印度洋偶极子与热带太平洋海洋表面温度异常多时间尺度相互作用初析

Multi-Scale Interactions between the Indian Ocean Dipole and the Tropical Pacific Sea Surface Temperature Anomalies

本文利用交叉谱方法,将印度洋偶极子(简称IOD)与ENSO的相关关系分解到不同的时间尺度上来分析,进而通过对海气耦合过程的初步分析,讨论了不同时间尺度上IOD与ENSO的相互作用。结果表明,IOD与ENSO在准1～2年、准3年、准4年等三个时间尺度上存在显著相关,同时,IOD还存在一个独立于ENSO的模态,主要表现在准8个月时间尺度上。从海气相互作用的角度看,在与ENSO相关的三个特征时间尺度上,IOD年际变率主要通过引发热带印度洋纬向风异常并且东传到太平洋,从而引起热带中东太平洋海温的年际变率。与ENSO相对独立的IOD模态则没有类似的纬向风异常东传过程。此外,在上述四个不同时间尺度上,产生IOD变率的印度洋海气耦合过程不尽相同,各具特点。

The two-year spaceborne lidar data are used to study the extinction-to-backscatter ratio,i.e.,lidar ratio（LR）,of cirrus clouds over China.The LRs are retrieved by the combination of the equation between multiply scattering factor and optical depth and the equation between LR and transmittance.Additionally,five data quality control standards have been made to assure the high availability.The mean value of LR is 24 without prominent monthly and seasonal variations.The LRs are relatively high in the intertropical convergence zone over China,and increase with latitude decreasing（approximately from 22 to 27）.This demonstrates that constant LR should be changed with latitude in order to enhance the quality of retrieval of cirrus cloud optical depth.