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| Titel |
Sea surface temperature patterns in Tropical Atlantic: principal component analysis and nonlinear principal component analysis |
| VerfasserIn |
S. C. Kenfack, K. F. Mkankam, G. Alory, Y. Du Penhoat, N. M. Hounkonnou, D. A. Vondou, G. N. Bawe |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
2198-5634
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics Discussions ; 1, no. 1 ; Nr. 1, no. 1 (2014-03-21), S.235-267 |
| Datensatznummer |
250115077
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| Publikation (Nr.) |
 copernicus.org/npgd-1-235-2014.pdf |
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| Zusammenfassung |
| Principal Component Analysis (PCA) is one of the popular statistical methods
for feature extraction. The neural network model has been performed on the
PCA to obtain nonlinear principal component analysis (NLPCA), which allows
the extraction of nonlinear features in the dataset missed by the PCA. NLPCA
is applied to the monthly Sea Surface Temperature (SST) data from the eastern
tropical Atlantic Ocean (29° W–21° E,
25° S–7° N) for the period 1982–2005. The focus is on the
differences between SST inter-annual variability patterns; either extracted
through traditional PCA or the NLPCA methods.The first mode of NLPCA explains
45.5% of the total variance of SST anomaly compared to 42%
explained by the first PCA. Results from previous studies that detected the
Atlantic cold tongue (ACT) as the main mode are confirmed. It is observed
that the maximum signal in the Gulf of Guinea (GOG) is located along coastal
Angola. In agreement with composite analysis, NLPCA exhibits two types of
ACT, referred to as weak and strong Atlantic cold tongues.
These two events are not totally symmetrical. NLPCA thus explains the results
given by both PCA and composite analysis. A particular area observed along
the northern boundary between 13 and 5° W vanishes in the strong ACT
case and reaches maximum extension to the west in the weak ACT case. It is
also observed that the original SST data correlates well with NLPCA and PCA,
but with a stronger correlation on ACT area for NLPCA and southwest in the
case of PCA. |
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