近40年北疆年积雪日数变化的CEOF分析

通过1961—2001年间北疆年积雪日数的CEOF分析,研究了40年来北疆年降雪日数的时空变化特点。结果表明：北疆年积雪日数场有波动特征。第一种类型为南—北一致偏多(偏少)型,空间位相相近,并有6．4年和3．6年的周期。第二种类型为西南—东北一致偏多(偏少)型,空间位相相近,并有6.4年的周期。第一复主分量的时间位相和第二复主分量的时间振幅峰值年可用于年积雪日数的预测。     

中国天山积雪对气候变化响应的多通径分析

基于天山山区1961-2013年60个气象站点实测气温、降水、相对湿度、日照时数和积雪深度等气候资料,结合时间序列分析、空间分析以及通径分析等方法,全面精确地获取了天山山区气候变化特征以及气候变化对积雪的通径影响。结果表明：天山山区气候变化显著,主要表现为整体增暖、局部变湿与黯化;气候变暖导致天山山区固态降水（降雪）保证率明显降低,尤其是低海拔区域。各气象要素对积雪不仅存在直接的单因素影响而且各气象要素之间还存在间接的相互交叉、相互联结的多因素影响。单因素影响通径分别为气温、降水和日照时数对积雪深度的3条直接影响通径;多因素影响通径分别为气温、降水和日照时数通过相互之间的内在关系对积雪深度产生的6条间接影响通径。最终结果表明气温是积雪变化的主要影响因素,其影响效应远远大于降水和日照时数的影响。     

Evaluation of snow water equivalent datasets over the Saint‐Maurice river basin region of southern Québec

A 10‐km gridded snow water equivalent (SWE) dataset is developed over the Saint‐Maurice River basin region in southern Québec from kriging of observed snow survey data for evaluation of SWE products. The gridded SWE dataset covers 1980–2014 and is based on manual gravimetric snow surveys carried out on February 1, March 1, March 15, April 1, and April 15 of each snow season, which captures the annual maximum SWE (SWEM) with a mean interpolation error of ±19%. The dataset is used to evaluate SWEM from a range of sources including satellite retrievals, reanalyses, Canadian regional climate models, and the Canadian Meteorological Centre operational snow depth analysis. We also evaluate a number of solid precipitation datasets to determine their contribution to systematic errors in estimated SWEM. None of the evaluated datasets is able to provide estimates of SWEM that are within operational requirements of ±15% error, and insufficient solid precipitation is determined to be one of the main reasons. The Climate System Forecast Reanalysis is the only dataset where snowfall is sufficiently large to generate SWEM values comparable to observations. Inconsistencies in precipitation are also found to have a strong impact on year‐to‐year variability in SWEM dataset performance and spread. Version 3.6.1 of the Canadian Land Surface Scheme land surface scheme driven with ERA‐Interim output downscaled by Version 5.0.1 of the Canadian Regional Climate Model was the best physically based model at explaining the observed spatial and temporal variability in SWEM (root‐mean‐square error [RMSE] = 33%) and has potential for lower error with adjusted precipitation. Operational snow products relying on the real‐time snow depth observing network performed poorly due to a lack of real‐time data and the strong local scale variability of point snow depth observations. The results underscore the need for more effort to be invested in improving solid precipitation estimates for use in snow hydrology applications.     

青藏高原积雪深度和雪水当量的被动微波遥感反演

利用1993年1月份的SSM/I亮度温度数据反演了青藏高原的雪水当量,首先使用被动微波SSM/I数据19和37GHz的水平极化数据来反演雪深,根据积雪时间的函数来计算实时的雪密度,由雪的深度和密度计算出雪水当量.最后,利用SSM/I数据的19和37GHz的垂直极化亮度温度梯度对计算出的雪水当量进行回归分析,得到了利用SSM/I数据直接反演雪水当量的算法.     

塔城市一次暴雪天气的分析

2003年2月22日塔城市出现一次暴雪天气过程。文章着重分析了此次天气过程的高空环流形势、地面形势、T—Td等，指出暖湿气流是造成暴雪的主要原因。     

Multiple mantle metasomatism beneath the Leizhou Peninsula,South China: evidence from elemental and Sr-Nd-Pb-Hf isotope geochemistry of the late Cenozoic volcanic rocks

