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徐栋, 李若麟, 王澄海. 全球变暖背景下亚非典型干旱区降水变化及其与水汽输送的关系研究[J]. 气候与环境研究, 2016, 21(6): 737-748. DOI: 10.3878/j.issn.1006-9585.2016.15256
引用本文: 徐栋, 李若麟, 王澄海. 全球变暖背景下亚非典型干旱区降水变化及其与水汽输送的关系研究[J]. 气候与环境研究, 2016, 21(6): 737-748. DOI: 10.3878/j.issn.1006-9585.2016.15256
XU Dong, LI Ruolin, WANG Chenghai. Characteristics of Precipitation Changes and Relationships with Water Vapor Transport in Typical Arid Regions of Asia and Africa under Global Warming[J]. Climatic and Environmental Research, 2016, 21(6): 737-748. DOI: 10.3878/j.issn.1006-9585.2016.15256
Citation: XU Dong, LI Ruolin, WANG Chenghai. Characteristics of Precipitation Changes and Relationships with Water Vapor Transport in Typical Arid Regions of Asia and Africa under Global Warming[J]. Climatic and Environmental Research, 2016, 21(6): 737-748. DOI: 10.3878/j.issn.1006-9585.2016.15256

全球变暖背景下亚非典型干旱区降水变化及其与水汽输送的关系研究

Characteristics of Precipitation Changes and Relationships with Water Vapor Transport in Typical Arid Regions of Asia and Africa under Global Warming

  • 摘要: 分析比较了中蒙(35°N~50°N,75°E~105°E)、中亚(28°N~50°N,50°E~67°E)和北非(15°N~32°N,17°W~32°E)三个典型干旱区水汽输送特征的异同,及其1961~2010年间的降水时空变化,分析了水汽来源和输送变化及其可能原因。结果显示,由于受不同的气候系统影响,中蒙、北非和中亚干旱区的降水在年内变化上有着显著不同。中蒙和北非干旱区降水呈现夏季风降水的特征;而中亚干旱区降水则为更多受到冬季风的影响。1961~2010年,随着全球气温上升,中蒙干旱区冬季纬向水汽输送增加而经向输送减少,总水汽输送增加;中亚干旱区冬季纬向输送减少而经向增加,总水汽输送减少;北非干旱区冬季纬向输送增加而经向输送减少,总水汽输送增加。夏季中蒙和北非干旱区经向、纬向输送均减小,中亚干旱区夏季纬向输送减少而经向减少,总输送增加。相应的,中蒙干旱区年、冬季和夏季降水分别以4.2、1.3和1.0 mm/10 a的趋势增加;而中亚干旱区冬季(1.2 mm/10 a)和夏季(0.1 mm/10 a)降水增加,年降水则呈减少趋势(-0.8 mm/10 a);北非干旱区年降水和夏季降水分别以0.5 mm/10 a和0.1 mm/10 a的速率增加。冬季中蒙干旱区主要水汽来源是水汽经向输送,而中亚干旱区水汽主要为纬向输送,经纬向水汽均为净输出是北非干旱区降水极少的主要原因,平均总水汽输送量约为-9.48×104 kg/s。冬季低纬度和高纬度环流通过定常波影响干旱区冬季降水。中蒙和中亚干旱区冬季降水主要受西太平洋到印度洋由南向北的波列影响,北非干旱区冬季降水主要和北大西洋上空由北到南的波列相联系。各干旱区的降水对海温变化有着不同的响应:中蒙干旱区冬季降水与冬季太平洋西海岸和印度洋海温呈显著正相关,夏季与海温相关不显著;中亚干旱区与地中海和阿拉伯海温相关,且与阿拉伯海温为正相关。

     

    Abstract: Climate in arid regions is sensitive and vulnerable, and has obviously changed under global warming. In this paper, climatic characteristics in three typical arid regions, i.e. the China-Mongolia arid region (CM) (35°N-50°N, 75°E-105°E), the central Asia arid region (CA) (28°N-50°N, 50°E-67°E), and North Africa arid region (NA) (15°N-32°N, 17°W-32°E), are analyzed. The features of annual and interannual precipitation variations and abrupt precipitation changes have been analyzed in these regions. Relationships between precipitation and SST (Sea Surface Temperature) and circulation are discussed. Furthermore, changes in precipitation and water vapor transport before and after the years of abrupt precipitation changes have also been discussed. The results indicate that in the context of global warming, more precipitation occurs in the summer in CM and NA; on the other hand, precipitation in CA is largely concentrated in the winter and spring. During the period of 1961-2010, annual precipitation in CM increased, winter and summer precipitation increased while annual precipitation decreased in CA, annual and summer precipitation increased in NA. Accordingly, annual, winter, and summer precipitation increased at a rate of 4.2, 1.3, and 1.0 mm/10 a respectively in CM. Winter (1.2 mm/10 a) and summer (0.1 mm/10 a) precipitation increased but annual precipitation decreased (-0.8 mm/10 a) in CA. Annual and summer precipitation increased at a rate of 0.5 mm/decade and 0.1 mm/10 a respectively, while winter precipitation didn't change obviously in NA. In the winter, meridional water vapor transport provides the primary water vapor supply for the arid zone in CM; zonal water vapor transport is the major water vapor source for CA; the water vapor supply for the NA arid region comes either from the zonal or from meridional moisture transport, and the average total water vapor output in NA is about -9.48×104 kg/s. Thereby decreases in net water vapor flux in NA is the major reason for NA drought. General circulation from the tropics to the Arctic can affect precipitation in arid regions through stationary wave activities. Winter precipitation in CM and CA are related to wave trains originated from the western Pacific Ocean and Indian Ocean. Winter precipitation in NA is positively correlated with wave trains propagating across the North Atlantic. However, rainfall response to SST is different in different regions selected for the present study. Winter rainfall in CM is significantly positively correlated with the West Pacific and Indian Ocean SST but the correlation turns insignificant in the summer. Rainfall in central Asia is closely related to the Mediterranean and Arabian Sea SSTs with a positive correlation with Arabian Sea SST but a negative correlation with the Mediterranean SST in the winter and a positive correlation in the summer. Rainfall in NA is related to the Mediterranean and the western Atlantic SST.

     

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