Intraseasonal Variability of Air Temperature Over East Asia in Boreal Summer

Frontiers in Digital Humanities

Nasuno, Tomoe¹  Yao, Suxiang²  Zhao, Chen³  Li, Tim³  Behera, Swadhin K.³ 

[1] Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan;International Pacific Research Center and Department of Atmospheric Sciences, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI, United States;Key Laboratory of Meteorological Disaster, Ministry of Education, Joint International Research Laboratory of Climate and Environmental Change, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China

关键词: East Asia;    Intraseasonal oscillation;    air temperature at 2m;    southeastward propagation;    heat wave;   

DOI  :  10.3389/feart.2017.00063

学科分类：社会科学、人文和艺术（综合）

来源: Frontiers

【 摘 要 】

The intraseasonal oscillation (ISO) of atmospheric temperature at 2m over East Asia (EA) in boreal summer is investigated through NCEP-NCAR reanalysis data for the period of 1979-2013. It is found that the surface air temperature in EA has a dominant period of 10-30 days and exhibits a southeastward propagation characteristic. The average zonal and meridional phase speed of the intraseasonal air temperature anomaly is about 2.6 longitudes and 1.7 latitudes per day, respectively. A diagnosis of the temperature budget suggests that the propagation of the intraseasonal temperature perturbation is primarily attributed to the advection by the mean wind and the advection of the summer mean temperature by the intraseasonal wind. An upper-tropospheric geopotential positive (negative) height anomaly is closely associated with a low-level warmer (cooler) air temperature anomaly and both anomalies propagate southeastward in a similar way. A wave activity flux analysis reveals that mid-latitude Rossby wave energy also propagates southeastward, consistent with the upper-tropospheric geopotential height propagation. This indicates that in addition to low-level advection mechanism, upper-tropospheric forcing through the hydrostatic relationship is another possible mechanism. A further statistical analysis indicates that heat waves in EA summer are modulated by the southeastward-propagating intraseasonal temperature mode.

【 授权许可】

CC BY