water Article Hydrological Extremes in the Canadian Prairies in the Last Decade due to the ENSO Teleconnection—A Comparative Case Study Using WRF Soumik Basu * , David J. Sauchyn and Muhammad Rehan Anis Prairie Adaptation Research Collaborative, Regina, SK S4S 0A2, Canada; [email protected] (D.J.S.); [email protected] (M.R.A.) * Correspondence: [email protected] Received: 8 September 2020; Accepted: 21 October 2020; Published: 23 October 2020 Abstract: In the Prairie provinces of Alberta, Saskatchewan, and Manitoba, agricultural production depends on winter and spring precipitation. There is large interannual variability related to the teleconnection between the regional hydroclimate and El Niño and La Niña in the Tropical Pacific. A modeling experiment was conducted to simulate climatic and hydrological parameters in the Canadian Prairie region during strong El Niño and La Niña events of the last decade in 2015–2016 and 2010–2011, respectively. The National Center for Atmospheric Research (NCAR) Weather Research and Forecasting (WRF) model was employed to perform two sets of sensitivity experiments with a nested domain at 10 km resolution using the European Centre for Medium-Range Weather Forecasts Reanalysis (ERA) interim data as the lateral boundary forcing. Analysis of the hourly model output provides a detailed simulation of the drier winter, with less soil moisture in the following spring, during the 2015–2016 El Niño and a wet winter during the La Niña of 2010–2011. The high-resolution WRF simulation of these recent weather events agrees well with observations from weather stations and water gauges. Therefore, we were able to take advantage of the WRF model to simulate recent weather with high spatial and temporal resolution and thus study the changes in hydrometeorological parameters across the Prairie during the two extreme hydrological events of the last decade. Keywords: Canadian Prairie climate; ENSO; downscaling; WRF 1. Introduction The Canadian Prairie provinces of Alberta, Saskatchewan, and Manitoba are known for their extreme seasonal climate and large interannual variability of hydrometeorological parameters [1,2]. Precipitation exhibits the largest spatial and temporal variability [3,4]. The major drivers of the interannual variability are the teleconnections with various large-scale climate patterns, especially El Niño Southern Oscillation (ENSO) [5–8]. Sea surface temperature (SST) anomalies in the tropical Pacific during the two phases of ENSO (El Niño/La Niña) affect North American mid-latitude weather through modulation of atmospheric circulation. The Oceanic Niño Index (ONI) is an index of SST anomalies in the tropical Pacific commonly used to estimate the intensity of the phases of ENSO. The ONI is calculated by averaging sea surface temperature anomalies in an area of the east-central equatorial Pacific Ocean (5◦ S to 5◦ N; 170◦ W to 120◦ W). A 3-month time average (running mean) is calculated to better isolate variability closely related to the ENSO. An ONI of +0.5 or higher indicates El Niño conditions when the east-central tropical Pacific is significantly warmer than normal. An ONI of 0.5 or lower corresponds to La Niña − conditions when SSTs in the region are cooler than usual. The last decade has experienced one of Water 2020, 12, 2970; doi:10.3390/w12112970 www.mdpi.com/journal/water Water 2020, 12, 2970 2 of 13 Water 2020, 12, x FOR PEER REVIEW 2 of 14 the strongest El Niño events of the century in 2015–2016 and a strong La Niña event in 2010–2011 (Figure 11).). AnAn ElEl NiñoNiño (La(La Niña)Niña) yearyear isis characterizedcharacterized byby warmerwarmer (colder)(colder) SSTsSSTs inin thethe tropicaltropical PacificPacific with associated changes in oceanic and atmosphericatmospheric circulation [9–12]. [9–12]. Ref. [13] [13] demonstrated how mid-tropospheric circulation characterized by ridgin ridgingg and troughing is associated with dry/cold dry/cold and wet weather, respectively, inin thethe CanadianCanadian Prairies.Prairies. Figure 1. Oceanic NiñoNiño IndexIndex (ONI) (ONI) calculated calculated from from NOAA NOAA Extended Extended Reconstructed Reconstructed SST SST v4 from v4 from 1854 1854to 2018. to 2018. The agriculture sector, in particular, is sensitive to the large interannual variability in precipitation The agriculture sector, in particular, is sensitive to the large interannual variability in requiring careful management of surface and soil water [14]. In winter and spring, extratropical cyclones precipitation requiring careful management of surface and soil water [14]. In winter and spring, extratropicalare the only sourcecyclones of are precipitation the only forsource the Canadianof precipitation Prairies for due the to Canadian its distance Prairies from