Tropical Pacific SST influence on seasonal streamflow variability in Ecuador

This study presents a basin wide assessment about the spatio-temporal variability of streamflows in Ecuador for the period 1979-2015. The influence of the tropical Pacific sea surface temperature (SST) on stremaflow variariability from February to April (FMA) period, as the months showing maximum stramflow for the wet season in Ecuador, and from the June to August (JJA), correspondign to the dry season, was analysed. First, a long-term trend analysis was carried out by applying the Sen's slope estimator and the Mann-Kendall test to monthly streamflow data from 45 gaging stations located in different basins across Ecuador. While the coastal region showed the highest generalized positive trends from July to January, the results for the Pacific Andean area suggested a strengthening of the seasonality, presenting an overall increase in the streamflow for all months except August, September and October, which showed negative trends. Second, a singular-value decomposition (SVD) was applied in order to find the main coupled variability patterns between the FMA streamflow and the quasi-coetaneous SST (December-February, DJF) and between the JJA streamflow and the coetaneous SST. The results revealed two main coupled modes for DJF SST/FMA streamflow, the first associated with the canonical El Ni\~no and the second with El Ni\~no Modoki. The latter exerted a major influence on FMA streamflow over most of Ecuador. For JJA streamflow, however, the pattern associated with the traditional El Ni\~no was even more relevant. These results establish the foundations for streamflow modelling in Ecuador based on the Pacific SST, showing the strong response of the streamflows to different types of El Ni\~no event

Coupling study of the Variable Infiltration Capacity (VIC) model with Weather Research and Forecasting (WRF) model to simulate the streamflow in the Guadalquivir Basin

Variable Infiltration Capacity (VIC) model is a large-scale hydrologic model. Land surface is modeled as a grid of large and uniform cells with sub-grid heterogeneity (e.g. land cover), while water influx is local, only depending from the interaction between grid cell and local atmosphere environment. Water streamflow is obtained separately from the land surface simulation, using the Routing Model. The goal of this work consists into set an optimal hydrological and climate model to study the evolution of the streamflow of Guadalquivir Basin, with different future land use, land cover and climate scenarios, implemented with the regional Weather Research and Forecasting (WRF) model. In this work we present some results concerning the calibration of the most relevant parameters of VIC model, comparing the streamflow simulations obtained from the observational climate data SPAIN02 and WRF outputs databases, with the use of observational reservoirs and gauging stations daily streamflow time series, obtained from CEDEX database, in the time period 1988-1997.El modelo Variable Infiltration Capacity (VIC) es un modelo hidrológico de gran escala. La superficie terrestre es modelada considerando una gran rejilla de celdas uniformes que presentan heterogeneidad a escala de sub-rejilla (esto es, cubierta superficial), mientras que el flujo de agua es local, únicamente dependiente de la interacción entre celdas y el medio ambiente local. El caudal de agua se obtiene separadamente a partir de la simulación de la superficie terrestre usando el denominado modelo Routing. El objetivo de este trabajo consiste en calibrar un modelo hidrológico y climático de forma óptima con el fin de estudiar la evolución del caudal en la Cuenca del Guadalquivir, con diferentes posibles usos del suelo futuros, cobertura superficial y escenarios climáticos, implementado con el modelo regional Weather Research and Forecasting (WRF). En este trabajo se presentan resultados relativos a la calibración de los parámetros más relevantes del modelo VIC, comparando las simulaciones de caudal obtenidas por el mismo a partir de los datos climáticos observacionales de SPAIN02 y de las salidas del modelo WRF, con los datos de caudal diario observacionales del CEDEX, para el periodo 1988-1997.This work has been financed by the projects P11-RNM-7941 (Junta de Andalucía-Spain) and CGL2013-48539-R (MINECO-Spain, FEDER)

Evaluación de simulaciones de la precipitación en clima presente usando el modelo WRF en la Península Ibérica

