On the relationship between mean monsoon precipitation and low pressure systems in climate model simulations
On the relationship between mean monsoon precipitation and low pressure systems in climate model simulations
复制标题
气候模式模拟中季风平均降水与低压系统的关系
DOI：
10.1175/jcli-d-14-00415.1
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发表时间：
2015
影响因子：
4.9
通讯作者：
R S Ajayamohan
中科院分区：
文献类型：
--
作者：
V. Praveen;S. Sandeep;R S Ajayamohan
西北偏北传播的低压系统（LPS）是印度夏季风（ISM）的重要组成部分。在再分析产品和气候模式模拟中对LPS的客观检测和跟踪是具有挑战性的，因为LPS的结构与热带气旋相比很弱。因此，再分析和气候模式模拟季风LPS的技巧是未知的。本文提出了一种鲁棒的方法来客观地识别和跟踪LPS，它模仿了传统的识别和跟踪算法的基础上检测封闭等压线的表面压力图表。新的LPS跟踪技术允许观察到的和模拟的LPS之间的公平比较。新的跟踪算法的基础上的分析表明，再分析从ERA-Interim和MERRA能够再现所观察到的气候和季风LPS的年际变化具有相当程度的准确性。此外，新开发的LPS检测和跟踪算法也被应用到耦合模式相互比较项目（CMIP 5）第5阶段的气候模式模拟。CMIP 5模型在LPS模拟方面表现出相当大的扩展。在印度中东部观测到的夏季季风降水总量中，约有60%与LPS活动有关，而在模式模拟中，这一比例在5%和60%之间变化。模拟结果表明，较真实地模拟天气活动的模式对季风降水的模拟效果较好。在模拟天气活动的模型到模型的变化被认为是与模型间传播的纬向风切变在印度地区，这是进一步联系在一起的热带东风急流在气候模型中的代表性不足。这些研究结果阐明了ISM降水，天气活动及其相互依存关系的模式模拟背后的机制。
The north-northwest-propagating low pressure systems (LPS) are an important component of the Indian summer monsoon (ISM). The objective detection and tracking of LPS in reanalysis products and climate model simulations are challenging because of the weak structure of the LPS compared to tropical cyclones. Therefore, the skill of reanalyses and climate models in simulating the monsoon LPS is unknown. A robust method is presented here to objectively identify and track LPS, which mimics the conventional identification and tracking algorithm based on detecting closed isobars on surface pressure charts. The new LPS tracking technique allows a fair comparison between the observed and simulated LPS. The analysis based on the new tracking algorithm shows that the reanalyses from ERA-Interim and MERRA were able to reproduce the observed climatology and interannual variability of the monsoon LPS with a fair degree of accuracy. Further, the newly developed LPS detection and tracking algorithm is also applied to the climate model simulations of phase 5 of the Coupled Model Intercomparison Project (CMIP5). The CMIP5 models show considerable spread in terms of their skill in LPS simulation. About 60% of the observed total summer monsoon precipitation over east-central India is found to be associated with LPS activities, while in model simulations this ratio varies between 5% and 60%. Those models that simulate synoptic activity realistically are found to have better skill in simulating seasonal mean monsoon precipitation. The model-to-model variability in the simulated synoptic activity is found to be linked to the intermodel spread in zonal wind shear over the Indian region, which is further linked to inadequate representation of the tropical easterly jet in climate models. These findings elucidate the mechanisms behind the model simulation of ISM precipitation, synoptic activity, and their interdependence.
影响因子：
8
作者：
U. Neu;M. G. Akperov;Nina Bellenbaum;R. Benestad;R. Blender;R. Caballero;A. Cocozza;H. Dacre;Yang Feng;K. Fraedrich;J. Grieger;S. Gulev;J. Hanley;T. Hewson;M. Inatsu;K. Keay;S. Kew;I. Kindem;G. Leckebusch;M. Liberato;P. Lionello;I. Mokhov;J. Pinto;C. Raible;M. Reale;I. Rudeva;M. Schuster;I. Simmonds;M. Sinclair;M. Sprenger;N. Tilinina;I. Trigo;S. Ulbrich;U. Ulbrich;Xiaolan L. Wang;H. Wernli
通讯作者：
U. Neu;M. G. Akperov;Nina Bellenbaum;R. Benestad;R. Blender;R. Caballero;A. Cocozza;H. Dacre;Yang Feng;K. Fraedrich;J. Grieger;S. Gulev;J. Hanley;T. Hewson;M. Inatsu;K. Keay;S. Kew;I. Kindem;G. Leckebusch;M. Liberato;P. Lionello;I. Mokhov;J. Pinto;C. Raible;M. Reale;I. Rudeva;M. Schuster;I. Simmonds;M. Sinclair;M. Sprenger;N. Tilinina;I. Trigo;S. Ulbrich;U. Ulbrich;Xiaolan L. Wang;H. Wernli