近53年内蒙古寒潮时空变化特征及其影响因素

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刘宪锋, 朱秀芳, 潘耀忠, 李双双, 张东海, 刘焱序. 近53年内蒙古寒潮时空变化特征及其影响因素. 69(7): 1013-1024
LIU Xianfeng, ZHU Xiufang, PAN Yaozhong, LI Shuangshuang, ZHANG Donghai, LIU Yanxu. The spatial-temporal changes of cold surge in Inner Mongolia during recent 53 years. Acte Geographica Sinica, 69(7): 1013-1024 复制到剪切板

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近53年内蒙古寒潮时空变化特征及其影响因素

刘宪锋^1,², 朱秀芳^1,², 潘耀忠^1,², 李双双^1,³, 张东海^1,², 刘焱序⁴

1. 北京师范大学地表过程与资源生态国家重点实验室, 北京 100875

2. 北京师范大学资源学院, 北京100875

3. 北京师范大学减灾与应急管理研究院, 北京 100875

4. 北京大学城市与环境学院, 北京 100871

朱秀芳 (1982-), 女, 浙江人, 副教授, 硕士生导师, 主要从事农业监测、灾害监测、土地利用/覆盖与气候响应、地表过程建模等方向的研究。E-mail: zhuxiufang@bnu.edu.cn

作者简介：刘宪锋 (1986-), 男, 黑龙江鹤岗人, 博士研究生, 主要从事资源环境遥感、灾害遥感研究。E-mail: fliuxianfeng7987@163.com

基金:国家“高分辨率对地观测系统”重大专项资助

摘要

利用内蒙古及其周边121个气象台站1960-2013年逐日最低气温数据,辅以分段线性回归模型、趋势分析及相关分析等方法,本文探讨了近53年内蒙古寒潮频次的时空变化特征及其影响因素。研究发现 (1) 近53年内蒙古单站寒潮频次总体呈下降趋势,降速为-0.5次/10a (-2.4~1.2次/10a),其中1991年之前降速为-1.1次/10a (-3.3~2.5次/10a),而1991年之后呈增加趋势,增速为0.45次/10a (-4.4~4.2次/10a);春季寒潮变化趋势与年变化趋势一致,且在各季节中变化最为显著;寒潮频次年内变化呈“双峰”结构特征,且以11月最多;(2) 空间上,内蒙古单站寒潮频次具有显著的空间差异特征,高发区集中在内蒙古的北部和中部地区,且北部高于中部。年代尺度对比来看,20世纪60-90年代寒潮高频区域范围在减少、低频区域范围在增加;而21世纪初期高频区域范围有所增加,增加区主要为内蒙古东部的图里河、小二沟,以及中部的西乌珠穆沁旗等地;(3) 就年尺度而言,寒潮主要受AO、NAO、CA、APVII和CQ控制,而各季节驱动因素有所差别,冬季寒潮与AO、NAO、SHI、CA、TPI、APVII、CW和IZ均达到显著相关关系,说明冬季寒潮受多种因素共同控制;秋季寒潮主要受CA和IM影响;而春季寒潮与CA和APVII关系显著。

关键词: 寒潮; 分段线性回归; Sen+Mann-Kendall分析法; 时空变化; 影响因素; 内蒙古

The spatial-temporal changes of cold surge in Inner Mongolia during recent 53 years

LIU Xianfeng^1,², ZHU Xiufang^1,², PAN Yaozhong^1,², LI Shuangshuang^1,³, ZHANG Donghai^1,², LIU Yanxu⁴

1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China

2. College of Resources Science & Technology, Beijing Normal University, Beijing 100875, China

3. Academy of Disaster Reduction and Emergency Management, Beijing Normal University, Beijing 100875, China

4. College of Urban and Environmental Sciences, Peking University, Beijing 100871, China

Fund:Foundation: Major Project of High-resolution Earth Observation System

Abstract

Using the daily minimum temperature data of 121 meteorological stations in Inner Mongolia and its surrounding areas, this paper analyzed the spatiotemporal variation of cold surge and its possible influencing factors in Inner Mongolia during 1960-2012, based on piecewise regression model, Sen+Mann-Kendall model, and correlation analysis. The results show that, (1) The occurrence frequency of single-station cold surge presented a decreasing trend in Inner Mongolia during recent 53 years, with a linear tendency of -0.5 times/10a (-2.4-1.2 times/10a), of which a significant decreasing trend was detected before 1991, being -1.1 times/10a (-3.3-2.5 times/10a), while an increasing trend of 0.45 times/10a (-4.4-4.2 times/10a) was found after 1991. On the seasonal scale, the trend of spring cold surge was consistent with that of the annual value, and the most obvious change of cold surge also occurred in spring. The frequency of monthly cold surge showed a bimodal structure, and November witnessed the highest incidence of cold surge. (2) Spatially, the high incidence of cold surge is mainly observed in the northern and central parts of Inner Mongolia, and higher in the northern than the central part. The inter-decadal characteristic also detected that high frequency and low frequency regions presented a decreasing trend and an increasing trend, respectively, during 1960-1990, while high frequency regions expanded after the 1990s, regions with high frequency of cold surge were mainly distributed in Tol Gol, Xiao’ergou, and Xi Ujimqin Banner. (3) On annual scale, the cold surge was dominated by AO, NAO, CA, APVII, and CQ, while the difference in driving forces among seasons was detected. Winter cold surge was significantly correlated with AO, NAO, SHI, CA, TPI, APVII, CW, and IZ, indicating that cold surge in winter was caused multifactor. Autumn cold surge was mainly affected by CA and IM, while spring cold surge was significantly correlated with CA and APVII.

Keyword: cold surge; piecewise regression; Sen+Mann-Kendall; spatiotemporal variations; influencing factors; Inner Mongolia

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1 引言

极端气候事件是指某类气候要素量值或统计值显著偏离其平均态、且达到或超过其观测或统计量值区间上下限附近特定阈值的事件^[1]。与气候平均态相比, 极端气候事件的发生更具反常性、突发性和不可预见性, 其对气候变化响应也更为敏感^[2], 并将对人类社会和自然环境产生巨大而深远的影响^[3]。IPCCAR5指出, 过去60年 (1951-2012) 全球平均气温上升0.72 ^oC (0.49~0.89 ^oC)^[4], 而我国1960-2009年地表平均气温亦升高了1.38 ^oC, 远高于全球或北半球同期增温速率^[5], 以北方增暖最为明显, 由此导致极端气候事件出现的频率和强度呈现出增加趋势^{[6, 7]}。极端事件 (如洪水、干旱、热浪和寒潮等) 的增多加重了人们的担忧, 使全球气候变化问题成为全球范围内最受关注的科学问题, 并受到了国内外学者和公众的广泛关注与研究。在众多极端气候事件中, 寒潮作为最主要的极端低温事件, 其对社会经济、生态系统以及人类健康的影响最为明显也最为直接, 因而成为最主要的气象灾害之一, 受到了学者们的广泛关注。

随着全球气候变化课题日益受到学界高度关注, 针对寒潮等极端气候研究日益成为国内外气候变化和综合防灾减灾研究领域的热点问题^[3]。寒潮作为影响我国冬半年的主要灾害性天气, 对社会经济造成了严重的损失。我国学者李宪之先生^[8]早在1955年就研究了东亚寒潮爆发过程, 并将我国寒潮划分为3类; 随后, 陶诗言先生^[9]针对影响我国大陆的冷空气源地和侵袭路径进行了深入分析; 王遵娅^[10]和钱维宏^[11]分别对我国寒潮时空变化及其影响因素进行了深入分析, 前者认为西伯利亚高压和冬季风强度的减弱是寒潮频次减少的可能原因, 而后者指出我国寒潮频次、降温事件、升压频率和大风频次都在减少, 在一定程度上导致了冬季最低温度平均值的升高, 从而形成持续的暖冬。事实上, 我国不同区域寒潮频次呈现出不同程度的减少趋势, 且区域间差异较为显著, 甚至有些地区近年来出现增加趋势^{[12, 13, 14, 15]}。在气候变暖背景下, 生态系统对极端低温事件的脆弱性逐渐增加, 因此, 关注极端低温 (如寒潮) 的时空变化特征及其归因研究对生态系统健康可持续发展显得尤为重要。

内蒙古地区以草原生态系统为主, 草原面积约占全国天然草原面积的20%^[16]。该地区不仅是全球变化最为敏感的区域之一, 而且也是我国寒潮侵袭最为严重的地区之一。极端气候事件的增多, 增加了气象灾害的不确定性, 使农牧业生产风险在加大, 危害生态安全和粮食安全^[17]。目前, 关于内蒙古近53年寒潮频次的时空变化特征及其可能影响因素尚不明晰。基于上述认识, 作者站在地理视角, 利用最新气象观测资料, 辅以分段线性回归模型、Sen +Mann-Kendall分析法以及相关分析等手段, 分析内蒙古近53年 (1960-2012年) 寒潮频次的时空变化特征, 并对其影响因素进行分析, 以期为应对气候变化和综合防灾减灾提供参考依据。

2 数据与方法

2.1 研究区概况

内蒙古地处中国北部边疆 (37° 24′ ~53° 23′ N和97° 12′ ~126° 04′ E), 是我国北方重要的生态屏障。全区气候属于干旱、半干旱气候向东南沿海湿润、半湿润季风气候的过渡带^[18], 其中大兴安岭和阴山山脉成为全区气候差异的重要自然分界线。植被类型从东北到西南依次为森林、草原、荒漠。同时, 内蒙古也是我国重要的畜牧业生产基地, 近几十年来, 全球气候变暖、人类活动加强等因素, 进一步加剧了生态环境的恶化程度, 且该区大部分植被处于干旱、半干旱的农牧交错地区, 生态环境十分脆弱, 从而成为对全球变化响应最为敏感的地区之一。

2.2 数据来源

为保证资料的完整性和连续性, 建立均一、稳定的气温序列, 本研究依据资料的连续性及最长时段性等标准, 共选取研究区及其周边121个气象台站的逐日最低气温数据, 资料时间跨度为1960-2013年, 所选站点均经过了严格的质量检查和控制, 包括极值检验和时间一致性检验等, 消除了非气候因素造成的影响, 以上数据源自中国气象科学数据共享服务网 (http://www.progressingeography.com/richhtml/0375-5444/html_resources/cdc.cma.gov.cn)。个别站点缺失数据采用邻近站点插值方法进行插补, 并进行一致性检验。应说明的是, 选取邻近站点插值法的原因是由于线性回归插补方法有可能平滑掉日间温差, 进而对寒潮频次计算结果造成影响。另外, 本文将当年9月1日-次年5月31日范围内的寒潮次数定义为一个完整的寒潮统计年的寒潮发生频次, 如1960年9月1日-1961年5月31日期间发生的寒潮次数作为1960年的寒潮频次, 依此类推。

