scholarly journals Modifying a dynamic global vegetation model for simulating large spatial scale land surface water balances

2012 ◽  
Vol 16 (8) ◽  
pp. 2547-2565 ◽  
Author(s):  
G. Tang ◽  
P. J. Bartlein
Keyword(s):  
Soil Moisture ◽  
Surface Water ◽  
Surface Runoff ◽  
Land Surface ◽  
Surface Hydrology ◽  
Large Spatial Scale ◽  
Land Surface Water ◽  
Land Surface Hydrology ◽  
Water Balances ◽  
Global Vegetation

Abstract. Satellite-based data, such as vegetation type and fractional vegetation cover, are widely used in hydrologic models to prescribe the vegetation state in a study region. Dynamic global vegetation models (DGVM) simulate land surface hydrology. Incorporation of satellite-based data into a DGVM may enhance a model's ability to simulate land surface hydrology by reducing the task of model parameterization and providing distributed information on land characteristics. The objectives of this study are to (i) modify a DGVM for simulating land surface water balances; (ii) evaluate the modified model in simulating actual evapotranspiration (ET), soil moisture, and surface runoff at regional or watershed scales; and (iii) gain insight into the ability of both the original and modified model to simulate large spatial scale land surface hydrology. To achieve these objectives, we introduce the "LPJ-hydrology" (LH) model which incorporates satellite-based data into the Lund-Potsdam-Jena (LPJ) DGVM. To evaluate the model we ran LH using historical (1981–2006) climate data and satellite-based land covers at 2.5 arc-min grid cells for the conterminous US and for the entire world using coarser climate and land cover data. We evaluated the simulated ET, soil moisture, and surface runoff using a set of observed or simulated data at different spatial scales. Our results demonstrate that spatial patterns of LH-simulated annual ET and surface runoff are in accordance with previously published data for the US; LH-modeled monthly stream flow for 12 major rivers in the US was consistent with observed values respectively during the years 1981–2006 (R2 > 0.46, p < 0.01; Nash-Sutcliffe Coefficient > 0.52). The modeled mean annual discharges for 10 major rivers worldwide also agreed well (differences < 15%) with observed values for these rivers. Compared to a degree-day method for snowmelt computation, the addition of the solar radiation effect on snowmelt enabled LH to better simulate monthly stream flow in winter and early spring for rivers located at mid-to-high latitudes. In addition, LH-modeled monthly soil moisture for the state of Illinois (US) agreed well (R2 = 0.79, p < 0.01) with observed data for the years 1984–2001. Overall, this study justifies both the feasibility of incorporating satellite-based land covers into a DGVM and the reliability of LH to simulate land-surface water balances. To better estimate surface/river runoff at mid-to-high latitudes, we recommended that LPJ-DGVM considers the effects of solar radiation on snowmelt.

scholarly journals Modifying a dynamic global vegetation model for simulating large spatial scale land surface water balance

2012 ◽  
Vol 9 (1) ◽  
pp. 1207-1249 ◽  
Author(s):  
G. Tang ◽  
P. J. Bartlein
Keyword(s):  
Soil Moisture ◽  
Surface Water ◽  
Water Balance ◽  
Spatial Scale ◽  
Surface Runoff ◽  
Land Surface ◽  
Large Spatial Scale ◽  
Land Surface Water ◽  
The Us ◽  
Land Covers

Abstract. Water balance models of simple structure are easier to grasp and more clearly connect cause and effect than models of complex structure. Such models are essential for studying large spatial scale land surface water balance in the context of climate and land cover change, both natural and anthropogenic. This study aims to (i) develop a large spatial scale water balance model by modifying a dynamic global vegetation model (DGVM), and (ii) test the model's performance in simulating actual evapotranspiration (ET), soil moisture and surface runoff for the coterminous United States (US). Toward these ends, we first introduced development of the "LPJ-Hydrology" (LH) model by incorporating satellite-based land covers into the Lund-Potsdam-Jena (LPJ) DGVM instead of dynamically simulating them. We then ran LH using historical (1982–2006) climate data and satellite-based land covers at 2.5 arc-min grid cells. The simulated ET, soil moisture and surface runoff were compared to existing sets of observed or simulated data for the US. The results indicated that LH captures well the variation of monthly actual ET (R2 = 0.61, p < 0.01) in the Everglades of Florida over the years 1996–2001. The modeled monthly soil moisture for Illinois of the US agrees well (R2 = 0.79, p < 0.01) with the observed over the years 1984–2001. The modeled monthly stream flow for most 12 major rivers in the US is consistent R2 > 0.46, p < 0.01; Nash-Sutcliffe Coefficients >0.52) with observed values over the years 1982–2006, respectively. The modeled spatial patterns of annual ET and surface runoff are in accordance with previously published data. Compared to its predecessor, LH simulates better monthly stream flow in winter and early spring by incorporating effects of solar radiation on snowmelt. Overall, this study proves the feasibility of incorporating satellite-based land-covers into a DGVM for simulating large spatial scale land surface water balance. LH developed in this study should be a useful tool for studying effects of climate and land cover change on land surface hydrology at large spatial scales.

