基于LASG/IAP大气环流谱模式的气候系统模式

THE CLIMATE SYSTEM MODEL FGOALS-s USING LASG/IAPSPECTRAL AGCM SAMIL AS ITS ATMOSPHERIC COMPONENT

中文关键词:  气候系统模式，大气环流谱模式，气候平均态，年际变化

英文关键词:Climate system model FGOALS-s,Atmospheric general circulation model SAMIL,Climate mean state,Interannual variability.

中文摘要:

      文章扼要介绍了基于LASG/IAP大气环流谱模式（SAMIL）的气候系统模式的新版FGOALS-s的发展和结构。出于发展一个在东亚季风模拟方面有一定优势的气候系统模式之目的，FGOALS-s的大气模式分量SAMIL采用了较高的水平分辨率R42, 这相当于2.8125°（经度）×1.66°（纬度），高于三角截断T42的分辨率。对FGOALS-s 在模拟大气、陆面、海洋和海冰的气候平均态，以及主要的年际变率信号方面的能力进行了检验。分析表明，FGOALS-s成功地控制了气候漂移趋势，能够较为真实地模拟大气、海洋和陆面的气候平均态，特别是受益于大气模式的较高分辨率，由中国西南向东北延伸的夏季风雨带的分布，在模式中得到较为真实的再现，表明该模式在东亚夏季风的模拟上具有较强能力。耦合模式能够成功再现El Ni o事件的非规则周期变化，但是其年际变化的振幅较之观测要弱。赤道中西太平洋年际变率的强度较之赤道中东太平洋要强。在中高纬度，模式模拟的北大西洋涛动模态，在空间分布上与观测接近。FGOALS-s模式存在的主要问题，是模拟的热带海温偏冷、而中纬度海温则偏暖，原因是模式模拟的云量分布存在偏差，它直接影响到海表的净热通量收支。模式模拟的北大西洋高纬度地区的海温明显偏冷，令该地区的年平均海冰分布的范围明显偏大；然而受南极周边海温偏高影响，南极洲周围的海冰范围则偏少。FGOALS -s的未来工作重点，宜放在大气模式的云过程、海洋模式的经向能量输送过程、以及海洋与大气的淡水通量耦合方案的改进方面。

英文摘要:

       This paper describes the development and framework of a new version of LASG/IAP climate system model namely FGOALS-s (Flexible Global Ocean Atmosphere Land System model -Spectral version), which employs the recently improved version of IAP/LASG spectral AGCM namely SAMIL as its atmospheric component. With the motivation of developing a state of the art coupled climate system model suitable for East Asian monsoon climate simulations, the atmospheric component of FGOALS-s, viz. SAMIL, employs a horizontal resolution of R42, which is equivalent to 2.8125°（longitude）×1.66°（latitude）. The performances of FGOALS-s in simulating the climate mean states of the atmosphere, land surface, ocean, and sea ice were evaluated using the output of a 200-years control run of FGOALS-s. The interannual variability of the tropical Pacific and the mode of North Atlantic Oscillation were also analyzed. The results indicate that the FGOALS-s model has been succeeded in controlling the long-term climate drift and has acceptable performances in realistically reproducing the climate mean states of the atmosphere, ocean and land surface. Of particular important, benefit from the relatively high horizontal resolution of the AGCM component, the observed southwest-northeastward extension of the main summertime rainbelt over East China is reasonably well reproduced in FGOALS-s, indicating the excellent performance of the model in East Asian summer monsoon simulations. One common problem of many coupled ocean atmosphere models is that the ENSO variability usually tends to be more regular than nature's, the FGOALS-s model, however, successfully reproduces an irregular ENSO cycle, although its amplitude is slightly weaker than the observation. In addition, the simulated interannual variability of the equatorial middle and western Pacific is stronger than that of the equatorial middle and eastern Pacific. In addition, the model also has reasonably well performance in reproducing the North Atlantic Oscillation mode, which is the dominant mode of wintertime climate over not only the North Atlantic domain but also the Northern Hemisphere. The main deficiency of the FGOALS-s model is that the simulated tropical SSTs are colder than the observation, while the middle latitudes are warmer than the observation. The deficiency in SST simulations has proved to be the results of the bias in net sea surface heat flux simulations, which is to great extent dominated by the bias of cloud amount simulations. Another typical deficiency of the FGOALS-s model is that the SSTs at high latitudes of North Atlantic are too cold, which leads to a larger sea-ice concentration than the observation in terms of annual mean state. In the mean time, the simulated warmer SSTs surrounding the Antarctic result in less sea-ice cover over there. Future improvements of the FGOALS-s model should focus on the treatment of cloud process in the AGCM, the meridional heat transport process of the OGCM, and the tuning of the air-sea freshwater coupling scheme.