为分析内蒙古寒潮频次变化的影响因素, 本文选取一系列与该区域气温变化密切相关的环流因子, 作为寒潮频次变化的驱动因素, 其中西伯利亚高压指数 (SHI) 采用NCEP/NCAR再分析资料中的逐月海平面气压数据计算获得; 冷空气 (CA)、青藏高原指数 (TPI)、亚洲极涡强度指数 (APVII)、东亚大槽强度 (CQ)、东亚大槽位置 (CW)、亚洲纬向环流指数 (IZ) 以及亚洲经向环流指数 (IM) 等逐月环流指数取自中国气象局国家气候中心气候变化与预测研究室发布的74项环流指数数据集; 北极涛动 (AO)、北大西洋涛动 (NAO) 等逐月指数取自美国国家海洋和大气管理局的气候预测中心 (http://www.progressingeography.com/richhtml/0375-5444/html_resources/www.cpc.ncep.noaa.gov/)。

本研究中采用的生态区矢量边界数据取自世界野生动物基金会的Terrestrial Ecoregions数据 (http://www.progressingeography.com/richhtml/0375-5444/html_resources/www.worldwildlife.org/), 该数据将全球划分为825个生态区, 其中内蒙古地区共有13个生态区^[19]。根据内蒙古的气候特征和植被分布特征, 并结合前人研究成果^[20], 将内蒙古分为三大生态区：东部森林生态区 (I区)、中部草原生态区 (II区) 和西部荒漠生态区 (III区)。

2.3 研究方法

2.3.1 寒潮标准定义依据《中华人民共和国国家标准》中的《寒潮等级》 (GB/T 21987-2008)和《冷空气等级》 (GB/T 20484-2006) 中的规定, 单站寒潮定义为：某地的日最低 (或日平均) 气温24 h内降温幅度≥ 8 ^oC, 或48 h内降温幅度≥ 10 ^oC, 或72 h内降温幅度≥ 12 ^oC, 而且使该地日最低气温≤ 4 ^oC的冷空气活动。区域寒潮是指一次寒潮过程中, 区域内40%以上站点均发生寒潮, 则定义为一次区域寒潮。由于日平均气温并非实际测得的温度, 而最低温度不受太阳辐射的影响, 可以较好地反映降温的相对幅度^[11]。因此, 本文采用最低气温计算寒潮发生频次。

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	图1 研究区概况及站点分布Fig. 1 Study area and distribution of meteorological stations

2.3.2 Sen趋势分析和Mann-Kendall统计检验方法本文采用非参数化趋势度^[21]方法来计算内蒙古寒潮频次的变化趋势, 并通过Mann-Kendall^[22]统计检验法对变化趋势的显著性进行检验。Sen趋势分析方法的优点是不需要样本服从一定的分布, 并且不受异常值的干扰, 对测量误差或离群数据具有较强的规避能力。公式如下：

$\begin{matrix} β = mean (\frac{x_{j} - x_{i}}{j - i}) \forall j > i \end{matrix}$ (1)

式中, β 为变化趋势; i、j为时间序数; x_i、x_j分别表示第i、j时间的寒潮频次; 当β > 0时, 表明寒潮频次呈上升趋势; 当β < 0时, 表明寒潮频次呈下降趋势。本文中规定Mann-Kendall检验达到0.05显著水平即认为寒潮频次发生显著变化。

2.3.3 分段线性回归模型为检测近53年内蒙古寒潮频次变化趋势的一致性, 本文采用分段线性回归模型进行分析。由于该模型能够有效提取长时间序列数据变化趋势的转折点, 有效弥补一元线性回归无法真实反映变化趋势的缺陷, 已被广泛用于气候变化趋势分析^{[23, 24]}, 公式如下：

$\begin{matrix} y = \{\begin{matrix} β_{0} + β_{1} t + ε, \\ β_{0} + β_{1} t + β_{2} (t - α) + ε, \end{matrix} \begin{matrix} t \leq α \\ t > α \end{matrix} \end{matrix}$ (2)

式中, y表示寒潮频次; β ₀为截距; β ₁和β ₁+β ₂分别表示转折点前后的斜率; t为年份; α 是检测出的时间序列转折点; ε 表示残差。以上各项系数均由最小二乘法求得, 并定义显著水平达到0.05, 即可认为发生显著变化。

3 结果分析

3.1 寒潮的时间变化特征

3.1.1 区域尺度 1960-2012年内蒙古单站寒潮频次呈显著下降趋势 (图2a), 降速为-0.5次/10a (P < 0.01)。由图可见, 寒潮频次变化具有明显的阶段性特征, 基于分段线性回归模型, 笔者检测出1991年为寒潮频次变化的转折点, 并分别对分段特征进行线性拟合, 结果表明：(1) 1960-1991年单站寒潮频次呈显著下降趋势, 降速达-1.1次/10a (P < 0.01); (2) 1991-2012年则呈增加趋势, 增速为0.45次/10a (P = 0.21)。我们进一步统计了持续2天和持续3天寒潮频次变化特征, 发现两者均在20世纪80年代中期发生转折, 但变化趋势存在差异：(1) 近53年持续2天寒潮频次呈显著下降趋势 (-0.016次/10a), 其中1985年之前呈极显著下降趋势 (-0.041次/10a), 1985年之后趋势并不明显; (2) 持续3天寒潮频次整体呈微弱下降趋势 (-0.0008次/10a), 但1984年之前呈显著下降趋势 (-0.014次/10a), 而之后呈显著增加趋势 (0.01次/10a)。

由于春季寒潮 (如倒春寒) 对当地农牧业生产造成的影响尤为严重, 我们重点分析了春季寒潮的变化趋势。图2b显示春季寒潮频次同样在1991年发生转折, 且1991年之前下降趋势为-0.5次/10a (P < 0.01), 高于秋季 (-0.4次/10a, P < 0.01) 和冬季 (-0.2次/10a, P = 0.22)同期趋势; 而1991年之后呈缓慢增加趋势, 同样春季 (0.165次/10a) > 秋季 (0.164次/10a) > 冬季 (0.122次/10a)。以上分析可以看出, 春季寒潮变化幅度最大, 而冬季寒潮频次变化相对稳定。

月尺度统计结果表明, 寒潮频次呈现“ 双峰” 结构, 高发时间主要集中10-11月和次年3月, 其中11月份寒潮频次最高, 为1.36次, 其次为10月份和3月份, 分别为1.26和1.22次, 而9月份寒潮次数最少, 仅为0.66次 (图2c)。

近53年内蒙古共发生区域寒潮147次, 平均每年2.8次, 寒潮最早出现日为2006年9月9日, 最晚出现日为1976年5月13日。年代尺度上, 20世纪60年代发生频次最多, 共计37次; 70年代共发生29次; 80-90年代区域寒潮频次进一步减少, 均为18次; 而21世纪初期区域寒潮频次有所增加, 共发生29次。从年际变化来看, 内蒙古区域寒潮整体呈下降趋势, 降速为-0.23次/10a, 但未通过显著性检验 (图2d)。

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图2 1960-2012年内蒙古寒潮频次时间变化特征(a.单站寒潮频次年际变化; b. 单站寒潮频次春季变化; c. 单站寒潮频次月份变化; d. 区域寒潮频次变化)Fig. 2 Temporal variation of cold surge frequency in Inner Mongolia during 1960-2012(a. Annual variation of cold surge of single station; b. Spring variation of cold surge of single station; c. Monthly variation of cold surge of single station; d. Regional variation of cold surge)

3.1.2 站点尺度为全面认识内蒙古寒潮频次变化特征, 本文进一步分析了内蒙古各站点的年际变化特征 (图3), 发现1980年之前寒潮频次整体较多, 尤其在1965年各站点均表现出一致的高值; 1980-1995年之间相对较少; 而1995年之后寒潮频次较前期又有所增加。由于近年来极端气候事件发生频率和强度不断加大, 为此我们着重探讨了2000-2012年寒潮频次变化特征, 研究发现：森林区各站点寒潮频次整体呈下降趋势 (-4.4~4.0次/10a); 草原区同样呈下降趋势 (-6.2~2.5次/10a), 但该区极端高值较多, 表明该区极端事件强度在增大, 对生态系统的影响在加大; 而荒漠区寒潮频次整体表现为弱增加趋势 (-3.0~6.3次/10a)。年际变化上, 寒潮频发地区 (蓝色条带) 主要分布在图里河、小二沟、阿尔山、西乌珠穆沁旗、达尔罕联合旗等地, 其中图里河为全区寒潮频次最多的站点, 而西乌珠穆沁旗近年来寒潮频次显著增加。

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	图3 1960-2012内蒙古逐站点寒潮频次变化特征Fig. 3 Annual variation of cold surge of each station in Inner Mongolia during 1960-2012

3.2 内蒙古寒潮空间变化特征

3.2.1 内蒙古寒潮空间分布特征在空间上, 内蒙古单站寒潮频次具有显著的空间差异, 高发区主要集中在内蒙古的北部和中部地区, 该区域集中位于大兴安岭西侧和阴山的北部, 且北部地区寒潮频次高于中部地区 (图4a)。从频次分布图来看, 近53年内蒙古单站寒潮频次呈“ 双峰” 结构, 频次在8~10次和14~16次的区域所占比例分别为26.17%和17.28%。分区结果显示, 森林区寒潮频次空间差异较大, 大兴安岭北部区寒潮频次在20次以上, 而大兴安岭中部和西辽河平原的大部分地区寒潮频次小于10次; 草原区大部分地区寒潮频次在14次以上, 高值区分布在内蒙古高原东部区, 以西乌珠穆沁旗地区最高; 而荒漠区寒潮频次呈东北向西南递减的空间分布特征, 其东部的西河套平原和内蒙古高原西部区寒潮频次在14次以上, 而其西部大部分地区在10次以下。

依据分段线性回归计算结果, 文中分别分析了转折点 (1991年) 前后的寒潮频次空间分布特征。就空间格局而言, 我们发现1960-1991年寒潮空间分布特征与近53年分布特征基本一致 (图4b), 明显不同的是该时期大兴安岭北部区高频 (20次以上) 区域少于53年平均值, 由此说明该区域高频寒潮主要由1991年之后贡献, 这一点由图4c可以得到证实; 另外, 1991年之后草原区寒潮频次整体减少, 高值区零星分布在西乌珠穆沁旗和西河套平原等地区 (图4c)。年代尺度对比来看 (图略), 20世纪60-90年代单站寒潮高频区域在减少、低频区域在增加, 而21世纪初期高频区域有所增加, 进一步证实近年来全球气候变化导致了极端事件发生频率和强度在加大。从以上分析可以看出, 寒潮高发区与内蒙古森林和草原分布区基本一致, 并且近年来寒潮发生频次和强度呈增加趋势, 由此推断空间位置上的叠加势必会对当地农牧业生产造成严重影响。

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	图4 内蒙古单站寒潮频次空间分布图Fig. 4 Spatial distribution of cold wave frequency of each station in Inner Mongolia

