CAJ | 학술논문

利用NCEP/NCAR北半球1958—1997年40a中平流层（10～70 hPa）逐日位势高度场再分析资料,计算出其余弦球函数～YC20的系数A20。根据A20稳定由负转正的日期,确定了中平流层各层环流由气旋型转换为反气旋型的日期。结果表明：1）由冬入夏,20 hPa环流最先由气旋型转换为反气旋型,平均为4月24日;6月17日向下传播到70hPa,历时54d,此时整个中平流层进入盛夏。2）50、70hPa环流转型日期具有明显的年代际变化特征。分析表明,50、70hPa环流转型日期与低纬平流层纬向风准两年振荡存在显著正相关关系。
이용NCEP/NCAR북반구1958—1997년40a중평류층（10～70 hPa）축일위세고도장재분석자료,계산출기여현구함수～YC20적계수A20。근거A20은정유부전정적일기,학정료중평류층각층배류유기선형전환위반기선형적일기。결과표명：1）유동입하,20 hPa배류최선유기선형전환위반기선형,평균위4월24일;6월17일향하전파도70hPa,력시54d,차시정개중평류층진입성하。2）50、70hPa배류전형일기구유명현적년대제변화특정。분석표명,50、70hPa배류전형일기여저위평류층위향풍준량년진탕존재현저정상관관계。
We calculated the coefficient（A02） of cosine Spherical harmonics by using the NCEP/NCAR middle stratosphere（10—70 hPa） reanalyzed daily height field data from 1958 to 1997.Then we derived the transformation date of middle stratosphere circulation from cyclone to anticyclone on the basis of the date when A02 converted steadily from negative to positive.The result shows that：1）The 20 hPa circulation first transformed from cyclone to anticyclone（averagely on April 24） and then the same occurred at 70 hPa 54 days later,thus the whole middle stratosphere was in summer;2）There is notable interdecadal variation in the transformation date at 50 hPa and 70 hPa.Our study shows that there exists remarkable correlation relationship between the transition date of circulations at 50 hPa and 70 hPa and the quasi-biennial oscillation（QBO） of the low-latitude stratosphere zonal wind.