摘要
利用ERA-Interim地表热通量再分析资料(包含感热通量及潜热通量数据)分析了1979年3月至2009年2月青藏高原地区(下称高原)地面加热场的时空分布特征及其年际变化趋势。突出青藏高原地面加热场与西风急流的联系,分别探讨了青藏高原春季感热及潜热变化的可能影响机制。结果表明:(1)高原感热空间分布大体呈现为自西北向东南递减的特征,潜热与感热呈反相的空间格局,自西北向东南逐渐增强。(2)相比于夏、秋、冬三季,春季高原地表热通量年际变化特征较为突出,其中感热通量显著减少,潜热通量显著增加[分别为-1.83和0.79 W·m^(-2)·(10a)^(-1)],该趋势和全年平均热通量年际变化情况一致。(3)就年际变化而言,春季感热通量与潜热通量之间存在明显的负相关(相关系数为-0.69),表明可能存在某一气候因子使得春季感热减弱而使潜热增强。进一步分析发现,高原地面加热场与西风急流存在密切的联系,春季西风急流的减弱在影响高原感热强度的同时,对高原潜热也具有较大影响。其可能影响机制如下:受高原上空西风急流减弱的影响,高原地表风速减弱从而导致感热通量显著减少;春季西风急流的减弱导致印缅槽的增强,在孟加拉湾上空形成一异常气旋环流,使该地区对流增强、水汽上升异常,同时气旋中北向暖湿气流将水汽携带至高原南侧,并通过影响高原降水量改变其潜热通量。
Based on a 30-yr set of daily surface heat flux data for 1979 -- 2008 over the Qinghai-Tibetan Plateau （QTP） from ERA-interim, the spatial distribution and long-term trends of sensible and latent heat flux over the QTP were analyzed respectively. The factors responsible for the trends of sensible heat flux and latent heat flux in spring were investigated in this paper and we discussed the relationship between the surface heating and the west- erly jet over the QTP emphases. Significant differences in spatial pattern and variability between sensible heat flux and latent heat flux were observed. The spatial distributions of seasonal-mean surface heating show that sensible heat flux increases from the southeast to the northwest over the QTP in seasons except spring, while latent heat flux increases from the northwest to the southeast of QTP throughout the four seasons. The decreasing of sensible heat flux and the increasing of latent heat flux occur in almost the QTP in the four seasons during the study time. Long-term variation of surface heating over the QTP in spring is more remarkable than the other three seasons. The maximum increasing rate of latent heat flux[ 0.79 W · m-2 · （10a） -l] and the maximum decreasing rate of sensible heat flux[ -1. 83 W · m-2 2 （10a）-1 ] appeare both in spring. In terms of the inter-annual variation of surface heating over the QTP, there is a significant negative correlation （R=-0. 69） between latent heat flux and sensible heat flux, which indicates that the changes of latent heat flux and sensible heat flux may be affected by the same climatic factor. Further analysis suggested that there is a close relationship between the surface heating field and the westerly jet over the QTP. The weakening trend of the westerly jet over the QTP has an important impact on the change of sensible heat flux as well as latent heat flux. The possible effect mechanisms are as fol- lows： The weakened of the westerly jet leads to a declining trend in the surface wind speed over the QTP, fur- thermore, contributes to the decrease of sensible heat flux. Besides, accompanied by the change of westerly jet, the India-Burma trough gets stronger leading to an anomalous cyclonic circulation over the Bay of Bengal. Due to the stronger convection, more water vapor content is found in the region, and also more moisture carded by the anomalous southeast flow forming in the cyclonic to the QTP. Accordingly, the stronger precipitation is found o- ver the QTP in spring. As a result, the latent heat flux over the QTP presents an increasing trend during three re- cent decades.
作者
樊威伟
马伟强
郑艳
杨智敏
FAN Weiwei;MA Weiqiang;ZHENG Yan;YANG Zhimin(College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, Gansu, China;Institute of Tibetan Plateau, Chinese Academy of Sciences, Beijing 100101, China;Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China 4. Nanjing University of Information Science and Technology, Nanjing 210000, Jiangsu, China)
出处
《高原气象》
CSCD
北大核心
2018年第3期591-601,共11页
Plateau Meteorology
基金
国家自然科学基金项目(41661144043
91637313
91737205
41522501)
中国科学院"百人计划"项目(马伟强)
中国科学院前沿科学重点研究项目(QYZDJ-SSW-DQC019)
中国科学院大学生"科创计划"项目
关键词
青藏高原
感热通量
潜热通量
西风急流
年际变化
Qinghai-Tibetan Plateau
sensible heat flux
latent heat flux
westerly jet
inter-annual variation