3.2.2 内蒙古寒潮空间趋势特征依据分段线性回归模型计算结果, 文中同样计算了整个研究时段及转折点前后的Sen趋势度, 并对变化趋势进行M-K显著性检验。图5a可以看出, 整个研究时段变化趋势介于-2.4~1.2次/10a, 其中呈减少趋势的区域占整个研究区的93.04%, 且明显减少的区域分布在兴安盟的西北部、锡林郭勒盟的东北部以及包头地区等; 呈增加趋势的零星分布在呼伦贝尔的图里河站以及阿拉善盟的巴音毛道站。

分段分析表明：1960-1991年变化趋势介于-3.3~2.5次/10a (图5b), 减少趋势显著大于整个研究时段的趋势, 其中99%以上的区域均呈减少趋势, 且减少趋势大于-1次/10a的区域占70.82%, 显著多于整个研究时段的12.67%, 其中呈显著减少的区域主要分布在赤峰市的赤峰站、翁牛特旗站、兴安盟的索伦站、锡林郭勒盟的东乌珠穆沁旗站, 以及阿拉善盟的额济纳旗站。而1991-2012年寒潮频次变化趋势介于-4.4~4.2次/10a (图5c), 呈减少趋势和增加趋势的区域分别占23.72%和76.28%, 显著增加区域主要分布在锡林郭勒盟的锡林浩特和西乌珠穆沁旗等地。

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	图5 1960-2012年内蒙古寒潮变化趋势空间分布图Fig. 5 Spatial distribution of trend of cold wave in Inner Mongolia during 1960-2012

从以上分析可以看出, 整个研究时段的趋势并不能很好地解释内蒙古寒潮频次变化特征, 而分段线性拟合较好地刻画了不同时段的变化趋势, 对于全面认识气候变化背景下极端事件变化趋势具有重要意义。

4 影响因素分析

4.1 大气环流的影响

已有研究表明：气候系统的涛动会导致区域大气环流的异常, 进而影响区域气候的特征^{[25, 26]}。本文利用相关分析方法, 探讨了寒潮频次变化的可能影响因素 (表1)。我们发现, 内蒙古寒潮频次与AO、NAO呈显著负相关关系, 相关系数分别为-0.41 (P < 0.01)和-0.31 (P < 0.05), 其中冬季寒潮频次与冬季AO、NAO呈极显著负相关关系, 相关系数分别为-0.36和-0.40, 均通过了显著水平0.01的检验。而寒潮频次与CA、APVII呈极显著正相关关系, 相关系数分别为0.50 (P < 0.01) 和0.47 (P < 0.01), 其中CA在不同季节均呈显著正相关关系, 而除秋季外, APVII与冬季和春季的相关系数均达到0.01显著水平。

表1 内蒙古寒潮频次与影响因子的相关分析 Fig. 1 Correlation coefficients between cold surge frequency and its influencing factors

此外, 寒潮频次与TPI、SHI、CW、IZ的相关性仅在冬季达到显著相关, 而与IM在秋季呈显著正相关关系。就年尺度而言, 寒潮主要受AO、NAO、CA、APVII和CQ控制。然而, 各季节控制因子有所差别, 除CQ和IM外, 冬季寒潮与各因子均达到显著水平0.05以上的相关性, 说明冬季寒潮受多种因素共同控制; 秋季寒潮主要受CA和IM影响; 而春季寒潮与CA和APVII关系显著。基于以上分析, 本文进一步对与内蒙古寒潮频次密切相关的影响因素的变化特征进行重点分析, 以得到更为细致的事实。

北极涛动 (AO) 对北半球大气环流以及冬半年北半球近地面许多气候要素都有显著影响^[27], 冬季北极涛动通过影响西伯利亚高压和东亚大槽等区域性大气环流来影响冬季风强度, 进而引起区域气温的变化。研究发现, 近53年AO指数呈增加趋势, 分段模型检测出其在1989年发生负位相转为正位相的转折, 与陈豫英^[28]等人研究结论一致。1989年之前AO指数呈增加趋势 (P = 0.07), 反映了极地高气压逐渐减弱而中纬度偏低气压逐渐增强, 极涡加强, 将冷空气控制在极地, 从而使西伯利亚高压和冬季风强度减弱, 向南爆发的冷空气频次下降, 与本文寒潮频次变化趋势一致; 1989年之后AO指数呈下降趋势 (P = 0.12), 负相位有所增加, 极涡减弱, 西伯利亚高压和冬季风强度增强, 向南爆发的冷空气频次增加, 与本研究结果一致。同样的趋势也在北大西洋涛动 (NAO) 指数的长期变化趋势中检测出来。以上分析说明AO和NAO是内蒙古寒潮的重要影响因素。

西伯利亚高压是寒潮发生的关键影响因素, 本文选取 (40° N~60° N, 80° E~120° E) 区域作为西伯利亚高压的主体, 通过计算该区域海平面气压平均值, 并经过标准化处理得到西伯利亚高压指数 (SHI)。我们发现, 内蒙古寒潮频次与SHI仅在冬季呈显著正相关关系, 而在秋季和春季均呈弱的正相关关系, 其原因主要是：西伯利亚高压在冬季较强, 对我国寒潮频次影响较大, 而在秋季和春季强度较小所致, 与前人研究结论较为一致^[10]。

值得注意的是, 龚道溢^[29]等人建立的近百年西伯利亚高压时间序列表明：西伯利亚高压在20世纪60年代最强, 而80-90年代变弱, 与本文寒潮频次的年代际变化特征相吻合, 进一步印证了西伯利亚高压是影响我国寒潮频次的重要因素。从长期趋势来看, SHI在1991年发生转折, 与寒潮频次变化转折年份一致, 其中1991年之前两者变化趋势较为一致, 而1991年之后, 西伯利亚高压指数上升趋势远高于寒潮频次上升趋势。

4.2 地形地貌的影响

大气环流和地理条件分别作用于气候, 其中大气环流能够在大尺度上较好解释寒潮的空间分布特征, 而区域内部地形差异成为探讨寒潮分布不均的重要因素。地形对区域水热条件具有再分配的作用, 并能够对入侵冷空气起到阻挡和分流作用, 因此其对寒潮的影响意义重大。研究区主要山脉包括位于东部的东北— 西南走向的大兴安岭山脉和中部东西走向的阴山山脉, 两者形成的面向西北方向的夹角区域直接受到西伯利亚冷空气的影响, 成为内蒙古寒潮最严重的区域, 而大兴安岭山脉东部和阴山山脉南部寒潮频次较少, 形成明显的空间分异特征, 其原因可能是冷空气爆发后长驱直入, 到达大兴安岭西麓和阴山北麓, 一方面由于山体阻挡作用, 冷空气爬坡速度较慢, 造成冷空气的滞留, 从而在山前形成寒潮高频区; 另一方面由于两山脉形成“ 易进难出” 型^{[30, 31]}的外围地形特征, 同样加重了寒潮的危害。而当入侵冷空气越过山体后, 在重力作用下, 移动速度较快, 对局地气候影响时间较短, 从而使大兴安岭东部和阴山南部地区的寒潮频次较少。

5 结论与讨论

5.1 结论

(1) 近53年内蒙古单站寒潮整体呈下降趋势, 降速为-0.5次/10a (-2.4~1.2次/10a), 并具有明显的阶段性变化特征, 其中1991之前呈显著减少趋势, 降速达-1.1次/10a (-3.3~2.5次/10a); 而1991年之后呈增加趋势, 增速为0.45次/10a (-4.4~4.2次/10a)。春季寒潮频次变化趋势与年变化趋势一致, 且在各季节中变化最为显著; 而寒潮频次年内变化表现为“ 双峰” 结构, 高频期主要集中在10-11月和次年3月, 且11月发生频次最多。

(2) 空间上, 内蒙古单站寒潮频次具有显著的空间差异特征, 高发区集中在内蒙古的北部和中部地区, 且北部高于中部。年代尺度对比来看, 20世纪60-90年代寒潮高频区域范围在减少、低频区域范围在增加; 而21世纪初期高频区域范围有所增加, 增加区主要为内蒙古东部的图里河、小二沟, 以及中部的西乌珠穆沁旗等地; 此外, 寒潮高发区与内蒙古森林和草原分布区基本一致, 空间位置上的叠加势必会对当地农牧业生产造成严重影响。

(3) 近53年内蒙古寒潮频次呈减少趋势的区域占整个研究区的93.04%。分段研究发现, 1960-1991年减少趋势显著大于整个研究时段的趋势, 其中99%以上的区域均呈减少趋势, 且减少趋势大于-1次/10a的区域占70.82%, 显著多于整个研究时段的12.67%; 而1991-2012年呈减少趋势和增加趋势的区域分别占23.72%和76.28%, 显著增加区域主要分布在锡林郭勒盟的锡林浩特和西乌珠穆沁旗等地。

(4) 就年尺度而言, 寒潮主要受AO、NAO、CA、APVII和CQ控制, 而各季节驱动因素有所差别, 冬季寒潮与AO、NAO、SHI、CA、TPI、APVII、CW和IZ均达到显著相关关系, 说明冬季寒潮受多种因素共同控制; 秋季寒潮主要受CA和IM影响; 而春季寒潮与CA和APVII关系显著。内蒙古寒潮频次变化趋势表明, 近年来寒潮频次呈现增加趋势, 与全球气候变化背景下, 极端气候事件不断增加的事实一致。

5.2 讨论

在全球气候变暖背景下, 大气环流特征、极端气候事件的频率和强度均发生了显著变化, 需要关注和加强这一领域的研究和分析, 提高对极端气候事件的认识水平, 并且未来生态系统会逐渐适应温暖的气候, 对极端低温事件的脆弱性逐渐增加, 一旦发生寒潮等极端低温事件将会对生态系统的结构和功能造成巨大而深远的影响。

值得注意的是, 春季是农作物播种的关键时期, 此阶段如果遭受寒潮等低温灾害将会造成巨大的经济损失, 因此, 加强春季倒春寒特征的分析对于农业生产具有举足轻重的作用。同时, 穆少杰^[19]等研究发现近10年内蒙古锡林郭勒高原东南部植被覆盖度显著减少, 该区域与本研究的近10年寒潮高发区相吻合, 而寒潮 (尤其是春季寒潮) 是否是造成植被覆盖变化的影响因素之一需要进一步研究和验证。

另外, 寒潮对当地牧草返青也会造成一定的影响, 尤其是近年来草原区寒潮强度呈增大趋势, 由此带来的对当地农牧业的不利影响尚不明晰, 因此, 关注寒潮事件时空变化特征, 加强寒潮风险评估是有效提高气候变化适应能力、增强综合防灾减灾能力的重要手段, 值得进一步关注。

The authors have declared that no competing interests exist.

