中国夏季气候对植被覆盖的影响:1982～2001(英文)     

HABIB Aziz Salim  陈晓玲  龚健雅  张力 《地球空间信息科学学报》2009,(1)

In this paper, we apply lagged correlation analysis to study the effects of vegetation cover on the summer climate in different zones of China, using NOAA/AVHRR normalized difference vegetation index (NDVI) data during the time period from 1982 to 2001 and climate data of 365 meteorological stations across China (precipitation from 1982 to 2001 and temperature from 1982 to 1998). The results show that there are positive correlations between spring NDVI and summer climate (temperature and precipitation) in m...  相似文献   

Lateral flow thresholds for aspen forested hillslopes on the Western Boreal Plain,Alberta, Canada     

T. E. Redding  K. J. Devito 《水文研究》2008,22(21):4287-4300

To predict the long‐term sustainability of water resources on the Boreal Plain region of northern Alberta, it is critical to understand when hillslopes generate runoff and connect with surface waters. The sub‐humid climate (P ≤ ET) and deep glacial sediments of this region result in large available soil storage capacity relative to moisture surpluses or deficits, leading to threshold‐dependent rainfall‐runoff relationships. Rainfall simulation experiments were conducted using large magnitude and high intensity applications to examine the thresholds in precipitation and soil moisture that are necessary to generate lateral flow from hillslope runoff plots representative of Luvisolic soils and an aspen canopy. Two adjacent plots (areas of 2·95 and 3·4 m²) of contrasting antecedent moisture conditions were examined; one had tree root uptake excluded for two months to increase soil moisture content, while the second plot allowed tree uptake over the growing season resulting in drier soils. Vertical flow as drainage and soil moisture storage dominated the water balances of both plots. Greater lateral flow occurred from the plot with higher antecedent moisture content. Results indicate that a minimum of 15–20 mm of rainfall is required to generate lateral flow, and only after the soils have been wetted to a depth of 0·75 m (C‐horizon). The depth and intensity of rainfall events that generated runoff > 1 mm have return periods of 25 years or greater and, when combined with the need for wet antecendent conditions, indicate that lateral flow generation on these hillslopes will occur infrequently. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

中南半岛对流对南海夏季风建立过程的影响   总被引：14，自引：1，他引：13  

温敏  何金海  肖子牛 《大气科学》2004,28(6):864-875

利用RegCM2模式进行数值试验,得到中南半岛对流对北半球副高带断裂、进而对孟加拉湾对流建立具有重要影响,而孟加拉湾对流建立后激发的Rossby波列又是南海夏季风建立的主要因子之一.进一步分析中南半岛对流、副高带断裂及南海夏季风建立的年际变化,得到中南半岛对流的强弱(活跃的早晚)与副高带在孟加拉湾北部断裂及南海夏季风爆发的早晚有密切关系.它们还与海温异常及纬圈环流的变化相联系:当赤道中东太平洋海温偏暖(冷)时,Walker环流偏弱(强),中南半岛对流偏弱(强),副高带断裂偏晚(早),南海夏季风建立偏迟(早).  相似文献   

河西走廊春末夏初降水的空间异常分布及年代际变化   总被引：7，自引：2，他引：5  

刘洪兰  李栋梁  郭江勇 《冰川冻土》2004,26(1):55-60

利用河西走廊19个气象代表站建站至2002年5～6月降水量资料, 分析了河西走廊春末夏初干旱的基本气候特征; 在利用EOF和REOF方法进行降水空间异常变化分析和气候分区的基础上,讨论了第一时间系数(PC1)及各区代表站降水量的年代际变化规律. 结果表明, 河西走廊春末夏初降水量在第一空间尺度上为全区一致; 在第二空间尺度上可分为3个气候区; 在第三空间尺度上可分为5个自然气候区. 1980年代为近50 a来降水最多的10 a, 1990年代有所减少, 20世纪末至21世纪初有明显增加. 前期冬季欧亚径向环流加强, 亚洲区极涡面积扩大、强度加强, 冷空气活动频繁, 将有利于次年春末夏初河西走廊降水偏多. 欧洲青藏高原华北西太平洋的波列, 特别是东亚大槽的填塞和青藏高原低值系统频繁活动, 造成了500 hPa高空场上"东高西低"的典型多雨流型.  相似文献   

