两个模式对平流层温度模拟的比较与分析

利用第5代欧洲中心—汉堡大气环流模式ECHAM5全球大气环流谱模式和中国气象局自主研发的GRAPES全球同化与预报模式分别对2010年1月1—6日全球平流层温度进行了模拟分析,结合相应时段的全球最终分析资料FNL,对比评估了两个模式对平流层温度的模拟效果,并对较为显著的误差现象进行了分析与探讨。结果表明:对于50 h Pa高度上的温度,ECHAM5模式模拟的温度与FNL资料的结果在研究时段内随时间的变化很小,而GRAPES模式模拟的结果在南半球随时间变化显著偏暖。进一步将ECHAM5和GRAPES模式所用的温度初始场进行对比研究表明,两者的分布形态非常形似,尤其是在南半球地区,大部分差值接近于零。将ECHAM5采用的全球臭氧廓线应用于GRAPES模式中,对比发现南半球平流层异常增温的现象仍然存在。因此,温度初始场和臭氧廓线的选取不是造成GRAPES模式模拟出现南半球平流层异常增温的主要原因,需要对GRAPES模式中其他动力及物理过程或参数选取做进一步的深入分析,以弄清其在平流层温度模拟中出现较大偏差的原因。

Comparison and analysis of stratospheric temperature simulated by two models

In this study,the 5th generation European Centre Hamburg general circulation model(ECHAM5) and global assimilation and prediction system(GRAPES),independently developed by the China Meteorological Administration,were used to simulate the stratospheric temperature during the period of January 1-6,2010.The results from the two models were then compared and analyzed,referring to the global final analysis(FNL) data.Through a series of comparisons,it was shown that the temperature variations at 50 hPa simulated by ECHAM5 and FNL varied little over time,whereas the simulations performed by GRAPES were significantly elevated in the Southern Hemisphere.The regional warming projected by GRAPES seemed too distinct and uncontrolled to be reasonable,although the warming pattern remained fairly stable with a value between 5 and 15 K relative to the start time.The temperature difference projected by ECHAM5 and FNL was small at the start time on the global scale.Over time,the values become larger in more locations,indicating a significant warming projected by GRAPES.In the Southern Hemisphere,where the warming by GRAPES was dominant,the maximal temperature difference was larger than 24 K at 30-60°S latitude,30-60°E longitude for the final two simulation days,then increased to more than 12 K over the entire Antarctic continent.The temperature initial condition comparison between ECHAM5 and GRAPES shows that they are significantly similar,especially in the Southern Hemisphere,with the difference values being about zero.Moreover,although the ozone profile of ECHAM5 was used in GRAPES,the warming in the Southern Hemisphere simulated by GRAPES still existed.Therefore,the errors produced by GRAPES were not significantly related to either factor.Atmospheric vapor and heating rate may also be factors leading to stratospheric warming,but in this preliminary study these factors could not be investigated,due to a number of technical problems.Further research focusing on the impact of factors such as vapor,heating rate,temperature,etc.will be conducted to further investigate the reasons for the simulated temperature errors produced by GRAPES.