En este estudio se ha llevado a cabo un conjunto de simulaciones de alta resolución espacio-temporal para un periodo de 31 años haciendo uso del modelo regional Weather Reserch and Forecasting (WRF) con el fin de evaluar la capacidad del modelo para simular la variabilidad de las precipitaciones en la Península Ibérica. Las simulaciones se realizaron usando como condiciones iniciales y de contorno los datos de reanálisis de ERA-Interim, como “condiciones de contorno perfectas”, y las salidas globales del modelo CMIP5 CESM corregidas en sesgo, sobre un dominio centrado en la PI anidado en el dominio EURO-CORDEX. La evaluación se basó en la comparación de las salidas del modelo con los datos observacionales Spain02 para las precipitaciones en España y PT02 para Portugal, a diferentes escalas temporales con el objetivo de poder averiguar si las simulaciones regionalizadas son capaces de capturar tanto los valores medios como los eventos extremos. Los resultados indican que aunque existen ciertos errores substanciales, WRF es capaz de capturar los principales patrones espaciales de la precipitación en la PI, resultando una herramienta útil a la hora de realizar simulaciones regionales para zonas con una topografía compleja como es la Península Ibérica.A set of 31-yr high-resolution simulations has been carried out with the regional Weather Research and Forecasting (WRF) model in order to evaluate its capability to simulate precipitation variability in the Iberian Peninsula. The WRF model was forced by the ERA-Interim data as “perfect boundary conditions”, and the global bias-corrected climate model outputs from CMIP5 CESM model, over a domain encompassing the IP and nested in the coarser EURO-CORDEX domain. Evaluation was based on comparison at different time scales in order to assess the model ability to capture long-term mean precipitation values and high-order statistics (extreme events). For this end, we used two different observational gridded datasets: the Spain02 data for Spanish precipitation and the PT02 data for Portugal. Although considerable errors are still observed, results show that WRF is able to capture the main spatial precipitation patterns in IP. Therefore, we can say that WRF provides useful information at regional scale, with significant improvement in complex terrain areas such as Iberian Peninsula.Este estudio está financiado por los proyectos P11-RNM-7941 (Junta de Andalucía-Spain) y CGL2013-48539-R (MINECO-Spain, FEDER)

Projected changes in the Iberian Peninsula drought characteristics

High spatial resolution drought projections for the Iberian Peninsula (IP) have been examined in terms of duration, frequency, and severity of drought events. For this end, a set of regional climate simulations was completed using the Weather Research and Forecasting (WRF) model driven by two global climate models (GCMs), the CCSM4 and the MPI-ESM-LR, for a near (2021-2050) and a far (2071-2100) future, and under two representative concentration pathway (RCP) scenarios (RCP4.5 and RCP8.5). Projected changes for these simulations were analyzed using two drought indices, the Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Precipitation Index (SPI), considering different timescales (3- and 12-months). The results showed that the IP is very likely to undergo longer and more severe drought events. Substantial changes in drought parameters (i.e., frequency, duration, and severity) were projected by both indices and at both time scales in most of the IP. These changes are particularly strong by the end of the century under RCP8.5. Meanwhile, the intensification of drought conditions is expected to be more moderate for the near future. However, the results also indicated key differences between indices. Projected drought conditions by using the SPEI showed more severe increases in drought events than those from SPI by the end of the century and, especially, for the high-emission scenario. The most extreme conditions were projected in terms of the duration of the events. Specifically, results from the 12-month SPEI analysis suggested a significant risk of megadrought events (drought events longer than 15 years) in many areas of IP by the end of the century under RCP8.5

Evaluación de simulaciones de la precipitación en clima presente usando el modelo WRF en la Península Ibérica

Ponencia presentada en: X Congreso de la Asociación Española de Climatología celebrado en Alicante entre el 5 y el 8 de octubre de 2016.[ES]En este estudio se ha llevado a cabo un conjunto de simulaciones de alta resolución espacio-temporal para un periodo de 31 años haciendo uso del modelo regional Weather Reserch and Forecasting (WRF) con el fin de evaluar la capacidad del modelo para simular la variabilidad de las precipitaciones en la Península Ibérica. Las simulaciones se realizaron usando como condiciones iniciales y de contorno los datos de reanálisis de ERA-Interim, como "condiciones de contorno perfectas", y las salidas globales del modelo CMIP5 CESM corregidas en sesgo, sobre un dominio centrado en la PI anidado en el dominio EURO-CORDEX. La evaluación se basó en la comparación de las salidas del modelo con los datos observacionales Spain02 para las precipitaciones en España y PT02 para Portugal, a diferentes escalas temporales con el objetivo de poder averiguar si las simulaciones regionalizadas son capaces de capturar tanto los valores medios como los eventos extremos.[EN]A set of 31-yr high-resolution simulations has been carried out with the regional Weather Research and Forecasting (WRF) model in order to evaluate its capability to simulate precipitation variability in the Iberian Peninsula. The WRF model was forced by the ERA-Interim data as “perfect boundary conditions”, and the global bias-corrected climate model outputs from CMIP5 CESM model, over a domain encompassing the IP and nested in the coarser EURO-CORDEX domain. Evaluation was based on comparison at different time scales in order to assess the model ability to capture long-term mean precipitation values and high-order statistics (extreme events). For this end, we used two different observational gridded datasets: the Spain02 data for Spanish precipitation and the PT02 data for Portugal.Este estudio está financiado por los proyectos P11-RNM-7941 (Junta de Andalucía-Spain) y CGL2013-48539-R (MINECO-Spain, FEDER)