ABSTRACT

We analysed whole-rock major and trace elements and Sr-Nd-Pb-Hf isotopes of the late Cenozoic volcanic rocks in the Leizhou Peninsula, South China to investigate their mantle source characteristics. These volcanic rocks, collected from Jiujiang, Tianyang and Huoju areas of the Leizhou Peninsula, are characterized by incompatible element enrichment but variable isotopic depletion. The volcanic rocks from Jiujiang and Tianyang show prominent primitive-mantle-normalized positive Nb, Ta and Sr anomalies and depleted Sr-Nd-Pb-Hf isotope compositions, whereas those from Huoju show slight positive to negative Nb and Ta anomalies, a prominent positive Pb anomaly, and more enriched Sr-Nd-Pb-Hf isotope compositions. Two types of mantle metasomatism are required to explain the geochemical characteristics of these rocks. The Jiujiang and Tianyang samples were largely derived from a mantle source metasomatized recently by a low-F melt. Such low-F melt is generated within the asthenospheric mantle, which is enriched in volatiles and incompatible elements with positive Sr anomaly and depleted Sr-Nd-Pb-Hf isotope compositions. The Huoju samples were largely derived from a mantle source metasomatized by recycled upper continental crust material. These two types of mantle metasomatism beneath the Leizhou Peninsula are consistent with trace element characteristics of mantle mineralogy (e.g. clinopyroxene vs. amphibole), which reflects source evolution in space and time (e.g. tectonic setting change).     

南、北极雪、冰、水中的痕量元素离子与水汽化学

应用水汽化学的方法学和理论,研究南,北极雪,冰,水中的Ｚｎ＾２＋等离子,南北,极雪,冰,水中Ｚｎ＾２＋,Ｃｄ＾２＋,Ｐｂ＾２＋,Ｃｕ＾２＋,Ｓｎ＾４＋,Ｂｉ＾３＋离子含量的空间变化很小,与水汽化学原理计算的离子总平均含量Ｚｎ＾２＋,５．０μｇ／Ｌ,Ｐｂ＾２＋＋０．０３０μｇ／Ｌ,Ｃｕ＾２＋＋０．７０μｇ／Ｌ,Ｓｎ＾４＋＋０．９９μｇ／Ｌ,Ｂｉ＾３＋＋０．１８μｇ／Ｌ相一致。南北极Ｚｎ＾２＋等离子处     

一种基于MODIS积雪产品的雪线高度提取方法

冰川雪线高度的遥感提取对冰川物质平衡研究具有重要意义。提出一种基于晴空环境下积雪覆盖频率的雪线高度提取方法。使用MOD10A1积雪产品中的像元积雪面积比例数据,提取了2000/2001-2014/2015年间高亚洲地区冰川消融期末雪线高度。使用实测的冰川年物质平衡资料和气象格网数据对提取的雪线高度变化的可信度进行分析。研究表明：近15 a高亚洲雪线高度变化及趋势具有明显的东西差异,雪线高度变化幅度自青藏高原内部地区向四周呈增加趋势,西部大于东部。提取的冰川雪线高度变化与观测的年物质平衡序列具有很高的相关性,对物质平衡波动的平均解释率可高达75%;与气象要素（气温、降水）的年际变化的相关性也较高,约61.58%的格网冰川雪线高度变化可以由夏季气温和季节降水解释。而高亚洲各分区冰川雪线高度的波动规律也与大气环流背景分布一致。因此提取的雪线高度变化具有冰川学意义,可以进一步应用于冰川物质平衡估算及模拟研究中。     

冰川/积雪-大气相互作用研究进展

冰川和积雪是冰冻圈的重要组成部分,在全球或区域气候系统中起着极其重要的作用.开展冰川/积雪-大气相互作用研究,是研究冰冻圈物理过程及其对气候系统反馈作用的必然需求,也是研究冰川/积雪对气候变化响应的有效手段,同时还可为全球(区域)气候和水文模式提供冰川/积雪面的地表特征参数.近一个世纪以来,在冰川/积雪面辐射特征、能量通量计算方法和平衡特征等方面开展了许多观测试验和理论研究,并取得了卓有成效的研究结果.但是在准确获取辐射通量、研发普适性较强的反照率参数化方案、复杂地形条件下能量通量的计算,以及发展分布式能量平衡模式等方面尚存在许多不确定性,仍面临许多技术难点,也是未来的研究重点.     

青藏高原积雪异常与贵州东、西部旱、寒灾害关系的初步分析

利用 195 8— 1992年的有关资料 ,对青藏高原冬、春季积雪异常与贵州春、夏季不同区域干旱和低温灾害的强弱关系进行了统计分析。结果发现 :青藏高原冬、春季积雪异常与贵州春、夏季不同区域干旱和低温灾害的强弱间存在明显的相关关系 ,高原异常多雪年贵州西部 4月春旱偏重 ;东部夏旱偏重 ,春季低温灾害偏轻。反之 ,高原异常少雪年贵州西部春旱和东部夏旱都偏轻 ,春季低温灾害偏重。