Tropical circulations and the associated rainfall anomalies during two contrasting years

Authors

  • Mary Toshie Kayano,

    1. Institute de Pesquisas Espaciais -INPE, Ministério de Ciěncia e Tecnologia-MCT, C.P. 515–12201– São José dos Campos, SP, Brasil
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  • Vadlamudi Brahmananda Rao,

    1. Institute de Pesquisas Espaciais -INPE, Ministério de Ciěncia e Tecnologia-MCT, C.P. 515–12201– São José dos Campos, SP, Brasil
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  • Antonio Divino Moura

    1. Institute de Pesquisas Espaciais -INPE, Ministério de Ciěncia e Tecnologia-MCT, C.P. 515–12201– São José dos Campos, SP, Brasil
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Abstract

The severe drought conditions observed during 1983 over a large extent of tropical lands were associated with the 1982–1983 El Niño event. In contrast, above normal rainfall was observed over these areas during 1984. The tropical circulations have been examined for these two contrasting years. The intensity and location of the rising and sinking motions were consistent with the rainfall anomalies and also with the outgoing longwave radiation anomalies. It was found that the north-south migration of the tropical trough played an important role in modulating the tropical rainfall during these two years. In the context of the currently acceptable theoretical notions of the tropical circulation, some of the observed characteristics could be explained in terms of an atmospheric response to tropical heat sources. The results suggest that seasonal changes were involved in the 1982–1983 El Niño collapse.

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