青藏高原大气热源及其估算的不确定性因素

doi:10.12006/j.issn.1673-1719.2018.111

摘要/Abstract

摘要：

基于1980—2016年的4套再分析资料(NCEP/DOE资料、MERRA2资料、ERA-Interim资料和JRA-55资料),采用计算大气热源的正算法和倒算法,研究青藏高原大气热源及其计算的不确定性因素,得到以下结论：(1)计算方法和资料均会导致结果的不确定性,正算法只能得到整层热源,而倒算法可得到热源垂直结构,但其结果准确性依赖于再分析资料精度;(2)对比4套再分析资料计算结果发现,正算法结果较倒算法结果普遍偏高,采用ERA-Interim资料,基于两种方法计算的大气热源年代际变化趋势一致。基于4套资料,采用倒算法计算的热源在1980—2016年呈现明显的年代际变化特征;(3)夏半年(3—8月)强热源区主要分布在青藏高原中东部,热源自下而上呈源-汇-源分布;(4)基于正算法和ERA-Interim资料估算的夏半年的降水潜热在喜马拉雅山南坡显著偏小,高原西部地区和南部冈底斯山一带则明显偏大。

关键词: 青藏高原, 大气热源, 不确定性, 正算法, 倒算法

Abstract:

The atmospheric heat source (AHS) over Tibetan Plateau (TP) during 1980-2016 was calculated using four reanalysis data (NCEP/DOE, MERRA2, ERA-Interim and JRA-55 data), and the uncertainties was also discussed. The main conclusions are as follows: (1) Methods and data can both make deviation. Indirect method can not only get the whole layer of AHS, but also the vertical structure of AHS, while its estimation precision mainly depends on reanalysis data. (2) Compared with four reanalysis data, we found that adopting two methods with ERA-Interim data can get consistent inter-decadal variation of AHS over TP, while the AHS value calculated by direct method is greater than the indirect method. The results from four reanalysis data by indirect method obtained the obviously identical decadal variation during 1980-2016. (3) Positive AHS mainly distributed in the center and eastern of TP during March-August, and the vertical structure of AHS is “source-sink-source” from surface to high troposphere. (4) The results revealed that latent heat flux calculated by ERA-Interim data is stronger in the western and southern Gangdise, and is weaken in the south slope of Himalaya range.

Key words: Tibetan Plateau, Atmospheric heat source, Uncertainties, Direct method, Indirect method

罗小青,徐建军. 青藏高原大气热源及其估算的不确定性因素[J]. 气候变化研究进展, 2019, 15(1): 33-40.

Xiao-Qing LUO,Jian-Jun XU. Estimate of atmospheric heat source over Tibetan Plateau and its uncertainties[J]. Climate Change Research, 2019, 15(1): 33-40.

图/表 6

图1 基于正算法(a)和倒算法(b)的4种再分析资料计算的1980—2016年青藏高原大气热源年代际变化注：虚线表示lowess平滑,红色分段直线分别表示ERA-I资料计算热源在1980—1998年,1999—2012年和2013—2016年的线性趋势。

Fig. 1 Inter-decadal variation of atmospheric heat source based on direct method (a) and indirect method (b) using four reanalysis data over the Tibetan Plateau during 1980-2016

图2 基于正算法(a) 和倒算法(b) 的4种再分析资料计算的大气热源箱线图

Fig. 2 Boxplot of atmospheric heat source based on direct method (a) and indirect method (b)

图3 基于4种再分析资料的1980—2016年夏半年（3—8月）500 hPa平均的大气热源

Fig. 3 March to August average of 500 hPa atmospheric heat source during 1980-2016 based on four reanalysis data

图4 基于ERA-Interim资料的1980—2016年夏半年（3—8月）850 hPa大气水平风场

Fig. 4 March to August average of 850 hPa horizontal wind during 1980-2016 based on ERA-Interim data

图5 基于4种再分析资料的1980—2016年青藏高原区域平均的Q1和Q2及各分量的垂直结构

Fig. 5 Vertical struction of atmospheric heat source, atmospheric moisture sink and their components based on four reanalysis data over Tibetan Plateau during 1980-2016

图6 1980—2007年夏季青藏高原区域ERA-Interim资料计算潜热与APHRODITE资料计算热源的差值

Fig. 6 Deviation of summer latent value between ERA-I and APHRODITE over Tibetan Plateau during 1980-2007

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