scholarly journals Lateral terrestrial water flow contribution to summer precipitation at continental scale – A comparison between Europe and West Africa with WRF‐Hydro ‐tag ensembles

2021 ◽  
Author(s):  
Joël Arnault ◽  
Benjamin Fersch ◽  
Thomas Rummler ◽  
Zhenyu Zhang ◽  
Gandome Mayeul Quenum ◽  
...  
Keyword(s):  
West Africa ◽  
Water Flow ◽  
Summer Precipitation ◽  
Continental Scale ◽  
Terrestrial Water

Contribution of lateral terrestrial water flow to precipitation – A WRF-Hydro ensemble analysis and continental evaporation tagging for Europe

2020 ◽  
Author(s):  
Joel Arnault ◽  
Benjamin Fersch ◽  
Thomas Rummler ◽  
Zhenyu Zhang ◽  
Jianhui Wei ◽  
...  
Keyword(s):  
Water Flow ◽  
Land Surface ◽  
Summer Precipitation ◽  
The State ◽  
Grid Spacing ◽  
Surface Evaporation ◽  
Terrestrial Water ◽  
Grid Points ◽  
Horizontal Grid ◽  
Land Water

<p>Land-atmosphere feedback processes are key components of the Earth climate system. In general, it is questionable to which extend the state of the land surface feeds back to the state of the atmosphere. This question can be addressed with a coupled land surface – atmospheric model, and the realism of the simulated feedbacks can be evaluated with a model-to-observation comparison. This study investigates the particular case of the process chain linking lateral terrestrial water flow, soil moisture, surface evaporation and precipitation. The focus is on summer precipitation in the European region. The study period is set to four months in June-September 2008. The tool to conduct this study is the coupled atmospheric – hydrological model WRF-Hydro, which allows surface and subsurface water routing. For the setup of the atmospheric part, a horizontal grid of 700x500 grid points with a grid spacing of 5 km, that is covering an area of 3500 km x 2500 km, and 50 vertical levels up to 10 hPa is chosen. For the setup of the land water routing, a horizontal grid of 14000x10000 grid points with a grid spacing of 250 m and 4 soil layers down to 2 m depth is chosen. The employed model version includes a surface evaporation tagging procedure in order to quantify the fraction of European precipitation originating from evaporation from all over the European continent. The method consists of generating a set of WRF-Hydro simulations with and without land water routing by using random realizations of the stochastic kinetic energy backscatter scheme, and assess the impact of lateral terrestrial water flow on precipitation with the daily gridded observational dataset for precipitation in Europe (E-OBS). An ensemble size of twenty members is used to disentangle the contribution of two processes responsible for precipitation differences between WRF-Hydro simulations with and without land water routing, namely the changes in surface evaporation and the atmosphere chaotic behavior. It is found that the consideration of lateral terrestrial water flow increases the amount of summer precipitation through enhanced surface evaporation up to 10%, which reduces the bias to E-OBS.</p>

Leading patterns of the satellite-era summer precipitation over West Africa and global associated teleconnections

2021 ◽  
pp. 105677
Author(s):  
Hyacinth C. Nnamchi ◽  
Victor N. Dike ◽  
Akintomide A. Akinsanola ◽  
Ugochukwu K. Okoro
Keyword(s):  
West Africa ◽  
Summer Precipitation

scholarly journals Role of Runoff–Infiltration Partitioning and Resolved Overland Flow on Land–Atmosphere Feedbacks: A Case Study with the WRF-Hydro Coupled Modeling System for West Africa

2016 ◽  
Vol 17 (5) ◽  
pp. 1489-1516 ◽  
Author(s):  
Joel Arnault ◽  
Sven Wagner ◽  
Thomas Rummler ◽  
Benjamin Fersch ◽  
Jan Bliefernicht ◽  
...  
Keyword(s):  
West Africa ◽  
Overland Flow ◽  
River Flow ◽  
Efficiency Coefficient ◽  
Wet Season ◽  
Coupled Modeling ◽  
Study Region ◽  
Outer Domain ◽  
Terrestrial Water

