scholarly journals Effects of a Groundwater Scheme on the Simulation of Soil Moisture and Evapotranspiration over Southern South America

2016 ◽  
Vol 17 (11) ◽  
pp. 2941-2957 ◽  
Author(s):  
J. Alejandro Martinez ◽  
Francina Dominguez ◽  
Gonzalo Miguez-Macho
Keyword(s):  
South America ◽  
Land Surface ◽  
Climate Model ◽  
Soil Column ◽  
Water Storage ◽  
Surface Model ◽  
Southern South America ◽  
La Plata ◽  
Continental Scale ◽  
La Plata Basin

Abstract The effects of groundwater dynamics on the representation of water storage and evapotranspiration (ET) over southern South America are studied from simulations with the Noah-MP land surface model. The model is run with three different configurations: one including the Miguez-Macho and Fan groundwater scheme, another with the Simple Groundwater Model (SIMGM), and the other with free drainage at the bottom of the soil column. The first objective is to assess the effects of the groundwater schemes using a grid size typical of regional climate model simulations at the continental scale (20 km). The phase and amplitude of the fluctuations in the terrestrial water storage over the southern Amazon are improved with one of the groundwater schemes. An increase in the moisture in the top 2 m of the soil is found in those regions where the water table is closer to the land surface, including the western and southern Amazon and the La Plata basin. This induces an increase in ET over the southern La Plata basin, where ET is water limited. There is also a seasonal increase in ET during the dry season over parts of the southern Amazon. The second objective is to assess the role of the horizontal resolution on the effects induced by the Miguez-Macho and Fan groundwater scheme using simulations with grid sizes of 5 and 20 km. Over the La Plata basin, the effect of groundwater on ET is amplified at the 5-km resolution. Notably, over parts of the Amazon, the groundwater scheme increases ET only at the higher 5-km resolution.

scholarly journals Continental Runoff into the Oceans (1950–2008)

2015 ◽  
Vol 16 (4) ◽  
pp. 1502-1520 ◽  
Author(s):  
Elizabeth A. Clark ◽  
Justin Sheffield ◽  
Michelle T. H. van Vliet ◽  
Bart Nijssen ◽  
Dennis P. Lettenmaier
Keyword(s):  
South America ◽  
Land Surface ◽  
Water Cycle ◽  
Land Surface Model ◽  
Hydrologic Model ◽  
Surface Model ◽  
Infiltration Capacity ◽  
Continental Scale ◽  
Wide Range ◽  
Continental Runoff

Abstract A common term in the continental and oceanic components of the global water cycle is freshwater discharge to the oceans. Many estimates of the annual average global discharge have been made over the past 100 yr with a surprisingly wide range. As more observations have become available and continental-scale land surface model simulations of runoff have improved, these past estimates are cast in a somewhat different light. In this paper, a combination of observations from 839 river gauging stations near the outlets of large river basins is used in combination with simulated runoff fields from two implementations of the Variable Infiltration Capacity land surface model to estimate continental runoff into the world’s oceans from 1950 to 2008. The gauges used account for ~58% of continental areas draining to the ocean worldwide, excluding Greenland and Antarctica. This study estimates that flows to the world’s oceans globally are 44 200 (±2660) km3 yr−1 (9% from Africa, 37% from Eurasia, 30% from South America, 16% from North America, and 8% from Australia–Oceania). These estimates are generally higher than previous estimates, with the largest differences in South America and Australia–Oceania. Given that roughly 42% of ocean-draining continental areas are ungauged, it is not surprising that estimates are sensitive to the land surface and hydrologic model (LSM) used, even with a correction applied to adjust for model bias. The results show that more and better in situ streamflow measurements would be most useful in reducing uncertainties, in particular in the southern tip of South America, the islands of Oceania, and central Africa.

scholarly journals Regional Model Simulations of the 2008 Drought in Southern South America Using a Consistent Set of Land Surface Properties

2014 ◽  
Vol 27 (17) ◽  
pp. 6754-6778 ◽  
Author(s):  
Omar V. Müller ◽  
Ernesto Hugo Berbery ◽  
Domingo Alcaraz-Segura ◽  
Michael B. Ek
Keyword(s):  
South America ◽  
Land Cover ◽  
Land Surface ◽  
Land Use Changes ◽  
Stomatal Resistance ◽  
Surface Model ◽  
Severe Drought ◽  
Area Index ◽  
Southern South America ◽  
Realistic Information