HAPEX—MOBILHY: A Hydrologic Atmospheric Experiment the Study of Water Budget and Evaporation Flux at the Climatic Scale

1986 ◽  
Vol 67 (2) ◽  
pp. 138-144 ◽  
Author(s):  
Jean-Claude André ◽  
Jean-Paul Goutorbe ◽  
Alain Perrier
Keyword(s):  
Remote Sensing ◽  
Soil Moisture ◽  
Land Surface ◽  
Water Budget ◽  
General Circulation ◽  
Circulation Model ◽  
Surface Energy Budget ◽  
Surface Hydrology ◽  
Land Surface Water ◽  
Evaporation Flux

The HAPEX-MOBILHY program is aimed at studying the hydrological budget and evaporation flux at the scale of a GCM (general circulation model) grid square, i.e., 104 km2. Different surface and subsurface networks will be operated during the year 1986, to measure and monitor soil moisture, surface-energy budget and surface hydrology, as well as atmospheric properties. A two-and-a-half-month special observing period will allow for detailed measurements of atmospheric fluxes and for intensive remote sensing of surface properties using well-instrumented aircraft. The main objective of the program, for which guest investigations are strongly encouraged, is to provide a data base against which parameterization schemes for the land-surface water budget will be tested and developed.

Understanding the Distinct Impacts of MCS and Non-MCS Rainfall on the Surface Water Balance in the Central United States Using a Numerical Water-Tagging Technique

2020 ◽  
Vol 21 (10) ◽  
pp. 2343-2357
Author(s):  
Huancui Hu ◽  
L. Ruby Leung ◽  
Zhe Feng
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Surface Water ◽  
Water Balance ◽  
Surface Runoff ◽  
Land Surface ◽  
Warm Season ◽  
Surface Model ◽  
Central United States ◽  
Infiltration Excess

ABSTRACTWarm-season rainfall associated with mesoscale convective systems (MCSs) in the central United States is characterized by higher intensity and nocturnal timing compared to rainfall from non-MCS systems, suggesting their potentially different footprints on the land surface. To differentiate the impacts of MCS and non-MCS rainfall on the surface water balance, a water tracer tool embedded in the Noah land surface model with multiparameterization options (WT-Noah-MP) is used to numerically “tag” water from MCS and non-MCS rainfall separately during April–August (1997–2018) and track their transit in the terrestrial system. From the water-tagging results, over 50% of warm-season rainfall leaves the surface–subsurface system through evapotranspiration by the end of August, but non-MCS rainfall contributes a larger fraction. However, MCS rainfall plays a more important role in generating surface runoff. These differences are mostly attributed to the rainfall intensity differences. The higher-intensity MCS rainfall tends to produce more surface runoff through infiltration excess flow and drives a deeper penetration of the rainwater into the soil. Over 70% of the top 10th percentile runoff is contributed by MCS rainfall, demonstrating its important contribution to local flooding. In contrast, lower-intensity non-MCS rainfall resides mostly in the top layer and contributes more to evapotranspiration through soil evaporation. Diurnal timing of rainfall has negligible effects on the flux partitioning for both MCS and non-MCS rainfall. Differences in soil moisture profiles for MCS and non-MCS rainfall and the resultant evapotranspiration suggest differences in their roles in soil moisture–precipitation feedbacks and ecohydrology.

Time Scales of Land Surface Hydrology

2006 ◽  
Vol 7 (5) ◽  
pp. 868-879 ◽  
Author(s):  
Aihui Wang ◽  
Xubin Zeng ◽  
Samuel S. P. Shen ◽  
Qing-Cun Zeng ◽  
Robert E. Dickinson
Keyword(s):  
Soil Moisture ◽  
Time Scales ◽  
Time Scale ◽  
Land Surface ◽  
Vertical Structure ◽  
Root Zone ◽  
Layer Model ◽  
Surface Hydrology ◽  
Soil System ◽  
Land Surface Hydrology

