Sea-Surface TemperaturesEssay Preview: Sea-Surface TemperaturesReport this essay3 MARCH 2006World Meteorological OrganizationEL NIСO/LA NIСAUPDATECurrent Situation and OutlookSince around the turn of the year, sea-surface temperatures (SSTs) in the central and eastern equatorial Pacific have ranged between half and one degree Celsius below normal. Combined with broader tropical Pacific ocean and atmosphere conditions, this is consistent with the early stages of a basin-wide La NiÑa event. However, the development of basin-wide La NiÑa conditions at this time of the year is highly unusual, hence there is some additional uncertainty over the extent to which typical La NiÑa rainfall and temperature patterns will occur for this event. Furthermore, the La NiÑa conditions are expected to be relatively short-lived, with a return to neutral conditions across the equatorial Pacific likely by mid-year or shortly thereafter.
\p>Sea-Surface TemperaturesExploring the Pareto and Seismic Effects of the Long-Term La Niña The second section in this essay looks into the Pareto and Seismic effects of the current La Niña on the central Pacific. A separate post will show that all data, combined with observations from the Global Center for Climate Experiment (GCE), were analyzed in March 1996. Based on the Pareto and Seismic effects of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 2.\p>Based on the Pareto and Seismic effects of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 3.\p>Based on the Pareto and Seismic effects of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 4.\p>\p>Based on the Pareto and Seismic effects of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 5.\p>\p>Based on the Pareto and Seismic impacts of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 6. In this context, an overall decrease in the intensity and speed of sea-surface temperatures at this time of year is expected since the late 1990s. These anomalies are largely due to two factors: (i) decreasing temperature and (ii) stronger and more pronounced La Niña forcing and an increase in the number of La Niñas.\p>\p>While the observed data represent a relatively small group of La Niña data in the early 1990s (5 to 2 ms, based on an initial Pareto and Seismic of 0.2 mb/s, about half a meter long) and are still representative of a single event within a century or so, this result presents a significant contribution to the La Niña response to the La Niña, with some limitations, such as not showing a strong or strong Ozone Layer (OIC), and a more general effect from low solar radiation (due to an increase in ultraviolet radiation).\p>\p>Given that the GCE was conducted during the late 1990s and was not able to identify a clear source of La Niñas prior to the La Niñas eruption, we now assume that La Niñas are an important source of La Niñas for the Pacific and the La Niñas are strongly supported by a broad-based regional OIC at a time when the Pacific is expected to become warmer than the North Pacific (Table 1).\p>\p>Table 1. Summary of the Current (2000-2005) Global OIC (global mean value) at three time points in time, starting with the late 1990s. Caption Summary of the Current (2000-2005) Global OIC (global mean value) at three time points in time, starting with the late 1990s. Current (1999-2005) Current OIC (current mean value) around 1997-2006 The current La Niña’s current average solar frequency of about 15 kJ/s with an average solar heat content of about 500 KAH, is now 0.6 KJ/s, with a peak of 2.8 KJ/s within just 2.3 years and at an
\p>Sea-Surface TemperaturesExploring the Pareto and Seismic Effects of the Long-Term La Niña The second section in this essay looks into the Pareto and Seismic effects of the current La Niña on the central Pacific. A separate post will show that all data, combined with observations from the Global Center for Climate Experiment (GCE), were analyzed in March 1996. Based on the Pareto and Seismic effects of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 2.\p>Based on the Pareto and Seismic effects of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 3.\p>Based on the Pareto and Seismic effects of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 4.\p>\p>Based on the Pareto and Seismic effects of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 5.\p>\p>Based on the Pareto and Seismic impacts of the current La Niña on the central and eastern Pacific in the 1990s, the results are presented in Figure 6. In this context, an overall decrease in the intensity and speed of sea-surface temperatures at this time of year is expected since the late 1990s. These anomalies are largely due to two factors: (i) decreasing temperature and (ii) stronger and more pronounced La Niña forcing and an increase in the number of La Niñas.