Relationships between the Definition of the Hyperplane Width to the Fidelity of Principal Component Loading Patterns

Richman, Michael B.; Gong, Xiaofeng

doi:10.1175/1520-0442(1999)012<1557:rbtdot>2.0.co;2

Cited by 59 publications

(50 citation statements)

References 18 publications

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“…Also it should be recalled that each component represents two opposite phases, differing in the sign of the PC loadings, thus two symmetric thresholds should be used to identify the most characteristic days of both modes. A search in the literature offers some advice regarding thresholds for the PC loadings (Bonell and Summer, 1992;Richman and Gong, 1999) but 'optimal' PC score thresholds have rarely been studied. The selection criteria are rather dependent on the aims of a particular project.…”

Section: Pc Scores Analysismentioning

confidence: 99%

Comprehensive analysis of the climate variability in the eastern Mediterranean. Part I: map‐pattern classification

Κωστοπούλου

Jones

2007

Intl Journal of Climatology

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Abstract:This paper provides an extended study of the dominant daily circulation patterns governing the climate variability in the eastern Mediterranean. The methodology adopted to determine the circulation patterns is based on combined analysis of the spatial and temporal variation of rotated principal components of sea-level pressure. A catalogue of characteristic seasonal composites is presented and discussed. It is found that, during winter and spring, large scale features situated in northern Europe affect the atmospheric circulation over the domain of study, whereas the Atlantic (Azores) anticyclone and the Asian Thermal Low define most of the observed circulation types in summer. In autumn, the area exhibits a rapid transition from the warm to cold season showing climatic features from both extreme seasons. Similarities between winter and spring/autumn patterns are detected and correlation analyses are employed between their spatial patterns to reveal that similar circulation patterns occur amongst the three seasons, which usually appear more pronounced during winter. Frequencies and trends of the proposed circulation types are examined for each season. A linear trend analysis for the overall period exhibits a significant increase in the anticyclonic types particularly in winter. With respect to the cyclonic types, statistically significant negative trends have been found in all seasons especially for types associated with depressional activity in central the Mediterranean.

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Section: Pc Scores Analysismentioning

confidence: 99%

Comprehensive analysis of the climate variability in the eastern Mediterranean. Part I: map‐pattern classification

Κωστοπούλου

Jones

2007

Intl Journal of Climatology

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“…The S-mode loadings cluster the stations with similar time behaviour (variance). Therefore, those loadings near 0 (Richman and Gong, 1999) are not reflected in the scores, and only the larger absolute PC loadings are interpretable. In the T-mode, the whole map of PC score may be interpreted.…”

Section: Discussionmentioning

confidence: 99%

Can principal component analysis provide atmospheric circulation or teleconnection patterns?

Compagnucci

Richman

2007

Intl Journal of Climatology

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104

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This investigation examines principal component (PC) methodology and the interpretation of the displays, such as eigenvalue magnitude, loadings and scores, which the methodology provides. The key question posed is, to what extent can S-and T-mode decompositions of a dispersion matrix yield the kinds of interpretations placed on them typically? In particular, a series of experiments are designed based on various amalgamations of three distinct synoptic flow patterns. Since these flow patterns are known, a priori, this allows testing via subtle alterations of the methodology to determine whether there is equivalence between the S-and T-mode decompositions, the degree to which the flow patterns or teleconnections can be recovered by each mode, and the interpretation of each mode.The findings are examined in two contexts: how well they classify the flow patterns, and how well they provide meaningful teleconnections. Both correlation and covariance dispersion matrices are used to determine differences that arise from the standardization. Additionally, unrotated and rotated results are included. By examining a variety of commonly applied methodologies, the results hold for a wider range of studies. Key findings are that eigenvalue degeneracy can influence one mode (but not the other) or both modes for any set of flow patterns resulting in pattern intermixing at times. Similarly, such degeneracy is found in one or both dispersion matrices. Congruence coefficients are used to provide a measure of validity by matching the PC loadings to the parent correlations and covariances. This matching is vital as the loadings exhibit dipoles that have been interpreted historically as physically meaningful, but the present work indicates they may arise purely through the methodology. Overall, we observe that S-mode results can be interpreted as teleconnection patterns and T-mode as flow patterns for well-designed analyses that are meticulously scrutinized for methodological problems.

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“…daily records of different months, single days and total monthly or yearly amount) for the period 1901-2000. Since the PCA is widely used this method will not be described here, for details see Richman and Gong (1999), Jolliffe (2002), Wilks (2006), Compagnucci and Richmann (2008) and many others.…”

Section: Classification Of Daily Precipitation Records By Means Of Pcamentioning

confidence: 99%

Multivariate testing of spatio-temporal consistence of daily precipitation records

Mächel

Kapala

2013

Adv. Sci. Res.

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Abstract. The project KLIDADIGI of the German Meteorological Service (DWD) systematically rescues historical daily climate data of Germany by keying and imaging. Up to now, daily nearly gap-free precipitation time series at 118 locations for the period 1901-2000 are collected and extended by digitalization of handwritten protocols. To screen the spatio-temporal consistence of these raw data, we apply principal component analysis (PCA) in S (spatial) mode for daily precipitation records as well as for indices such as the number of rainy days above a certain threshold, intensity and absolute daily maximum in monthly, seasonal or annual resolution. Results of this screening test indicate that the PCA is a useful tool for detection of questionable stations and data preprocessing for further quality control and homogenization.

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Relationships between the Definition of the Hyperplane Width to the Fidelity of Principal Component Loading Patterns

Cited by 59 publications

References 18 publications

Comprehensive analysis of the climate variability in the eastern Mediterranean. Part I: map‐pattern classification

Comprehensive analysis of the climate variability in the eastern Mediterranean. Part I: map‐pattern classification

Can principal component analysis provide atmospheric circulation or teleconnection patterns?

Multivariate testing of spatio-temporal consistence of daily precipitation records

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