青藏高原冬春积雪和地表热源影响亚洲夏季风的研究进展   总被引：2，自引：0，他引：2  

段安民  肖志祥  王子谦 《大气科学》2018,42(4):755-766

青藏高原冬春积雪和地表热源的气候效应是青藏高原气候动力学的两个重要内容。大量资料分析和数值试验研究均表明这两个因子对亚洲季风有一定的预测意义,本文对此做了比较系统的回顾和总结,并进一步比较了青藏高原积雪和地表热源影响东亚和南亚夏季降水的异同。结果表明,东亚夏季降水在年际和年代际尺度上均存在"三极型"和"南北反相"型的空间分布特征,高原春季地表热源在年代际和年际尺度上主要影响东亚夏季降水"三极型"模态;在年代际尺度上它是中国东部出现"南涝北旱"格局的重要原因,而高原冬季积雪的作用相反。另一方面,高原冬季积雪在年际和年代际尺度上对印度夏季风降水的预测效果均要优于高原地表热源。无论是空间分布还是时间演变特征,高原冬季积雪与春季地表热源整体上均无统计意义上的显著联系。不断完善高原地面观测网和改进模式在高原地区的模拟性能,将是进一步深入理解高原积雪和地表热源影响亚洲季风物理过程和机制的关键所在。  相似文献   

中国风吹雪区划   总被引：10，自引：0，他引：10  

王中隆  张志忠 《山地学报》1999,17(4):312-317

分析了我国风吹雪及其变化趋势,指出风吹雪和雪崩不能放在一起区划的原因,提出了风吹雪区划的理论,原则,要求和区划单位系统,指标及方法,据此,把中国风吹雪区划分为２个区域,３个大区,１３个地带,３９个地区和１３１个区,使其更加显示出专门区划的特色。  相似文献   

A quantitative assessment of snow shielding effects on surface exposure dating from a western North American 10Be data compilation     

《Quaternary Geochronology》2023

To better assess the spatiotemporal variations of the snow shielding effect on surface exposure dating, we compiled a dataset of 1341 ¹⁰Be ages from alpine moraines and glacially eroded valleys across western North America, and conducted a sensitivity test with both modern and time-integrated snow data covering the same region. Our analyses reveal significant differences in snow shielding both across our geographic domain and through time. In our time-integrated experiments we find snow-based exposure age corrections as low as 3.5% in the Great Basin region and high as 28.4% in the Pacific Northwest for samples dating to the Last Glacial Maximum (LGM) when no wind-sweeping is assumed. As demonstrated with our time-varying snow conditions with a global climate model and a positive degree day model, modern snow conditions across western North America cannot account for the varying snow patterns under large scale climate shifts since the LGM. The snow-based exposure age corrections from the modern data differ from those calculated by our time-varying model by up to 17% across our model domain. In addition, we find that the ¹⁰Be ages calculated under two end-member scenarios regarding wind-sweeping effects, specifically whether boulders were shielded only when the total snow accumulation exceeded boulder heights or were always shielded when the snow was present, can differ by ∼7.6% on average for LGM aged samples. Our analyses provide a model-based estimates of the spatiotemporal variability and complexity of snow shielding effects on surface exposure dates across western North America and highlight the need to consider snow depth variations both spatially and temporally when conducting surface exposure dating in terrains where snowfall accumulation is significant.  相似文献   