Abstract This work discusses the land surface–atmosphere interactions during the severe drought of 2008 in southern South America, which was among the most severe in the last 50 years in terms of both intensity and extent. Once precipitation returned to normal values, it took about two months for the soil moisture content and vegetation to recover. The land surface effects were examined by contrasting long-term simulations using a consistent set of satellite-derived annually varying land surface biophysical properties against simulations using the conventional land-cover types in the Weather Research and Forecasting Model–Noah land surface model (WRF–Noah). The new land-cover dataset is based on ecosystem functional properties that capture changes in vegetation status due to climate anomalies and land-use changes. The results show that the use of realistic information of vegetation states enhances the model performance, reducing the precipitation biases over the drought region and over areas of excessive precipitation. The precipitation bias reductions are attributed to the corresponding changes in greenness fraction, leaf area index, stomatal resistance, and surface roughness. The temperature simulation shows a generalized increase, which is attributable to a lower vegetation greenness and a doubling of the stomatal resistance that reduces the evapotranspiration rate. The increase of temperature has a beneficial effect toward the eastern part of the domain with a notable reduction of the bias, but not over the central region where the bias is increased. The overall results suggest that an improved representation of the surface processes may contribute to improving the predictive skill of the model system.

scholarly journals Impacts of a Groundwater Scheme on Hydroclimatological Conditions over Southern South America

2016 ◽  
Vol 17 (11) ◽  
pp. 2959-2978 ◽  
Author(s):  
J. Alejandro Martinez ◽  
Francina Dominguez ◽  
Gonzalo Miguez-Macho
Keyword(s):  
South America ◽  
Rainy Season ◽  
Root Zone ◽  
Sensitivity Study ◽  
Near Surface ◽  
Southern South America ◽  
La Plata ◽  
La Plata Basin ◽  
Simulated Precipitation ◽  
The Impact

Abstract A sensitivity study of the impact of a groundwater scheme on hydrometeorological variables in coupled land–atmosphere simulations over southern South America is presented. It is found that shallow water tables in the groundwater scheme lead to reduced drainage and even upward capillary fluxes over parts of the central and southern La Plata basin. This leads to an increase in the simulated moisture in the root zone, which in turn produces an increase in evapotranspiration (ET) over the southern part of the domain, where ET is water limited. There is also a decrease in the near-surface temperature, in the range 0.5°–1.0°C. During the dry season, the increases in ET and relative humidity over the central La Plata coincide with an increase in precipitation downstream. Including groundwater leads to an increase in precipitation over parts of the central and southern La Plata basin during the early rainy season (October–December). The overall increase in ET and precipitation over the southern La Plata basin during the early rainy season is 13% and 10%, respectively. The additional precipitation comes from both an increase in the availability of atmospheric moisture when the groundwater scheme is used and its effect on the atmospheric instability. In the La Plata basin, including a representation of groundwater increases simulated precipitation and partially alleviates a warm and dry bias present in simulations without realistic subsurface hydrology.

A principal component analysis approach to assess CHIRPS precipitation dataset for the study of climate variability of the La Plata Basin, Southern South America

2020 ◽  
Vol 103 (1) ◽  
pp. 767-783
Author(s):  
Wilmar Loaiza Cerón ◽  
Jorge Molina-Carpio ◽  
Irma Ayes Rivera ◽  
Rita Valeria Andreoli ◽  
Mary Toshie Kayano ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
South America ◽  
Climate Variability ◽  
Principal Component ◽  
Component Analysis ◽  
Analysis Approach ◽  
Southern South America ◽  
La Plata ◽  
La Plata Basin

Recent intensification of extreme precipitation events in the La Plata Basin in Southern South America (1981–2018)

2021 ◽  
Vol 249 ◽  
pp. 105299
Author(s):  
Wilmar L. Cerón ◽  
Mary T. Kayano ◽  
Rita V. Andreoli ◽  
Alvaro Avila-Diaz ◽  
Irma Ayes ◽  
...  
Keyword(s):  
South America ◽  
Extreme Precipitation ◽  
Southern South America ◽  
La Plata ◽  
Extreme Precipitation Events ◽  
La Plata Basin ◽  
Precipitation Events

scholarly journals Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0): applications to numerical weather forecasting and the CO<sub>2</sub> budget in South America

