CAJ | 학술논문

利用NCEP/NCAR 再分析资料和CMAP、GPCP卫星反演降水资料，对比分析了东亚与北美东部地区降水和大尺度大气环流季节演变特征的差异。结果显示，东亚和北美东部地区冬季环流形势较为相似，而夏季差异则较大，这正是东亚为季风区，北美为非季风区的表现。此外，基于季风的两大特征量“风”和“雨”，分析了两地降水和低空风场季节变化的显著差异：东亚副热带地区降水季节变率大，呈“夏湿冬干”的季风降水特征，低层盛行风向随季节逆转，冬季盛行偏北风，夏季盛行偏南风，具有显著的副热带季风区特征。北美东部副热带地区全年雨量分配均匀，低层常年盛行偏西风，呈现非季风区特征。进一步的分析发现，作为季风基本推动力的海、陆热力差异在东亚和北美东部地区有着显著的区别：东亚地区的经向和纬向温度梯度随季节反转的特征显著；而北美东部地区虽有纬向温度梯度的季节反转但幅度很小，且经向海、陆热力差异随季节反转不明显。此外，与青藏高原和落基山脉相伴的纬向环流也存在显著差异。鉴于此，提出经向和纬向海、陆热力梯度反转特征的不同以及青藏高原和落基山脉地形的不同作用很可能是造成东亚副热带季风气候而北美东部非季风气候的主要原因，上述结论还有待于数值试验的进一步证实。
이용NCEP/NCAR 재분석자료화CMAP、GPCP위성반연강수자료，대비분석료동아여북미동부지구강수화대척도대기배류계절연변특정적차이。결과현시，동아화북미동부지구동계배류형세교위상사，이하계차이칙교대，저정시동아위계풍구，북미위비계풍구적표현。차외，기우계풍적량대특정량“풍”화“우”，분석료량지강수화저공풍장계절변화적현저차이：동아부열대지구강수계절변솔대，정“하습동간”적계풍강수특정，저층성행풍향수계절역전，동계성행편북풍，하계성행편남풍，구유현저적부열대계풍구특정。북미동부부열대지구전년우량분배균균，저층상년성행편서풍，정현비계풍구특정。진일보적분석발현，작위계풍기본추동력적해、륙열력차이재동아화북미동부지구유착현저적구별：동아지구적경향화위향온도제도수계절반전적특정현저；이북미동부지구수유위향온도제도적계절반전단폭도흔소，차경향해、륙열력차이수계절반전불명현。차외，여청장고원화락기산맥상반적위향배류야존재현저차이。감우차，제출경향화위향해、륙열력제도반전특정적불동이급청장고원화락기산맥지형적불동작용흔가능시조성동아부열대계풍기후이북미동부비계풍기후적주요원인，상술결론환유대우수치시험적진일보증실。
Based on the NCEP/NCAR gridded reanalysis data and the CMAP,GPCP data,a study is conducted with focus on the comparative analysis of seasonal variations of the precipitation and large scale circulation between East Asia and eastern North America.The results suggest that the circulation pattern of the two regions is similar in winter but different in summer. Besides,based on"wind"and"rainfall"which are the two characteristics of monsoon,we find that the seasonal variation of precipitation and low level wind is very different:The seasonal difference of the precipitation over East Asia is significant,pres-enting the monsoon rainfall characteristic called"wet summer and dry winter".In the lower troposphere,the prevailing wind direction in East Asia in summer is opposite to that in winter.However,the situation in eastern North America is opposite. Furthermore,as the essential driving force of monsoon,the land sea thermal contrast in East Asia is different from that in east-ern North America.There is prominent inversion of meridional and zonal temperature gradient along with the seasonal shift in East Asia.On the other hand,the inversion does exist in zonal temperature gradient in eastern North America,but does not in meridional temperature gradient.Besides,that the large scale circulation is different in the two regions is also attributed to the difference between the Tibet Plateau and Rocky Mountains.Therefore,the differences of the seasonal evolution of meridional and zonal temperature gradient and the forcing of Tibet Plateau and Rocky Mountains may be the main causes of the subtropical monsoon climate in East Asia as well as the non-monsoon climate in North America.The numerical experiment will be needed to confirm this conclusion.