  刘海龙 《大气科学进展》2013,30(3):819-840

The present study examines simulated oceanic climatology in the Flexible Global Ocean-Atmosphere-Land System model, Grid-point Version 2 (FGOALS-g2) forced by historical external forcing data. The oceanic temperatures and circulations in FGOALS-g2 were found to be comparable to those observed, and substantially improved compared to those simulated by the previous version, FGOALS-g1.0. Compared with simulations by FGOALS-g1.0, the shallow mixed layer depths were better captured in the eastern Atlantic and Pacific Ocean in FGOALS-g2. In the high latitudes of the Northern Hemisphere, the cold biases of SST were about 1°C–5°C smaller in FGOALS-g2. The associated sea ice distributions and their seasonal cycles were more realistic in FGOALS-g2. The pattern of Atlantic Meridional Overturning Circulation (AMOC) was better simulated in FGOALS-g2, although its magnitude was larger than that found in observed data. The simulated Antarctic Circumpolar Current (ACC) transport was about 140 Sv through the Drake Passage, which is close to that observed. Moreover, Antarctic Intermediate Water (AAIW) was better captured in FGOALS-g2. However, large SST cold biases (>3°C) were still found to exist around major western boundary currents and in the Barents Sea, which can be explained by excessively strong oceanic cold advection and unresolved processes owing to the coarse resolution. In the Indo-Pacific warm pool, the cold biases were partly related to the excessive loss of heat from the ocean. Along the eastern coast in the Atlantic and Pacific Oceans, the warm biases were due to overestimation of shortwave radiation. In the Indian Ocean and Southern Ocean, the surface fresh biases were mainly due to the biases of precipitation. In the tropical Pacific Ocean, the surface fresh biases (>2 psu) were mainly caused by excessive precipitation and oceanic advection. In the Indo-Pacific Ocean, fresh biases were also found to dominate in the upper 1000 m, except in the northeastern Indian Ocean. There were warm and salty biases (3°C–4°C and 1–2 psu) from the surface to the bottom in the Labrador Sea, which might be due to large amounts of heat transport and excessive evaporation, respectively. For vertical structures, the maximal biases of temperature and salinity were found to be located at depths of >600 m in the Arctic Ocean, and their values exceeded 4°C and 2 psu, respectively.  相似文献   

2011年初云南东部极端低温冰冻灾害天气气候特征及成因分析     

杨素雨  李华宏  严华生  牛法宝 《成都信息工程学院学报》2012,27(1):71-76

利用NCEP/NCAA再分析资料,国家气候中心74项环流指数及云南省122个观测站资料,结合诊断、合成和相关分析等方法,探讨2011年初云南东部极端低温冰冻灾害天气气候特征及成因,并与2008年初低温冰冻灾害进行对比分析。旨在寻找云南低温冰冻天气的预报着眼点,为提前做好防灾减灾工作提供决策依据。研究表明:500hPa高度场欧亚中高纬呈两槽一脊,西西伯利亚高压脊异常强大,贝巴之间为东西向横槽,东亚中高纬呈"+-+"的高度场距平分布,西太平洋副热带高压异常偏东偏弱,南海副高异常偏南偏弱是2011年1月云南东部频遭冷空气影响的大尺度大气环流背景。另外,相关分析发现NINO4区海温持续异常偏冷对应云南东部气温异常偏低。较2008年初持续近2个月的低温雨雪冰冻灾害相比,虽然2011年灾害影响时间较短,范围较小,但冷空气过程频发,昆明准静止锋长时间控制云南东部,最终造成近50年来的极端低温冰冻灾害。  相似文献