Abstract The analysis of land–atmosphere feedbacks requires detailed representation of land processes in atmospheric models. The focus here is on runoff–infiltration partitioning and resolved overland flow. In the standard version of WRF, runoff–infiltration partitioning is described as a purely vertical process. In WRF-Hydro, runoff is enhanced with lateral water flows. The study region is the Sissili catchment (12 800 km2) in West Africa, and the study period is from March 2003 to February 2004. The WRF setup here includes an outer and inner domain at 10- and 2-km resolution covering the West Africa and Sissili regions, respectively. In this WRF-Hydro setup, the inner domain is coupled with a subgrid at 500-m resolution to compute overland and river flow. Model results are compared with TRMM precipitation, model tree ensemble (MTE) evapotranspiration, Climate Change Initiative (CCI) soil moisture, CRU temperature, and streamflow observation. The role of runoff–infiltration partitioning and resolved overland flow on land–atmosphere feedbacks is addressed with a sensitivity analysis of WRF results to the runoff–infiltration partitioning parameter and a comparison between WRF and WRF-Hydro results, respectively. In the outer domain, precipitation is sensitive to runoff–infiltration partitioning at the scale of the Sissili area (~100 × 100 km2), but not of area A (500 × 2500 km2). In the inner domain, where precipitation patterns are mainly prescribed by lateral boundary conditions, sensitivity is small, but additionally resolved overland flow here clearly increases infiltration and evapotranspiration at the beginning of the wet season when soils are still dry. The WRF-Hydro setup presented here shows potential for joint atmospheric and terrestrial water balance studies and reproduces observed daily discharge with a Nash–Sutcliffe model efficiency coefficient of 0.43.

scholarly journals Toward continental hydrologic–hydrodynamic modeling in South America

2018 ◽  
Vol 22 (9) ◽  
pp. 4815-4842 ◽  
Author(s):  
Vinícius A. Siqueira ◽  
Rodrigo C. D. Paiva ◽  
Ayan S. Fleischmann ◽  
Fernando M. Fan ◽  
Anderson L. Ruhoff ◽  
...  
Keyword(s):  
South America ◽  
Land Surface ◽  
River Discharge ◽  
Hydrological Modeling ◽  
Water Levels ◽  
Scale Model ◽  
Global Models ◽  
Discharge Data ◽  
Continental Scale ◽  
Terrestrial Water

Abstract. Providing reliable estimates of streamflow and hydrological fluxes is a major challenge for water resources management over national and transnational basins in South America. Global hydrological models and land surface models are a possible solution to simulate the terrestrial water cycle at the continental scale, but issues about parameterization and limitations in representing lowland river systems can place constraints on these models to meet local needs. In an attempt to overcome such limitations, we extended a regional, fully coupled hydrologic–hydrodynamic model (MGB; Modelo hidrológico de Grandes Bacias) to the continental domain of South America and assessed its performance using daily river discharge, water levels from independent sources (in situ, satellite altimetry), estimates of terrestrial water storage (TWS) and evapotranspiration (ET) from remote sensing and other available global datasets. In addition, river discharge was compared with outputs from global models acquired through the eartH2Observe project (HTESSEL/CaMa-Flood, LISFLOOD and WaterGAP3), providing the first cross-scale assessment (regional/continental  ×  global models) that makes use of spatially distributed, daily discharge data. A satisfactory representation of discharge and water levels was obtained (Nash–Sutcliffe efficiency, NSE > 0.6 in 55 % of the cases) and the continental model was able to capture patterns of seasonality and magnitude of TWS and ET, especially over the largest basins of South America. After the comparison with global models, we found that it is possible to obtain considerable improvement on daily river discharge, even by using current global forcing data, just by combining parameterization and better routing physics based on regional experience. Issues about the potential sources of errors related to both global- and continental-scale modeling are discussed, as well as future directions for improving large-scale model applications in this continent. We hope that our study provides important insights to reduce the gap between global and regional hydrological modeling communities.