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[11]	Qian Weihong, Zhang Weiwei. Changes in cold wave events and warm winter in China during the last 46 years. Chinese Journal of Atmospheric Sciences, 2007, 31(6): 1266-1278. [钱维宏, 张玮玮. 我国近46 年来的寒潮时空变化与冬季增暖. 大气科学, 2007, 31(6): 1266-1278. ] [本文引用:2] [CJCR: 1.948]
[12]	Zhou Y, Ren G. Change in extreme temperature event frequency over mainland China, 1961-2008. Climate Research, 2011, 50(2): 125-139. [本文引用:1] [JCR: 2.684]
[13]	Chen Yeguo, He Dongyan, Nong Mengsong. Change of cold wave in the Nanning area under global warming. Advances in Climate Change Research, 2008, 4(4): 245-249. [陈业国, 何冬燕, 农孟松. 全球变暖背景下南宁地区寒潮活动的变化. 气候变化研究进展, 2008, 4(4): 245-249. ] [本文引用:1] [CJCR: 1.3396]
[14]	Wang Zhengwang, Zhao Guixiang, Zhang Ruiting et al Characteristic analysis of cold wave weather in southeast area of Shanxi Province during last 40 years. Journal of Natural Disasters, 2010, 19(6): 55-60. [王正旺, 赵桂香, 张瑞庭, 等. 山西东南部地区近 40 年寒潮气候特征分析. 自然灾害学报, 2010, 19(6): 55-60. ] [本文引用:1] [CJCR: 0.911]
[15]	Mansur Sabit. Climatic characteristics of cold wave and its impact on agriculture in southern Xinjiang in recent 60 years. Journal of Natural Resources, 2012, 27(12): 2145-2152. [满苏尔·沙比提. 南疆近60a来寒潮气候特征及其对农业生产的影响. 自然资源学报, 2012, 27(12): 2145-2152. ] [本文引用:1] [CJCR: 2.407]
[16]	Guo Linghui, Wu Shaohong, Zhao Dongsheng et al Change trends of growing season over Inner Mongolia in the past 50 years. Scientia Geographica Sinica, 2013, 33(4): 505-512. [郭灵辉, 吴绍洪, 赵东升, 等. 近50年内蒙古地区生长季变化趋势. 地理科学, 2013, 33(4): 505-512. ] [本文引用:1] [CJCR: 2.779]
[17]	Wang Mingjiu, Zhang Cunhou. Climate change in Inner Mongolia grassland and the effects on pastoral animal husband ry. Inner Mongolia Prataculture, 2013, 25(1): 5-12. [王明玖, 张存厚. 内蒙古草地气候变化及对畜牧业的影响分析. 内蒙古草业, 2013, 25(1): 5-12. ] [本文引用:1]
[18]	Sun Yanling, Guo Peng, Yan Xiaodong et al Dynamics of vegetation cover and its relationship with climate change and human activities in Inner Mongolia. Journal of Natural Resources, 2010, 25(3): 407-414. [孙艳玲, 郭鹏, 延晓冬, 等. 内蒙古植被覆盖变化及其与气候、人类活动的关系. 自然资源学报, 2010, 25(3): 407-414. ] [本文引用:1] [CJCR: 2.407]
[19]	Mu Shaojie, Li Jianlong, Chen Yizhao et al Spatial differences of variations of vegetation coverage in Inner Mongolia during 2001-2010 Acta Geographica Sinica, 2012, 67(9): 1255-1268. [穆少杰, 李建龙, 陈奕兆等. 2001-2010 年内蒙古植被覆盖度时空变化特征. 地理学报, 2012, 67(9): 1255-1268. ] [本文引用:2] [CJCR: 2.937]
[20]	John R, Chen J, Lu N et al Predicting plant diversity based on remote sensing products in the semi-arid region of Inner Mongolia. Remote Sensing of Environment, 2008, 112(5): 2018-2032. [本文引用:1] [JCR: 5.103]
[21]	Sen P K. Estimates of the regression coefficient based on Kendall's tau. Journal of the American Statistical Association, 1968, 63(324): 1379-1389. [本文引用:1] [JCR: 1.834]
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[24]	Sun J, Wang X, Chen A et al NDVI indicated characteristics of vegetation cover change in China's metropolises over the last three decades. Environmental monitoring and assessment, 2011, 179(1-4): 1-14. [本文引用:1] [JCR: 1.592]
[25]	Ding Yihui, Wen Shigeng, Li Yunjin. A study of dynamic structures of the Siberian high in winter. Acta Meteorologica Sinica, 1991, 49(4): 430-439. [丁一汇, 温市耕, 李运锦. 冬季西伯利亚高压动力结构的研究. 气象学报, 1991, 49(4): 430-439. ] [本文引用:1] [JCR: 0.799] [CJCR: 0.363]
[26]	Wen C, Graf H F, Ronghui H. The interannual variability of East Asian winter monsoon and its relation to the summer monsoon. Advances in Atmospheric Sciences, 2000, 17(1): 48-60. [本文引用:1] [JCR: 1.338] [CJCR: 0.9244]
[27]	Yao Junqiang, Liu Zhihui, Yang Qing et al Temperature variability and its possible causes in the typical basins of the arid Central Asia in recent 130 years. Acta Geographica Sinica, 2014, 69(3): 291-302. [姚俊强, 刘志辉, 杨青等. 近 130 年来中亚干旱区典型流域气温变化及其影响因子. 地理学报, 2014, 69(3): 291-302. ] [本文引用:1] [CJCR: 2.937]
[28]	Chen Yuying, Chen Nan, Ma Jinren et al Variety of Ningxia cold waves in the last 48 years and its possible reasons. Journal of Natural Resources, 2010, 25(6): 939-951. [陈豫英, 陈楠, 马金仁等. 近 48 a 宁夏寒潮的变化特征及可能影响的成因初步分析. 自然资源学报, 2010, 25(6): 939-951. ] [本文引用:1] [CJCR: 2.407]
[29]	Gong Daoyi, Wang Shaowu. Influence of Arctic Oscillation on winter climate over China. Acta Geographica Sinica, 2003, 58(4): 559-568. [龚道溢, 王绍武. 近百年北极涛动对中国冬季气候的影响. 地理学报, 2003, 58(4): 559-568. ] [本文引用:1] [CJCR: 2.937]
[30]	Huang Shoubo. Advance in the investigation of the topographical microclimate in China. Geographical Research, 1986, 5(2): 90-101. [黄寿波. 我国地形小气候研究概况与展望. 地理研究, 1986, 5(2): 90-101. ] [本文引用:1]
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2014

0.0

1.959

Zheng

Jingyun

, Hao

Zhixin

, Fang

Xiuqi

et al. Changing characteristics of extreme climate events during past 2000 years in China. Progress in Geography, 2014, 33(1): 3-12.

[郑景云, 郝志新, 方修琦等. 中国过去 2000 年极端气候事件变化的若干特征. 地理科学进展, 2014, 33(1): 3-12. ]

In the current research on climate changes it is a hot topic to study the changes of extreme climatic events during historical periods. In this paper, based on the reconstructions from multiple proxy types including historical documents, tree-rings, ice cores and lake sediments in the published literature of the recent 20 years, we summarized the characteristics of changes of extreme climate events during the past 2000 years in China. The analysis shows that: (1) During the cold periods of 1500-1900 and 220-580, there appeared extremely cold winters that were even colder than the cold winters in the years after 1950, and there appeared hot summers with daily highest temperature exceeding record high of the years in the 20th century as well. In the past 1600 years, the cold summer events in Northeast of China mainly occurred during the period of 1400-1900. (2) In the eastern monsoon region of China, the extreme drought events prevailed during the periods of 301-400, 751-800, 1051-1150, 1501-1550 and 1601-1650, the extreme flood events often occurred during the periods of 101-150, 251-300, 951-1000, 1701-1750, 1801-1850 and 1901-1950, and for the period of 1551-1600, coexisting extreme drought and extreme flood events occurred most frequently. The frequency of persistent extreme drought was higher during the 7th-8th century, 12th-14th century and late-15th century to mid-17th century; the frequency of sustaining extreme flood was higher during the 10th-11th century and after the mid-17th century. The time intervals of extreme drought/flood events are different in North China, Yangtze and Huaihe River Valley and south of Yangtze River. In addition, the notable extreme drought events, such as "Chong Zhen Drought" in the Ming Dynasty, and "Ding Wu Famine" in the Qing Dynasty, were recognized. (3) In the arid region of Northwest China, the extreme drought events mainly occurred during the periods of 1471-1520, 1581-1650, 1711-1760, 1811-1860 and 1921-1970. 1710s was the most severe drought decade during the past 1000 years. However, due to the very limited climate proxy data for this region, the primary characteristics of complete change process of the extreme events were difficult to evaluate. (4) Although drought frequently occurred in southwest of China during the early 21th century, the extreme drought events as severe as the one in Sichuan and Chongqing in 2006 occurred many times during the historical periods.

1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China; 2. School of Geography, Beijing Normal University, Beijing 100875, China

历史时期极端气候事件变化是当前气候变化研究的热点领域。本文根据近20 年这一研究领域的主要文献，对中国过去2000 年极端气候事件变化特征进行了梳理和总结。已有认识表明：① 在1500-1900 年和220-580年等气候寒冷期，中国不但多次出现过较1950 年以后所出现的极端冷冬更为显著的寒冷事件，而且其间的相对温暖时段也出现过日最高气温超过20 世纪极端记录的炎夏。② 在中国东部季风区，在公元301-400、751-800、1051-1150、1501-1550 和1601-1650 年极端干旱多发；101-150、251-300、951-1000、1701-1750、1801-1850 和1901-1950 年极端大涝多发；1551-1600 年则是极端干旱与大涝并发最为频繁的时段。7-8 世纪、12-14 世纪和15 世纪后期-17 世纪中期多发极端连旱；10-11 世纪及17 世纪中期以后，多发极端连涝。华北、江淮和江南3 个地区的极端干旱和大涝事件多发时段存在差异；此外，历史极端连旱事件如“崇祯大旱”和“丁戊奇荒”等也得到辨识。③ 在西北干旱区，极端干旱主要集中发生在1471-1520 年、1581-1650 年、1711-1760 年、1811-1860 年和1921-1970 年等5个时段，其中18 世纪10 年代可能是过去千年极端干旱最严重的年代。④ 在西南地区，虽然21 世纪初旱灾频发，但与2006年川渝特大干旱相仿的事件在史上也曾多次发生过。

... 1 引言极端气候事件是指某类气候要素量值或统计值显著偏离其平均态、且达到或超过其观测或统计量值区间上下限附近特定阈值的事件^[1] ...

2009

0.0

2.779

Cui

Linli

, Shi

Jun

, Zhou

Weidong.

Characteristics of extreme temperature variations and their response to urbanization in Shanghai.

Scientia Geographica Sinica, 2009, 29(1): 93-97.

