华东地区月平均气温统计降尺度方法比较   总被引：1，自引：0，他引：1  

高红霞  汤剑平 《气象科学》2015,35(6):760-768

用中国地面气象观测站的逐日气温观测资料和NCEP/NCAR再分析资料,分别使用基于多元线性回归(MLR)和3种主成分分析(PCA)的统计降尺度方法,对1959-2008年的华东地区的月平均气温分两个时段进行统计降尺度分析并加以检验,比较了不同降尺度方法的结果。结果表明:对于华东地区气温的统计降尺度预报,基于MLR的统计降尺度方法相对于3种PCA方法而言,对单站年际变化模拟方面有一定优势。PCA方法应用于统计降尺度时,预报因子的区域选择是影响统计降尺度结果的重要因素之一。对于温度进行统计降尺度分析时,预报因子中包含温度因子是非常必要的;所试验的4种降尺度方法,对各站点多年平均情况的模拟要好于对区域平均的年际变化的模拟。  相似文献   

Potential impact of future climate change on crop yield in northeastern China   总被引：1，自引：0，他引：1  

Mengzi Zhou  Huijun Wang 《大气科学进展》2015,32(7):889-897

We evaluated the potential impact of future climate change on spring maize and single-crop rice in northeastern China(NEC) by employing climate and crop models. Based on historical data, diurnal temperature change exhibited a distinct negative relationship with maize yield, whereas minimum temperature correlated positively to rice yield. Corresponding to the evaluated climate change derived from coupled climate models included in the Coupled Model Intercomparison Project Phase 5(CMIP5) under the Representative Concentration Pathway 4.5 scenario(RCP4.5), the projected maize yield changes for three future periods [2010–39(period 1), 2040–69(period 2), and 2070–99(period 3)] relative to the mean yield in the baseline period(1976–2005) were 2.92%, 3.11% and 2.63%, respectively. By contrast, the evaluated rice yields showed slightly larger increases of 7.19%, 12.39%, and 14.83%, respectively. The uncertainties in the crop response are discussed by considering the uncertainties obtained from both the climate and the crop models. The range of impact of the uncertainty became markedly wider when integrating these two sources of uncertainty. The probabilistic assessments of the evaluated change showed maize yield to be relatively stable from period 1 to period 3, while the rice yield showed an increasing trend over time. The results presented in this paper suggest a tendency of the yields of maize and rice in NEC to increase(but with great uncertainty) against the background of global warming, which may offer some valuable guidance to government policymakers.  相似文献   

Influence of future tropical cyclone track changes on their basin-wide intensity over the western North Pacific: Downscaled CMIP5 projections     

Chao Wang  Liguang Wu 《大气科学进展》2015,32(5):613-623

The possible changes of tropical cyclone(TC) tracks and their influence on the future basin-wide intensity of TCs over the western North Pacific(WNP) are examined based on the projected large-scale environments derived from a selection of CMIP5(Coupled Model Intercomparison Project Phase 5) models. Specific attention is paid to the performance of the CMIP5 climate models in simulating the large-scale environment for TC development over the WNP. A downscaling system including individual models for simulating the TC track and intensity is used to select the CMIP5 models and to simulate the TC activity in the future.The assessment of the future track and intensity changes of TCs is based on the projected large-scale environment in the21 st century from a selection of nine CMIP5 climate models under the Representative Concentration Pathway 4.5(RCP4.5)scenario. Due to changes in mean steering flows, the influence of TCs over the South China Sea area is projected to decrease,with an increasing number of TCs taking a northwestward track. Changes in prevailing tracks and their contribution to basin-wide intensity change show considerable inter-model variability. The influences of changes in prevailing track make a marked contribution to TC intensity change in some models, tending to counteract the effect of SST warming. This study suggests that attention should be paid to the simulated large-scale environment when assessing the future changes in regional TC activity based on climate models. In addition, the change in prevailing tracks should be considered when assessing future TC intensity change.  相似文献   

