An All-Season Real-Time Multivariate MJO Index: Development of an Index for Monitoring and Prediction
TLDR
A seasonally independent index for monitoring the Madden-Julian oscillation (MJO) is described in this paper, which is based on a pair of empirical orthogonal functions (EOFs) of the combined fields of near-equatorially averaged 850-hPa zonal wind, 200-hpa zonal winds, and satellite-observed outgoing longwave radiation (OLR) data.Abstract:
A seasonally independent index for monitoring the Madden–Julian oscillation (MJO) is described. It is based on a pair of empirical orthogonal functions (EOFs) of the combined fields of near-equatorially averaged 850-hPa zonal wind, 200-hPa zonal wind, and satellite-observed outgoing longwave radiation (OLR) data. Projection of the daily observed data onto the multiple-variable EOFs, with the annual cycle and components of interannual variability removed, yields principal component (PC) time series that vary mostly on the intraseasonal time scale of the MJO only. This projection thus serves as an effective filter for the MJO without the need for conventional time filtering, making the PC time series an effective index for real-time use. The pair of PC time series that form the index are called the Real-time Multivariate MJO series 1 (RMM1) and 2 (RMM2). The properties of the RMM series and the spatial patterns of atmospheric variability they capture are explored. Despite the fact that RMM1 and RMM...read more
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References
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Description of Global-Scale Circulation Cells in the Tropics with a 40–50 Day Period
Roland A. Madden,Paul R. Julian +1 more
TL;DR: In this article, a long time series (5-10 years) of station pressure and upper air data from stations located in the tropics are subjected to spectral and cross-spectral analysis to investigate the spatial extent of a previously detected oscillation in various variables with a period range of 40-50 days.
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