ASPECTOS METODOLÓGICOS DEL USO DEL ANÁLISIS DE COMPONENTES PRINCIPALES EN CAMPOS DE ANOMALIAS DE ALTURA GEOPOTENCIAL EN EL SUR DE SUDAMERICA

BETTOLLI, MARIA LAURA; VARGAS, WALTER M; PENALBA, OLGA C

REVISTA BRASILEIRA DE METEOROLOGIA

Sociedad Brasileira de Meteorologia

Año: 2007 vol. 22 p. 273 - 285

0102-7786

RESUMEN En este trabajo se discutieron aspectos metodológicos del uso del Análisis de Componentes Principales (ACP) a fin de verificar la eficacia del método para el conjunto de campos diarios de anomalías de altura geopotencial de 1000 y 500 hPa de los reanálisis 2 del NCEP en el sur de Sudamérica de los años 1979-2001 en el período comprendido entre octubre y mayo. Este análisis metodológico se realizó con el objetivo de obtener una base representativa de la información para clasificaciones sinópticas futuras. Se evaluó la necesidad de realizar rotaciones ortogonales y su efectividad, encontrando que éstas no mejoran la redistribución de la varianza explicada. A partir de una submuestra de 100 días elegidos al azar se analizó la in. uencia del efecto de la persistencia de los campos diarios consecutivos. Dicho efecto no modificó sustancialmente los resultados del ACP y no introdujo otras componentes principales significativas. El conjunto de datos de anomalías de altura geopotencial puede reducirse efectivamente realizando un ACP como técnica de síntesis. Este resultado se corroboró utilizando el test de esfericidad de Bartlett y una prueba empírica modificando la matriz de correlación. Finalmente, para representar un campo de anomalía real y, de esta manera, facilitarle un sentido físico es necesaria la combinación de dos o más CP. Palabras claves: patrones sinópticos; altura geopotencial; sur de Sudamérica; análisis de componentes principales principales principales principales patrones sinópticos; altura geopotencial; sur de Sudamérica; análisis de componentes principales ABSTRACT: METHODOLOGICAL ASPECTS OF THE USE OF THE PRINCIPAL COMPONENT ANALYSIS OF 1000 AND 500 hPa ANOMALIES OF GEOPOTENTIAL HEIGHT FIELDS IN SOUTHERN SOUTH AMERICA. This paper presents a discussion of methodological aspects of the use of the principal component analysis (PCA) to verify its eficacy synthesis for the daily 1000 and 500 hPa anomalies of geopotential height fields of the October to May 1979-2001 NCEP reanalyses II in southern South America. This analysis was performed in order to obtain a representative data base for future synoptic classifications. The need of orthogonal rotations and their eficacy was analyzed showing that the explained variance redistribution was not improved. A random sub-sample of 100 days was used to study the influence of the persistence effect of consecutive daily fields. This effect did not significantly modify the PCA results and did not introduce other significant PCs. The set of geopotential height data may be considerably reduced using PCA as a synthesis technique. This result was corroborated using Bartlett’s sphericity test and an empirical test on the modified correlation matrix. Finally, to represent a real field and thus facilitate a physical sense, it is found that the combination of two or more PCs is necessary. ANALYSIS OF 1000 AND 500 hPa ANOMALIES OF GEOPOTENTIAL HEIGHT FIELDS IN SOUTHERN SOUTH AMERICA. This paper presents a discussion of methodological aspects of the use of the principal component analysis (PCA) to verify its eficacy synthesis for the daily 1000 and 500 hPa anomalies of geopotential height fields of the October to May 1979-2001 NCEP reanalyses II in southern South America. This analysis was performed in order to obtain a representative data base for future synoptic classifications. The need of orthogonal rotations and their eficacy was analyzed showing that the explained variance redistribution was not improved. A random sub-sample of 100 days was used to study the influence of the persistence effect of consecutive daily fields. This effect did not significantly modify the PCA results and did not introduce other significant PCs. The set of geopotential height data may be considerably reduced using PCA as a synthesis technique. This result was corroborated using Bartlett’s sphericity test and an empirical test on the modified correlation matrix. Finally, to represent a real field and thus facilitate a physical sense, it is found that the combination of two or more PCs is necessary. ANALYSIS OF 1000 AND 500 hPa ANOMALIES OF GEOPOTENTIAL HEIGHT FIELDS IN SOUTHERN SOUTH AMERICA. This paper presents a discussion of methodological aspects of the use of the principal component analysis (PCA) to verify its eficacy synthesis for the daily 1000 and 500 hPa anomalies of geopotential height fields of the October to May 1979-2001 NCEP reanalyses II in southern South America. This analysis was performed in order to obtain a representative data base for future synoptic classifications. The need of orthogonal rotations and their eficacy was analyzed showing that the explained variance redistribution was not improved. A random sub-sample of 100 days was used to study the influence of the persistence effect of consecutive daily fields. This effect did not significantly modify the PCA results and did not introduce other significant PCs. The set of geopotential height data may be considerably reduced using PCA as a synthesis technique. This result was corroborated using Bartlett’s sphericity test and an empirical test on the modified correlation matrix. Finally, to represent a real field and thus facilitate a physical sense, it is found that the combination of two or more PCs is necessary. ANALYSIS OF 1000 AND 500 hPa ANOMALIES OF GEOPOTENTIAL HEIGHT FIELDS IN SOUTHERN SOUTH AMERICA. This paper presents a discussion of methodological aspects of the use of the principal component analysis (PCA) to verify its eficacy synthesis for the daily 1000 and 500 hPa anomalies of geopotential height fields of the October to May 1979-2001 NCEP reanalyses II in southern South America. This analysis was performed in order to obtain a representative data base for future synoptic classifications. The need of orthogonal rotations and their eficacy was analyzed showing that the explained variance redistribution was not improved. A random sub-sample of 100 days was used to study the influence of the persistence effect of consecutive daily fields. This effect did not significantly modify the PCA results and did not introduce other significant PCs. The set of geopotential height data may be considerably reduced using PCA as a synthesis technique. This result was corroborated using Bartlett’s sphericity test and an empirical test on the modified correlation matrix. Finally, to represent a real field and thus facilitate a physical sense, it is found that the combination of two or more PCs is necessary. METHODOLOGICAL ASPECTS OF THE USE OF THE PRINCIPAL COMPONENT ANALYSIS OF 1000 AND 500 hPa ANOMALIES OF GEOPOTENTIAL HEIGHT FIELDS IN SOUTHERN SOUTH AMERICA. This paper presents a discussion of methodological aspects of the use of the principal component analysis (PCA) to verify its eficacy synthesis for the daily 1000 and 500 hPa anomalies of geopotential height fields of the October to May 1979-2001 NCEP reanalyses II in southern South America. This analysis was performed in order to obtain a representative data base for future synoptic classifications. The need of orthogonal rotations and their eficacy was analyzed showing that the explained variance redistribution was not improved. A random sub-sample of 100 days was used to study the influence of the persistence effect of consecutive daily fields. This effect did not significantly modify the PCA results and did not introduce other significant PCs. The set of geopotential height data may be considerably reduced using PCA as a synthesis technique. This result was corroborated using Bartlett’s sphericity test and an empirical test on the modified correlation matrix. Finally, to represent a real field and thus facilitate a physical sense, it is found that the combination of two or more PCs is necessary. Keywords: synoptic pattern; geopotential height; southern South America; principal component analysis. analysis. analysis. analysis. synoptic pattern; geopotential height; southern South America; principal component analysis.