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1.
Ocean Assimilation System (OAS) is an important component for decadal prediction experiment, providing initial conditions. Evaluating the atmosphere response in OAS can provide reference for analyzing results from decadal prediction. We analyzed the interdecadal change in relation between the East Asian Summer Monsoon (EASM) and El Niño/Southern Oscillation (ENSO) in the previous winter based on an OAS on the coupled climate model FGOALS-s2. It shows that two factors impact the performance: ① interdecadal change of Ssea Surface Temperature (SST) pattern in the summer Indo-Pacific Basin related with ENSO in previous winter and ② bias in model response of the western North Pacific anticyclone to tropical SST anomalies. The anticyclone shows steady relation with the warm eastern Indian Ocean. When ENSO’s impact on the summer Indian Ocean is strengthened around the end of 1970s, the OAS can reproduce the strengthened EASM-ENSO relation. However, the trend of intensified EASM-ENSO relation in the OAS is still significant after the mid-1990s due to the stronger link between the anticyclone and the northeastern Indian Ocean, differing with the observation which shows a weakened effect of the Indian Ocean on the anticyclone. In addition, the bias in response to the SST anomalies in the central Pacific also partly contributes to the failure in reproducing the weakening EASM-ENSO relation after the mid-1990s. It implies that prediction skill of interdecadal ENSO impact on the tropical Indo-Pacific SST and response bias of model to SST anomalies may to some extent limit the capability to predict the interdecadal change in the EASM-ENSO relation. 相似文献
2.
《地学前缘(英文版)》2015,6(6)
Global warming and climate change is one of the most extensively researched and discussed topical issues affecting the environment.Although there are enough historical evidence to support the theory that climate change is a natural phenomenon,many research scientists are widely in agreement that the increase in temperature in the 20 th century is anthropologically related.The associated effects are the variability of rainfall and cyclonic patterns that are being observed globally.In Southeast Asia the link between global warming and the seasonal atmospheric flow during the monsoon seasons shows varying degree of fuzziness.This study investigates the impact of climate change on the seasonality of monsoon Asia and its effect on the variability of monsoon rainfall in Southeast Asia.The comparison of decadal variation of precipitation and temperature anomalies before the 1970 s found general increases which were mostly varying.But beyond the 1970 s,global precipitation anomalous showed increases that almost corresponded with increases in global temperature anomalies for the same period.There are frequent changes and a shift westward of the Indian summer monsoon.Although precipitation is observed to be 70%below normal levels,in some areas the topography affects the intensity of rainfall.These shifting phenomenon of other monsoon season in the region are impacting on the variability of rainfall and the onset of monsoons in Southeast Asia and is predicted to delay for 15 days the onset of the monsoon in the future.The variability of monsoon rainfall in the SEA region is observed to be decadal and the frequency and intensity of intermittent flooding of some areas during the monsoon season have serious consequences on the human,financial,infrastructure and food security of the region. 相似文献
3.
Explosive volcanic eruptions are known to be a leading cause of natural climate change. There has been a growing recognition that there is a measurable climate system response even to moderate-sized volcanic eruptions. In this study, we investigated the hindcast skills of the Pacific Sea Surface Temperatures (SSTs) using the hindcast experiments based on the near-term climate prediction system DecPreS developed by the Institute of Atmospheric Physics (IAP)(hereafter DP-EnOI-IAU experiments). The DP-EnOI-IAU experiments were run for initial years from 1960 to 2005. These hindcasts took into account observed stratospheric aerosol concentrations that included the four large tropical volcanic eruptions during that period. The time evolution over the entire hindcast period for skill in predicting the patterns of the 3~7 year prediction averages for Pacific SSTs showed that there was statistically significant skill for most years except for a dramatic drop in skill during the 1980s and 1990s. Decadal hindcast skill is reduced if the post-eruption model response deviates the internal El Niño variability in the observations. The simulations showed a post-eruption SST of a La Niña-like pattern in the third northern winter after the 1982 El Chichon eruption and a El Niño-like pattern after the 1991 Pinatubo eruption, which were opposite in sign to what was in the observations. This lead to the loss of hindcast skill for years in the 1980s and 1990s affected by the eruptions. Agung (1963) happened to have post-eruption Pacific SSTs more similar to the observations and thus did not degrade prediction skill in the hindcasts. 相似文献
4.
