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La Niña
#1
Visto che hanno aggiornato or ora il MEI Index per il bimestre appena trascorso, ho pensato fosse opportuno aprire un 3d a parte.

La NINA si presenta nuovamente EAST BASED, dopo che una Kelvin Wave aveva portato tutti i valori delle aree ENSO monitorate a -1.4 la settimana scorsa.

Ecco infatti le Anomalie:

Niño 4 -1.4ºC
Niño 3.4 -1.3ºC
Niño 3 -1.6ºC
Niño1+2 -1.7ºC

La NINA è inoltre rimasta su valori stabili negli ultimi mesi, passando da MEI -1.81 del bimestre Luglio/Agosto, a -1.99 del bimestre Agosto/Settembre, a infine -1.91 del trimestre appena trascorso, ossia Settembre/Ottobre.
Si può quindi ancora ricondurre a NINA STRONG, osservando i valori MEI.

Ecco una mappa delle Anomalie:

[Immagine: nina.jpg]
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#2
Ricordo che avevo già scritto un articolo a riguardo de LA NINA, sottolineando il suo ruolo cruciale per il prossimo Inverno:

http://worldwildweather.altervista.org/i...no-venturo
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#3
Alla serie storica bisognerebbe aggiungere parte di questi anni:

1871/1872 - NINA MODERATE
1872/1873 - NINA MODERATE
1873/1874 - NINA STRONG
1874/1875 - NINA MODERATE
1875/1876 - NINA MODERATE
1879/1880 - NINA MODERATE
1881/1882 - NINA MODERATE
1882/1883 - NINA MODERATE
1886/1887 - NINA MODERATE
1889/1890 - NINA MODERATE
1890/1891 - NINA MODERATE
1892/1893 - NINA STRONG
1893/1894 - NINA MODERATE
1894/1895 - NINA MODERATE
1897/1898 - NINA MODERATE
1898/1899 - NINA MODERATE
1903/1904 - NINA MODERATE
1906/1907 - NINA MODERATE
1908/1909 - NINA MODERATE
1909/1910 - NINA STRONG
1910/1911 - NINA MODERATE
1915/1916 - NINA MODERATE
1916/1917 - NINA STRONG
1917/1918 - NINA MODERATE
1922/1923 - NINA MODERATE
1924/1925 - NINA MODERATE
1939/1940 - NINA MODERATE
1942/1943 - NINA STRONG
1943/1944 - NINA MODERATE
1944/1945 - NINA MODERATE
1945/1946 - NINA MODERATE
1944/1945 - NINA MODERATE
1947/1948 - NINA MODERATE
1949/1950 - NINA STRONG

ftp://www.coaps.fsu.edu/pub/JMA_SST_Inde...y.filter-5
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#4
mesociclone Ha scritto:Alla serie storica bisognerebbe aggiungere parte di questi anni:

1871/1872 - NINA MODERATE
1872/1873 - NINA MODERATE
1873/1874 - NINA STRONG
1874/1875 - NINA MODERATE
1875/1876 - NINA MODERATE
1879/1880 - NINA MODERATE
1881/1882 - NINA MODERATE
1882/1883 - NINA MODERATE
1886/1887 - NINA MODERATE
1889/1890 - NINA MODERATE
1890/1891 - NINA MODERATE
1892/1893 - NINA STRONG
1893/1894 - NINA MODERATE
1894/1895 - NINA MODERATE
1897/1898 - NINA MODERATE
1898/1899 - NINA MODERATE
1903/1904 - NINA MODERATE
1906/1907 - NINA MODERATE
1908/1909 - NINA MODERATE
1909/1910 - NINA STRONG
1910/1911 - NINA MODERATE
1915/1916 - NINA MODERATE
1916/1917 - NINA STRONG
1917/1918 - NINA MODERATE
1922/1923 - NINA MODERATE
1924/1925 - NINA MODERATE
1939/1940 - NINA MODERATE
1942/1943 - NINA STRONG
1943/1944 - NINA MODERATE
1944/1945 - NINA MODERATE
1945/1946 - NINA MODERATE
1944/1945 - NINA MODERATE
1947/1948 - NINA MODERATE
1949/1950 - NINA STRONG

ftp://www.coaps.fsu.edu/pub/JMA_SST_Inde...y.filter-5

Il problema è che non c'è modo di sapere quali siano gli anni di NINA Est e quelli di NINA West.
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#5
mesociclone Ha scritto:Il problema è che non c'è modo di sapere quali siano gli anni di NINA Est e quelli di NINA West.