Seasonal prediction of June rainfall over South China: Model assessment and statistical downscaling     

Kun-Hui Ye  Chi-Yung Tam  Wen Zhou  Soo-Jin Sohn 《大气科学进展》2015,32(5):680-689

The performances of various dynamical models from the Asia-Pacific Economic Cooperation(APEC) Climate Center(APCC) multi-model ensemble(MME) in predicting station-scale rainfall in South China(SC) in June were evaluated.It was found that the MME mean of model hindcasts can skillfully predict the June rainfall anomaly averaged over the SC domain.This could be related to the MME's ability in capturing the observed linkages between SC rainfall and atmospheric large-scale circulation anomalies in the Indo-Pacific region.Further assessment of station-scale June rainfall prediction based on direct model output(DMO) over 97 stations in SC revealed that the MME mean outperforms each individual model.However,poor prediction abilities in some in-land and southeastern SC stations are apparent in the MME mean and in a number of models.In order to improve the performance at those stations with poor DMO prediction skill,a station-based statistical downscaling scheme was constructed and applied to the individual and MME mean hindcast runs.For several models,this scheme can outperform DMO at more than 30 stations,because it can tap into the abilities of the models in capturing the anomalous Indo-Paciric circulation to which SC rainfall is considerably sensitive.Therefore,enhanced rainfall prediction abilities in these models should make them more useful for disaster preparedness and mitigation purposes.  相似文献   

多源遥感数据的降水空间降尺度研究——以川渝地区为例   总被引：2，自引：0，他引：2  

嵇涛  刘睿  杨华  何太蓉  吴建峰 《地球信息科学学报》2015,(1):108-117

大量研究表明,通过传统地面气象站点实测的单点数据,不能有效地反映降水的空间变化特征。目前,以遥感数据获取的降水产品已得到了广泛的应用,但在地形地势复杂区域,遥感降水产品的空间分辨率与数据精度等方面仍然存在着极大的不足。因此,本文以四川重庆(川渝)地区为例,通过建立降水产品降尺度算法,以实现降水产品的降尺度估算,提高降水数据的空间分辨率。依据在不同尺度下(0.25°、0.50°、0.75°和1.00°),TRMM 3B43、地理因子,以及MOD13A3(NDVI)之间存在的相关关系,构建了多元回归模型。通过对比这4种尺度下的回归模型,选择其中精度最高的作为最终的降尺度算法,然后再把这种降尺度算法应用到1 km分辨率下进行降水估算。进一步,以区域差异分析(GDA)和区域比率分析法(GRA)对降尺度估算的降水数据进行校正,并结合部分地面气象站点实测的降水数据进行验证。验证结果表明:降尺度算法是可靠的,能有效提升降水产品的空间分辨率,同时GDA和GRA校正方法能减小误差,进一步提升降水估算的精度,满足区域地表过程应用的需求。  相似文献   

未来黄、东海营养盐浓度变化情景预测   总被引：1，自引：0，他引：1  

赵一丁  杨波  魏皓  赵亮 《海洋与湖沼》2015,46(5):983-994

本文基于FGOALS(Flexible Global Ocean-Atmosphere-Land System model)对未来气候情景的预测结果,结合千年生态评估的未来两个情景下的河流营养盐载荷特征,利用黄、东海水动力模型和生态模型并采用降尺度的方法对未来黄、东海营养盐的分布特征进行情景预测。结果表明,两个情景下未来河口邻近海区营养盐浓度将显著增加,富营养化加剧;GO(Global Orchestration)情景下,河流无机氮载荷增幅较大,夏季黄海中部无机氮浓度明显升高;AM(Adapting mosaic)情景下,由于河流无机磷载荷增幅较大,海区氮磷比有所下降,夏季黄海中部表层无机氮浓度降低,而在底层升高。通过敏感性实验并结合收支分析对各海区水动力条件未来变化、河流载荷变化的相对贡献进行了评估:相对于水温和水动力环境改变,河流营养盐排放量的增长是未来营养盐浓度增加的主要原因。营养盐收支分析表明,未来对流和混合输运的变化有助于黄海营养盐浓度的增加,夏季生物量升高造成更多碎屑沉降并在底层矿化使得层化季节冷水团底部营养盐浓度增长;长江口邻近海区营养盐浓度增长主要受冲淡水羽流的影响;净初级生产增加加剧了营养盐的消耗。  相似文献   

