期刊
CLIMATE DYNAMICS
卷 52, 期 5-6, 页码 3609-3629出版社
SPRINGER
DOI: 10.1007/s00382-018-4403-0
关键词
WRF model; El Nino; Precipitation; ERA-Interim; Dynamical downscaling; Tropical Andes
资金
- Programa de investigacion en la gestion de riesgo asociado con cambio climatico y ambiental en cuencas hidrograficas (UT-GRA), Colciencias [543-2011]
- IAI-INPE Internship program: Understanding Climate Change and Variability in the Americas
- Desert Research Institute/Division of Atmospheric Sciences
- COLCIENCIAS [FP44842-856-2014]
Precipitation in the tropical Andes is strongly influenced by the ENSO phases and orographic effects. In particular, precipitation can be drastically reduced during El Nino. Decision-making about water resources relies on modelling precipitation as the main source for water availability. Here we evaluate ERA-Interim ' s capacity to represent precipitation in the mountainous central Colombian Andes, a strategic region for water supply and hydropower generation, for different phases of ENSO during 1998-2012. Our results show that ERA-Interim fails to reproduce important features of precipitation spatial and temporal variability during different ENSO phases. Most critical in these results is how ERA-Interim overestimates precipitation during the dry season in El Nino years, which corresponds to the most critical condition for water supply. We show that ERA-Interim limitations are likely related to its simplified representation of the complex topography in the region, which excludes the inter-Andean Cauca river valley. To improve this, we implement a dynamical downscaling experiment using the WRF regional climate model, including a sensitivity analysis that considers three convective parameterization schemes and a convection-permitting simulation. WRF downscaling outperforms ERA-Interim in the representation of precipitation during the dry season of El Nino years, especially through correcting positive precipitation biases. This improvement is related to a better representation of orographic effects in WRF simulations. Our results suggest that ERA-Interim and, more generally, climate simulations with comparable coarse resolutions, may produce misleading precipitation overestimations in the tropical Andes if they do not adequately represent inter-Andean valleys, with important implications for water resources management.
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