长江源沱沱河区45a来的气候变化特征 总被引：11，自引：3，他引：8
利用1959—2003年长江源区沱沱河气象站气温、降水、积雪等地面观测资料,对年代际的气候变化特征及其影响进行了分析.结果表明:该区域45 a来夏季增温比较明显.20世纪90年代四季平均气温、平均最高和平均最低气温比最冷的80(或60)年代偏高0.6~1.2℃;降水量(含积雪量)冬季呈增加的趋势,夏季呈减少的趋势,秋、春季降水量增加而积雪量减少;年大风日数80—90年代较60—70年代偏多.80年代是夏季温度升高、降水减少、大风日数增多的暖干气候背景,90年代以来继续加剧,并逐步扩展到春、秋季节,使得该区域的草场退化、冰川和冻土消融加快、湿地资源减少、生态环境恶化. 相似文献
5.
Due to the limitations of model performances, the predictive skills of current climate models for the Asian-Australian summer monsoon precipitation are still poor. The prediction based on the combination of statistical and dynamic approaches is an effective way to improve the predictive skills. We used such method to identify the predictable modes of the Asian-Australian summer monsoon precipitation with clear physical interpretation from the historical observational data. Then we combined the principal components time series of these modes predicted by the coupled models, which is derived from the seasonal prediction experiments in the ENSEMBLES project, and the corresponding spatial patterns derived from the above observational analysis to reconstruct the precipitation field. These formed a statistical-dynamic seasonal prediction model for the Asian-Australian summer monsoon precipitation. We analyzed the predictive skills of the model at 1-, 4-and 7-month leads. The result shows that the forecast skills of the statistical-dynamic prediction model are higher than those of the simple dynamic predictions. In addition, the predictive skills of the Multi-Model Ensemble (MME) mean are superior to those of any individual models. Therefore, it is very necessary to implement multi-model ensemble prediction for the monsoon precipitation. 相似文献
6.
This study investigated the decadal relationship between the East Asian (EA) summer precipitation (EASP) and global sea surface temperature anomaly (SSTA) patterns. Maximum covariance analysis (MCA) was used to identify the coupling relationship between EASP and global SSTA. Four leading coupling modes were identified by MCA and they explained 27.7%,12.5%,8.9%,and 7.3% of the total variance, respectively. The spatial pattern of EASP of the first leading mode exhibited more-than-normal precipitation in most regions of EA. The second mode of EASP depicted a north-south “-+-” tripole pattern. The third one showed a “wet south and dry north” pattern, and the fourth mode exhibited a north-south “+-+” tripole pattern. The four coupling modes were suggested to be modulated by the global warming, Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), and North Pacific Gyre Oscillation (NPGO), respectively.The atmospheric processes and mechanisms underlying such modulations were also investigated. In the first coupling mode, global warming was favorable for increasing water vapor and precipitation over most parts of EA. In the second mode, PDO weakened the EA summer monsoon circulation, and it decreased precipitation in northern and southern EA regions and increased precipitation in the central EA region. The third mode was affected by AMO, which displaced the EA trough southward and weakened the convective activity over the northern EA region, thus leading to deficient precipitation in northern EA region. In the fourth mode, the EA summer monsoon was strengthened by NPGO, thus increasing precipitation in the northern and southern regions and decreasing precipitation in the central region. 相似文献
7.