基于破碎临界区的新型拍岸浪统计计算模型研究     

YANG Jiaxuan  LI Xunqiang  ZHU Shouxian  ZHANG Wenjing  WANG Lei 《海洋学报(英文版)》2015,34(5):81-85

When waves propagate from deep water to shallow water, wave heights and steepness increase and then waves roll back and break. This phenomenon is called surf. Currently, the present statistical calcula...  相似文献   

基于Landsat-8遥感影像和LiDAR测深数据的水深主被动遥   总被引：1，自引：0，他引：1  

田震  马毅  张靖宇  梁建 《海洋技术学报》2015,34(2):1-8

主被动遥感结合反演远海岛礁周边水深信息,不仅可以有效弥补传统测深方法覆盖范围小且费时费力的不足,也可为航运安全、海洋减灾、生态环境保护等领域提供基础资料。以夏威夷瓦胡岛周边水深反演为例,应用Landsat-8多光谱遥感数据和机载Li DAR测深数据,开展了不同密度Li DAR测深数据对水深多光谱遥感反演精度的影响分析、不同水深网格化处理方法对水深遥感反演结果的影响分析和基于少量Li DAR控制区块的大区域水深反演能力分析三方面的研究工作。结果表明:(1)Li DAR测深数据密度的改变对水深反演结果的影响不大,变化后的水深反演结果与原始的水深反演结果相比,平均相对误差变化在0.3%以内,平均绝对误差变化在0.03m以内;(2)采用均值格网处理方法的多光谱遥感水深反演精度要略高于采用中值格网处理方法的水深反演精度,具体体现在均值的平均绝对误差要比中值的低0.04~0.05 m,平均相对误差低1%~10%,反演结果的残差分布显示在0~2 m和20~25 m的水深段内均值统计法的残差分布更集中且其平均值接近于0 m,而在其它水深段二者的残差分布基本相同;(3)基于少量Li DAR控制区块的大区域遥感水深反演结果较为理想,两个检查区块的水深反演结果 R2、平均绝对误差和平均相对误差分别为:0.877,1.66 m,3.5%和0.941,1.62 m,28.4%。反演结果分段分析表明各水深段内反演的精度都比较理想,平均绝对误差除20~25 m水深段外,均低于2.5 m,平均相对误差除0~2 m,2~5 m外,均低于25%。  相似文献   

GIS科普资源发布系统实现的关键技术     

袁家勇  公茂玉  高诗亮 《测绘科学》2011,36(3):239-240,218

科普资源发布系统利用GIS强大的空间查询与分析功能,方便市民浏览、查询与统计科普资源情况,掌握更多科普知识.本文主要论述了系统设计与实现过程中应用的关键技术,详细给出了栅格影像自动选择的方法,矢量栅格匹配的原理,以及统计图的绘制技术.最后介绍了系统的开发模式与软件环境,给出了统计效果图.  相似文献   

基于验后方差估计原理导出的选权迭代法剔除粗差     

孙同贺 《测绘与空间地理信息》2011,34(1):215-217

将抗差估计的思想融入到粗差探测的算法中,设计出对模型误差,特别是粗差具有抵抗能力的粗差探测算法.基于验后方差估计原理导出的选权迭代法即为抗差佑计的一种,首先是应用最小二乘法来计算观测值的参数x、残差V、协因数阵Qvv及单位权σ0 的初值,然后再根据残差和有关的参数,按所选择的权函数,计算每个观测值的权,经过迭代计算求得...  相似文献