北半球温带气旋的模拟和预估研究Ⅰ∶6个 CMIP5耦合模式模拟能力的检验

摘要

Simulation performance of the 6 CMIP5 (Coupled Model Intercomparison Project Phase 5)coupled models,in terms of activity frequency,numbers,central pressure,life span,traveling distance,and deepening rate of extratropical cyclones (ECs)over the Northern Hemisphere,were validated by comparing with the ERA¯40 reanalysis data of European Centre for Medium¯Range Weather Forecasting (ECMWF)during 1958—2001.The analysis result shows that:(1)the frequency distri¯ butions of life span,deepening rate and traveling distance of the ECs are found to be realistic in all the 6 models,and the linear reducing trend of central pressure of the ECs can be simulated by the models;while some system bias exist between simulation results and ERA¯40,mainly including longer lifetime and slower deepening rate in simulations.(2)All the 6 models can repro¯ duce the 2 main EC activity areas,and,among them,there are 5 models which overestimate the EC activity frequency over the eastern Europe¯central Asia,central Siberian¯western Siberian and eastern Asia continent,and all the models underestimate ac¯ tivity frequency over the region from northern Europe to central Siberian.And,(3)both the number of the total processes and strong ECs simulated by the models are less than the ERA¯40 results.The simulated decadal oscillation periods of cyclone processes are slightly longer,and the simulated decadal oscillations of central pressure are weaker.From the above,it can be seen that the CMIP5 coupled models can reproduce main features of EC activity over the Northern Hemisphere during the 44 years,but some regional and systematic deviations still remain.%利用欧洲中期天气预报中心（ECMWF）1958—2001年的 ERA¯40再分析数据和 CMIP5（Coupled Model Intercompar¯ ison Project Phase 5）的6个耦合模式的模拟结果对北半球温带气旋活动频率、气旋数目、中心最低气压、生命期、移动距离及加深速率的模拟能力进行了检验。结果表明：（1）6个模式基本都能反映气旋生命期、加深速率和移动距离的频率分布，并且模拟出了气旋中心气压降低的线性变化趋势，但模拟结果和 ERA¯40存在一定的系统偏差，主要是模拟的生命期偏长，加深速率偏小。（2）6个模式都模拟出北半球的2个主要温带气旋活动区，但相对 ERA¯40再分析数据，5个模式在东欧—中亚、中西伯利亚—西西伯利亚和东亚大陆的气旋活动频率偏高，所有模式在欧洲北部至中西伯利亚地区的气旋活动频率偏低。（3）模式模拟的温带气旋年总过程数和强气旋过程数均小于 ERA¯40的结果，模拟的气旋过程数的年代际振荡周期略偏长，模拟的中心气压的年代际振荡偏弱。总体上 CMIP5的耦合模式能再现44 a 北半球温带气旋活动的主要特征，但仍存在一些区域性及系统性的偏差。