海表温度异常影响东亚夏季风年代际变化的数值模拟   总被引：2，自引：2，他引：0       下载免费PDF全文

曾刚  伯忠凯  孙照渤  倪东鸿  李忠贤 《大气科学学报》2013,36(3):286-296

采用1950-2000年逐月观测的不同海域(全球、热带外、热带、热带印度洋-太平洋、热带印度洋及热带太平洋)海表温度分别驱动NCAR CAM3全球大气环流模式,进行了多组长时间积分试验,对比ERA-40和NCEP/NCAR再分析资料,讨论了这些海域海表温度异常对东亚夏季风年代际变化的影响。数值试验结果表明:全球、热带、热带印度洋-太平洋和热带太平洋海表温度变化对东亚夏季风的年代际变化具有重要作用,均模拟出了东亚夏季风在20世纪70年代中后期发生的年代际减弱现象,以及强、弱夏季风年代夏季大气环流异常分布的显著不同,这与观测结果较一致,表明热带太平洋是影响东亚夏季风此次年代际变化的关键海区;利用热带印度洋海表温度驱动模式模拟出的东亚夏季风在20世纪70年代中后期发生年代际增强现象,即当热带印度洋海表温度年代际偏暖(冷)时,东亚夏季风年代际增强(减弱),与热带太平洋海表温度变化对东亚夏季风年代际变化的影响相反;热带太平洋海表温度年代际背景的变化对东亚夏季风在20世纪70年代中后期的年代际减弱有重要作用。  相似文献   

Introduction to the Regional Coupled Model WRF4-LICOM: Performance and Model Intercomparison over the Western North Pacific     

Liwei ZOU  Tianjun ZHOU  Jianping TANG  Hailong LIU 《大气科学进展》2020,37(8):800-816

Regional coupled modeling is one of the frontiers of regional climate modeling, but intercomparison has not been well coordinated. In this study, a community regional climate model, WRF4, with a resolution of 15 km, was coupled with a high-resolution(0.1°) North Pacific Ocean model(LICOM_np). The performance of the regional coupled model,WRF4_LICOM, was compared to that of another regional coupled model, RegCM4_LICOM, which was a coupling of version 4 of the Regional Climate Model(RegCM4) with LICOM_np. The analysis focused on the 2005 western North Pacific summer monsoon rainfall. The results showed that the regional coupled models with either RegCM4 or WRF4 as their atmospheric model component simulated the broad features over the WNP reasonably well. Quantitative intercomparison of the regional coupled simulations exhibited different biases for different climate variables.RegCM4_LICOM exhibited smaller biases in its simulation of the averaged June–July–August SST and rainfall, while WRF4_LICOM better captured the tropical cyclone(TC) intensity, the percentage contributions of rainfall induced by TCs to the total rainfall, and the diurnal cycle of rainfall and stratiform percentages, especially over land areas. The different behaviors in rainfall simulated by the two models were partly ascribed to the behaviors in the simulated western North Pacific subtropical high(WNPSH). The stronger(weaker) WNPSH in WRF4_LICOM(RegCM4_LICOM) was driven by overestimated(underestimated) diabatic heating, which peaked at approximately 450 hPa over the region around the Philippines in association with different condensation–radiation processes. Coupling of WRF4 with LIOCM is a crucial step towards the development of the next generation of regional earth system models at the Chinese Academy of Sciences.  相似文献   

Predicting June Mean Rainfall in the Middle/Lower Yangtze River Basin     

Gill M. MARTIN  Nick J. DUNSTONE  Adam A. SCAIFE  Philip E. BETT 《大气科学进展》2020,37(1):29-41

We demonstrate that there is significant skill in the GloSea5 operational seasonal forecasting system for predicting June mean rainfall in the middle/lower Yangtze River basin up to four months in advance.Much of the rainfall in this region during June is contributed by the mei-yu rain band.We find that similar skill exists for predicting the East Asian summer monsoon index(EASMI)on monthly time scales,and that the latter could be used as a proxy to predict the regional rainfall.However,there appears to be little to be gained from using the predicted EASMI as a proxy for regional rainfall on monthly time scales compared with predicting the rainfall directly.Although interannual variability of the June mean rainfall is affected by synoptic and intraseasonal variations,which may be inherently unpredictable on the seasonal forecasting time scale,the major influence of equatorial Pacific sea surface temperatures from the preceding winter on the June mean rainfall is captured by the model through their influence on the western North Pacific subtropical high.The ability to predict the June mean rainfall in the middle and lower Yangtze River basin at a lead time of up to 4 months suggests the potential for providing early information to contingency planners on the availability of water during the summer season.  相似文献   