scholarly journals A Multi-Sourced Data Retrodiction of Remotely Sensed Terrestrial Water Storage Changes for West Africa

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 401 ◽  
Author(s):  
Vagner Ferreira ◽  
Samuel Andam-Akorful ◽  
Ramia Dannouf ◽  
Emmanuel Adu-Afari
Keyword(s):  
West Africa ◽  
Water Storage ◽  
Remotely Sensed ◽  
Climate Indices ◽  
Terrestrial Water Storage ◽  
Drought Assessment ◽  
Grace Data ◽  
Short Period ◽  
Terrestrial Water ◽  
Land Data Assimilation System

Remotely sensed terrestrial water storage changes (TWSC) from the past Gravity Recovery and Climate Experiment (GRACE) mission cover a relatively short period (≈15 years). This short span presents challenges for long-term studies (e.g., drought assessment) in data-poor regions like West Africa (WA). Thus, we developed a Nonlinear Autoregressive model with eXogenous input (NARX) neural network to backcast GRACE-derived TWSC series to 1979 over WA. We trained the network to simulate TWSC based on its relationship with rainfall, evaporation, surface temperature, net-precipitation, soil moisture, and climate indices. The reconstructed TWSC series, upon validation, indicate high skill performance with a root-mean-square error (RMSE) of 11.83 mm/month and coefficient correlation of 0.89. The validation was performed considering only 15% of the available TWSC data not used to train the network. More so, we used the total water content changes (TWCC) synthesized from Noah driven global land data assimilation system in a simulation under the same condition as the GRACE data. The results based on this simulation show the feasibility of the NARX networks in hindcasting TWCC with RMSE of 8.06 mm/month and correlation coefficient of 0.88. The NARX network proved robust to adequately reconstruct GRACE-derived TWSC estimates back to 1979.

scholarly journals Precipitation Sensitivity to the Uncertainty of Terrestrial Water Flow in WRF-Hydro: An Ensemble Analysis for Central Europe

2018 ◽  
Vol 19 (6) ◽  
pp. 1007-1025 ◽  
Author(s):  
Joël Arnault ◽  
Thomas Rummler ◽  
Florian Baur ◽  
Sebastian Lerch ◽  
Sven Wagner ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Spatial Variability ◽  
Central Europe ◽  
Water Flow ◽  
Daily Precipitation ◽  
Three Dimensional ◽  
Wrf Model ◽  
Vertical Direction ◽  
Surface Flux ◽  
Terrestrial Water

Abstract Precipitation is affected by soil moisture spatial variability. However, this variability is not well represented in atmospheric models that do not consider soil moisture transport as a three-dimensional process. This study investigates the sensitivity of precipitation to the uncertainty in the representation of terrestrial water flow. The tools used for this investigation are the Weather Research and Forecasting (WRF) Model and its hydrologically enhanced version, WRF-Hydro, applied over central Europe during April–October 2008. The model grid is convection permitting, with a horizontal spacing of 2.8 km. The WRF-Hydro subgrid employs a 280-m resolution to resolve lateral terrestrial water flow. A WRF/WRF-Hydro ensemble is constructed by modifying the parameter controlling the partitioning between surface runoff and infiltration and by varying the planetary boundary layer (PBL) scheme. This ensemble represents terrestrial water flow uncertainty originating from the consideration of resolved lateral flow, terrestrial water flow uncertainty in the vertical direction, and turbulence parameterization uncertainty. The uncertainty of terrestrial water flow noticeably increases the normalized ensemble spread of daily precipitation where topography is moderate, surface flux spatial variability is high, and the weather regime is dominated by local processes. The adjusted continuous ranked probability score shows that the PBL uncertainty improves the skill of an ensemble subset in reproducing daily precipitation from the E-OBS observational product by 16%–20%. In comparison to WRF, WRF-Hydro improves this skill by 0.4%–0.7%. The reproduction of observed daily discharge with Nash–Sutcliffe model efficiency coefficients generally above 0.3 demonstrates the potential of WRF-Hydro in hydrological science.

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