2013 ◽  
Vol 6 (1) ◽  
pp. 453-494 ◽  
Author(s):  
D. S. Moreira ◽  
S. R. Freitas ◽  
J. P. Bonatti ◽  
L. M. Mercado ◽  
N. M. É. Rosário ◽  
...  
Keyword(s):  
South America ◽  
Atmospheric Chemistry ◽  
Land Surface ◽  
Amazon Basin ◽  
Mean Squared Error ◽  
Weather Forecasting ◽  
Dew Point ◽  
Surface Model ◽  
Co2 Concentrations ◽  
Wide Range

Abstract. This article presents the development of a new numerical system denominated JULES-CCATT-BRAMS, which resulted from the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. The performance of this system in relation to several meteorological variables (wind speed at 10 m, air temperature at 2 m, dew point temperature at 2 m, pressure reduced to mean sea level and 6 h accumulated precipitation) and the CO2 concentration above an extensive area of South America is also presented, focusing on the Amazon basin. The evaluations were conducted for two periods, the wet (March) and dry (September) seasons of 2010. The statistics used to perform the evaluation included bias (BIAS) and root mean squared error (RMSE). The errors were calculated in relation to observations at conventional stations in airports and automatic stations. In addition, CO2 concentrations in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with aircraft data. The results of this study show that the JULES model coupled to CCATT-BRAMS provided a significant gain in performance in the evaluated atmospheric fields relative to those simulated by the LEAF (version 3) surface model originally utilized by CCATT-BRAMS. Simulations of CO2 concentrations in Amazonia and a comparison with observations are also discussed and show that the system presents a gain in performance relative to previous studies. Finally, we discuss a wide range of numerical studies integrating coupled atmospheric, land surface and chemistry processes that could be produced with the system described here. Therefore, this work presents to the scientific community a free tool, with good performance in relation to the observed data and re-analyses, able to produce atmospheric simulations/forecasts at different resolutions, for any period of time and in any region of the globe.

scholarly journals Modelling northern peatlands area and carbon dynamics since the Holocene with the ORCHIDEE-PEAT land surface model (SVN r5488)

2018 ◽  
Author(s):  
Chunjing Qiu ◽  
Dan Zhu ◽  
Philippe Ciais ◽  
Bertrand Guenet ◽  
Shushi Peng ◽  
...  
Keyword(s):  
Carbon Storage ◽  
Land Surface ◽  
Net Primary Production ◽  
Soil Column ◽  
Land Surface Model ◽  
Surface Model ◽  
Past Century ◽  
Positive Trend ◽  
Peat Core ◽  
Northern Peatlands

Abstract. The importance of northern peatlands in the global carbon cycle has recently been recognized, especially for long-term changes. Yet, the complex interactions between climate and peatland hydrology, carbon storage and area dynamics make it challenging to represent these systems in land surface models. This study describes how peatland are included as an independent sub-grid hydrological soil unit (HSU) into the ORCHIDEE-MICT land surface model. The peatland soil column in this tile is characterized by multi-layered vertical water and carbon transport, and peat-specific hydrological properties. A cost-efficient TOPMODEL approach is implemented to simulate the dynamics of peatland area, calibrated by present-day wetland areas that are regularly inundated or subject to shallow water tables. The model is tested across a range of northern peatland sites and for gridded simulations over the Northern Hemisphere (> 30° N). Simulated northern peatland area (3.9 million km2), peat carbon stock (463 PgC) and peat depth are generally consistent with observed estimates of peatland area (3.4–4.0 million km2), peat carbon (270–540 PgC) and data compilations of peat core depths. Our results show that both net primary production (NPP) and heterotrophic respiration (HR) of northern peatlands increased over the past century in response to CO2 and climate change. NPP increased more rapidly than HR, and thus net ecosystem production (NEP) exhibited a positive trend, contributing a cumulative carbon storage of 11.13 Pg C since 1901, most of it being realized after the 1950s.

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