Some Space–Time Spectral Analyses of Tropical Convection and Planetary-Scale Waves
Some Space–Time Spectral Analyses of Tropical Convection and Planetary-Scale Waves
复制标题
DOI：
10.1175/2008jas2675.1
复制
发表时间：
2008-09
影响因子：
3.1
通讯作者：
H. Hendon;M. Wheeler
中科院分区：
文献类型：
--
作者：
H. Hendon;M. Wheeler
本文从时空谱分析的三个方面探讨了用Madden-Julian振荡(MJO)和其他赤道波模诊断热带对流的组织：1)背景谱的定义，2)谱的交替方差保持显示；3)时空相干谱。这里假设每个纬向波数的背景光谱是由红色噪声过程产生的。热带对流的红噪声过程的相关去相关时间是纬向风的一半，反映了控制每个场的不同物理过程。出射长波辐射(OLR)的赤道波模相关的谱峰的重要性与通过对原始谱进行特别平滑而得到的背景谱相似。OLR是降水深对流和突出于红色背景谱上方的纬向风的指标。
Abstract Three aspects of space–time spectral analysis are explored for diagnosis of the organization of tropical convection by the Madden–Julian oscillation (MJO) and other equatorial wave modes: 1) definition of the background spectrum upon which spectral peaks are assessed, 2) alternate variance preserving display of the spectra, and 3) the space–time coherence spectrum. Here the background spectrum at each zonal wavenumber is assumed to result from a red noise process. The associated decorrelation time for the red noise process for tropical convection is found to be half as long as for zonal wind, reflecting the different physical processes controlling each field. The significance of spectral peaks associated with equatorial wave modes for outgoing longwave radiation (OLR), which is a proxy for precipitating deep convection, and zonal winds that stand out above the red background spectrum is similar to that identified using a background spectrum resulting from ad hoc smoothing of the original spectrum...