[崔林丽, 史军, 周伟东. 上海极端气温变化特征及其对城市化的响应. 地理科学, 2009, 29(1): 93-97. ]

Based on the daily maximum and minimum temperature in meteorological stations of Shanghai, the temporal characteristics of extreme temperature variation during 1873-2007 and the response of extreme temperature to urbanization during 1960-2007 were studied.The results show that, as a whole, the extreme high temperature and high temperature days varied without significant tendency, but the extreme low temperature varied significantly with a rate of linear increasing tendency of 0.27 ℃ per 10 years, and the low temperature days varied significantly with a rate of linear decreasing tendency of 1.14 d per 10 years from 1873 to 2007.In the period from 2001 to 2007, Shanghai had the most high temperature days and the least low temperature days in the past 135 years.The extreme high temperature was mainly negative anomaly in the periods from 1876 to 1884 and from 1960 to 1989, but it was mainly positive anomaly in the periods from 1885 to 1955 and from 1990 to 2007.The extreme low temperature was mainly negative anomaly before 1994, then, in the continuous 14 years from 1994 to 2007, it was positive anomaly.High temperature days were mainly positive anomaly in the periods from 1891 to 1898, from 1920 to 1953, and from 2000 to 2007, but they were mainly negative anomaly in the periods from 1874 to 1888 and from 1961 to 1989.Low temperature days were mainly positive anomaly before 1988, then, in the continuous 20 years from 1988 to 2007, they were negative anomaly.From 1960 to 2007, the extreme high temperature and the high temperature days increased more in urban areas, and less in suburbs and exurbs of Shanghai.The extreme low temperature and the low temperature days decreased more in urban areas and suburbs, and less in exurbs.The difference of extreme high temperature between urban areas and suburbs increased significantly with a rate of linear tendency of 0.26 ℃ per 10 years, but that difference between suburbs and exurbs varied insignificantly.The difference of high temperature days between urban areas and suburbs increased significantly with a rate of linear tendency of 1.95 d per 10 years, and the difference between suburbs and exurbs increased significantly with a rate of linear tendency of 0.77 d per 10 years.From the 1980s, extreme high temperature in urban areas was higher than that in suburbs and exurbs, and the high temperature days in urban areas was more than that in suburbs and exurbs in Shanghai obviously.From the 1990s, extreme high temperature in suburbs was higher obviously than that in exurbs, and at the beginning of the 21st century, the high temperature days in suburbs were more obviously than those in exurbs in Shanghai.The difference of extreme low temperature between urban areas and suburbs varied insignificantly, but that between suburbs and exurbs increased significantly with a rate of linear tendency of 0.31 ℃ per 10 years.From the 1960s, the extreme low temperature in urban areas was higher than that in suburbs and exurbs, and from the 1980s, the extreme low temperature in suburbs was higher than that in exurbs in Shanghai.The difference of low temperature days between urban areas and suburbs varied insignificantly, but that difference between exurbs and suburbs increased significantly with a rate of linear tendency of 0.79 d per 10 years.The low temperature days in urban areas and suburbs were nearly same from 1960 to 2007, and from the 1980s, they were less than that in exurbs in Shanghai obviously.

1. Shanghai Center for Satellite Remote Sensing and Application, Shanghai 201100; 2. Shanghai Climate Center, Shanghai 200030

利用上海气象站逐日最高和最低气温资料,分析上海极端气温时间变化特征及对上海城市化的响应过程。结果表明上海1873~2007年极端最高气温总体上无显著变化趋势,极端最低气温以0.27℃/10 a的线性倾向率显著增加,2001~2007年,上海高温日数最多,低温日数最少。1960~2007年,上海极端最高气温和高温日数在市区增加较多,近郊和远郊增加较少;极端最低气温和低温日数市区和近郊减少较多,远郊减少较少。

... 与气候平均态相比,极端气候事件的发生更具反常性、突发性和不可预见性,其对气候变化响应也更为敏感^[2],并将对人类社会和自然环境产生巨大而深远的影响^[3] ...

2000

0.0

Easterling D

, Meehl G

, Parmesan

et al. Climate extremes: Observations, modeling, and impacts. Science, 2000, 289(5487): 2068-2074.

1 National Oceanic and Atmospheric Administration (NOAA)/National Climatic Data Center, 151 Patton Avenue, Asheville, NC 28801,USA. 2 National Center for Atmospheric Research, Boulder, CO 80303, USA. 3 Integrative Biology, University of Texas, Austin, TX 78712, USA. 4 Illinois State Water Survey, Champaign, IL 61820, USA.

... 随着全球气候变化课题日益受到学界高度关注,针对寒潮等极端气候研究日益成为国内外气候变化和综合防灾减灾研究领域的热点问题^[3] ...

2013

0.0

... 89 ^oC)^[4],而我国1960-2009年地表平均气温亦升高了1 ...

2011

0.0

... 38 ^oC,远高于全球或北半球同期增温速率^[5],以北方增暖最为明显,由此导致极端气候事件出现的频率和强度呈现出增加趋势^[6,7] ...

1997

0.799

0.363

... 38 ^oC,远高于全球或北半球同期增温速率^[5],以北方增暖最为明显,由此导致极端气候事件出现的频率和强度呈现出增加趋势^[6,7] ...

1999

3.634

0.0

... 38 ^oC,远高于全球或北半球同期增温速率^[5],以北方增暖最为明显,由此导致极端气候事件出现的频率和强度呈现出增加趋势^[6,7] ...

1955

0.0

... 我国学者李宪之先生^[8]早在1955年就研究了东亚寒潮爆发过程,并将我国寒潮划分为3类 ...

1957

0.799

0.363

... 随后,陶诗言先生^[9]针对影响我国大陆的冷空气源地和侵袭路径进行了深入分析 ...

2006

0.0

1.948

Wang

Zunya

, Ding

Yihui.

Climate change of the cold wave frequency of China in the last 53 years and the possible reasons.

Chinese Journal of Atmospheric Sciences, 2006, 30(6): 1068-1076.

[王遵娅, 丁一汇. 近 53 年中国寒潮的变化特征及其可能原因. 大气科学, 2006, 30(6): 1068-1076. ]

利用1951～2004年中国740站逐日温度资料, 对中国寒潮频次的气候特征及其变化进行了分析, 并在此基础上对中国寒潮频次减少的可能原因进行了讨论: 冬季西伯利亚高压和东亚冬季风强度与中国寒潮频次呈显著的正相关.秋冬季节西伯利亚上空低层冷堆温度和中国寒潮频次呈显著的负相关.在气候变暖的大背景下, 西伯利亚高压和冬季风强度的减弱使得冬季中国地表温度持续升高, 而温度的这种变化与中国寒潮频次及其相伴随大风频次的减少均有密切的联系.西伯利亚高压和冬季风强度的减弱, 西伯利亚上空低层冷堆温度和中国地表温度的显著升高是中国寒潮及其相伴随大风频次减少的可能原因.

... 王遵娅^[10]和钱维宏^[11]分别对我国寒潮时空变化及其影响因素进行了深入分析,前者认为西伯利亚高压和冬季风强度的减弱是寒潮频次减少的可能原因,而后者指出我国寒潮频次、降温事件、升压频率和大风频次都在减少,在一定程度上导致了冬季最低温度平均值的升高,从而形成持续的暖冬 ...

... 我们发现,内蒙古寒潮频次与SHI仅在冬季呈显著正相关关系,而在秋季和春季均呈弱的正相关关系,其原因主要是：西伯利亚高压在冬季较强,对我国寒潮频次影响较大,而在秋季和春季强度较小所致,与前人研究结论较为一致^[10] ...

2007

0.0

1.948

Qian

Weihong

, Zhang

Weiwei.

Changes in cold wave events and warm winter in China during the last 46 years.

Chinese Journal of Atmospheric Sciences, 2007, 31(6): 1266-1278.

[钱维宏, 张玮玮. 我国近46 年来的寒潮时空变化与冬季增暖. 大气科学, 2007, 31(6): 1266-1278. ]

使用中国气象局资料中心整编的572个站点1960年1月1日到2005年12月31日日最低温度、日平均气压、日平均风速和北极涛动 (AO) 指数等气象要素, 从一个新的角度分析了我国寒潮时空变化与冬季增暖的联系.寒潮爆发以降温、升压和大风天气为主要特征.定义1日和2日降温达到10℃以上的降温事件为寒潮, 大于20℃为极端寒潮.发生在我国的寒潮以北方 (35°N以北) 最多, 其次是中国东部的江南地区.东北的寒潮始于10月, 而河套和江南的寒潮在4月份比较频繁.把10月到次年4月寒潮频繁活动的时段确定为冬季风时期.在所有的降温事件中, 只有不到1/3的事件伴随有升压和大风天气.过去的45个冬季风期间, 寒潮和极端寒潮事件普遍减少, 我国新疆、华北、东北和华东减少最为显著, 减少的最大幅度达到1～2次/10 a.降温事件、升压频次和大风频次也都在减少.AO指数升高表征了西风带上天气尺度斜压波动的减少和减弱, 从而导致我国中高纬度寒潮事件的减少.降温频次的减少在一定程度上导致了冬季最低温度平均值的升高, 形成了持续的暖冬.

... 由于日平均气温并非实际测得的温度,而最低温度不受太阳辐射的影响,可以较好地反映降温的相对幅度^[11] ...

2011

2.684

0.0

... 事实上,我国不同区域寒潮频次呈现出不同程度的减少趋势,且区域间差异较为显著,甚至有些地区近年来出现增加趋势^{[12,13,14,15]} ...

2008

0.0

1.3396

Chen

Yeguo

, He

Dongyan

, Nong

Mengsong.

Change of cold wave in the Nanning area under global warming.

Advances in Climate Change Research, 2008, 4(4): 245-249.

[陈业国, 何冬燕, 农孟松. 全球变暖背景下南宁地区寒潮活动的变化. 气候变化研究进展, 2008, 4(4): 245-249. ]

Using the daily mean/minimum air temperatures data at 8 weather stations in the Nanning area during 1961-2005, we analyzed the change characteristics of cold wave activity in the Nanning area in recent 45 years and the impact of anomalous circulations on the frequency of the cold wave events affecting Nanning. The results show that the cold wave activity period is different in various areas of the Nanning area, that is, the cold wave activity begins early but ends late in the east, while it begins late but ends early in the northwest. The cold waves occur mainly in December, January and February. Over the past 45 years, cold waves had two abnormal changes in the early 1970s and late 1990s. The general trend of cold wave activity is decreasing at a rate of 0.12 time/10 a. This phenomenon is mainly related to the obvious rise in daily minimum temperature. The typical circulation characteristics for strong/weak cold wave activity years are illustrated with respective composite 500 hPa height anomaly fields.

