Multichannel Singular Spectral Analysis Research Articles

Detecting spatio-temporal precipitation variability in Portugal using multichannel singular spectral analysis

A spatio-temporal variability study of annual precipitation in Portugal has been performed using the multichannel singular spectral analysis (MSSA). The spatio-temporal variability patterns, which can represent progressive signals, reveal significant periodic characteristics that have not been unambiguously detected in previous studies using other methods. In this study, MSSA detects periodic behaviour in annual precipitation of about 3 and 9 years. Similar periodic signals of about 4 and 8 years are detected when singular spectral analysis (SSA) is applied to a series of a North Atlantic oscillation (NAO) index. The strong correlation between the NAO and precipitation variability in Portugal reinforces the importance of detection of these signals with similar periodic characteristics. Copyright © 2006 Royal Meteorological Society

Contrasting Indian Ocean SST variability with and without ENSO influence: A coupled atmosphere-ocean GCM study

In this study, we perform experiments with a coupled atmosphere-ocean general circulation model (CGCM) to examine ENSO’s influence on the interannual sea-surface temperature (SST) variability of the tropical Indian Ocean. The control experiment includes both the Indian and Pacific Oceans in the ocean model component of the CGCM (the Indo-Pacific Run). The anomaly experiment excludes ENSO’s influence by including only the Indian Ocean while prescribing monthly-varying climatological SSTs for the Pacific Ocean (the Indian-Ocean Run). In the Indo-Pacific Run, an oscillatory mode of the Indian Ocean SST variability is identified by a multi-channel singular spectral analysis (MSSA). The oscillatory mode comprises two patterns that can be identified with the Indian Ocean Zonal Mode (IOZM) and a basin-wide warming/cooling mode respectively. In the model, the IOZM peaks about 3–5 months after ENSO reaches its maximum intensity. The basin mode peaks 8 months after the IOZM. The timing and associated SST patterns suggests that the IOZM is related to ENSO, and the basin-wide warming/cooling develops as a result of the decay of the IOZM spreading SST anomalies from western Indian Ocean to the eastern Indian Ocean. In contrast, in the Indian-Ocean Run, no oscillatory modes can be identified by the MSSA, even though the Indian Ocean SST variability is characterized by east–west SST contrast patterns similar to the IOZM. In both control and anomaly runs, IOZM-like SST variability appears to be associated with forcings from fluctuations of the Indian monsoon. Our modeling results suggest that the oscillatory feature of the IOZM is primarily forced by ENSO.

Atmospheric Flow Indices and Interannual Great Salt Lake Variability

This paper identifies connections between the time variability of the volume of the Great Salt Lake (GSL), Utah, and selected atmospheric circulation indices. The indices considered are the Southern Oscillation Index (SOI), the Pacific/North America (PNA) climatic pattern, and the Central North Pacific (CNP) index. We focus on interannual time scales. Low-frequency (interannual or interdecadal) relationships between the Great Salt Lake (GSL) volume change and atmospheric circulation indices are of importance because of their significance for the understanding and prediction of the GSL volume. We use Singular Spectral Analysis (SSA), Multichannel Singular Spectral Analysis (MSSA), and Multitaper Spectral Analysis [or Multitaper Method (MTM)], to identify persistent or nearly periodic patterns in time in each series. MSSA examines the joint modes of variability across the time series, while SSA decomposes each series into its component time patterns. MTM is used for identification of peaks and frequency band structure.