The Expendable Bathythermograph (XBT) Programme used a mix of T4 (450m) and T7(750 m) XBT’s during the pre-TOGA periods. Studies are needed to determine how to use the T4/T7 datatogether, in particular with regard to...The Expendable Bathythermograph (XBT) Programme used a mix of T4 (450m) and T7(750 m) XBT’s during the pre-TOGA periods. Studies are needed to determine how to use the T4/T7 datatogether, in particular with regard to a reference level for calculation of dynamic height and geostrophiccurrents. Temperature profiles to 750 m collected from 1986 through 1989 on the trackline across theIndonesian throughflow between NW Australia and Java are used to show the relations between dynamicbeight and geostriohic flow using reference levels at 400 db and 750 db. A very high temporalcorrelation between vertically averaged temperture in the upper 400 m and dynamic height at 50 m rela-tive to 750 db was found. The corresponding regression relationships are presented for all one degree lati-tude bins along the section and can be used for dynamical calculation of currents in the upper 400 m rel-ative to 750 db .An attempt is made to estimate volume transport relative to 750 db from 400 m pro-files. Problems which make展开更多
利用"西北干旱区陆气相互作用野外观测实验"加密观测期间敦煌站的实测资料以及大涡模式,通过一系列改变地表热通量和风切变的敏感性数值试验,分析了地表热通量和风切变对边界层对流的强度、形式,以及对对流边界层结构和发展...利用"西北干旱区陆气相互作用野外观测实验"加密观测期间敦煌站的实测资料以及大涡模式,通过一系列改变地表热通量和风切变的敏感性数值试验,分析了地表热通量和风切变对边界层对流的强度、形式,以及对对流边界层结构和发展的影响。模拟结果显示风切变一定,增大地表热通量时,由于近地层湍流运动增强,向上输送的热量也较多,使对流边界层变暖增厚,而且边界层对流的强度明显增强,对流泡发展的高度也较高。当地表热通量一定,增大风切变时,由于风切变使夹卷作用增强,将逆温层中的暖空气向下卷入混合层中,使对流边界层增暖增厚,但是对流泡容易破碎,对流的强度也较弱。另外通过在模式近地层释放绝对浓度为100的被动示踪物方法,用最小二乘法定量地分析了地表热通量和风切变分别与示踪物抬升效率和传输高度的关系。分析结果表明,风切变小于10.5×10-3 s-1时,增大地表热通量加强了上层动量的下传,使示踪物的抬升效率也线性增大;地表热通量小于462.5 W m-2时,增大风切变减弱了边界层对流的强度,从而使示踪物的抬升效率减弱。当风切变一定时,示踪物的平均传输高度随地表热通量增加而增大,而地表热通量一定,只有风切变大于临界值时,示踪物平均传输高度才随风切变的增加而增大,而临界风速的大小由地表热通量决定。展开更多
文摘The Expendable Bathythermograph (XBT) Programme used a mix of T4 (450m) and T7(750 m) XBT’s during the pre-TOGA periods. Studies are needed to determine how to use the T4/T7 datatogether, in particular with regard to a reference level for calculation of dynamic height and geostrophiccurrents. Temperature profiles to 750 m collected from 1986 through 1989 on the trackline across theIndonesian throughflow between NW Australia and Java are used to show the relations between dynamicbeight and geostriohic flow using reference levels at 400 db and 750 db. A very high temporalcorrelation between vertically averaged temperture in the upper 400 m and dynamic height at 50 m rela-tive to 750 db was found. The corresponding regression relationships are presented for all one degree lati-tude bins along the section and can be used for dynamical calculation of currents in the upper 400 m rel-ative to 750 db .An attempt is made to estimate volume transport relative to 750 db from 400 m pro-files. Problems which make
文摘利用"西北干旱区陆气相互作用野外观测实验"加密观测期间敦煌站的实测资料以及大涡模式,通过一系列改变地表热通量和风切变的敏感性数值试验,分析了地表热通量和风切变对边界层对流的强度、形式,以及对对流边界层结构和发展的影响。模拟结果显示风切变一定,增大地表热通量时,由于近地层湍流运动增强,向上输送的热量也较多,使对流边界层变暖增厚,而且边界层对流的强度明显增强,对流泡发展的高度也较高。当地表热通量一定,增大风切变时,由于风切变使夹卷作用增强,将逆温层中的暖空气向下卷入混合层中,使对流边界层增暖增厚,但是对流泡容易破碎,对流的强度也较弱。另外通过在模式近地层释放绝对浓度为100的被动示踪物方法,用最小二乘法定量地分析了地表热通量和风切变分别与示踪物抬升效率和传输高度的关系。分析结果表明,风切变小于10.5×10-3 s-1时,增大地表热通量加强了上层动量的下传,使示踪物的抬升效率也线性增大;地表热通量小于462.5 W m-2时,增大风切变减弱了边界层对流的强度,从而使示踪物的抬升效率减弱。当风切变一定时,示踪物的平均传输高度随地表热通量增加而增大,而地表热通量一定,只有风切变大于临界值时,示踪物平均传输高度才随风切变的增加而增大,而临界风速的大小由地表热通量决定。