Guangxi Meteorological Observatory

利用1961-2005年南宁地区8个气象观测站的逐日平均气温和最低气温资料，分析近45 a南宁地区寒潮活动的特征及其多年变化特点，并且研究了环流场异常对寒潮事件发生频率的影响。结果表明，南宁地区寒潮活动期区域差异较大：东部开始早，结束晚；西北部开始晚，结束早，寒潮出现在12、1和2月。近45 a来，寒潮具有两次跃变异常，分别发生在20世纪70年代前期和90年代后期；寒潮活动总的趋势是减少的，减少频数为0.12次/10 a，这主要与日最低气温比较高有关。此外，针对强寒潮活动年和弱寒潮活动年，给出了500 hPa典型高度距平场特征。

... 事实上,我国不同区域寒潮频次呈现出不同程度的减少趋势,且区域间差异较为显著,甚至有些地区近年来出现增加趋势^{[12,13,14,15]} ...

2010

0.0

0.911

... 事实上,我国不同区域寒潮频次呈现出不同程度的减少趋势,且区域间差异较为显著,甚至有些地区近年来出现增加趋势^{[12,13,14,15]} ...

2012

0.0

2.407

Mansur

Sabit.

Climatic characteristics of cold wave and its impact on agriculture in southern Xinjiang in recent 60 years.

Journal of Natural Resources, 2012, 27(12): 2145-2152.

[满苏尔·沙比提. 南疆近60a来寒潮气候特征及其对农业生产的影响. 自然资源学报, 2012, 27(12): 2145-2152. ]

The cold wave is one of the main natural disasters in Xinjiang. Because of sparse vegetation cover, large temperate difference and strong cold air mass to the south, it is easy to form cold wave. This paper analyzed the spatial distribution, seasonal and annual changes and forming reasons of the cold wave based on the data of cold wave frequency, duration and its impact on cropland, livestock and economic damage encompassing from 1949 to 2008 in five districts in southern Xinjiang. The results showed that: 1)In recent 60 years, the occurrence of cold wave in mountain areas in southern Xinjiang is more frequent than that in plain area, northern part more than southern part, and the magnitude of cold wave induced temperature drop at southern foot hills of the Tianshan Mountains is greater than in the northern mountain area. According to special distribution, the maximum frequency of the cold wave took place in Bayingolin Mongol Autonomous Prefecture, and then in Aksu Prefecture, Kizilsu Kirghiz Autonomous Prefecture and Hotan Prefecture in turns. Kashgar Prefecture is in an intermediate place. 2)In recent 60 years, annual variation of cold wave frequency is pronounced, and it displayed a decreasing trend, especially, since 1999. The cold wave is strong from September to May of the next year, April and May reach the maximum in the one year time. Decreasing of the extreme temperature happens from April to May and from September to October. 3)Although, frequency of cold wave has a decreasing trend under climate change, its damages to the agriculture are enormous. With the expansion of crop area and the development of socio-economy in southern Xinjiang, the cold wave disasters to agriculture have an increasing trend.

School of Geographical Science and Tourism, Xinjiang Normal University, Urumqi 830054, China

寒潮是我区主要灾害性天气之一,南疆植被稀少,温差大,强冷空气南下,容易形成寒潮。论文利用南疆5地(州)1949-2008年间的寒潮发生频次、持续时间及其造成的受灾农田面积、死亡牲畜、经济损失数据资料,对南疆寒潮空间分布、年际变化、季节变化、形成原因及其对农业生产影响进行深入分析。分析得出:①近60 a来,南疆寒潮发生频次山区多于平原、北部多于南部,而寒潮过程降温幅度天山南麓绿洲带大于北部山区;对地(州)而言,巴州发生频次最多,受灾最严重,阿克苏次于巴州,克州与和田寒潮频次与受灾最少,喀什居中。②近60 a来,寒潮发生频次年际变化幅度较大,总体上呈现略有减少趋势,特别是1999年来频次明显减少;每年9月至翌年5月是寒潮活动期,以5月和4月发生频次最高,极端最大降温以4-5月和9-10月居多。③在气候变暖背景下,虽寒潮频次总体上呈略有减少趋势,但由于4-5月寒潮较多,而且小麦返青拔节,棉花出苗蕾铃,果树生芽开花,其抗寒能力下降,遇到明显降温,就会发生冻害,加上绿洲种植面积扩大,社会经济发展,承载体单位面积的受灾成本提高,使南疆寒潮低温冻害灾害呈显著增多趋势。

... 事实上,我国不同区域寒潮频次呈现出不同程度的减少趋势,且区域间差异较为显著,甚至有些地区近年来出现增加趋势^{[12,13,14,15]} ...

2013

0.0

2.779

Guo

Linghui

, Wu

Shaohong

, Zhao

Dongsheng

et al

Change trends of growing season over Inner Mongolia in the past 50 years.

Scientia Geographica Sinica, 2013, 33(4): 505-512.

[郭灵辉, 吴绍洪, 赵东升, 等. 近50年内蒙古地区生长季变化趋势. 地理科学, 2013, 33(4): 505-512. ]

In this study, the characteristics of change trends of growing season and their spatial differences among the different indicators over Inner Mongolia were analyzed, using meteorological data recorded in 47 meteorological stations over the year 1961-2010, based on Mann-Kendall trend test and linear regression method. The results showed that the growing season length of Inner Mongolia region increased significantly from 1961 to 2010, about 13.0-17.0 days. The high consistency among different indices meant that thermal growing season can be used as an key application indicators to reflect temperature changes in this region. However, the average growing season trends over the whole region largely covered the spatial differences between the indices. Growing season trends in western and central Inner Mongolia were more sensitive to the temperature threshold. e.g. the start of the growing season of 0℃ threshold shifted relatively earlier, and the length increased strongly in Alxa League, while the increasing end and length was more prominent under 10℃ threshold in Ulanqab and Xilingol League. Including or excluding a frost criterion had a significant impact on the growing season trends in most central parts of Inner Mongolia, especially on the beginning of the growing season.

1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China

以内蒙古地区47 个气象站点1961~2010 年气象数据为基础,应用Mann-Kendall 趋势性检验和线性回归法分析了不同指标下内蒙古地区生长季变化趋势特征以及区域差异。结果表明:1961~2010 年内蒙古地区生长季长度增加趋势明显,增加幅度约为13.0~17.0 d,各指标间差异小、一致性较高,可作为表征该区温度变化的一个重要应用指标;整个内蒙古地区生长季趋势的平均状态很大程度上掩盖了指标间的区域差异,内蒙古中西部地区生长季变化对温度阈值比较敏感,阿拉善盟地区0℃阈值生长季开始时间提前、生长季长度延长较强烈,乌兰察布盟以及锡林郭勒盟等地10℃阈值生长季结束时间延后、生长季长度增加更为突出;有无霜期限制对内蒙古中部大部分地区生长季趋势影响较大,尤其是对生长季开始时间。

... 内蒙古地区以草原生态系统为主,草原面积约占全国天然草原面积的20%^[16] ...

2013

0.0

... 极端气候事件的增多,增加了气象灾害的不确定性,使农牧业生产风险在加大,危害生态安全和粮食安全^[17] ...

2010

0.0

2.407

Sun

Yanling

, Guo

Peng

, Yan

Xiaodong

et al

Dynamics of vegetation cover and its relationship with climate change and human activities in Inner Mongolia.

Journal of Natural Resources, 2010, 25(3): 407-414.

[孙艳玲, 郭鹏, 延晓冬, 等. 内蒙古植被覆盖变化及其与气候、人类活动的关系. 自然资源学报, 2010, 25(3): 407-414. ]

植被覆盖状况是评估生态环境的重要指标。利用GIMMS数据集的8km分辨率的NDVI数据和气候数据，对内蒙古地区1982—2000年植被覆盖变化进行了分析，并评估了降水与该地区植被的相关关系，在此基础上探讨了人类活动对内蒙古地区植被覆盖变化的影响。研究中采用了相关分析和残差分析，结果表明，在过去19年中内蒙古地区植被NDVI总体上呈轻微上升趋势，且存在着显著的空间差异。同时内蒙古地区植被NDVI与降水有很好的相关性，植被受降水的影响较大。此外，人类活动对内蒙古一些地区的植被变化也起到了建设或破坏的作用。

... 全区气候属于干旱、半干旱气候向东南沿海湿润、半湿润季风气候的过渡带^[18],其中大兴安岭和阴山山脉成为全区气候差异的重要自然分界线 ...

2012

0.0

2.937

Shaojie

, Li

Jianlong

, Chen

Yizhao

et al

Spatial differences of variations of vegetation coverage in Inner Mongolia during 2001-2010

Acta Geographica Sinica, 2012, 67(9): 1255-1268.

[穆少杰, 李建龙, 陈奕兆等. 2001-2010 年内蒙古植被覆盖度时空变化特征. 地理学报, 2012, 67(9): 1255-1268. ]

Global climate change has led to significant vegetation changes in the past half century. Inner Mongolia, most of which was located in arid and semi-arid areas, is undergoing a process of prominent warming and drying. It is necessary to investigate the response of vegetation to the climatic variations (temperature and precipitation) for a better understanding of the accumulated consequence of climate change. Vegetation coverage, which is an important indicator for evaluating terrestrial environment, is used to monitor vegetation change. MODIS-NDVI data and climate data were used to analyze the vegetation dynamics and its relationship with climate change on different spatial (forest, grassland and desert biome) and temporal (yearly and monthly) scales in Inner Mongolia during 2001-2010. It was found that vegetation coverage increased from west to east across Inner Mongolia with a change rate of 0.2/10°N. During 2001-2010, the mean vegetation coverage was 0.57, 0.4 and 0.16 in forest, grassland and desert biome, respectively, exhibiting evident spatial heterogeneities. There is a slight increase of vegetation coverage over the study period. Across Inner Mongolia, the vegetation coverages with extremely significant and significant increase accounted for 11.25% and 29.13% of the total study area, respectively, while those with extremely significant and significant decrease were 7.65% and 26.61%, respectively. The correlation analysis between vegetation coverage and climate shows that annual vegetation coverage was better correlated with precipitation, while the change of monthly vegetation coverage is consistent with both the changes of temperature and precipitation, indicating that the vegetation growth within a year is more sensitive to the joint function of hydrothermal combination rather than either climate factor. The vegetation coverage of forest biome was mainly affected by temperature on both yearly and monthly scales, while that of desert biome was mainly influenced by precipitation on the two temporal scales.

