A Mechanism of the Interdecadal Changes of the Global Low-Frequency Oscillation

作者：Yang, Ruowen; Chen, Quanliang^*; Liu, Yuyun; Wang, Lin

来源：Atmosphere, 2018, 9(8): 292.

DOI：10.3390/atmos9080292

• low-frequency oscillation
• interdecadal change
• atmospheric basic flow
• e-folding time
• barotropic primitive equations

Based on the National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis dataset from 1948 to 2009, this study reveals that global low-frequency oscillation features two major temporal bands. One is a quasi-60-day period known as the intraseasonal oscillation (ISO), and the other is a quasi-15-day period known as the quasi-biweekly oscillation (QBWO). After the mid-1970s, both the ISO and QBWO become intensified and more active, and these changes are equivalently barotropic. The primitive barotropic equations are adopted to study the involved mechanism. It reveals that the e-folding time of the least stable modes of both the ISO and QWBO becomes shorter if the model is solved under the atmospheric basic state after the mid-1970s than if solved under the basic state before the mid-1970s. This result suggests that the atmospheric basic flow after the mid-1970s facilitates a more rapid growth of the ISO and QBWO, and thereby an intensification of the low-frequency oscillations at the two bands.

• 出版日期2018-8
• 单位中国科学院大学; 中国科学院大气物理研究所; 成都信息工程大学; 云南大学