基于黄河河源区干流各水文站和有关气象站、雨量站的气温、降水与径流观测资料, 分析了该区域的气候变化特征与趋势及其水文响应. 结果表明: 在全球变暖的大背景下, 自20世纪80年代后期开始西北地区西部新疆、甘肃河西走廊西部等地降水量显著增加、气候明显由"暖干"转向"暖湿"后, 到21世纪初的年代中期后黄河源区降水量亦出现明显的增长, 气候明显转向暖湿. 最新的观测数据显示, 2005年以来河源区平均年降水量已连续多年超过多年均值进入一个多雨期, 河源区各断面来水量也于2008年后连续多年超过多年均值, 进入一个连续丰水段, 并于2012年达到了自1989年以后20余年来的最大值. 这种变化的前景如何, 目前尚不能确定, 尚需对未来河源区气候在时间与空间上变化的速度和程度进一步观察和分析. 根据对与该区域气候关系密切的东亚季风活动的研究成果以及对河源区气候与径流变化的观测事实及趋势推测, 未来黄河源区气候向暖湿的转化在时间尺度上年代际的可能性较大. 相似文献
8.
选取位于我国东北多年冻土区南缘的海拉尔河流域作为研究对象,根据海拉尔河水文站1958-2008年的逐月实测径流量资料,用径流量的年内年际变化、各季占年径流量的百分比、年内不均匀系数、集中度以及降水量-径流量双累积曲线等不同指标,分析研究了海拉尔河上游径流量年际变化和年内分配的规律.研究表明：近50 a来海拉尔河径流量总体上呈递减趋势,并且径流量的递减与面上降水量的递减总体上一致;春、秋季节径流量均呈现出下降趋势,冬季径流量呈增加趋势. 冬季径流量增加可能是冬季积雪增多以及流域多年冻土退化,积雪对冻结的抑制有利于冬季的产流,从而使冬季产流增加所致. 径流量年内分配不均匀程度增加,秋季径流量比重显著下降,水资源年内分布集中程度增加,这一现象可能是由于夏季风的减弱所致. 通过运用双累积曲线法,研究区降水与径流的关系在1980年前后发生了明显变化,产流表现为增加趋势,但1999年后产流能力显著下降. 相似文献
9.
利用1961-2011年我国东北地区(包括黑龙江、吉林、辽宁、内蒙古东部)的冬季降水资料,分析了东北地区冬季降水量的时空分布和冬季降水日数的时空分布,对比分析了东亚冬季风对我国东北地区冬季降水的影响. 结果表明：东北地区冬季降水量和降水日数分布有明显的区域差异,以内蒙古东南部、辽宁西北部、吉林西部、黑龙江西南部为低值中心,外围辽宁东部,吉林南部,黑龙江东部、中北部、北部,内蒙古东北部等地区为高值区;冬季降水量年际变化呈增加的线性趋势,1980年代中期以后冬季降水量的高值和低值都有明显的增大;年降雪日数年际变化呈线性增加趋势. 1948-2011年东亚冬季风强度指数的结果表明,东亚冬季风呈明显的线性减弱趋势,弱东亚季风主要集中在20世纪80年代中期以后,除内蒙古东南部等少数区域外,我国东北大部分地区的冬季降水量都和东亚冬季风呈负相关. 对应地,东北地区冬季降水量增大,年际变化的幅度变化增大,降水日数增量较小,这可能与东北地区冬季极端降水天气和干旱天气增加有关. 在东亚范围内,我国东北地区冬季降水多年200 hPa U风增强、500 hPa高压减弱、850 hPa东海南风增强,冬季降水少年则相反. 相似文献
10.
1960-2003年新疆山区与平原积雪长期变化的对比分析 总被引：35，自引：17，他引：18
对新疆91个地面站44a(1960—2003年)的>0cm积雪日数、冬季最大积雪厚度、冬季降水量和冬季平均温度统计分析,结果发现:伴随着20世纪80年代以来明显的增温增湿变化,新疆积雪呈轻度增长趋势,90年代增加明显.积雪日数和厚度与冬季降水量呈正相关,但与冬季平均温度没有明显相关关系.将91个地面站分成24个山区站和67个平原站的进一步分析表明,山区积雪增幅大于平原,而平原的冬季温度和降水增幅大于山区.60年代和90年代山区和平原呈两个相反方向的同步变化(60年代少雪、少降水和降温;90年代多雪、多降水和增温),但幅度略有不同.70年代和80年代山区和平原无论积雪还是温度、降水量都呈现明显不同的变化. 相似文献
11.