1. School of Life Science, Nanjing University, Nanjing 210093, China; 2. International Institute for Earth System Science, Nanjing University, Nanjing 210093, China

基于MODIS-NDVI 遥感数据反演了内蒙古地区2001-2010 年植被覆盖度的空间格局和变化规律, 并结合该地区同期降雨量和温度数据, 分别从不同空间和时间尺度上分析了森林生态区、草原生态区和荒漠生态区植被的年际变化和月际变化对气候变化的响应。结果表明:(1) 内蒙古植被覆盖度在空间上呈现东高西低的分布特征, 自西向东的变化速率为0.2/10°N, 10 年间森林、草原和荒漠生态区的年均植被覆盖度分别为0.57、0.4 和0.16;(2) 2001-2010年, 内蒙古植被覆盖度总体上呈上升趋势, 研究区内植被覆盖度极显著增加和显著增加的面积分别占总面积的11.25%和29.13%, 二者之和大于植被覆盖度极显著减少和显著减少的面积比例之和, 后者分别为7.65%和26.61%;(3) 在年际水平上, 内蒙古植被生长总体上与降雨量的关系更加密切, 而在月际水平上, 降雨量和温度对植被生长的影响作用相当, 说明年内植被生长更依赖于水热组合的共同作用, 而与单一气候因子的相关性降低;(4) 森林生态区植被覆盖度在年/月际水平上均与温度的相关性较强, 荒漠生态区植被覆盖度在年/月际水平上均与降雨量相关性较强, 而草原生态区植被覆盖度在年际水平上主要受降雨影响, 在月际水平上与二者相关性相当;(5) 草原区月植被覆盖度对降雨量的响应存在时滞效应。

... org/),该数据将全球划分为825个生态区,其中内蒙古地区共有13个生态区^[19] ...

... 同时,穆少杰^[19]等研究发现近10年内蒙古锡林郭勒高原东南部植被覆盖度显著减少,该区域与本研究的近10年寒潮高发区相吻合,而寒潮 (尤其是春季寒潮) 是否是造成植被覆盖变化的影响因素之一需要进一步研究和验证 ...

2008

5.103

0.0

John

, Chen

, Lu

et al

Predicting plant diversity based on remote sensing products in the semi-arid region of Inner Mongolia.

Remote Sensing of Environment, 2008, 112(5): 2018-2032.

... 根据内蒙古的气候特征和植被分布特征,并结合前人研究成果^[20],将内蒙古分为三大生态区：东部森林生态区 (I区)、中部草原生态区 (II区) 和西部荒漠生态区 (III区) ...

1968

1.834

0.0

... 2 Sen趋势分析和Mann-Kendall统计检验方法本文采用非参数化趋势度^[21]方法来计算内蒙古寒潮频次的变化趋势,并通过Mann-Kendall^[22]统计检验法对变化趋势的显著性进行检验 ...

1948

0.0

2004

3.982

0.0

... 由于该模型能够有效提取长时间序列数据变化趋势的转折点,有效弥补一元线性回归无法真实反映变化趋势的缺陷,已被广泛用于气候变化趋势分析^[23,24],公式如下： ...

2011

1.592

0.0

Sun

, Wang

, Chen

et al

NDVI indicated characteristics of vegetation cover change in China's metropolises over the last three decades.

Environmental monitoring and assessment, 2011, 179(1-4): 1-14.

How urban vegetation was influenced by three decades of intensive urbanization in China is of great interest but rarely studied. In this paper, we used satellite derived Normalized Difference Vegetation Index (NDVI) and socioeconomic data to evaluate effects of urbanization on vegetation cover in China’s 117 metropolises over the last three decades. Our results suggest that current urbanization has caused deterioration of urban vegetation across most cities in China, particularly in East China. At the national scale, average urban area NDVI (NDVI u ) significantly decreased during the last three decades ( P u did not show statistically significant trend before 1990 but decrease remarkably after 1990 ( P u turning point. The year when NDVI u started to decline significantly for Central China and East China was 1987 and 1990, respectively, while NDVI u in West China remained relatively constant until 1998. NDVI u changes in the Yangtze River Delta and the Pearl River Delta, two regions which has been undergoing the most rapid urbanization in China, also show different characteristics. The Pearl River Delta experienced a rapid decline in NDVI u from the early 1980s to the mid-1990s; while in the Yangtze River Delta, NDVI u did not decline significantly until the early 1990s. Such different patterns of NDVI u changes are closely linked with policy-oriented difference in urbanization dynamics of these regions, which highlights the importance of implementing a sustainable urban development policy.

1.Department of Ecology, College of Urban and Environmental Sciences, Key Laboratory for Earth Surface Processes of the Ministry of Education, and Center of Climate Research, Peking University, Beijing, 100871 China 2.Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA

1991

0.799

0.363

Ding

Yihui

, Wen

Shigeng

, Li

Yunjin.

A study of dynamic structures of the Siberian high in winter.

Acta Meteorologica Sinica, 1991, 49(4): 430-439.

[丁一汇, 温市耕, 李运锦. 冬季西伯利亚高压动力结构的研究. 气象学报, 1991, 49(4): 430-439. ]

The present paper has studied the dynamic structures of the Siberian high during it's build-up. It has been found that at the initial stage of formation of the Siberian high, the positive vorticity dominates the region of the high in the troposphere. There is convergence at low-level and high-level, respectively, with divergence in between. Correspondingly, there is the upward motion in the layer below 700 hPa and downward motion above 700 hPa. At the mature stage of the high, the significant negative vorticity and strong divergent airflows are observed in the lower and middle troposphere while there are the positive vorticity and convergent airflows in the upper troposphere. The downward motion occurs in the whole layer of the troposphere. This fact shows that the strong mass convergence in the middle and upper troposphere is a major factor leading to the development of the Siberian high. The diagnostic analysis made by the use of the vorticity equation further indicates that the generation and intensificanon of the negative vorticity in the high troposphere mainly result from the effects of the advection of the negative vorticity in the middle and upper troposprere, whereas at low-level the divergence term(divergence) is the major factor for the generation of the negative vortieity. On the other hand, the heat budget of the Siberian high has revealed a deep layer of cooling, thus inducing the downward motion in the troposphere and then convergence at mid and high levels and divergence at low-level. This condition is favorable for the enhancement of the high. Therefore, the build-up of the Siberian high results from the combined effects of dynamic and thermal factors.

本文研究了冬季西伯利亚高压建立时期的动力结构.研究得到,在高压建立前期,对流层中以正涡度为主.低层和高层有弱的辐合,中层是辐散;相应在700hPa以下是上升,以上是下沉.但当反气旋发展时,高层为正涡度和辐合气流,低层为负涡度和辐散气流,整层为下沉运动.这表明对流层中、上层的强质量辐合是导致西伯利亚高压发展的一个重要因子.涡度方程的诊断表明,西伯利亚高压区负涡度的出现和加强是对流层中、上层负涡度平流和低层散度项的作用.另外,西伯利亚高压热平衡计算表明,对流层有深厚的冷却层(热汇).这种非绝热冷却将在对流层中导致深厚的下沉运动,从而引起中高层的辐合,低层的辐散,有利于高压的加强.因而西伯利亚高压是在动力和热力因子共同作用下形成的.

... 1 大气环流的影响已有研究表明：气候系统的涛动会导致区域大气环流的异常,进而影响区域气候的特征^[25,26] ...

2000

1.338

0.9244

Wen

, Graf H

, Ronghui

The interannual variability of East Asian winter monsoon and its relation to the summer monsoon.

Advances in Atmospheric Sciences, 2000, 17(1): 48-60.

Based on the NCEP/NCAR reanalysis data the interannual variability of the East Asian winter monsoon (EAWM) is studied with a newly defined EAWM intensity index. The marked features for a strong (weak) winter monsoon include strong (weak) northerly winds along coastal East Asia, cold (warm) East Asian continent and surrounding sea and warm (cold) ocean from the subtropical central Pacific to the tropical western Pacific, high (low) pressure in East Asian continent and low (high) pressure in the adjacent ocean and deep (weak) East Asian trough at 500 hPa. These interannual variations are shown to be closely connected to the SST anomaly in the tropical Pacific, both in the western and eastern Pacific. The results suggest that the strength of the EAWM is mainly influenced by the processes associated with the SST anomaly over the tropical Pacific. The EAWM generally becomes weak when there is a positive SST anomaly in the tropical eastern Pacific (El Ni?o), and it becomes strong when there is a negative SST anomaly (La Ni?a). Moreover, the SST anomaly in the South China Sea is found to be Closely related to the EAWM and may persist to the following summer. Both the circulation at 850 hPa and the rainfall in China confirm the connection between the EAWM and the following East Asian summer monsoon. The possible reason for the recent 1998 summer flood in China is briefly discussed too.

Institute of Atmospheric Physics; Chinese Academy of Sciences; 1000080,Max-Planck-Institute of Meteorology; Hamburg; Germany,Institute of Atmospheric Physics; Chinese Acadmy of Sciences; 100080

... 1 大气环流的影响已有研究表明：气候系统的涛动会导致区域大气环流的异常,进而影响区域气候的特征^[25,26] ...

2014

0.0

2.937

Yao

Junqiang

, Liu

Zhihui

, Yang

Qing

et al

Temperature variability and its possible causes in the typical basins of the arid Central Asia in recent 130 years.

Acta Geographica Sinica, 2014, 69(3): 291-302.

[姚俊强, 刘志辉, 杨青等. 近 130 年来中亚干旱区典型流域气温变化及其影响因子. 地理学报, 2014, 69(3): 291-302. ]

Basin-scale is of the special significance to the climate change research in arid areas. In this study, data from five typical basins of the arid Central Asia are analyzed to investigate changes in annual temperature during the period of 1881-2011. The nonparametric Mann- Kendall test, wavelet analysis and the correlation analysis are used to identify trend, multiple time scale feature and their possible causes in the annual temperature. The results show that the average annual temperature had an increasing trend in the main basins (except Amu Darya Basin) of the arid Central Asia in the past 130 years. The rising rate is consistent with that of the northern hemisphere, much higher than that of the global average and surrounding region, suggesting that the arid Central Asia is more sensitive to climate change than other regions. Abrupt change point in annual temperature occurred around the year of 1986, and showed significant multi-time scale periodic oscillation, which is mainly due to the physical external force and internal climate-control system. The Central Asian vortexes' activity has a significant effect on annual temperature of the typical basins, followed by the northern annual mode cycle variation and the Tibetan Plateau, while the greenhouse effect caused by CO 2 gas emissions in the arid Central Asia can not be ignored. Temperatures show an aperiodic cycle which is related to the BC, PDO and TBO, and we can confirm that temperature in the arid Central Asia is closely related to the atmospheric circulation, sea surface temperature and solar activity.

