Alvarado, LFernández, W2024-06-182024-06-182001Alvarado, L.F. y Fernández, W. (2001). Variabilidad interanual y estacional de la atmósfera libre sobre Costa Rica durante eventos de El Niño. Tópicos Meteorológicos y Oceanográficos, 8(2), 116-144.https://daki.cigefi.ucr.ac.cr/handle/123456789/153In this article the main climatic fluctuations of the free atmosphere over Costa Rica during El Niño events are diagnosed by means of using a composite technique of the anomalies of the meteorological fields. These climatic fluctuations include: (i) the greater warming (cooling) of the air in all the troposphere (stratosphere), (ii) the decrease in atmospheric pressure at the surface, (iii) the greater values of equivalent potential temperatue (θe) and the greater depth of the convectively unstable layer, (iv) the greater magnitude of the trade winds during the summer and their decrease during winter, (v) a more intense wind shear between winter and summer, (vi) the west (east) phase at the equator is reflected in Costa Rica as an intensification (weakening) of the dominant easterly winds, (vii) the CBO signal shows a spectral maximum in the 27 months period. It is more intense at 30 hPa and disappears completely at 100, where the period of the spectral energy maximum approximately coincides with the cycle of El Niño phenomenon.esArticle