TY - JOUR
T1 - Extreme rainfall forecast with the WRF-ARW model in the Central Andes of Peru
AU - Moya-álvarez, Aldo S.
AU - Gálvez, José
AU - Holguín, Andrea
AU - Estevan, René
AU - Kumar, Shailendra
AU - Villalobos, Elver
AU - Martínez-Castro, Daniel
AU - Silva, Yamina
N1 - Publisher Copyright:
© 2018 by the authors.
PY - 2018/9/18
Y1 - 2018/9/18
N2 - The ability of the WRF-ARW (Weather Research and Forecasting-Advanced Research WRF) model to forecast extreme rainfall in the Central Andes of Peru is evaluated in this study, using observations from stations located in the Mantaro basin and GOES (Geostationary Operational Environmental Satellite) images. The evaluation analyzes the synoptic conditions averaged over 40 extreme event cases, and considers model simulations organized in 4 nested domains. We first establish that atypical events in the region are those with more than 27 mm of rainfall per day when averaging over all the stations. More than 50% of the selected cases occurred during January, February, and April, with the most extreme occurring during February. The average synoptic conditions show negative geopotential anomalies and positive humidity anomalies in 700 and 500 hPa. At 200 hPa, the subtropical upper ridge or "Bolivian high" was present, with its northern divergent flank over the Mantaro basin. Simulation results show that the Weather Research and Forecasting (WRF) model underestimates rainfall totals in approximately 50-60% of cases, mainly in the south of the basin and in the extreme west along the mountain range. The analysis of two case studies shows that the underestimation by the model is probably due to three reasons: inability to generate convection in the upstream Amazon during early morning hours, apparently related to processes of larger scales; limitations on describing mesoscale processes that lead to vertical movements capable of producing extreme rainfall; and limitations on the microphysics scheme to generate heavy rainfall.
AB - The ability of the WRF-ARW (Weather Research and Forecasting-Advanced Research WRF) model to forecast extreme rainfall in the Central Andes of Peru is evaluated in this study, using observations from stations located in the Mantaro basin and GOES (Geostationary Operational Environmental Satellite) images. The evaluation analyzes the synoptic conditions averaged over 40 extreme event cases, and considers model simulations organized in 4 nested domains. We first establish that atypical events in the region are those with more than 27 mm of rainfall per day when averaging over all the stations. More than 50% of the selected cases occurred during January, February, and April, with the most extreme occurring during February. The average synoptic conditions show negative geopotential anomalies and positive humidity anomalies in 700 and 500 hPa. At 200 hPa, the subtropical upper ridge or "Bolivian high" was present, with its northern divergent flank over the Mantaro basin. Simulation results show that the Weather Research and Forecasting (WRF) model underestimates rainfall totals in approximately 50-60% of cases, mainly in the south of the basin and in the extreme west along the mountain range. The analysis of two case studies shows that the underestimation by the model is probably due to three reasons: inability to generate convection in the upstream Amazon during early morning hours, apparently related to processes of larger scales; limitations on describing mesoscale processes that lead to vertical movements capable of producing extreme rainfall; and limitations on the microphysics scheme to generate heavy rainfall.
KW - Central Andes
KW - Extreme precipitation events
KW - Mantaro basin
KW - Mesoscale processes
KW - Model configuration
KW - Model verification
KW - Synoptic conditions
KW - WRF
UR - http://www.scopus.com/inward/record.url?scp=85053630471&partnerID=8YFLogxK
U2 - 10.3390/atmos9090362
DO - 10.3390/atmos9090362
M3 - Article
AN - SCOPUS:85053630471
SN - 2073-4433
VL - 9
JO - Atmosphere
JF - Atmosphere
IS - 9
M1 - 362
ER -