过去2000年亚澳夏季风降水百年际变化特征及成因的模拟研究     

井云清  刘健  万凌峰  张宏栎 《气象学报》2020,78(1):60-71

利用地球系统模式（CESM）开展过去2000 年气候模拟试验,在利用观测资料、再分析资料对模拟资料进行检验的基础上,探讨百年时间尺度上亚澳夏季风降水的时、空变化特征及其成因,对于认识百年尺度气候变化规律、定量区分自然因子和人类活动对亚澳夏季风的影响具有重要意义。结果表明:过去2000 年亚澳夏季风降水和温度的波动较为一致,暖期降水多,冷期降水少。两者相关系数为0.83,达到99%置信度。此外,亚澳夏季风降水存在105、130、180 a的百年尺度周期。亚澳夏季风降水经验正交函数分解第一模态在印度洋北部呈南北反向的分布型态,在东亚地区呈负、正、负的分布型态;第二模态在印度洋北部呈正、负、正的分布型态,在东亚地区呈全区一致型的分布型态。经验正交函数分解第一特征向量和第二特征向量的正、负值中心大多出现在印度洋北部地区,南北呈不对称分布。亚澳夏季风降水的105 a周期主要受火山活动和土地利用/覆盖的影响,130 a周期主要受太阳辐射、气候系统内部变率的影响,180 a周期主要受火山活动的影响。从经验正交函数分解第一特征向量来看,整个亚澳夏季风降水主要受土地利用/覆盖、太阳辐射的影响;第二特征向量表明亚澳夏季风降水在百年际空间变化上主要受太阳辐射和气候系统内部变率的影响;第三特征向量表明亚澳夏季风降水在百年际空间变化上主要受气候系统内部变率和温室气体的影响。该研究对揭示百年际时间尺度气候变化特征、辨识影响气候变化的自然因素与人为因素、理解其影响气候的物理机制等具有重要意义,也为应对该区域气候变化提供了参考依据。   相似文献   

大气季节内振荡对夏季登陆广东台风的影响     

叶烁旎  凌征 《广东气象》2020,(2):1-6

基于热带气旋最佳路径资料和向外长波辐射数据,结合高斯滤波、经验正交函数分解和合成分析等方法,探讨了20~90 d周期的MJO(Madden-Julian Oscillation)和10~20 d周期的QBWO(Quasi-Biweekly Oscillation)两类大气季节内振荡对夏季(5-9月)登陆广东台风的影响。结果表明:MJO和QBWO对登陆广东台风个数、强度、位置和运动方向均有显著影响:当MJO和QBWO的对流中心(抑制中心)靠近广东沿岸时,登陆广东的台风数量多(少)、强度大(小)、登陆位置偏东(西)、登陆后东向运动的台风数量偏多(少)。在此基础上,还进一步探讨了MJO和QBWO对生成于南海和西北太平洋的这两类登陆广东台风的影响及两者对登陆广东台风的共同影响。  相似文献   

2018年南京梅雨异常特征及环流分析          下载免费PDF全文

金琼  戴竹君  李聪  李菁 《大气科学学报》2020,43(3):557-567

利用自动站降水数据和NCEP/NCAR再分析资料,结合江苏入、出梅指标对2018年南京梅雨进行讨论,分析导致当年南京梅雨异常的环流因子特征。结果表明：1）当年入梅偏晚、出梅正常,梅雨分布不均匀,总量偏少,其中南部异常偏少8成;2）前期南支槽活动频繁,副热带高压相比同期偏南,季节北跳偏迟,且南亚高压主体偏强,位置偏东偏北,导致入梅偏迟;3）入梅后,副热带高压大幅度北抬,南亚高压东伸明显,加之东北冷涡活动弱,使得冷暖气流交汇偏北,因此江苏沿江地区梅雨量偏少;4）南京地区的梅雨量与6-7月副热带高压的南北跨度具有显著的负相关;5）东亚夏季风偏强时,南京中北部地区的梅雨量很可能偏少。  相似文献