以RS/GIS为主要手段, 以基于60年代末航片绘制的那曲县1: 10万地形图、1990年TM遥感数据、2000年ETM遥感数据和1∶25万DEM数据为主要数据源, 结合那曲县温度、降水等资料, 对那曲县湿地分布、面积变迁和驱动力进行分析, 结果表明: 那曲县湿地变迁总体趋势自20世纪70年代以来呈萎缩趋势。空间差异表现为: 那曲县西部小型断陷湖盆谷地区域的湿地面积自70年代以来一直呈现萎缩趋势, 东部、南部高山宽谷地区、河源区湿地自经历70～90年代扩张后, 在90年代面积转为萎缩。气候波动和频繁的人类活动是湿地变迁的驱动力, 湿地的地质、水文等背景因素的不同可能是变迁差异的重要原因。 相似文献
12.
利用水文气象站点数据采用线性趋势分析法和Mann-kendall检验法分析了哈密地区与水资源息息相关的山区与平原区气候要素变化的差异性。结果表明：山区与平原区实测站点气候要素多年平均月系列变化规律与趋势基本一致,在量上存在一定的差异;气象站点与水文站点降水要素均呈波动增加的趋势,总体不明显,山区与平原无明显的差别,相对以头道沟站降水增加较明显;气温均呈波动升高的趋势,并且受所处的地理位置影响较大,在相近经度方向上山区气温的升高幅度高于平原区;哈密气象站与头道沟水文站点降水以上世纪70年代增幅最明显,而伊吾气象站和苇子峡水文站以上世纪80-90年代降水增幅最明显;气温除伊吾气象站上世纪90年代升温明显外,其他各站点均以70-80年代升温最明显。 相似文献
13.
中天山及其北麓的降水变化及其原因分析 总被引：2，自引：1，他引：1
利用中天山地带85.0°～90.0°E,42.5°～45.0°N范围内17个气象站1961-2000年的降水、气温观测数据及美国NCEP/NCAR1950-2000年再分析月平均资料进行计算和分析,结果表明:这一区域近年来降水呈现上升趋势,且冬、夏季相对显著,山区降水增幅大于山前平原地带.年代际变化表现为60-70年代降水量减少,80-90年代逐步增加.大气可降水量多年也表现为增加趋势.近50a来该地区上空的水汽输送状况显示,年平均大气水汽输入为9217.8×108m3,输出水汽8625.7×108m3,净收支为592.0×108m3,且水汽收支主要取决于夏半年的水汽输入量,境外全年输入的水汽只有6.4%转化为降水.从50-90年代水汽净收支总体上呈减少趋势,只在90年代有略微增长.结合该地区的河流径流增加、冰川物质平衡一直处于亏损状态,说明中天山北麓近年来降水量增加的主要原因是由于该地区内部的水循环量增加和水循环速率提高. 相似文献
14.
近40 a来青藏高原地区总辐射变化特征分析 总被引：1，自引：1，他引：0
利用青藏高原及周边22个日射站近40 a的总辐射及日照百分率资料确定了Angstrom-Prescott模型(APM)系数, 结合高原及毗邻地区116个地面站的资料估算了高原地区近40 a的总辐射. 结果表明: 高原主体光照充沛, 年均日照时数可达3000 h以上, 有较好的利用前景; 总辐射40 a平均年总量在高原西部为高值区, 此高值带向东北和东南延伸, 其中北支可抵达内蒙古高原.年代际变化在高原及周边地区不一致, 但从整体上看, 总辐射距平值60、 70年代为正值, 表明这一时期高原总辐射增大; 80、 90年代总辐射距平为负, 这一时期总辐射减小. 火山活动是该时段总辐射减小的一个重要原因; 总辐射随着纬度的增大而减小, 随着海拔、 日照百分率的增大而增大. 纬度、 海拔、 日照3个因子中, 日照是总辐射的一个主要影响因子, 纬度对总辐射影响较大, 海拔对总辐射影响较小; 高原地区总辐射变差系数大值区在高原西部. 就平均状况而言, 高原地区总辐射变差系数仅为0.031, 表明高原地区总辐射波动相对较小, 总辐射较稳定. 相似文献
15.
