CAJ | 학술논문

用NCEP/NCAR 100 hPa月平均位势高度场再分析资料定义了6、7、8月逐月南亚高压的面积(S)、强度(P)、中心位置(λ_c,φ_c)3种环流指数,求出了它们1948-2007年的60 a序列.用它们对夏季南亚高压气候及异常特征作了初步分析,结果表明:(1)南亚高压6月气候强度最弱、面积最小,中心位于尼泊尔西南边界;7月最强、最大,中心位于巴基斯坦北部;8月较7月略减弱、减小,但较6月强、大,中心位于印度北部.(2)南亚高压各月强度、面积异常作年际准同步变化,故异常分析中P′ 可代表S′;P′有季内一致性,同年6、7、8月P′同号率达41/60.(3)南亚高压6、7、8月强度的慢变分量小波功率谱在20世纪70年代末前后均通过α=0.05的显著性检验,故P′存在显著年代际变化.(4)南亚高压历年各月的中心位置分布区域作准纬向分布,其经(纬)向延伸范围与该月气候强度成正(反)比;中心位置异常存在明显的年代际变化特征.
용NCEP/NCAR 100 hPa월평균위세고도장재분석자료정의료6、7、8월축월남아고압적면적(S)、강도(P)、중심위치(λ_c,φ_c)3충배류지수,구출료타문1948-2007년적60 a서렬.용타문대하계남아고압기후급이상특정작료초보분석,결과표명:(1)남아고압6월기후강도최약、면적최소,중심위우니박이서남변계;7월최강、최대,중심위우파기사탄북부;8월교7월략감약、감소,단교6월강、대,중심위우인도북부.(2)남아고압각월강도、면적이상작년제준동보변화,고이상분석중P′ 가대표S′;P′유계내일치성,동년6、7、8월P′동호솔체41/60.(3)남아고압6、7、8월강도적만변분량소파공솔보재20세기70년대말전후균통과α=0.05적현저성검험,고P′존재현저년대제변화.(4)남아고압력년각월적중심위치분포구역작준위향분포,기경(위)향연신범위여해월기후강도성정(반)비;중심위치이상존재명현적년대제변화특정.
Based on the monthly mean geopotential height at 100 hPa of the NCEP/NCAR reanalysis data,three circulation indices are defined for South Asian High(SAH) in June,July and August,which are area index S,intensity index P and center location index(λ_c,φ_c).The three time series from 1948 to 2007 are calculated,which are used to study the climatic and anomalous characteristics of SAH in summer.The results show that:(1)SAH is the weakest with minimum area,and its center is located in the southwest border of Nepal in June.It is the strongest with maximum area,and its center is located in the northern of Pakistan in July.It is weaker and smaller in August than that in July,but stronger and bigger than that in June,and its center is located in the northern of India.(2)S′(area index anomaly) can be replaced with P′(intensity index anomaly) in the anomaly analysis due to the interannual quasi-synchronized variations of the intensity and area anomalies for SAH in each month.P′ of June,July and August have an intraseasonal consistency,and their same sign ratio reaches 41/60 in the same year.(3)The wavelet power spectrums of slowly varying components of SAH intensity in June,July and August all pass the statistical test at 0.05 significance level in the late 1970s or so,thus P′ of June,July and August have significant interdecadal variations.(4)The center locations of SAH in June,July and August from 1948 to 2007 show quasi-latitudinal distributions with apparent features of interdecadal abnormal variations,and their longitudinal(latitudinal) extended areas are proportional(inversely proportional) to the climatological intensity.