积雪在El Niño影响东亚夏季气候异常中的作用          下载免费PDF全文

王妍凤  孙旭光  杨修群 《地球物理学报》2017,60(9):3325-3337

本文利用1948-2010年Global Land Data Assimilation System（GLDAS）NOAH陆面模式资料、GPCC月平均降水资料和NCAR/NCEP全球月平均再分析资料,采用滤波、距平合成和线性相关等方法,分析了El Niño成熟位相冬季欧亚大陆积雪异常的分布特征,研究了关键区积雪融化对后期春、夏季土壤湿度、土壤温度以及大气环流与降水的影响,揭示了El Niño事件通过关键区积雪储存其强迫信号并影响东亚夏季气候异常的机制和过程.主要结论如下：El Niño成熟阶段冬季伊朗高原、巴尔喀什湖东北部和青藏高原南麓区域是雪深异常的三个关键区,这些区域的雪深、雪融和土壤湿度有明显的正相关;这三个关键区雪深异常通过春季融雪将冬季El Niño信号传递给春、夏季局地土壤湿度,通过减少感热通量和增加潜热通量对大气环流产生影响;春末夏初伊朗高原土壤湿度异常对东亚夏季气候异常的影响最大,其引起的降水异常与El Niño次年夏季降水异常分布基本一致,春夏季青藏高原南麓和巴尔喀什湖附近土壤湿度也都明显增加,均会对中国华北降水增加有显著正贡献.总之,在利用El Niño事件研究和预测东亚夏季气候异常时,还应考虑关键区雪深异常对El Niño信号的存储和调制作用.  相似文献   

RADARSAT数字图像积雪覆盖下地物解译方法   总被引：1，自引：0，他引：1  

徐宗宝  梁天刚  陈全功  董安祥 《高原气象》2005,24(1):123-128

采用加拿大RADARSAT雷达数字图像,以新疆阿勒泰地区阿勒泰市、布尔津、吉木乃、哈巴河、福海5个县(市)为典型试验区,研究了积雪覆盖下雷达遥感图像地物解译的基本原理和几何纠正方法,比较分析了标准模式的地理参考高分辨率合成孔径雷达图像与经过亮度增强、边缘增强、图像增强、斑点压缩和纹理分析处理的图像上地物目视解译的特点,建立了积雪覆盖下雷达图像上耕地、水系、交通道路、居民地等与抗灾救灾密切相关的地物的解译标志。结果表明,可弥补可见光及近红外遥感积雪监测的缺陷,为雪灾发生区的救援决策提供科学依据。  相似文献   

青海省雪灾气候预测的地气图方法   总被引：8，自引：5，他引：3  

汤懋苍  张拥军  唐红玉  李栋梁 《高原气象》2005,24(3):316-319

通过对青海省1960年以来全省各气象站的雪灾资料统计分析,结合青海省南部(下称青南)地区8月份的地气形势,发现二者之间有很好的相关：夏季地热涡和正鞍形场多对应冬季为重雪灾;地冷涡和负鞍形场多对应冬季为轻灾或无灾。春夏季上游的中强地震可加强冬季的雪灾。由此表明,利用地气图方法可以较好地预测青海省的雪灾。  相似文献   

Hydrothermal pattern of frozen soil in Nam Co lake basin,the Tibetan Plateau   总被引：3，自引：0，他引：3  

Keming Tian  Jingshi Liu  Shichang Kang  Iain B. Campbell  Fei Zhang  Qianggong Zhang  Wei Lu 《Environmental Geology》2009,57(8):1775-1784

Hydrothermal processes and the regimes of frozen soil formed in alpine regions with glaciers and lake area are complex and important for ecological environment but have not been studied in Tibet. Based on soil temperature and moisture data from October 2005 to September 2006 collected in the Nam Co lake basin, Tibetan Plateau (TP), those questions were discussed. The mean annual air temperature was −3.4°C with 8 months below 0°C. Air and soil temperature varied between −25.3~13.1°C and −10.3~8.8°C, respectively. Soil moisture variations in the active layer were small with the minimum value of 1.4%, but were influenced greatly by snowmelt, rainfall and evaporation, varying up to 53.8%. The active layer froze later, thawed earlier and was thinner, however, the lower altitude limit of permafrost is higher than that in most areas of TP. The effects of soil moisture (unfrozen water content) on soil temperature, which were estimated through proposed models, were more significant near ground surface than the other layers. The surface soil temperature decreased with snowcover, the effect of cold snow meltwater infiltration on soil thermal conditions was negligible, however, the effect of rainfall infiltration was evident causing thermal disruptions.  相似文献   

Environmental significance of snowpit chemistry in the typical monsoonal temperate glacier region,Baishui glacier no. 1, Mt Yulong,China   总被引：1，自引：0，他引：1  

