Advances in Earth Science ›› 2015, Vol. 30 ›› Issue (6): 724-736. doi: 10.11867/j.issn.1001-8166.2015.06.0724

• Orginal Article • Previous Articles    

Effects of Quasi-biennual Oscillation on Tropical Tropopause and Deep Convective Activities

Liu Wei 1, 2, Tian Wenshou 1, Shu Jianchuan 3, Zhang Jiankai 1, Hu Dingzhu 1   

  1. 1. Key Laboratory of Semi Arid Climate Change Ministry of Education College of Atmospheric Sciences Lanzhou University Lanzhou730000 China; 2. Meteorological Service Center of Qinghai Bureau Xining810000 China; 3. Chengdu Plateau Meteorological Institute of China Meteorological Administration Chengdu 610072 China
  • Online:2015-06-25 Published:2015-06-25

Liu Wei, Tian Wenshou, Shu Jianchuan, Zhang Jiankai, Hu Dingzhu. Effects of Quasi-biennual Oscillation on Tropical Tropopause and Deep Convective Activities[J]. Advances in Earth Science, 2015, 30(6): 724-736.

Using NCEP reanalysis data and composite method, the effects of the QuasiBiennual Oscillation (QBO) on tropical tropopause and deep convection were analyzed and the possible mechanisms were investigated. The analysis indicates that the effects of the QBO on tropical tropopause and Out going Longwave Radiation (OLR) have significant seasonal and spatial variations. The effects of the QBO on tropical tropopause and OLR are most significant in winter and autumn while relatively insignificant in spring and summer. The tropical tropopause height and temperature anomalies associated with the QBO exhibit a belted distribution in the tropics while the OLR anomalies have both positive and negative anomalies along the equator. The effect of the QBO on OLR is most significant within the convection active regions within the tropics. In Indonesia and tropical western pacific regions, in particular, the convective activities are stronger during the QBO east phase than that during the QBO west phase. The difference of the horizontal distribution between the QBO-induced tropical tropopause height anomalies and OLR anomalies implies that the effect of the QBO on tropical tropopause is mainly due to the downward propagation of zonal wind shear anomalies induced by the QBO and the indirect QBO effect on tropopause via modulating tropical convective activities is a secondary factor. Further analysis of the possible mechanisms responsible for the effect of the QBO on OLR reveals that the buoyancy frequency anomalies and Convective Potential Energy (CAPE) anomalies associated with the QBO are spatially in accordance with the QBO-induced OLR anomalies, suggesting that the QBO can affect tropical convective activities not only via modulating the tropical tropopause, but also through modulating the static stability and the CAPE in the tropical troposphere.

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