thedue Pacificto its distanceOcean and from its locationthe Pacific on Ocean the westward and its (leeward)location on side the of westward the Rocky (leeward) Mountains. side Winter of the snowfall Rocky Mountains.and subsequent Winter spring snowfall melt and supply subsequent soil moisture spring for melt the supply production soil moisture of crops. for With the recentproduction climate of crops.change, With the recent storm tracksclimate exhibit change, an the overall storm poleward tracks exhibit shift accordingan overall poleward to the analysis shift ofaccording observational to the analysisdata and of climate observational model output data inand northern climate high model latitudes output [15 –17in ].northern Reference high [18] showed,latitudes however,[15–17]. Referencethat elevated [18] tropical showed, Pacific however, sea surface that temperatureselevated tropical cause Pacific a southward sea surface shift oftemperatures the storm track cause over a southwardNorth America. shift Previousof the storm investigations track over reveal North a strongAmerica. regional Previous and investigations seasonal dependence reveal a of strong storm regionalactivity andand extremeseasonal weather dependence events of[ 15storm]. activity and extreme weather events [15]. The Prairie Prairie region region of of Canada Canada experiences experiences both both severe severe drought drought and andextreme extreme precipitation. precipitation. The coefficientThe coefficient of variation of variation of the of cl theimate climate moisture moisture index index in Canada in Canada is highest is highest over overthe Prairies the Prairies and southernand southern interior interior British British Columbia Columbia [19–21]. [19–21 ].Previous Previous studies studies [22–24] [22–24 ]have have investigated investigated the atmospheric, hydrological, and land surface proces processesses associated with extreme hydroclimatic events such as as severe severe droughts droughts and and floods. floods. While While variou variouss studies studies [5], [ 5reference], reference [25–27] [25– 27have] have examined examined the recordedthe recorded Prairie Prairie weather weather associated associated with with ENSO, ENSO, but but the the linkages linkages between between El El Niño/La Niño/La Niña Niña and hydrological parametersparameters have have not not been been simulated simulated for for the the extreme extreme phases phases of ENSO. of ENSO. The relatively The relatively scarce scarcedistribution distribution of weather of stationsweather suggests stations a model-basedsuggests a detailedmodel-based spatial detailed analysis ofspatial climatological analysis andof climatologicalhydrological parameters and hydrological during parameters ENSO events. during So, inENSO this study,events. we So, investigate in this study, the teleconnectionswe investigate thebetween teleconnections the strong Elbetween Niño in the 2015–2016 strong El and Niño strong in 2015–2016 La Niña inand 2010–2011 strong La and Niña hydrometeorological in 2010–2011 and hydrometeorologicalparameters in the Canadian parameters Prairies in the using Canadian high-resolution Prairies outputusing high-resolution from the Weather output Research from andthe WeatherForecasting Research Model and (WRF). Forecasting This study Model compares (WRF). the Th twois study extreme compares hydrological the two scenarios extreme in hydrological the Prairies scenariosin the context in the of Prairies ENSO teleconnection in the context of in ENSO the last teleconnection decades. in the last decades. 2. Methodology and Modeling Experiment 2. Methodology and Modeling Experiment The National Center for Atmospheric Research (NCAR) Weather Research and Forecasting (WRF) The National Center for Atmospheric Research (NCAR) Weather Research and Forecasting model version 4.0 [28] is a mesoscale numerical weather prediction system suitable for atmospheric (WRF) model version 4.0 [28] is a mesoscale numerical weather prediction system suitable for research and operational forecasting with a resolution of thousands of kilometers to a few meters. atmospheric research and operational forecasting with a resolution of thousands of kilometers to a few meters. The WRF model offers a wide choice of physics and dynamical packages along with different parameterization options, which makes it widely used for regional climate studies. Water 2020, 12, 2970 3 of 13 The WRF model offers a wide choice of physics and dynamical packages along with different parameterizationWater 2020, 12, x FOR options, PEER REVIEW which makes it widely used for regional climate studies. 3 of 14 In this study, the WRF model was configured with a nested domain (two-way nesting but In this study, the WRF model was configured with