Hounsou-Gbo G.A., Servain Jacques, Araujo M., Martins E.S., Bourlès Bernard, Caniaux G. (2016). Oceanic indices for forecasting seasonal rainfall over the northern part of Brazilian northeast. American Journal of Climate Change, 5 (2), p. 261-274. ISSN 2167-9495.
Titre du document
Oceanic indices for forecasting seasonal rainfall over the northern part of Brazilian northeast
Année de publication
2016
Type de document
Article
Auteurs
Hounsou-Gbo G.A., Servain Jacques, Araujo M., Martins E.S., Bourlès Bernard, Caniaux G.
Source
American Journal of Climate Change, 2016,
5 (2), p. 261-274 ISSN 2167-9495
A relationship between oceanic conditions in the northwestern equatorial Atlantic (NWEA) and the seasonal rainfall over the northern part of Brazilian Northeast (NNEB) allows large climate events to be forecasted with a delay of a few months. Observed sea surface variables (sea surface temperature, wind stress and latent heat flux) and reanalyzed temperature and salinity profiles at depths of 0 - 150 m are used during 1974-2008. Perturbations in the Wind-Evaporation-SST mechanism over the NWEA during the last months of the year and the first months of the following year are of primary importance in evaluating the risk that strong climate events will affect the subsequent seasonal rainfall (in March-April) over the NNEB. Especially interesting are the Barrier Layer Thickness (BLT) and Ocean Heat Content (OHC) in the NWEA region from August-September through the subsequent months, during which a slow and steady evolution is apparent, with the highest signal occurring in October-November. Through their relationship with the local surface dynamic conditions, such BLT and OHC perturbations during the last months of the year can be used as a valuable indicator for forecasting wet or dry events over the NNEB during the subsequent rainfall season. A proposal is discussed to deploy additional temperature/conductivity sensors down to a depth of 140 m at three PIRATA moorings located in the NWEA region. That will be necessary if the BLT and other parameters of energy exchange between the ocean and atmosphere are to be estimated in real time and with a sufficiently high vertical resolution.
