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The present paper provides an analysis and a long-term forecasting scheme of the Oceanic Niño Index (ONI) using the continuous wavelet transform. First, it appears that oscillatory components with main periods of about 17, 31, 43, 61 and 140 months govern most of the variability of the signal, which is consistent with previous works. Then, this information enables us to derive a simple algorithm to model and forecast ONI. The model is based on the observation that the modes extracted from the signal are generally phased with positive or negative anomalies of ONI (El Niño and La Niña events). Such a feature is exploited to generate locally stationary curves that mimic this behavior and which can be easily extrapolated to form a basic forecast. The wavelet transform is then used again to smooth out the process and finalize the predictions. The skills of the technique described in this paper are assessed through retroactive forecasts of past El Niño and La Niña events and via classic indicators computed as functions of the lead time. The main asset of the proposed model resides in its long-lead prediction skills. Consequently, this approach should prove helpful as a complement to other models for estimating the long-term trends of ONI. [ABSTRACT FROM AUTHOR]

Many researchers have recognized the long distance teleconnections between El Niño–Southern Oscillation (ENSO) events and some other processes in the global climate system happening in areas often very far from the equatorial zone of the Pacific Ocean. In this paper we investigate similar links between ENSO and extratropical processes taken in their whole set. For this goal we compute differences between the sea-level pressure and the near-surface air (sea surface) temperature global fields which correspond to either El Niño or La Niña events observed since the end of the XIX century and up to the beginning of the XXI century. As a result, we establish that an integrity exists of ENSO and the extratropical teleconnections such as North Atlantic Oscillation (NAO), Arctic Oscillation (AO), the Northern Hemisphere annular (NHA) mode as well as the Pacific–North American (PNA) pattern, and their analogs in the Southern Hemisphere in the interannual timescale. Named this integrity the Global Atmospheric Oscillation (GAO), we define two representative indices of GAO, and investigate the temporal dynamics of these indices. This investigation reveals that GAO's extratropical components may be real irrespective of ENSO while the latter accompanies GAO in all cases. Moreover, in view of a general eastward propagation of the GAO as a spatial structure, some its extratropical components show changes of their features prior the El Niño (La Niña) begins to form. Using these features as fingerprints of the forthcoming evolution of ENSO, we define another GAO index for the El Niño prediction with the lead-time of about 1 year. At last, we establish that some of the CMIP5-models reproduce GAO reasonably well. [ABSTRACT FROM AUTHOR]

The variability of the upper ocean heat content (OHC) of the South China Sea (SCS) has a significant regional climate impact on the surrounding East and Southeast Asian countries. In this paper, the spatial–temporal variations of the upper OHC in the SCS and their relations to El Niño-Southern Oscillation (ENSO) are analyzed using empirical orthogonal functions and correlation analysis. The mechanisms for the interannual OHC variability associated with ENSO and regime shift in 1998 are further examined using composite and correlation analysis methods. The results show that the OHC anomaly field is mainly composed of two leading modes, i.e., an in-phase oscillation mode and a zonal anti-phase oscillation mode. The in-phase oscillation mode exhibits strong interannual variability with periods of 2–5 years, which is well related to ENSO at a lead of 6 months, and experienced a regime shift in 1998. The anti-phase oscillation mode shows only a strong interannual variability with periods of 2–4 years well related to ENSO at a lag of 4 months. The composite analysis reveals that horizontal thermal advection mainly controlled by wind forcing plays a primary role in modulating the interannual OHC variability associated with ENSO, while net surface heat flux is the secondary source. And the OHC regime shift in 1998 primarily results from both the strong cold advection during the extremely strong El Niño in 1997 and the subsequent warm advection during the strong La Niña in 1998. [ABSTRACT FROM AUTHOR]

The present paper presents a diagnostic study of two recent monsoon years, of which one is dry monsoon year (2009) and the other is wet monsoon year (2010). The study utilized the IMD gridded rainfall data set in addition to the Reynolds SST, NCEP-NCAR reanalysis wind and temperature products, and NOAA OLR. The study revealed that the months July and August are the most crucial months to decide whether the ISMR is wet or dry. However, during July 2009, most of the Indian subcontinent received more than 60 % in the central and western coastal regions. In a wet monsoon year, about 35-45 % of rainfall is contributed during June and July in most parts of India. During these years, the influence of features in the Pacific Ocean played vital role on the Indian summer monsoon rainfall. During 2009, Pacific SST was above normal in nino regions, characteristic of the El Nino structure; however, during 2010, the nino regions were clearly below normal temperature, indicating the La Nina pattern. The associated atmospheric general circulation through equatorial Walker and regional Hadley circulation modulates the tropospheric temperature, and hence the organized convective cloud bands. These cloud bands show different characteristics in northward propagation during dry and wet years of ISMR. During a dry year, the propagation speed and magnitudes are considerably higher than during a wet monsoon year. [ABSTRACT FROM AUTHOR]