共查询到19条相似文献，搜索用时 830 毫秒
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投影寻踪聚类分析是根据设计的投影指标函数,并在相关约束条件下进行问题优化分析的过程.给出了用于求解投影指标函数的粒子群算法,并将构造的模型应用于森林承载力评价.仿真实验结果表明:与基于遗传算法优化的模型比较,基于粒子群优化的模型简单、容易实现并且没有许多参数需要调整;在应用上,基于粒子群优化的模型可获得更优的解,并可预计模型在森林承载力评价中具有重要的应用价值. 相似文献
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投影寻踪回归模型及其在降水预测中的应用 总被引：2，自引：0，他引：2
于扬 《成都气象学院学报》2000,15(3):213-217
介绍了投影寻踪回归（ＰＰＲ）预测建划的基本思想和算法,并将投影寻踪混合回归９ＰＰＭＲ）和逐步回归（ＳＲ）应用于降水预测数值试验。结果表明,ＰＰＭＲ模型的拟合和预测效果均优于ＳＲ模型的相应效果。 相似文献
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科学合理地评估气象灾害造成的损失, 对减灾、防灾决策具有重要意义。为了建立不同气象灾害系统均能适用的投影寻踪回归 (projection pursuit regression, PPR) 矩阵表示灾情评估模型,在对气象灾情指标值进行规范变换基础上,规范变换后的各指标皆等效于同一个规范指标,因而只需构建对任意2个规范指标值适用的投影寻踪回归 (projection pursuit regression based on normalized index value, NV-PPR) NV-PPR (2) 模型和3个规范指标值适用的投影寻踪回归NV-PPR (3) 模型;对3个以上指标的气象灾害系统NV-PPR建模,只需将其分解为若干个NV-PPR (2) 模型和 (或) NV-PPR (3) 模型的组合即可。模型用于广东省台风和重庆市两起雷电灾情评估,并与其他方法的评估结果进行比较。结果表明:基于NV-PPR的气象灾情评估模型不受指标数量的限制,具有简单、实用的特点,该模型还可推广为适用于其他灾情评估。 相似文献
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投影寻踪回归与BP神经网络方法在前汛期降水预测中的比较研究 总被引：1，自引：0，他引：1
以1962—2006年粤北地区7个站4—6月前汛期降水量资料为基础,将前汛期降水量与74项环流指数资料进行灰色关联度分析,确定了影响粤北地区前汛期降水量的16个关键环流指数因子,分别应用投影寻踪回归、BP神经网络和逐步回归方法,建立前汛期降水趋势预测模型,对粤北地区前汛期降水趋势进行预测。结果表明：投影寻踪回归和BP神经网络方法的预测能力均优于传统的逐步回归模型。其中,PPR模型比BP神经网络方法的预测效果更好。 相似文献
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以1962—2006年粤北地区7个站4—6月前汛期降水量资料为基础,将前汛期降水量与74项环流指数资料进行灰色关联度分析,确定了影响粤北地区前汛期降水量的16个关键环流指数因子,分别应用投影寻踪回归、BP神经网络和逐步回归方法,建立前汛期降水趋势预测模型,对粤北地区前汛期降水趋势进行预测。结果表明:投影寻踪回归和BP神经网络方法的预测能力均优于传统的逐步回归模型。其中,PPR模型比BP神经网络方法的预测效果更好。 相似文献
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投影寻踪回归模型及其在降水预测中的应用 总被引：2，自引：0，他引：2
介绍了以投影寻踪回归（ＰＰＲ）进行预测建模的基本思想和算法实现。通过将ＰＰＲ和逐步回归（ＳＲ）应用于降水实例预测,结果表明ＰＰＰ模型的拟合和预测检验结果均优于ＳＲ的相应结果。 相似文献
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Projections of annual mean air temperature and precipitation over the globe and in China during the 21st century by the BCC Climate System Model BCC_CSM1.0 
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下载免费PDF全文 Evaluating the projection capability of climate models is an important task in climate model development and climate change studies. The projection capability of the Beijing Climate Center (BCC) Climate System Model BCC CSM1.0 is analyzed in this study. We focus on evaluating the projected annual mean air temperature and precipitation during the 21st century under three emission scenarios (Special Report on Emission Scenarios (SRES) B1, A1B, and A2) of the BCC CSM1.0 model, along with comparisons with 22 CMIP3 (Coupled Model Intercomparison Project Phase 3) climate models. Air temperature averaged both globally and within China is projected to increase continuously throughout the 21st century, while precipitation increases intermittently under each of the three emission scenarios, with some specific temporal and spatial characteristics. The changes in globally-averaged and China-averaged air temperature and precipitation simulated by the BCC CSM1.0 model are within the range of CMIP3 model results. On average, the changes of precipitation and temperature are more pronounced over China than over the globe, which is also in agreement with the CMIP3 models. The projection capability of the BCC CSM1.0 model is comparable to that of other climate system models. Furthermore, the results reveal that the climate change response to greenhouse gas emissions is stronger over China than in the global mean, which implies that China may be particularly sensitive to climate change in the 21st century. 相似文献