Regional drought variability assessment over Spain using WRF model

This study assesses the ability of the Weather Research & Forecasting (WRF) model to reproduce dry and wet periods in a complex terrain region such as Spain. For this end, we have computed two different drought indices: the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI), which is able to identify the drought patterns in a context of global warming. For comparative purposes, we also computed the drought indices using two different data sources as observational data: the monthly rainfall from MOPREDAS and the (maximum and minimum) monthly temperature from MOTEDAS gridded datasets. ERA-Interim data were also used to calculate the drought indices in order to determinate the improvement obtained using dynamical downscaling regarding to the driving data. Results show that WRF provides an improvement over ERA-Interim in term of droughts simulations, presenting higher temporal correlations with respect to observational data. This fact suggests that WRF outputs may be more suitable than larger-scale fields from General Circulation Models (GCMs) to perform future projections of droughts events.Este estudio evalúa la habilidad del modelo Weather Research & Forecasting (WRF) para reproducir periodos húmedos y secos en terrenos geográficamente complejos como España. Con este objetivo se han calculado dos índices de sequía diferentes: el Índice Estandarizado de Precipitación (SPI) y el Índice Estandarizado de Precipitación Evapotranspiración (SPEI), capaz de identificar patrones de sequía en el contexto de calentamiento global. Con propósitos comparativos, se calcularon también los índices de sequía usando dos bases de datos diferentes como datos observacionales: las precipitaciones mensuales de los datos en rejilla de MOPREDAS y las temperaturas (máximas y mínimas) mensuales de MOTEDAS. Los resultados muestran que las salidas del modelo WRF suponen una mejora con respecto a los datos de ERA-Interim en cuanto a las simulaciones de sequías presentando mayores coeficientes de correlación temporal con los datos observacionales. Este hecho sugiere que las salidas de WRF pueden ser más idóneas que los datos de Modelos Climáticos Globales (GCMs) a la hora de realizar proyecciones futuras para episodios de sequía.This work has been financed by the projects P11-RNM-7941 (Junta de Andalucía-Spain) and CGL2013-48539-R (MINECO-Spain, FEDER)

Climatic and geologic controls on the piezometry of the Querença-Silves karst aquifer, Algarve (Portugal)

Karst aquifers in semi-arid regions, like Queren double dagger a-Silves (Portugal), are particularly vulnerable to climate variability. For the first time in this region, the temporal structure of a groundwater-level time series (1985-2010) was explored using the continuous wavelet transform. The investigation focused on a set of four piezometers, two at each side of the S. Marcos-Quarteira fault, to demonstrate how each of the two sectors of the aquifer respond to climate-induced patterns. Singular spectral analysis applied to an extended set of piezometers enabled identification of several quasi-periodic modes of variability, with periods of 6.5, 4.3, 3.2 and 2.6 years, which can be explained by low-frequency climate patterns. The geologic forcing accounts for similar to 15 % of the differential variability between the eastern and western sectors of the aquifer. The western sector displays spatially homogenous piezometric variations, large memory effects and low-pass filtering characteristics, which are consistent with relatively large and uniform values of water storage capacity and transmissivity properties. In this sector, the 6.5-year mode of variability accounts for similar to 70 % of the total variance of the groundwater levels. The eastern sector shows larger spatial and temporal heterogeneity, is more reactive to short-term variations, and is less influenced by the low-frequency components related to climate patterns