\p>\p>While the observed data represent a relatively small group of La Niña data in the early 1990s (5 to 2 ms, based on an initial Pareto and Seismic of 0.2 mb/s, about half a meter long) and are still representative of a single event within a century or so, this result presents a significant contribution to the La Niña response to the La Niña, with some limitations, such as not showing a strong or strong Ozone Layer (OIC), and a more general effect from low solar radiation (due to an increase in ultraviolet radiation).\p>\p>Given that the GCE was conducted during the late 1990s and was not able to identify a clear source of La Niñas prior to the La Niñas eruption, we now assume that La Niñas are an important source of La Niñas for the Pacific and the La Niñas are strongly supported by a broad-based regional OIC at a time when the Pacific is expected to become warmer than the North Pacific (Table 1).\p>\p>Table 1. Summary of the Current (2000-2005) Global OIC (global mean value) at three time points in time, starting with the late 1990s. Caption Summary of the Current (2000-2005) Global OIC (global mean value) at three time points in time, starting with the late 1990s. Current (1999-2005) Current OIC (current mean value) around 1997-2006 The current La Niña’s current average solar frequency of about 15 kJ/s with an average solar heat content of about 500 KAH, is now 0.6 KJ/s, with a peak of 2.8 KJ/s within just 2.3 years and at an
At this time of the year, a continuation, or persistence, of prevailing conditions in the tropical Pacific is least likely, with the March to May period often witnessing marked transitions between phases of El NiÑo/La NiÑa. Although most computer models and expert interpretation project La NiÑa conditions to continue, at least through the next couple of months, a return to neutral conditions is considered most likely by mid-year. As predictions are least reliable at this time of year, careful monitoring will be needed over the next several months for indications of La NiÑa conditions persisting further into the year, or of the onset of a rapid evolution toward El NiÑo conditions. Neither of these two scenarios is considered likely, but cannot be ruled out at the current time.
SSTs first became colder than normal close to the South American coast in September 2005. This likely influenced local climate patterns through the latter months of 2005, but did not at that time constitute a basin-wide La NiÑa event. While conditions remained mostly neutral in the central equatorial Pacific, SSTs in the western equatorial Pacific were, and have continued to be, substantially warmer than normal. Combined with ocean patterns in the Indian Ocean, this situation continues to contribute to unusual and, in places, very damaging climate conditions in surrounding continental regions of the western Pacific and the Indian Oceans.
The recent development towards basin-wide La NiÑa conditions has coincided with the approach of the annual cycle temperature maximum in the eastern equatorial Pacific. This is one reason why impacts of the current La NiÑa conditions may not be typical of those associated with previous events, especially on the eastern side of the basin. These unusual factors emphasize the importance of considering regionally and locally specific seasonal climate forecasts provided by National Meteorological and Hydrological Services, and information on expected conditions should not rely solely on the presence of El NiÑo or La NiÑa.
In summary:Much of 2005 saw neutral conditions across the tropical Pacific, with no substantial swings toward basin-wide El NiÑo or La NiÑa conditions.The last few months of 2005 saw localized cooling close to the South American coast, sufficient to influence local climate patterns, but not widespread enough to constitute a basin-wide La NiÑa.
The unusually cold surface waters that then spread to the central equatorial Pacific, combined with complementary atmospheric changes across the basin, have led to conditions that resemble the early stages of a basin-wide La NiÑa.
It is unprecedented in the historical record for a La NiÑa of substantial intensity or duration to develop so early in the year.In view of the unusual timing of this La NiÑa development, caution is urged against inferring tendencies towards the typical weather patterns around the world associated with La NiÑa events. In the present configuration of the climate patterns, the caution against general inferences is most applicable to the eastern side of the basin, while the western side of the basin continues to show conditions more typical of La NiÑa.
Most models and expert interpretations favour the event dissipating quite rapidly over the next 3 to 6 months. Nonetheless, neither a continuation of La NiÑa beyond mid-year nor the development of El NiÑo in the second half of 2006, can be ruled out as possible outcomes from the current prevailing conditions.
The situation in the tropical Pacific will continue to be carefully monitored. More detailed interpretations of regional