El Niño is the appearance of anomalously warm water along the coast of Ecuador and Peru as far south as Lima (12°S). The connection between Earth’s oceans and atmosphere has a direct impact on the weather and climate conditions we experience. Ciò è determinato dai meccanismi di teleconnessione che legano differenti regioni del globo. A partire dalla normale configurazione barica presente nel Pacifico Equatoriale, caratterizzata da un centro di bassa pressione vicino all’Australia ed un centro di alta pressione vicino al Perù, l’indebolimento degli L’abbiamo definita precedentemente come la controparte del Niño ed infatti durante la Niña avvengono fenomeni diametralmente opposti.Ritorniamo alla normale configurazione barica presente nel Pacifico Equatoriale, caratterizzata da un centro di bassa pressione vicino all’Australia ed un centro di alta pressione vicino al Perù. Due dei meccanismi più noti di teleconnessione sono le Grazie all’osservazione via satellite, alla strumentazione meteo-oceanografica ed ai modelli, è possibile prevedere l’arrivo del Niño e della Niña, ma purtroppo nonostante le moderne tecnologie questi fenomeni risultano ancora oggi un gran problema per molte popolazioni. Comparison of 2 Big El Niño events (82-83, 97-98) Mailing Address. An SST anomaly of +0.5°C in the Niño 3.4 region is sufficient to reach this threshold from late March to mid-June. The most commonly used region is the Niño 3.4 region, and the most commonly used threshold is a positive SST departure from normal greater than or equal to +0.5°C. During the remainder of the year a larger SST anomaly, up to +1.5°C in November-December-January, is required in order to reach the threshold to support persistent deep convection in that region.SST values in the Niño 3.4 region may not be the best choice for determining La Niña episodes but, for consistency, the index has been defined by negative anomalies in this area. El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short.
SST Animations of Recent El Niño (warm) Events Using weekly data (NCEP Data Source) 1: 1982-83 SST (JAN82 - JUL83) 2: 1991-92 SST (JAN91 - JUL92) 3: 1994-95 SST (JAN94 - JUL95) 4: 1997-98 SST (JAN97 - DEC98) Comparison of these 4 El Niño events. Per studiare El Niño, si osservano vari parametri tra cui la temperatura superficiale del mare SST della fascia equatoriale del Pacifico. Time series of weekly SST and Climatology for the 4 Niño regions.
Essendo più intensi gli Alisei, aumenta l’upwelling e si raffreddano ulteriormente le acque prossime alle coste peruviane. Copyright 2000-2020 Tutti i diritti riservati MeteoInDiretta è un progetto Tempo di meteo srl p.i.02241200464
El Niño (La Niña) is a phenomenon in the equatorial Pacific Ocean … This means a normal- ized sea surface temperature (SST) anomaly exceeding one standard deviation for at least four (4) consecutive months. Since this region encompasses the western half of the equatorial cold tongue region, it provides a good measure of important changes in SST and SST gradients that result in changes in the pattern of deep tropical convection and atmospheric circulation.
Time-longitude section of SST anomalies (5 o N-5 o S) Time series of weekly SST anomalies for the 4 Niño regions. Oceanic Niño Index (ONI) The ONI is based on SST departures from average in the Niño 3.4 region, and is a principal measure for monitoring, assessing, and predicting ENSO. Niño 1+2 (0-10S, 90W-80W): The Niño 1+2 region is the smallest and eastern-most of the Niño SST regions, and corresponds with the region of coastal South America where El Niño was first recognized by the local populations. The criteria, that is often used to classify El Niño episodes, is that five consecutive 3-month running mean SST anomalies exceed the threshold.Studies have shown that a necessary condition for the development and persistence of deep convection (enhanced cloudiness and precipitation) in the Tropics is that the local SST be 28°C or greater. El Niño and La Niña, together called the El Niño Southern Oscillation (ENSO), are periodic departures from expected sea surface temperatures (SSTs) in the equatorial Pacific Ocean. This index tends to have the largest variance of … Alzandosi il termoclino e spostandosi zonalmente più ad ovest, a causa degli intensi processi di mixing verticale sotto le coste del Perù, aumenta l’avvezione di acqua più fredda dal Perù verso l’Australia.
Ciò implica un periodo di intensa siccità in Sud America e l’intensificazione delle perturbazioni nella regione occidentale del Pacifico Equatoriale. Sea Surface Temperature (SST) Weekly SST Anomalies. A better choice might be the Sea surface temperature anomalies were calculated using the Extended Reconstructed Sea Surface Temperature version 4 (For more information on El Niño and La Niña, please visit Defined as the three-month running-mean SST departures in the Niño 3.4 region.
El Niño (La Niña) is a phenomenon in the equatorial Pacific Ocean characterized by a five consecutive 3-month running mean of sea surface temperature (SST) anomalies in the Historically, scientists have classified the intensity of El Niño based on SST anomalies exceeding a pre-selected threshold in a certain region of the equatorial Pacific. Once the pattern of deep convection has been altered due to anomalous SSTs, the tropical and subtropical atmospheric circulation adjusts to the new pattern of tropical heating, resulting in anomalous patterns of precipitation and temperature that extend well beyond the region of the equatorial Pacific.