新疆阿勒泰地区近50 a夏季极端降水事件变化特征 总被引：3，自引：2，他引：1
利用新疆阿勒泰地区近50 a(1961-2010年)7站夏季(6-8月)逐日降水资料、NCEP/NCAR资料及大气环流指数,采用百分位定义法确定各站夏季极端降水事件阈值,运用线性趋势、突变分析、滑动t检验、Morlet小波分析及相关分析等方法来分析该地区夏季极端降水事件的气候变化.研究表明:阿勒泰地区各站夏季极端降水事件阈值为9.0~13.1 mm·d-1,阈值存在明显的空间分布差异,且地形及海拔高度对该地区夏季极端降水事件阈值均有影响,海拔高度与阈值两者基本呈指数关系.近50 a来阿勒泰地区夏季极端降水频数及强度的年代际变化具有较好的同步性,均表现为20世纪80年代中期之前频数(强度)偏少(弱),80年代中期以后频数(强度)增多(增强),并于20世纪90年代中期达到最多(最强),但进入2000年后频数(强度)开始减少(减弱).近50 a来阿勒泰地区夏季极端降水事件年际变化的持续性较好,大部分站均没有出现显著性突变,只有阿勒泰、富蕴站在20世纪80年代末期及90年代初出现了明显的突变.北非大西洋北美副高脊线、北非副高脊线、西藏高原A指数是影响该地区夏季极端降水事件的主要因子. 相似文献
16.
This study assesses retrospective decadal prediction skill of Sea Surface Temperature (SST) variability in initialized climate prediction experiments (INT) with the Beijing Climate Center Climate System Model (BCC_CSM1.1). Ensemble forecasts were evaluated using observations, and compared to an ensemble of uninitialized simulations (NoINT). The results show as follows: ①The warming trend of global mean SST simulated by the INT runs is closer to the observation than that in the NoINT runs.②The INT runs show high SST prediction skills over broad regions of tropical Atlantic, western tropical Pacific and tropical Indian Oceans. ③ In the North Pacific and the east-central tropical Pacific Ocean, the prediction skills are very weak, and there are few improvements coming from the initialization in the INT runs. ④ In the southern Indian Ocean, the prediction skills of the INT runs are significantly larger than that of the NoINT runs, with the maximum skill at the 3~6 and 4~7 years lead time. The above-mentioned conclusions are similar to the results of other climate models. However, the prediction skill in the North Atlantic Ocean is much lower than that of other models, especially in the subpolar region. The low skills in the Atlantic Ocean may be attributed to the misrepresentation of the lead-lag relationship between the Atlantic meridional heat transport and the SST in the BCC_CSM1.1. 相似文献
17.
青藏高原气候变化的若干事实及其年际振荡的成因探讨 总被引：1，自引：0，他引：1
利用1961-2012年青藏高原88个气象台站逐月气温、降水以及温室气体等气候系统监测资料和CMIP5输出的未来气候变化情景数据,分析了近52年来青藏高原气候变化暖湿化的若干事实,揭示了其年际振荡与温室气体、高原加热场、高原季风、AO等气候系统因子的关系,预测了未来20~40年青藏高原可能的气候变化趋势。研究表明：近52年来青藏高原在总体保持气候变暖的趋势下自2006年以来出现了某些增暖趋于缓和的迹象,较全球变化滞后了8年左右;降水量的增加在青藏高原具有明显的普遍性和显著性,气候变湿较变暖具有一定的滞后性,降水量变化的5年短周期日趋不显著,而12年、25年较长周期逐渐明显且仍呈增多趋势。由于温室气体、气溶胶持续增加、高原夏季风趋强、ENSO事件和太阳辐射减少,青藏高原气候持续增暖但有所缓和;春季高原加热场增强、高原夏季风爆发提前且保持强劲,使得高原春、夏季和年降水量增加,而秋、冬季AO相对稳定少动,东亚大槽强度无明显变化,高原冬季风变化不甚显著,导致了高原秋、冬季降水量无明显变化。未来20~40年青藏高原仍有可能继续保持气温升高、降水增加趋势。 相似文献
18.
