El Niño retires and we wait for La Niña ...
Analyzing the previous events, similar to the current event, it is clear that the key months to have greater certainty of an eventual passage to the La Niña phase are May and June. Anyway, the models indicate that in the quarter June, July, August, we should be in the neutral phase.
First of all, it should be noted that March was one of the driest months of the last fifty years according to the Chilean Meteorological Directorate, which belongs to the Directorate General of Civil Aeronautics, DGAC. This reality closes a quarter in which the variables show a deficit of precipitations that reached worrying levels.
Contemplating the main area of blueberry production, which is from the Fourth to the Tenth Region, the observed rainfall deficit shows indices ranging from 40mm to 140mm. In spite of the abundant precipitations of April in the central zone of the country the deficit tends to be maintained from 2015.
Meteorological indicators indicate that the El Niño phenomenon, FEN, is in a decline phase, although it still remains at moderate intensity. The observations of the anomaly of the sea surface temperature, SST, of El Niño 3.4 was + 1.64 ° C. A significant decrease has been observed in the last few weeks in all El Niño regions, reaching 1.3 ° C until the first week of April in the El Niño 3.4 region.
Another characteristic feature of the decline of El Niño, is with respect to the anomalies of the sub-surface waters, which show the incorporation of colder and deeper waters at surface levels (from 155m to 55m). According to this, the reason for the decrease in sea temperature is similar to those experienced in the transition of the events of 1982-1983 and 1997-1998, which presented strong cooling during May.
In the 1982-1983 event, the TSM remained in the neutral-to-cold range, failing to move to a definitive La Niña phase, while in the 1997-1998 period, during the quarter of June, July, August, we were already in the La Niña phase, producing a negative impact on rainfall.
Analyzing the previous events, similar to the current event, it is clear that the key months to have greater certainty of an eventual passage to the La Niña phase are May and June. Anyway, the models indicate that in the quarter June, July, August, we should be in the neutral phase.
Precipitation
Based on the observations of the March SST of 2016 and the Climate Prediction Tool (CPT), which measures the variables, precipitation, maximum temperature and minimum temperature, the climate prediction for the months of April , May and June, for the blueberry production areas, will be the following:
- The Fourth Region will be presented around normal.
- In the central zone it will vary between normal and dry, taking into account that all stations are forecast in the lower limit of the normal range.
- In the southern zone the forecast indicates normal, but several stations are without a weather signal.
With regard to the extreme temperatures for the same areas, it is indicated that the maximum temperature will be above normal between the Fourth and Fifth Regions, and also between the Ninth and the Tenth Regions, in the rest of the regions considered in the production area of blueberries will be presented as normal temperature.
The minimum temperature will also be above normal between the Fourth and Fifth Regions, however in the rest of the contemplated regions will be presented within the normal ranges.
All this scenario indicates that frost will come with spring, more specifically in the months of September and October, so it is necessary to take the precautions of the case for crops vulnerable to these phenomena.
Acronyms and regions of the phenomenon
The El Niño Phenomenon, FEN, we also identify as El Niño, Southern Oscillation, ENSO, which is the interaction of an oceanic-atmospheric phenomenon that occurs in the tropical Pacific Ocean region every 2 to 7 years. This global cycle has two phases:
- In the ocean it manifests as an oscillation of the sea surface temperature between a warm phase, corresponding to El Niño, and a cold phase corresponding to La Niña, along the tropical Pacific
- In the atmosphere it manifests as an oscillation between a negative phase, corresponding to El Niño, and a positive phase, corresponding to La Niña, of the Southern Oscillation, OS.
The Southern Oscillation, OS, one of the most important manifestations of interannual variability and constitutes a fluctuation in the ocean - atmosphere system.
The Southern Oscillation Index, IOS, is an indicator of the presence of an ENSO event, which measures the difference between the average monthly anomaly of surface atmospheric pressure in Tahiti and the port of Darwin, Australia. When this number is positive, we have a La Niña event and when the number is negative, it is El Niño.
On the other hand, the phenomenon is divided into regions to have a better understanding of how events develop, both El Niño and La Niña, along the equatorial Pacific Ocean and from West to East.
- The Niño 1 + 2 region includes the coasts of Peru and Ecuador including the Galapagos Islands, this region represents an indicator of the changes induced by El Niño in the patterns of variability of the Pacific coast of South America.
- The 3 and 4 regions are located on the western side of the Pacific and are characterized by the highest sea surface temperature anomalies.
- The Niño 3.4 region is a subregion comprised between the Niño 4 and 3 regions and represents a good indicator of the correlation between the sea surface temperature and the Southern Oscillation index (ENSO).
Source: Blueberrieschile.cl - Blueberriesconsulting.com
ARTÍCULOS RELACIONADOS
