斯堪的纳维亚遥相关对我国西南西部深秋降水的影响

刘扬; 刘屹岷

doi:10.3878/j.issn.1006-9585.2016.16029

斯堪的纳维亚遥相关对我国西南西部深秋降水的影响

doi: 10.3878/j.issn.1006-9585.2016.16029

刘扬^{1, 2, 3,},
刘屹岷^1, ,

1.
中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室, 北京 100029
2.
中国科学院大学, 北京 100049
3.
国家气象中心, 北京 100081

基金项目:

公益性行业（气象）科研专项 GYHY201406001

国家自然科学基金项目 91437219

中国科学院战略性先导科技专项 XDA11010402

详细信息

作者简介:
刘扬,女,1988年出生,博士研究生,主要从事气候动力学研究。E-mail:liuyang@lasg.iap.ac.cn

通讯作者:
刘屹岷,E-mail:lym@lasg.iap.ac.cn

中图分类号: P461
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- 被引次数: 0
出版历程
- 收稿日期: 2016-01-27
- 网络出版日期: 2016-03-30
- 刊出日期: 2017-01-01

The Impact of the Scandinavian Teleconnection Pattern on Late Autumn Rainfall in the Western Region of Southwest China

Yang LIU^{1, 2, 3
,},
Yimin LIU^{1
, ,}

1.
State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029
2.
University of Chinese Academy of Sciences, Beijing 100049
3.
National Meteorological Center, Beijing 100081

Funds:

Special Scientific Research Fund of Meteorological Public Welfare Profession of China GYHY201406001

National Natural ScienceFoundation of China 91437219

Chinese Academy of Sciences Strategic Priority Program XDA11010402

摘要

摘要: 使用中国台站降水数据和NCEP/NCAR再分析资料，分析了1961~2012年深秋斯堪的纳维亚遥相类型（SCA）与同期我国西南西部降水的关系，以及SCA型环流异常影响西南西部降水的具体物理过程。结果表明：SCA型遥相关与西南西部降水存在显著的负相关关系，且具有非对称性：SCA正位相时西南西部降水偏少，而SCA负位相与西南西部降水的关系不显著。SCA正位相年西南西部的降水偏少与该地区对流层中下层的异常下沉运动有关。垂直运动方程诊断结果表明该异常下沉运动主要是由冷平流异常维持。气候态风场对温度异常场的平流在西南西部的冷平流异常中起主要作用。SCA正位相时，西南西部地区的东侧有暖异常，而其西侧的印度半岛北部及伊朗高原地区为冷异常，在平均西风作用下，西南西部有冷平流异常，造成该地区的异常下沉运动，从而降水偏少。
- 斯堪的纳维亚遥相关 /
- 西南 /
- 深秋 /
- 降水
Abstract: Based on rainfall datasets obtained from meteorological stations in China and the NCEP/NCAR reanalysis data, the simultaneous relationship between the Scandinavian teleconnection pattern (SCA) and late autumn precipitation over the western region of Southwest China (WSWC) during 1961-2012 is investigated. Results show that there is a significant negative correlation between the SCA index and the rainfall over WSWC. The negative correlation is asymmetric. During the positive SCA years, the rainfall in WSWC is less than that in normal years. However, during the negative SCA years, the relationship between the SCA index and the rainfall over WSWC is not significant. The negative rainfall anomaly over WSWC during positive SCA years is consistent with local anomalous descending motion in the lower and middle troposphere. The diagnostic analysis of the vertical motion equation indicates that the local descending motion is primarily maintained by anomalous cold temperature advection. The advection of anomalous temperature by mean westerlies contributes most to the anomalous cold temperature advection in WSWC. The downstream Rossby wave propagation triggered by the positive SCA pattern weakens the East Asian trough. Consequently, the eastern part of Southwest China becomes warmer. The climatological westerly wind brings anomalously cold air into the WSWC area, resulting in local descending motion and drought.
- Scandinavian teleconnection /
- Southwest China /
- Late autumn /
- Rainfall