Li Zongxing  He Yuanqing  Pang Hongxi  Wilfred H. Theakstone  Zhang Ningning  He Xianzhong  Wang Shijing  Pu Tao  Du Jiankuo 《Environmental Geology》2009,58(6):1319-1328

Samples were collected from two snowpits in Baishui glacier no. 1, Mt Yulong, China, in May 2006. Snowpit chemistry was studied, using ion tracer techniques, HYSPLIT model, factor analysis, correlation and trend analysis. It indicated that total cation concentration is higher in 4,900-m snowpit than in 4,750-m snowpit, whereas total anion concentration is higher in 4,750-m snowpit. Cations, especially Ca²⁺, dominate ionic concentrations in Baishui glacier no. 1. According to correlation analysis and factor analysis, ions can be categorized as follows: Cl⁻ and NO₃ ⁻ as Group 1, SO₄ ²⁻ as Group 2, Mg²⁺ and Ca²⁺ as Group 3, Na⁺ as Group 4, K⁺ as Group 5. Contribution made by terrestrial dust to ionic concentration accounts for 52.27, 100, 99.36, 98.91, 96.16 and 99.97% of Cl⁻, NO₃ ⁻, SO₄ ²⁻, K⁺, Mg²⁺ and Ca²⁺, respectively, in 4,900-m snowpit, and for 64.00, 100, 99.57, 98.63, 96.25 and 99.97% in 4,750-m snowpit. Local dust is the principal source of snowpit chemical components. Pollutants brought from industrial areas of South Asia, Southeast Asia and South China by monsoonal circulation also makes some contribution to anion concentrations, but pollution associated with human activities makes a very slight contribution in study area. The chemical characteristics of two snowpits are different owing to the difference of deposition mechanism and local environment in different altitudes.  相似文献   

热带大气季节内振荡与2008年初中国南方雪灾的关系   总被引：1，自引：0，他引：1       下载免费PDF全文

朱红蕊  刘赫男  张洪玲  王春华 《气象与环境学报》2013,29(4):77-83

利用热带大气季节内振荡(MJO)指数、向外长波辐射(OLR)资料和NCEP/NCAR全球逐日再分析资料以及中国南方地区降水资料,应用合成分析等探讨了MJO与2008年初南方雪灾的关系,进而从MJO角度研究雪灾过程成因。结果表明：雪灾过程中,MJO存在明显的东传现象,即由西太平洋向东传送至印度洋附近。伴随着MJO的向东传播,中国南方降水强度及集中区也在随之变化,MJO在一定程度上对雪灾过程有调制作用。通过对OLR的分析,表明2008年初中国南方4次异常降水(雪)过程受到了MJO两次东传的影响,第一次导致西太平洋副热带高压持续偏强,第二次导致南支槽活跃;副热带高压西侧偏南风带来的暖湿气流,以及南支槽带来的印度洋和孟加拉湾的暖湿气流不断向中国输送,为中国南方强降水过程提供了水汽条件。  相似文献   

Impacts of a bottom trawling exclusion zone on Snow Crab abundance and fish harvester behavior in the Labrador Sea, Canada     

Darrell R.J. Mullowney  Corey J. MorrisEarl G. Dawe  Katherine R. Skanes 《Marine Policy》2012,36(3):567-575

The Hawke Box trawling exclusion zone off southern Labrador is a 8610 km² closed area implemented in 2003 to protect soft-shelled pre-recruit Snow Crab and juvenile cod from mortality imposed by shrimp trawling and other bottom-impact fisheries. This study utilizes survey, logbook, and observer data from the Snow Crab and Northern Shrimp fisheries to assess the effectiveness of the Hawke Box in protecting and possibly enhancing the Snow Crab resource off southern Labrador. The results indicate that the exclusion zone has failed to protect pre-recruit crabs largely due to a redistribution and intensification of directed Snow Crab effort inside the Box in the years following closure. This unexpected outcome resulted in a high level of fishery-induced mortality to pre-recruit crabs and masked any potential positive outcomes from the cessation of trawling. The shortcomings that contributed to the failure of this exclusion area are discussed in relation to the current state of knowledge on the effectiveness of marine protected areas in general as management tools for conserving aquatic resources.  相似文献