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Theimpact of global warming on the aridity in South America SA is investigated.For this purpose, the methodology for generating surrogate climate-changescenarios with a RCM is employed. For the present climate CTRL the RCM isinitialized with and driven by ECMWF-ERA-Interim reanalysis data. Two aridityindices are used: the Budyko and the UNEP indices. The results for the CTR arein agreement with other model studies which indicate future warming;rainfall increases in southeastern South America, Ecuador and Peru anddecreases in the central and eastern Amazon. In general the model reproduces the aridityin the continent compared with the observed data for both indices. Thedistribution of aridity over SA in surrogate climate-change scenario shows anincrease of the dryness in the continent. Over Amazonia the aridity increases23.9% for the UNEP index and 3.1% for the Budyko index, suggesting thatportions of the Amazonia forest are replaced by dry land area. The semi-aridzone over northeast Brazil expands westward, attaining the interior of northBrazil. In this region the aridity increases 20% for the UNEP index and 0.6%for the Budyko index indicating that areas of humid regime may be occupied byareas with dry land regime. The RCM was also integrated driven by the AOGCMECHAM5-MPI-OM for the reference climate CTRL2 and under A1B SRES scenario.The results for the present-day climate are similar in CTRL2 and CTRL, and arein agreement with CRU data. The distribution of the aridity for the presentclimate seems to be better represented in CTRL using both Budyko and UNEP indices.The changes in aridity future climate minus control are higher in the runforced by the A1B SRES scenario. Although the UNEP and Budyko indices showpotentialities and limitations to represent the aridity distribution over SA,the changes in aridity due to a pseudo-scenario of global warming are higherusing the UNEP index.

KEYWORDS

Aridity in South America, Surrogate Climate-Change Scenario, Regional Climate Model

Cite this paper

Franchito, S. , Fernandez, J. and Pareja, D. 2014 Surrogate Climate Change Scenario and Projections with a Regional Climate Model: Impact on the Aridity in South America. American Journal of Climate Change, 3, 474-489. doi: 10.4236-ajcc.2014.35041.





Author: Sergio H. Franchito*, Julio P. Reyes Fernandez, David Pareja

Source: http://www.scirp.org/



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