HTML全文

图 1 1961～2012 年深秋(11 月)去除线性趋势的(a)SCA 指数与中国同期降水的相关系数分布[阴影表示通过90%置信水平检验，灰色方框表示西南西部区域(20°N～30°N，97.5°E～105°E)]、(b)标准化SCA 指数和西南西部降水指数的时间序列、(c)标准化SCA 指数与西南西部降水指数的散点图

Figure 1. (a)Correlation coefficient distribution between the SCA index and late autumn(Nov)precipitation in China during 1961−2012 [shaded areas are for values significant above the 90% confidence level; the grey-line rectangular box represents the western area of Southwest China(WSWC，20°N−30°N，97.5°E−105°E)];(b)time series of the normalized SCA index and WSWC rain index for 1961−2012;(c)scatter plot of the WSWC rain index against the normalized SCA index(the linear trends of indices and rainfall have been removed)

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图 2 SCA(a)正位相年和(b)负位相年合成的降水异常场(单位：mm/d，等值线间隔为0.2，实/虚线表示正/负值，阴影表示通过90%置信水平检验)

Figure 2. Composite anomalies of precipitation(units: mm/d)for the(a)positive and(b)negative SCA years(contour interval is 0.2，and solid/dashed lines are for positive/negative values; shaded areas are for values significant above the 90% confidence level)

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图 3 SCA 正位相年合成的(a)500 hPa 垂直速度异常场，(b)20°N～30°N 平均的垂直速度异常的经度—高度剖面。带点区域表示通过90%置信水平检验

Figure 3. Composite vertical velocity anomalies(a)at 500 hPa and(b)in the zonal−vertical cross section averaged over 20°N−30°N for the positive SCA years. Areas with dots are significant at the 90% confidence level

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图 4 SCA 正位相年合成的20°N～30°N 平均的垂直运动方程中(a)B 项异常、(b)C 项异常的经度—高度剖面(带点区域表示通过90%置信水平检验)，(c)各个SCA 正位相年西南西部区域平均的500 hPa B 项异常和C 项异常

Figure 4. The zonal−vertical cross sections of composite(a)term B and(b)term C anomalies averaged over 20°N−30°N for the positive SCA years(areas with dots are significant at the 90% confidence level)，(c)the anomalies of term B and term C averaged over WSWC at 500 hPa for each of the positive SCA years

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图 5 SCA 正位相年合成的500 hPa(a)温度平流异常、(b)T-adv1、(c)T-adv2、(d)T-adv3

Figure 5. The composite(a)anomalous temperature advection，(b)T-adv1，(c)T-adv2，and(d)T-adv3 at 500 hPa for the positive SCA years

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图 6 500 hPa 的(a)SCA 正位相年合成的异常温度场(带点区域通过90%置信水平检验)、(b)气候态风场、(c)气候态温度场、(d)SCA 正位相年的合成的异常风场(黑色矢量表示通过90%置信水平检验)

Figure 6. (a)The anomalous temperature composited for the positive SCA years(areas with anomalies are significant at the 90% confidence level)，(b)the climatological mean wind，(c)the climatological mean temperature，and(d)the anomalous wind composited for the positive SCA years(black vectors denote the anomalies are significant at the 90% confidence level)at 500 hPa

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图 7 SCA 正位相年合成的北半球500 hPa(a)温度异常场，(b)位势高度异常场(阴影)和异常波活动通量(矢量，略去值小于0.4 个单位的矢量)。带点区域表示通过90%置信水平检验

Figure 7. Composite anomalies of(a)temperature and(b)geopotential height(shaded)and wave activity fluxes(vectors，values less than 0.4 units are omitted)at 500 hPa for the positive SCA years. Areas with dots are significant at the 90% confidence level

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表 1 SCA 正位相年合成的600～400 hPa 各层西南西部平均的公式(4)右端各项对温度平流异常的贡献率及其平均

Table 1. Percentage contributions of individual terms on the right hand side of Equation(4)to the temperature advection anomalies averaged over WSWC at each pressure level between 600−400 hPa and the average

对温度平流异常的贡献率

高度层/hPa T-adv1 T-adv2 T-adv3

600 0.7 0.24 0.06

500 0.85 0.07 0.08

400 0.99 -0.12 0.13

平均 0.75 0.17 0.08

下载: 导出CSV

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