中国西北地区的干旱与旱灾——变化趋势与对策 总被引：16，自引：1，他引：16
干旱与水资源短缺是西北地区的基本环境特征。西北地区在气候变暖的背景下,区域降水量出现了明显的区域差异:西北西部的新疆地区,20世纪80年代以来降水量增加;西北东部大部分地区降水量持续减少,干旱、连旱趋势增加;黄河流域西北区域降水量减少,干旱化趋势最为显著。在气候干旱化增强的背景下,新疆地区总体上经过70年代的枯水期后,在80年代中期开始较大范围内径流量呈现增加趋势;河西东部、西北东部的黄河流域等地区,70年代以来径流持续减少,大部分河流枯水频率在78%以上,水文干旱化趋势显著。水资源的开发利用、水土保持以及土地利用等人类活动使得西北地区水文干旱进一步加剧。干旱是西北地区最为严重的自然灾害之一,受干旱化气候和水文变化趋势的影响,黄河流域和内陆流域干旱灾害不断加剧,近50a干旱灾害受灾面积急剧扩张,旱灾造成的农业粮食损失不断增加。从创新水资源开发利用途径与管理等角度,提出了提高气候变化的地区适应性和区域水-经济系统旱灾抵御能力的对策与建议。 相似文献
19.
NACHIKETA ACHARYA S C KAR MAKARAND A KULKARNI U C MOHANTY L N SAHOO 《Journal of Earth System Science》2011,120(5):795-805
The northeast (NE) monsoon season (October, November and December) is the major period of rainfall activity over south peninsular
India. This study is mainly focused on the prediction of northeast monsoon rainfall using lead-1 products (forecasts for the
season issued in beginning of September) of seven general circulation models (GCMs). An examination of the performances of
these GCMs during hindcast runs (1982–2008) indicates that these models are not able to simulate the observed interannual
variability of rainfall. Inaccurate response of the models to sea surface temperatures may be one of the probable reasons
for the poor performance of these models to predict seasonal mean rainfall anomalies over the study domain. An attempt has
been made to improve the accuracy of predicted rainfall using three different multi-model ensemble (MME) schemes, viz., simple arithmetic mean of models (EM), principal component regression (PCR) and singular value decomposition based multiple
linear regressions (SVD). It is found out that among these three schemes, SVD based MME has more skill than other MME schemes
as well as member models. 相似文献
20.
吉林近50a来气候的年代际变化特征及其突变分析 总被引：16，自引：6，他引：10
利用吉林省50个地面气象站的观测资料对近50 a来吉林气候的年代际变化进行了诊断分析, 结果表明: 吉林省的年平均气温在20世纪50年代呈下降趋势, 60年代为相对低温期, 70年代开始表现出逐渐增温的趋势; 20世纪50年代降水量逐渐减少, 60-70年代为相对降水少的时期, 80年代降水略有增加, 进入90年代以后, 降水量又表现为逐渐减少的趋势. 近50 a来气候的年代际变化经历了一个"冷湿-冷干-暖湿-暖干"的过程.吉林省的最高、最低气温在近50 a内的总体趋势都是上升的, 但从增温率来看, 最低气温大约是最高气温的2.3倍.采用分段线性拟合的方法对吉林省年降水量和年平均气温进行气候突变的检验, 发现年降水量在1977和1987年各有一次突变, 年平均气温只在1969年发生了一次突变. 相似文献