0 引言
1 数据和方法
2 1988年东风爆发概述
图1 历年东风爆发指数及Niño3.4指数(a)、1988年赤道太平洋纬向风应力异常及东风爆发时间-经度演变(b)(图a中的红色柱子指示1988年的东风爆发指数。图b中的风应力异常正值代表西风应力异常,负值代表东风应力异常,绿色轮廓线指示东风爆发事件。后文同此。) Fig.1 Historical easterly wind surges indexes and Niño3.4 indexes (a), time-longitude evolution of zonal wind stress anomalies over the equatorial Pacific and easterly wind surges in 1988 (b) (In figure a, the red bar denotes the easterly wind surges index for 1988. In figure b, positive values of wind stress anomalies represent westerly wind stress anomalies, negative values represent easterly wind stress anomalies, the green contour lines indicate easterly wind surges events. The same convention applies to subsequent figures.) |
3 赤道太平洋海温梯度对1988年东风爆发的贡献
图2 1988年热带太平洋平均海温异常和风应力异常(a)、赤道太平洋海温梯度演变(b)以及赤道太平洋纬向风应力异常变化(c)(图a中仅显示在95%置信水平下显著的海温异常及风应力异常;图中实线框表示赤道东太平洋区域(180°—80°W,5°S—5°N),虚线框表示赤道西太平洋区域(120°E—180°,5°S—5°N)。图c中的绿色虚线框为图4a中识别出的3月底东风爆发事件。) Fig.2 Annual mean sea surface temperature (SST) anomalies and wind stress anomalies across the tropical Pacific (a), evolution of the equatorial Pacific SST gradient (b), and variations in zonal wind stress anomalies over the equatorial Pacific (c) in 1988 (In figure a, only significant SST anomalies and wind stress anomalies are displayed at the 95% confidence level. The solid box indicates the equatorial eastern Pacific region (180°-80°W, 5°S-5°N), and the dashed box indicates the equatorial western Pacific region (120°E-180°, 5°S-5°N). In figure c, the green dashed box indicates the easterly wind surges at the end of March identified in figure 4a.) |
4 1988年3月底东风爆发事件的成因
图5 1988年3月1日—4月15日的OLR异常和风应力异常演变(a~c),3月1日—4月15日沿赤道OLR异常及纬向风应力异常的时间-经度图(d)(图a~c中,在95%置信水平下显著的OLR异常打点表示,只显示在95%置信水平下显著的风应力异常。图d中,绿色虚线框为图4a中识别的东风爆发时间。) Fig.5 Evolution of OLR anomalies and wind stress anomalies from March 1 to April 15, 1988 (a-c), and time-longitude diagrams of OLR anomalies and zonal wind stress anomalies along the equator from March 1 to April 15 (d) (In figures a-c, dots indicate OLR anomalies significant at the 95% confidence level, only significant wind stress anomalies are displayed at the 95% confidence level. In figure d, the green dashed box indicates the easterly wind surges period identified in figure 4a.) |
图6 1988年3月1日—4月15日沿赤道平均后滤波OLR异常的时间-经度图(a)以及 1982年1月—2020年12月的MJO Wheeler-Hendon相位图(b)(图a中,红色轮廓线表示滤波后OLR异常小于-1倍标准差的区域,即MJO对流活跃相位。图b中1988年3月的MJO指数用红色突出显示。) Fig.6 Time-longitude distribution of filtered OLR anomalies averaged along the equator from March 1 to April 15, 1988 (a), and the Wheeler-Hendon phase diagram of MJO for January 1982 to December 2020 (b) (In figure a, the red contour represents region where the filtered OLR anomalies are less than -1 standard deviation (MJO convective phase). In figure b, the MJO index for March 1988 is highlighted in red.) |
图7 海洋性大陆(100°E—140°E,15°S—15°N)历史MJO对流活跃相位期间OLR异常和风应力异常的合成图(在95%置信水平下显著的OLR异常打点表示。只显示在95%置信水平下显著的风应力异常。) Fig.7 Composites of OLR anomalies and wind stress anomalies over the Maritime Continent (100°E-140°E, 15°S-15°N) during historical convectively active phases of the MJO (Dots indicate OLR anomalies significant at the 95% confidence level. Only significant wind stress anomalies are displayed at the 95% confidence level.) |