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Evaluating the projection capability of climate models is an important task in climate model development
and climate change studies. The projection capability of the Beijing Climate Center (BCC) Climate System
Model BCC_CSM1.0 is analyzed in this study. We focus on evaluating the projected annual mean air
temperature and precipitation during the 21st century under three emission scenarios (Special Report on
Emission Scenarios (SRES) B1, A1B, and A2) of the BCC_CSM1.0 model, along with comparisons with
22 CMIP3 (Coupled Model Intercomparison Project Phase 3) climate models. Air temperature averaged
both globally and within China is projected to increase continuously throughout the 21st century, while
precipitation increases intermittently under each of the three emission scenarios, with some specific temporal
and spatial characteristics. The changes in globally-averaged and China-averaged air temperature and
precipitation simulated by the BCC_CSM1.0 model are within the range of CMIP3 model results. On
average, the changes of precipitation and temperature are more pronounced over China than over the globe,
which is also in agreement with the CMIP3 models. The projection capability of the BCC_CSM1.0 model is
comparable to that of other climate system models. Furthermore, the results reveal that the climate change
response to greenhouse gas emissions is stronger over China than in the global mean, which implies that
China may be particularly sensitive to climate change in the 21st century. 相似文献
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Regional climate change patterns identified by cluster analysis 总被引：1，自引：0，他引：1
Climate change caused by anthropogenic greenhouse emissions leads to impacts on a global and a regional scale. A quantitative
picture of the projected changes on a regional scale can help to decide on appropriate mitigation and adaptation measures.
In the past, regional climate change results have often been presented on rectangular areas. But climate is not bound to a
rectangular shape and each climate variable shows a distinct pattern of change. Therefore, the regions over which the simulated
climate change results are aggregated should be based on the variable(s) of interest, on current mean climate as well as on
the projected future changes. A cluster analysis algorithm is used here to define regions encompassing a similar mean climate
and similar projected changes. The number and the size of the regions depend on the variable(s) of interest, the local climate
pattern and on the uncertainty introduced by model disagreement. The new regions defined by the cluster analysis algorithm
include information about regional climatic features which can be of a rather small scale. Comparing the regions used so far
for large scale regional climate change studies and the new regions it can be shown that the spacial uncertainty of the projected
changes of different climate variables is reduced significantly, i.e. both the mean climate and the expected changes are more
consistent within one region and therefore more representative for local impacts. 相似文献
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CMIP5气候模式对中国未来气候变化的预估和应用 总被引：2，自引：0，他引：2
气候模式是研究气候系统和气候变化的有力工具,其模拟结果是进行气候预测和气候变化风险评估的重要数据基础。随着全球气候变暖速度加快,地表生态环境、水文动态循环过程、社会经济发展等都受到其影响,进而影响到人类的生产和生活。利用气候模式对未来气候变化特征进行评估和预测,可为人类调整发展策略以适应气候变化提供科学依据。通过汇总CMIP5(Coupled Model Intercomparison Project Phase 5)模式在气候变化方面的相关研究,综述了CMIP5气候模式在农业生产、水文动态监控以及其他领域中的应用,最后指出了CMIP5气候模式在模拟预估未来气候变化上存在的不足,并展望了CMIP5气候模式在未来的应用。 相似文献