Par impossibile che non ci sian i dati.....
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#6
Comunque a proposito della differenza della tipologia dell'ENSO, posto questo scritto di Kao & Yu:

EP= East Phase
CP= Central Phase

Citazione:Two different types of ENSO are described and contrasted in this paper according
to their spatial structure: one centers in the eastern Pacific and the other in the central
Pacific.
Composite analysis and hierarchical cluster analysis are applied to identify the
positive and negative phase of these two SST anomaly structures. The EP-ENSO is closer
to the canonical ENSO and fits very well with the evolution described by the delayedoscillator
theory of ENSO. This type of ENSO appears to be a basin-wide coupling
phenomenon, which relies on thermocline variations for its generation and phase reversal.
The CP type of ENSO has most of its major SST, surface wind, and subsurface ocean
variations in the central equatorial Pacific. This type involves only a shallow layer (about
100 meters) of subsurface ocean temperature variations. Since this ENSO type starts its
development from surface, it is likely that local atmospheric forcing is important to this
type of ENSO, such as those associated with Madden and Julian oscillation (Madden and
Julian 1971) and Asian or Australian monsoons. It is noticed that the CP-ENSO does not
have a phase-reversal feature in its evolution, while such a feature can be identified for
the EP-ENSO. These two ENSO types also exhibit different teleconnection with the
Indian Ocean, with the EP-ENSO links more closely with the tropical Indian Ocean while
the CP-ENSO links more with the Southern Indian Ocean.
From the composite analysis, we further prove that the warm and cold phases of
CP-ENSO tend to have similar physical characteristics and similar patterns. They show
alike evolution and phase locking features, implying CP type of El Niño and La Niña
should share a common physical process. The difference between warm and cold phases
of EP-ENSO could be the results of stronger or weaker intensity. Otherwise, EP types of
El Niño and La Niña basically have similar patterns and evolutions. The weaker strength
of EP-La Niña compared to EP-El Niño could be a result of the subsurface ocean
distribution. As suggested in Rodgers (2004), the cold water in the eastern equatorial
Pacific generally comes from the upwelling, and the temperature of cold water below the
thermocline has not much difference from the SST in the cold tongue region. Thus, the
negative SST anomalies are limited by the weak vertical temperature gradient in the
eastern tropical Pacific. On the other hand, the warm SST anomalies usually come from
the warm pool region, where is much warmer than the SST in the cold tongue region. As
a result, El Niño in the cold tongue region tends to have larger intensity than the La Niña
in the same region.
Our results point out the possibility that there may be more than one type of ENSO
in the tropical Pacific.
A similar idea was recently suggested by Ashok et al. (2007). We
found the PC time series of our CP-ENSO has a high correlation (a correlation coefficient
of 0.82) with the so-called “El Niño Modoki index” that they define to identify the noncanonical
ENSO events.
Their index was based on the difference between SST anomalies
in the central equatorial Pacific and those in the eastern and western Pacific. Nevertheless,
more analyses are needed to better identify the underlying dynamics of these two types of
ENSO and to determine for sure if they are different modes of interannual tropical
variability. The possibility exits that they may be related to the nonlinear properties of the
same ENSO dynamics.
As elaborated in several recent studies (e.g., Rodgers et al. 2004;
An and Jin 2004; Schopf and Burgman 2006), the nonlinearity can lead to spatial
asymmetry between the El Niño and La Niña phases of ENSO. Also as suggested by
Harrison and Schopf (1984), ENSO SST anomalies could appear in the central or eastern
Pacific related to the season of Kelvin wave propagation. Our results of different onset
time for the EP- and CP-ENSO could be related to their argument. The results presented
in this paper suggest that there is a need to defined new ENSO indices to better monitor
the different types of ENSO activity.
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#7
Grazie a Blizzard di MNW, so che 1909/1910 e 1916/1917 furono caratterizzati da NINA STRONG EAST BASED, ma non so come abbia fatto a determinarli.
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#8
Molto interessante...

NINA EAST, Anomalie a 500hpa NOAA rispetto alla media 1968-1996

[Immagine: 2371526031412817.png]

Queste invece le Anomalie 1909/10 + 1916/1917

[Immagine: 23715260314121031.png]
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#9
mesociclone Ha scritto:Grazie a Blizzard di MNW, so che 1909/1910 e 1916/1917 furono caratterizzati da NINA STRONG EAST BASED, ma non so come abbia fatto a determinarli.

Prova a chiedere a lui no????
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#10
forse questo vi interessa

Here are the rules. I win by default if no La Niña is declared, or if the DJF trimonthly is warmer than -0.5 (that is, if it is not part of the La Nina). Numbers quoted are for the LOWEST (strongest) trimonthly. Note that the formula used for dominance is R=a+(b/2)-(c/2)-d , where a is region 1+2, b is region 3, c is region 3.4, and d is region 4. Positive results denote a cooler west, and negative results denote a cooler east.


West dominance (west is cooler 4 of 5 months Nov-Mar AND the avg of the 5):

-0.9 or higher: I win.

-1.0 or lower: You win.


No dominance (neither side is cooler for both 4 of the 5 months Nov-Mar and the avg of the 5):

-0.9 or higher: I win.

-1.0 to -1.2: Draw.

-1.3 or lower: You win.


East dominance (east is cooler 4 of 5 months Nov-Mar AND the avg of the 5):

-1.4 or higher: I win.

-1.5 or lower: Draw.
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