中国东部高空颠簸时空分布特征及其与热带中东太平洋海温的关系

本文利用1979～2014年NCEP-DOE日平均再分析资料和中国区域2375份航空器空中颠簸报告资料，研究中国东部区域高空颠簸的时空分布特征及其与热带中东太平洋海温异常（简称“海温异常”；空间范围:5°S～5°N，120°～170°W）的关系以及产生这种关系的可能原因。结果表明:中国东部地区高空颠簸与东亚副热带西风急流之间存在显著时空相关关系，其原因是高空纬向风引起的垂直风切变是构成高空颠簸时空分布的主导因素。中国东部夏季高空颠簸与海温异常存在正相关关系；冬季呈现南北两个正负相关区:以30°N为界，北部区域存在显著的负相关，南部区存在显著的正相关，在30°N急流轴附近区域无显著相关关系。海温异常影响中国高空颠簸时空分布的可能原因是海温变化引起对流层高层温度出现异常，进而影响温度的经向梯度，导致东亚副热带西风急流强度和位置出现异常（夏季，急流轴南侧出现西风异常；冬季，急流轴北侧出现东风异常，南侧出现西风异常）。高空纬向风的变化导致纬向风的垂直梯度和经向梯度出现异常，最终影响高空颠簸的时空分布特征。对流层高层温度的异常变化可能是由与热带海温异常相关的平流层水汽变化所引起。

Spatiotemporal Characteristics of High Altitude Turbulence over Eastern China and Their Relationship with the Equatorial Central and Eastern Pacific Sea Surface Temperature

Based on NCEP-DOE daily reanalysis data (1979-2014) and 2375 aircraft reports of high altitude turbulence (HAT) in China, the spatiotemporal characteristics of HAT over eastern China and their relationship with the tropical central and eastern Pacific sea surface temperature (Niño3.4 SST) are investigated. The focus of the present study is the physical mechanisms linking the tropical SST anomalies (spatial scope: 5°S-5°N, 120°-170°W) and HAT over eastern China. Results suggest that the spatiotemporal patterns of HAT over eastern China are well correlated with the East Asian subtropical westerly jet (EASWJ), since the EASWJ-induced vertical wind shear is the dominant factor affecting the spatiotemporal variations of HAT. In the summer, a positive correlation exists between the HAT intensity and Niño3.4 SST anomalies. In the winter, positive and negative correlation zones both are present over eastern China with 30°N as the dividing line between them. Significant negative (positive) correlation between HAT and Niño3.4 SST anomalies exists in northern (southern) China. The possible mechanism associated with the impact of Niño3.4 SST anomalies on the HAT over eastern China has been proposed to be: the ENSO-related upper troposphere temperature anomalies lead to changes in meridional temperature gradient of upper troposphere, which result in changes in the intensity and position of the EASWJ. The changes in the EASWJ lead to anomalies of vertical and meridional gradients of high-altitude zonal winds, which ultimately affect the temporal-spatial variations of HAT. The ENSO-related upper troposphere temperature anomalies may be caused by changes in the water vapor maxing ratio in the stratosphere.