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气候变化科学方面的几个最新认知 总被引：1，自引：0，他引：1
IPCC第六次评估报告（AR6）第一工作组报告主要从以下几个方面的进展提升了我们对气候系统变化、气候变化原因以及预估未来气候系统变化等方面的认知,对过去气候变化及其与人类活动的关系有了更加清晰、可靠的认识。综合多重证据评估指出,全球气候正经历着前所未有的变化;包括极端事件在内的归因进展已把人类活动对气候系统影响的认识从大气圈扩展到水圈、冰冻圈和生物圈,进一步强化了人类活动影响全球和区域气候的认识;有关区域气候变化信息的内容更加丰富,与各行业和敏感地区的气候变化影响联系更加紧密,使这些信息能更好地为气候变化风险评估和气候变化区域适应提供支持;气候模式和约束预估方法的发展以及对气候敏感度认识的深化,减少了未来不同排放情景下全球地表温度（Global Surface Temperature,GST)、海平面上升和海洋热含量的变化预估的不确定性。这份最新报告对我国提升气候变化研究水平和防灾减灾应对能力具有十分重要的指导意义。 相似文献
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我国夏季降水及相关大气环流场未来变化的预估及不确定性分析 总被引：8，自引：1，他引：7
利用政府间气候变化专门委员会第四次评估报告(IPCCAR4)的15个耦合气候模式在不同排放情景下的模拟结果,对我国夏季降水及相关大气环流场的未来时空变化特征与模式之间的不确定性作了研究。结果表明,在全球变暖背景下,我国夏季降水表现出较强的局地特征。其中,我国东部和高原地区的降水在21世纪表现出明显的增加趋势,而且这种趋势随着变暖的加剧而增强,同时模式模拟结果之间的一致性也更好,表明这一结果的可信度较高。在全球变暖背景下,我国新疆南部地区表现为持续的降水减少趋势,而我国西南地区夏季降水的变化则呈现出先减少(21世纪初)后增加的特征,不同模式对降水这些局地特征的模拟也都表现出较好的一致性。其他地区夏季降水在21世纪的变化不大,同时模式模拟的一致性也较差。多模式模拟的我国未来百年夏季降水的这些变化特征在温室气体高、中、低不同排放情景下基本一致,A2情景预估结果变化最大,A1B次之,B1相对最小。东亚夏季大气环流场的预估结果显示,在全球变暖的背景下,大部分模式的模拟结果都表明,东亚夏季风环流有所增强,从而使得由低纬度大洋和南海地区向我国大陆的水汽输送增加,造成该地区大气含水量的增多,从而为我国东部地区夏季降水的增加提供有利条件。此外,随着全球变暖的加剧,西太平洋副热带高压持续增强,其变化对我国东部地区夏季降水的影响程度和范围也明显增大。这些环流场及其不确定性的分析结果进一步加强了我国夏季降水未来变化预估结果的可信度。 相似文献
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E. D. Nadezhina V. I. Matsak A. A. Semioshina I. M. Shkol’nik 《Russian Meteorology and Hydrology》2010,35(12):791-798
Features are considered of using a two-dimensional model of the atmospheric boundary layer for estimation of coastal fog parameters for the Siberian reservoirs, based on reanalysis and on output data of a regional climate model. The model fog characteristics are compared with observations at the reservoirs of Surgut power plants. Examples are given of the fog characteristic calculation for the projected Evenki hydrosystem. It is shown that the data of regional climate model can be used if the changes are taken into account of background climate in the area of the projected reservoir. 相似文献
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Future Changes of Drought and Flood Events in China under a Global Warming Scenario 总被引：1，自引：0，他引：1 下载免费PDF全文
下载免费PDF全文 This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under the SRES(Special Report on Emissions Scenarios) A1B scenario.The standardized precipitation index(SPI),which has well performance in monitoring the drought/flood characteristics(in terms of their intensity,duration,and spatial extent) in China,is used in this study.The projected results of 22 coupled models and the RegCM3 simulation are consistent.These models project a decrease in the frequency of droughts in most parts of northern China and a slight increase in the frequency in some parts of southern China.Considering China as a whole,the spatial extents of droughts are projected to be significantly reduced.In contrast,future flood events over most parts of China are projected to occur more frequently with stronger intensity and longer duration than those prevalent currently.Additionally,the spatial extents of flood events are projected to significantly increase. 相似文献
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依据IPCC第六次评估报告（AR6）第一工作组报告第四章的内容,对未来全球气候的预估结果进行解读。报告对21世纪全球表面气温、降水、大尺度环流和变率模态、冰冻圈和海洋圈的可能变化进行了系统评估,并对2100年以后的气候变化做了合理估计。评估指出全球平均表面气温将在未来20年内达到或超过1.5℃,平均降水也将增加,但随季节和区域而异,同时变率将增大。大尺度环流和变率模态受内部变率影响较大。到21世纪末,北冰洋可能出现无冰期;全球海洋会继续酸化,平均海平面将持续上升,百年内上升幅度依赖不同排放情景,都在2100年后继续升高。在最新的评估中采用多种约束方法,减小了预估不确定性的范围。AR6对于低排放情景以及“小概率高增暖情节”的关注为应对气候变化提供了更多、更完整的信息。综合报告的评估结果指出,未来需要进一步减小区域,特别是季风区气候预估的不确定性,并从科学研究和模式发展两方面加强我国气候预估能力的建设。 相似文献