Influencia de la niña y el niño sobre la precipitación de la ciudad de Villahermosa, Tabasco, México

The La Niña and El Niño effect was analized from the precipitation of Villahermosa city, in Tabasco, during the dry, moist and canicular periods. This effect was graphically and statistically analyzed from the average of ten days precipitation of the years of La Niña (cold phase), of El Niño (warm phase) and of the mixed years (which are ones influenced by the warm, the cold and normal phase, or sometimes by the three) with the normal years (years without event), between the period of 1950-2000. During La Niña¿s events the precipitation of the dry period decreased by 36 % with regard to the normal value, and in the moist and canicular periods it increased by 9 % and 57 %, respectively. When El Niño occurred the precipitation of the dry period decreased by 27 %, while for the moist and canicular periods it increased 0.5 % and 12 %, respectively. In the mixed years the precipitation decreased in all periods: in the dry period by 30 %, in the moist perid by 18 % and in the canicular period by 6 %. Afterwards, the Fisher's variances comparison test was applied, to estimate whether the variation of ten days precipitation during the event was aleatory or whether it originated from an ocean-atmosphere phenomenon. The variation of the precipitation of the dry and canicular periods during La Niña was significant (p = 0.001) and although it was not significant for the moist period (p = 0.05). In El Niño's case it was significant (p = 0.01) for the dry and canicular periods, but it was not significant for the moist period (p = 0.05). For the mixed years the decrease of the precipitation of the dry and moist periods was significant ( p = 0.001) and it was also significant for the canicular period (p = 0.05). The statistical analysis showed that the El Niño and La Niña events, affected the precipitation of the dry and canicular periods of Villahermosa city and for the mixed years it affects all periods. El efecto de La Niña y El Niño se estudió sobre la precipitación de la ciudad de Villahermosa, Tabasco, durante los períodos seco, húmedo y canicular. Este efecto se analizó gráficamente y estadísticamente mediante la precipitación promedio por decena, de los años de La Niña (fase fría), El Niño (fase caliente) y años mixtos (estos años tienen influencia de fase caliente, fría y fase normal o de las tres) con los años normales (años sin evento) del período 1950-2000. Durante los eventos de La Niña la precipitación del período seco disminuyó 36 % con respecto al valor no