1. College of Resources and Environment, Key Laboratory of Oasis Ecology of Ministry of Education, Xinjiang University, Urumqi 830046, China; 2. Institute of Arid Ecology and Environment, Xinjiang University, Urumqi 830046, China; 3. International Center for Desert Affairs-Research on Sustainable Development in Arid and Semi-arid Lands, Urumqi 830046, China; 4. Institute of Desert Meteorology, China Meteorological Administration, Urumqi 830002, China; 5. College of Resources and Environment, Lanzhou University, Lanzhou 730000, China

利用中亚干旱区5 大主要典型流域代表性气象站点近130 年逐月实测气温数据，结合线性趋势、Mann-Kenndall 非参数检验和小波分析等方法，研究了各流域气温的多时间尺度特征，并探讨了引起气温变化的可能因素。研究发现，在近130 年来中亚干旱区各主要流域（除阿姆河外）年均气温均呈上升趋势，增温趋势高于全球和周边地区，中亚干旱区气温对全球变化的响应比其他地区更加明显。20 世纪80 年代之后更加明显，并表现出明显的多时间尺度周期振荡特征，这主要是自然外强迫动力作用、气候系统内部变化和人类活动相互叠加的结果，亚洲极涡强度减弱和面积缩小对主要流域气温变化的作用明显，其次是北半球环状模（北极涛动）和青藏高原的影响，而CO 2 引起的温室气体增温效应在中亚干旱区也不容忽视。气温表现出与布吕克纳周期（BC）、太平洋年代际涛动（PDO）和准2~3 年振荡周期（TBO）等有关的显著周期，可以证实中亚干旱区气温变化与大气环流、海温和太阳活动等密切相关。

... 北极涛动 (AO) 对北半球大气环流以及冬半年北半球近地面许多气候要素都有显著影响^[27],冬季北极涛动通过影响西伯利亚高压和东亚大槽等区域性大气环流来影响冬季风强度,进而引起区域气温的变化 ...

2010

0.0

2.407

Chen

Yuying

, Chen

Nan

, Ma

Jinren

et al

Variety of Ningxia cold waves in the last 48 years and its possible reasons.

Journal of Natural Resources, 2010, 25(6): 939-951.

[陈豫英, 陈楠, 马金仁等. 近 48 a 宁夏寒潮的变化特征及可能影响的成因初步分析. 自然资源学报, 2010, 25(6): 939-951. ]

By using the daily surface temperature data of Ningxia, monthly characteristic values of 500 hPa circulation of the Northern Hemisphere, Arctic Oscillation Index (AOI) and NCEP/NCAR reanalyzed data during 1961-2008, the climatic characteristics of the variety of cold waves in Ningxia are analyzed, and the possible reasons for it are further discussed. The result indicates:the cold wave activities are distinct different in Ningxia different regions, and mainly occur in spring; in the recent 48 years, cold waves in Ningxia increased slightly in spring and autumn, decreased slightly in winter; the frequency of cold waves in Ningxia has negative correlation with AOI and temperature, positive correlation with the intensity of Siberian high, East Asian winter monsoon and the frequency of cold air activities invaded China, and the correlativity is obvious in autumn, winter and inconspicuous in spring; under the background of global warming, with the phase of AOI transformed from negative into positive from the end of 1980s, the intensity of winter Siberian high and East Asian winter monsoon has weakened, and made the surface temperature continue rising in Ningxia, this is one of the possible reasons for the decrease of Ningxia cold waves in winter; in spring, there has the similar variety but differs in the following points:the Siberian high played a more significant role in cold wave activities before the mid-1980s, while the impact of cold air activities on cold waves was more obvious with the continuou temperature rising after then; meanwhile, the Siberian high and the cold air activities impacted the cold waves more directly and more obviously in autumn. Studies also found, that with continued global warming, the impact of Arctic Oscillation on Siberian high and East Asian winter monsoon has weakened after the 21st century. Therefore, the mutual feedback among the Arctic Oscillation, Siberian high, the frequency of cold air activities, the East Asian winter monsoon and temperature is the possible reason for the variety of Ningxia cold wave frequency.

1. Key Laboratory of Meteorological Disaster Prevention and Reduction of Ningxia, Yinchuan 75000; 2. Ningxia Meteorological Observatory, Yinchuan 750002, China

利用1961—2008年宁夏日温度及逐月北半球500 hPa环流特征量、北极涛动指数(AOI)和NCAR／NCEP再分析资料,对宁夏寒潮频次变化的气候特征进行了分析,并对影响其变化的可能原因进行了讨论,结果表明:宁夏寒潮活动各地差异较大,主要出现在春季;近48年,春秋季寒潮频次呈弱增加趋势,冬季呈弱减少趋势;寒潮频次与AOI、气温呈负相关,与西伯利亚高压、东亚冬季风强度及入侵中国的冷空气活动频次呈正相关,相关关系在秋冬季明显,春季不明显;在气候变暖的大背景下,从20世纪80年代末开始,随着AOI从负位相转为正位相,冬季西伯利亚高压和东亚冬季风强度的减弱使得宁夏地表温度持续升高,是宁夏冬季寒潮频次减少的可能原因;春季也有类似的变化,不同的是:20世纪80年代中期以前,西伯利亚高压对寒潮活动作用更显著,之后,随气温持续增暖,冷空气活动对寒潮频次的影响更明显;秋季,西伯利亚高压和冷空气活动对寒潮的影响更直接明显。研究还发现,进入21世纪后,随着全球持续增暖,北极涛动对西伯利亚高压和东亚冬季风的影响有所减弱。因此,北极涛动、西伯利亚高压、冷空气活动频次、东亚冬季风、气温这几者之间的相互反馈作用是宁夏寒潮频次变化的可能原因。

... 研究发现,近53年AO指数呈增加趋势,分段模型检测出其在1989年发生负位相转为正位相的转折,与陈豫英^[28]等人研究结论一致 ...

2003

0.0

2.937

Gong

Daoyi

, Wang

Shaowu.

Influence of Arctic Oscillation on winter climate over China.

Acta Geographica Sinica, 2003, 58(4): 559-568.

[龚道溢, 王绍武. 近百年北极涛动对中国冬季气候的影响. 地理学报, 2003, 58(4): 559-568. ]

In this study the relationships between the Arctic Oscillation and climate in China in boreal winter are investigated. The data used in this study include NCEP/NCAR Reanalysis monthly mean sea level pressure, 500 hPa geopotential heights, two Arctic Oscillation indices, and the observed temperature and precipitation. Correlation analysis for the last 41 years shows that the winter temperature and precipitation in China change in phase with AO. High positive correlation between temperature and AO is above +0.4 and appears in the northern China. High correlation coefficients between precipitation and AO cover the southern China (close to the South China Sea) and the central China (between 30 o -40 o N and east of ~100 o E), with the values varying between +0.3 and +0.4. The correlation between the 160-station average temperature and the simultaneous sea level pressure show that the winter temperature of China is strongly connected to the sea level pressure over the high latitudes of Eurasia continent. The center is located in Siberia with values lower than -0.6. The partial correlation between the intensity of Siberian High and averaged temperature in China remains -0.58, when AO keeps constant. But the partial correlation between temperature and AO is only 0.14 when the influence of Siberian High is excluded. The relationship between AO and precipitation is also significant. The partial correlation between AO and mean precipitation of 160 stations is 0.36. But when the AO's influence is excluded, the partial correlation between the intensity of Siberian High and precipitation is only -0.16. This suggests that during the past several decades the precipitation was strongly affected by AO, but for the temperature the Siberian High plays a more important role. AO and the Siberian High correlate at -0.51, according to the data for the period 1958/59-1994/95. The possible dynamical connection between AO and the Siberian High needs further study. Using the long-term series of AO and the Siberian High spanning 1899/1900-1994/1995, their connections to climate in China are analyzed too. At the interdecadal time scale the AO shows significant influence on both temperature and precipitation. Partial correlation between AO and temperature is 0.66. For precipitation the correlation coefficient is 0.70.

1. Key Laboratory of Environmental Change and Natural Disaster Institute of Resources Science, Beijing Normal University, Beijing 100875, China; 2. Department of Atmospheric Science, Peking University, Beijing 100871, China

北极涛动 (AO) 是北半球冬季热带外行星尺度大气环流最重要的一个模态，对北半球及区域气候有重要影响。利用中国近50年和近百年气温和降水资料分析了北极涛动对我国冬季气候的影响。当AO指数偏强时，我国大部分地区冬季气温偏高，同时降水也偏多。AO和西伯利亚高压对我国冬季气候的影响在年际和年代际尺度上有不同的特征，在年际尺度上西伯利亚高压对我国气温的影响要远强于AO，而AO对我国降水的影响则比西伯利亚高压的影响要显著。这种关系也可以通过比较分析对流层低层和中高层环流形势在AO不同位相时的变化得到进一步验证。这说明AO对我国冬季气温和降水影响的机制是不一样的。在年代际尺度上，AO对气温和降水都有显著的影响。AO和西伯利亚高压一起能解释近百年来我国冬季温度和降水方差的35% 和11%。

... 值得注意的是,龚道溢^[29]等人建立的近百年西伯利亚高压时间序列表明：西伯利亚高压在20世纪60年代最强,而80-90年代变弱,与本文寒潮频次的年代际变化特征相吻合,进一步印证了西伯利亚高压是影响我国寒潮频次的重要因素 ...

1986

0.0

Huang

Shoubo.

Advance in the investigation of the topographical microclimate in China.

Geographical Research, 1986, 5(2): 90-101.

[黄寿波. 我国地形小气候研究概况与展望. 地理研究, 1986, 5(2): 90-101. ]

Mountainous and hilly regions cover a vast area of China. The mountainous topography is complex and various. Much differences in their landforms, altitudes, direction and slope resulted in much differences in the topographic microclimate, which would control the distribution of vegetations and soils, and thus it is not suitable to grow temperature demanded crops (such as citrus and, tea plants) in the unfavourable microclimatic conditions at the north and the middle subtropical areas in China, This paper summarizes the investigation on the survey of the topographic microclimate in China since mid-1950's. The primary content is as follows.(1) The influence of slope orientation (direction and slope) on the microclimate. The main character of the microclimate in the mountainous and hilly region in the changes of sunshine, radiant flux, temperature, precipitation and other meteorological elements with the slope orientation,(2) The influence of undulating country (top of a mountain, mountain slope, mountain valley) on the microclimate,(3) The influence of surrounding topography in a small scale region on the microclimate. Four types of the surrounding topography are studied according to their influences on minimum temperature and wind speed for both ra-diational and advectional weathers,(4) The influence of composition among hills on the microclimate,(5) A study of the topography inversion. Some regularities of the vertical distributions of the meteorological elements in the major mountainous and hilly region in China were found out,(6) The influence of special topography (such as a horseshoe shape topography) on the microclimate.As a result, we must select different species of crops and plants to suit the various microclimate conditions respectively, and to develop the diversified agriculture and forest in the mountainous and hilly regions in China.

Zhejiang Agricultural University

我国山地和丘陵的面积约占土地总面积的70%.因此,研究地形小气候对于了解山区气候资源,合理开发山区经济,发展农业生产具有重要意义.地形小气候与山地气候不同,前者是指相对高差在几米到几百米,水平距离在10米到10公里范围内的小的起伏地形对气候的影响,其特征主要表现在个别气象要素的数值和个别的天气现象上,且局限在近地面的空气层中.

... 型^[30,31]的外围地形特征,同样加重了寒潮的危害 ...

1956

0.0

2.937

... 型^[30,31]的外围地形特征,同样加重了寒潮的危害 ...