CAJ | 학술논문

与其他耦合环流模式一样,LASG耦合模式FGCM-0也存在虚假的"双ITCZ".为了认识FGCM-0中"双ITCZ",首先研究了FGCM-0的大气分量模式,即NCAR(美国国家大气研究中心)的公用气候模式CCM3对秘鲁和加利福尼亚沿岸低云以及低层大气整体稳定度的模拟能力.发现:尽管CCM3模拟的低层大气整体稳定度与利用NCEP(美国国家环境预报中心)再分析资料分析的结果较一致,但模拟的低云量比ISCCP(国际卫星云气候计划)观测值显著偏少.利用ISCCP低云量与由NCEP再分析温度场分析的低层整体稳定度之间的回归关系,修改了CCM3中低云参数化方案,并用于敏感性试验,以研究副热带东太平洋低云对FGCM-0中"双ITCZ"的影响.结果发现,修改的方案能显著增强对低云量的模拟,秘鲁沿岸冷海域低云量增加能显著减弱赤道以南热带东太平洋海表面温度(SST)的暖偏差,但同时也将使赤道冷舌增强、向西伸展更远;加利福尼亚沿岸低云量增加可以有效减弱赤道以北ITCZ区SST暖偏差.为了检验秘鲁沿岸SST与低云间的正反馈,又实施了一个控制秘鲁沿岸SST的敏感性试验,结果表明:控制秘鲁沿岸SST抑制其增暖,对自东南太平洋向西北至中、西赤道太平洋广大区域产生的影响,与增加秘鲁沿岸低云量产生的影响相似.
여기타우합배류모식일양,LASG우합모식FGCM-0야존재허가적"쌍ITCZ".위료인식FGCM-0중"쌍ITCZ",수선연구료FGCM-0적대기분량모식,즉NCAR(미국국가대기연구중심)적공용기후모식CCM3대비로화가리복니아연안저운이급저층대기정체은정도적모의능력.발현:진관CCM3모의적저층대기정체은정도여이용NCEP(미국국가배경예보중심)재분석자료분석적결과교일치,단모의적저운량비ISCCP(국제위성운기후계화)관측치현저편소.이용ISCCP저운량여유NCEP재분석온도장분석적저층정체은정도지간적회귀관계,수개료CCM3중저운삼수화방안,병용우민감성시험,이연구부열대동태평양저운대FGCM-0중"쌍ITCZ"적영향.결과발현,수개적방안능현저증강대저운량적모의,비로연안랭해역저운량증가능현저감약적도이남열대동태평양해표면온도(SST)적난편차,단동시야장사적도랭설증강、향서신전경원;가리복니아연안저운량증가가이유효감약적도이북ITCZ구SST난편차.위료검험비로연안SST여저운간적정반궤,우실시료일개공제비로연안SST적민감성시험,결과표명:공제비로연안SST억제기증난,대자동남태평양향서북지중、서적도태평양엄대구역산생적영향,여증가비로연안저운양산생적영향상사.
Like many other coupled models, the Flexible coupled General Circulation Model (FGCM-0) suffersfrom the spurious "Double ITCZ". In order to understand the "Double ITCZ" in FGCM-0, this study firstexamines the low-level cloud cover and the bulk stability of the low troposphere over the eastern subtropicalPacific simulated by the National Center for Atmospheric Research (NCAR) Community Climate Modelversion 3 (CCM3), which is the atmosphere component model of FGCM-0. It is found that the bulkstability of the low troposphere simulated by CCM3 is very consistent with the one derived from theNational Center for Environmental Prediction (NCEP) reanalysis, but the simulated low-level cloud coveris much less than that derived from the International Satellite Cloud Climatology Project (ISCCP) D2data. Based on the regression equations between the low-level cloud cover from the ISCCP data and thebulk stability of the low troposphere derived from the NCEP reanalysis, the parameterization scheme otlow-level cloud in CCM3 is modified and used in sensitivity experiments to examine the impact of low-levelcloud over the eastern subtropical Pacific on the spurious "Double ITCZ" in FGCM-0. Results show thatthe modified scheme causes the simulated low-level cloud cover to be improved locally over the cold oceans.Increasing the low-level cloud cover off Peru not only significantly alleviates the SST warm biases in thesoutheastern tropical Pacific, but also causes the equatorial cold tongue to be strengthened and to extendfurther west. Increasing the low-level cloud fraction off California effectively reduces the SST warm biasesin ITCZ north of the equator. In order to examine the feedback between the SST and low-level cloudcover off Peru, one additional sensitivity experiment is performed in which the SST over the cold ocean offPeru is restored. It shows that decreasing the SST results in similar impacts over the wide regions fromthe southeastern tropical Pacific northwestwards to the western/central equatorial Pacific as increasing thelow-level cloud cover does.