SILVA, M. R. D.; http://lattes.cnpq.br/2348451072796468; SILVA, Melquizedek Rafael Duarte da.
Résumé:
Studies on climate change, especially at the watershed scale, require better spatial
resolutions than those of Global Circulation Models (GCMs). One way to address this
limitation is through downscaling, which refers to techniques for scaling down or
regionalizing. This regionalization, based on physical or statistical approaches, is applied
to the output variables of GCMs so that they provide a better signal of climate at the
spatial scale of interest. The objective of this research was to evaluate changes in climate
patterns through statistical regionalization applied to the Model for Interdisciplinary
Research on Climate (MIROC), versions 5 and 6, in the São Francisco Watershed (SFW).
This watershed is essential for supplying water to rural and urban areas in the Brazilian
Northeast, especially in its semiarid region. To assess regional climate changes, the Bias
Correction Constructed Analogs with Quantile Mapping Reordering (BCCAQ) statistical
reduction method was applied to the daily precipitation, maximum temperature, and
minimum temperature variables of MIROC5 and MIROC6. Regionalizations for
historical climate were compared with original MIROC outputs using measures of mean
error (ME), root mean square error (RMSE), standard deviation ratio (rSD), coefficient
of determination (R²), and percentage bias relative to the mean of observations (PBIAS),
as well as spatial distribution and time series. The results indicate that regionalization
reduces systematic bias for maximum and minimum temperatures, with small corrections
to both maximum and minimum values in both calibration and validation periods.
Regarding precipitation, BCCAQ satisfactorily corrected the annual precipitation cycle
but overestimated in the headwaters region of the river, the Upper São Francisco (USF).
Regionalization measures showed absolutely lower ME, RMSE, rSD, and PIBIAS in all
sub-regions of the basin. In the study for future scenarios, maximum and minimum
temperatures increase throughout the basin and sub-regions, mainly in SSP5-8.5 and RCP
8.5 scenarios, with a slight decrease in precipitation in the USF and Middle SFW regions.