Tempisque-Bebedero Basin (Costa Rica)

Climate

The Tempisque-Bebedero catchment system is characterized by a seasonally tropical climate (Aw – Köppen-Geiger updated world climate classification) with a marked dry and wet season cycle and small temperature variability over a year (Peel et al., 2007). The dry season typically lasts from December into April with virtually no rainfall. After a short transition period rains reach a first maximum in May/June. This first maximum is followed by a dry period of 2-3 weeks in July, usually referred to as the mid-summer drought (Magaña et al., 1999). The rain maximum is reached in October related to the position of the Intertropical Convergence Zone (ITCZ).
The highest mean annual precipitation (close to 4m/yr) was recorded across the highest elevations along the continental divide (Figure 5) with the floodplains showing the least rainfall (around 1.3m/yr). The latter area is part of the Central American dry corridor and the driest region of Costa Rica.

The following Figure 6 shows the long-term 95 years annual rainfall anomaly in % at Cañas, Guanacaste (see Figure for location). There might be an increasing trend for drier years clustering together since the 1970s.

References and further reading:

Fondo Nacional de Financiamiento Forestal FONAFIFO (2012) Estudio de cobertura forestal de Costa Rica 2009-2010.

Instituto Nacional de Estadística y Censos, INEC (2014) VI Censo Nacional Agropecuario.

Magaña, V., Amador, J.A., and Medina, S. (1999) The midsummer drought over Mexico and Central America. J. Climate, 12 (1967): 1577-1588, doi: http://dx.doi.org/10.1175/1520-0442 (1999)012<1577:TMDOMA>2.0.CO;2.

Peel, M. C., Finlayson, B. L., and McMahon, T. A. (2007) Updated world map of the Köppen-Geiger climate classification. Hydrol. Earth Syst. Sci., 11, 1633-1644, doi:10.5194/hess-11-1633-2007.

Tecnológico de Costa Rica, TEC (2014) Altas de Costa Rica.

Waylen, M.E. (1996) Interannual variability of monthly precipitation in Costa Rica. J. Climate, 9: 2606-2613, doi: http://dx.doi.org/10.1175/1520-0442(1996)009<2606:IVOMPI>2.0.CO;2.

WorldClim global product: http://www.worldclim.org/tiles.php?Zone=23