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Tombita
Barrufa una pregunta, ¿tu sabes cada cuanto tiempo actualiza la NOAA el forecast de los indices NAO y AO?
La verdad es que llevan mucho tiempo ya marcando el desplome de los 2 índices... pero no se si se actualiza cada x horas/dias...
Un saludo
P.D.: Quien lo sepa que responda, me dirijo a Barrufa simplemente porque es el último que ha hablado del tema.
El gráfico es diario.
NOAA
North Atlantic Oscillation / Pacific - North American pattern (NAO/PNA)
Calculating the Daily PNA and NAO teleconnection indices
The calculation procedure and base period have changed for calculating the daily NAO and PNA teleconnection indices. These changes have been made to eliminate inconsistencies in the way that the monthly and daily indices are calculated.
The procedure used to calculate the daily PNA and NAO teleconnection indices is based on the Rotated Principal Component Analysis (RPCA) used by Barnston and Livezey (1987, Mon. Wea. Rev., 115, 1083-1126). This procedure isolates the primary teleconnection patterns for all months and allows time series of the patterns to be constructed. To obtain the teleconnection patterns, the RPCA technique is applied to monthly standardized 500-mb height anomalies obtained from the CDAS in the analysis region 20°N-90°N between January 1950 and December 2000. Click here for more information on the teleconnection pattern calculation procedures.
The monthly teleconnection patterns are now linearly interpolated to the day in question, and therefore account for the seasonality inherent in the NAO and PNA patterns. Previously, the annual mean PNA and NAO patterns were used, which were based on monthly non-standardized anomalies. The standardized anomalies are now calculated based on the 1950-2000 climatological daily mean and standard deviation, whereas the anomalies were previously calculated from the 1971-2000 base period daily means.
The daily teleconnection indices are now calculated using the Least Squares regression approach identical to that used for the monthly indices. Therefore, all of the teleconnection patterns valid for the day in question are now recognized when calculating the PNA and NAO indices. The daily indices now represent the combination of teleconnection patterns that accounts for the most spatial variance of the observed anomaly map on any given day. Previously, the indices represented the spatial correlation between the annual mean loading pattern of the NAO or PNA and the daily height anomalies, and did not account for the spatial overlap that exists amongst the various teleconnection patterns.2. North Atlantic Oscillation / Pacific - North American pattern (NAO/PNA)
Calculating the Daily PNA and NAO teleconnection indices
The calculation procedure and base period have changed for calculating the daily NAO and PNA teleconnection indices. These changes have been made to eliminate inconsistencies in the way that the monthly and daily indices are calculated.
The procedure used to calculate the daily PNA and NAO teleconnection indices is based on the Rotated Principal Component Analysis (RPCA) used by Barnston and Livezey (1987, Mon. Wea. Rev., 115, 1083-1126). This procedure isolates the primary teleconnection patterns for all months and allows time series of the patterns to be constructed. To obtain the teleconnection patterns, the RPCA technique is applied to monthly standardized 500-mb height anomalies obtained from the CDAS in the analysis region 20°N-90°N between January 1950 and December 2000. Click here for more information on the teleconnection pattern calculation procedures.
The monthly teleconnection patterns are now linearly interpolated to the day in question, and therefore account for the seasonality inherent in the NAO and PNA patterns. Previously, the annual mean PNA and NAO patterns were used, which were based on monthly non-standardized anomalies. The standardized anomalies are now calculated based on the 1950-2000 climatological daily mean and standard deviation, whereas the anomalies were previously calculated from the 1971-2000 base period daily means.
The daily teleconnection indices are now calculated using the Least Squares regression approach identical to that used for the monthly indices. Therefore, all of the teleconnection patterns valid for the day in question are now recognized when calculating the PNA and NAO indices. The daily indices now represent the combination of teleconnection patterns that accounts for the most spatial variance of the observed anomaly map on any given day. Previously, the indices represented the spatial correlation between the annual mean loading pattern of the NAO or PNA and the daily height anomalies, and did not account for the spatial overlap that exists amongst the various teleconnection patterns.
[
www.cpc.noaa.gov]
para las estimaciones se usan varios factores:
Lo mas importante es la recurrencia espacio-temporal, así como la "conexión" con otros índices indicativos,
mas factores que se pueden evalúar son los biológicos (SOME REMARKS ON THE N.A.O. INDEX, RELATED OCEANOGRAPHIC FACTORS, AND ITS POSSIBLE FIT TO THE RECRUITMENT INDEX OF THE NORTH ATLANTIC SWORDFISH (Xiphias gladius), ICCAT WORKSHOP ON ENVIRONMENT AND TUNA ECRUITMENT..
Vamos, que la predicción va antes, y se va modificando a medida que se adquieren datos, manteniendo el horizonte de predicción.
Links que explican bien la diferencia entre NAO positiva y negativa:
[
www.ldeo.columbia.edu]
Otro mas con ubena información:
[
www.cpc.noaa.gov]
Resuminedo..
NAO positiva:
Borrasca Islandia y Anticiclón Azores fortalecidos. Tendencia a centrarse ambos al NE. (Islandia- Escandinavia y Península e interior continente, respectivamente)
La circulación es muy zonal y por latitudes medias-altas. Precipitaciones escasas para nosotros
NAO negativa.
Borrasca Islandia y Anticiclón Azores debilitados Tendencia a centrarse ambos al SO. (Islandia-Groenlandia-Canada y Azores-USA, respectivamente). Hay casos en que el anticiclón incluso hace mutis por el foro, casi que desaparece.
La circulación es muy meridional y pródiga en lluvias para nosotros, tal como ya hemos visto.
PD aunque Martin Vilde y otros se esfuerzan en querer demostrar que la correlación entre una NAO negativa con mayores precipitaciones no es significativa en muchas zonas de España
[
www.cervantesvirtual.com]
Tal como me comento el prestigioso forero Metragirta de Meteored a una pregunta sobre ello que le hice..
Bueno Barrufa. En el caso de la fachada mediterránea no podemos fijarnos únicamente en una teleconexión. El estudio de Martín Vidé no es un hecho aislado, hay muchos parecidos que se empecinan en dar datos similares de influencia de la NAO en esa zona. Y es que el clima es muy complejo y en este caso podrían influir más otras teleconexiones que la NAO, sin obviar que una NAOi negativa es generosa con casi todo el mediterráneo, por el patrón de circulación general que provoca.
Me refiero al MOI (Mediterranean Oscillation Index) o al WeMO. De ésta última te dejo un enlace del propio Martí-Vide:
[www.ub.es]
Y también una tesis doctoral de López Bustins, Joan Albert
[www.tesisenxarxa.net]
Ademas tengo algún estudio (guardado en oro y paño) sobre zonas del Pirineo como la de Andorra donde se demuestra una gran correlación entre una NAO negativa y mayor cantidad de precipitaciones en invierno,
Saludos