Abstract This paper intends to investigate the time scales of land surface hydrology and enhance the understanding of the hydrological cycle between the atmosphere, vegetation, and soil. A three-layer model for land surface hydrology is developed to study the temporal variation and vertical structure of water reservoirs in the vegetation–soil system in response to precipitation forcing. The model is an extension of the existing one-layer bucket model. A new time scale is derived, and it better represents the response time scale of soil moisture in the root zone than the previously derived inherent time scale (i.e., the ratio of the field capacity to the potential evaporation). It is found that different water reservoirs of the vegetation–soil system have different time scales. Precipitation forcing is mainly concentrated on short time scales with small low-frequency components, but it can cause long time-scale disturbances in the soil moisture of root zone. This time scale increases with soil depth, but it can be reduced significantly under wetter conditions. Although the time scale of total water content in the vertical column in the three-layer model is similar to that of the one-layer bucket model, the time scale of evapotranspiration is very different. This suggests the need to consider the vertical structure in land surface hydrology reservoirs and in climate study.

Remote sensing: hydrology

2009 ◽  
Vol 33 (4) ◽  
pp. 490-509 ◽  
Author(s):  
Qiuhong Tang ◽  
Huilin Gao ◽  
Hui Lu ◽  
Dennis P. Lettenmaier
Keyword(s):  
Remote Sensing ◽  
Surface Water ◽  
Land Surface ◽  
Water Budget ◽  
Current Status ◽  
State Variables ◽  
Surface Hydrology ◽  
Earth Observing System ◽  
Land Surface Water ◽  
Terrestrial Water

Satellite remote sensing is a viable source of observations of land surface hydrologic fluxes and state variables, particularly in regions where in situ networks are sparse. Over the last 10 years, the study of land surface hydrology using remote sensing techniques has advanced greatly with the launch of NASA’s Earth Observing System (EOS) and other research satellite platforms, and with the development of more sophisticated retrieval algorithms. Most of the constituent variables in the land surface water balance (eg, precipitation, evapotranspiration, snow and ice, soil moisture, and terrestrial water storage variations) are now observable at varying spatial and temporal resolutions and accuracy via remote sensing. We evaluate the current status of estimates of each of these variables, as well as river discharge, the direct estimation of which is not yet possible. Although most of the constituent variables are observable by remote sensing, attempts to close the surface water budget from remote sensing alone have generally been unsuccessful, suggesting that current generation sensors and platforms are not yet able to provide hydrologically consistent observations of the land surface water budget at any spatial scale.

scholarly journals Variability of phenology and fluxes of water and carbon with observed and simulated soil moisture in the Ent Terrestrial Biosphere Model (Ent TBM version 1.0.1.0.0)

2015 ◽  
Vol 8 (12) ◽  
pp. 3837-3865 ◽  
Author(s):  
Y. Kim ◽  
P. R. Moorcroft ◽  
I. Aleinov ◽  
M. J. Puma ◽  
N. Y. Kiang
Keyword(s):  
Soil Moisture ◽  
Leaf Area ◽  
Land Surface ◽  
Surface Hydrology ◽  
Terrestrial Biosphere ◽  
Dynamic Global Vegetation Model ◽  
Area Index ◽  
Frost Hardening ◽  
Land Surface Hydrology ◽  
Biosphere Model

Abstract. The Ent Terrestrial Biosphere Model (Ent TBM) is a mixed-canopy dynamic global vegetation model developed specifically for coupling with land surface hydrology and general circulation models (GCMs). This study describes the leaf phenology submodel implemented in the Ent TBM version 1.0.1.0.0 coupled to the carbon allocation scheme of the Ecosystem Demography (ED) model. The phenology submodel adopts a combination of responses to temperature (growing degree days and frost hardening), soil moisture (linearity of stress with relative saturation) and radiation (light length). Growth of leaves, sapwood, fine roots, stem wood and coarse roots is updated on a daily basis. We evaluate the performance in reproducing observed leaf seasonal growth as well as water and carbon fluxes for four plant functional types at five Fluxnet sites, with both observed and prognostic hydrology, and observed and prognostic seasonal leaf area index. The phenology submodel is able to capture the timing and magnitude of leaf-out and senescence for temperate broadleaf deciduous forest (Harvard Forest and Morgan–Monroe State Forest, US), C3 annual grassland (Vaira Ranch, US) and California oak savanna (Tonzi Ranch, US). For evergreen needleleaf forest (Hyytiäla, Finland), the phenology submodel captures the effect of frost hardening of photosynthetic capacity on seasonal fluxes and leaf area. We address the importance of customizing parameter sets of vegetation soil moisture stress response to the particular land surface hydrology scheme. We identify model deficiencies that reveal important dynamics and parameter needs.

scholarly journals Variability of phenology and fluxes of water and carbon with observed and simulated soil moisture in the Ent Terrestrial Biosphere Model (Ent TBM version 1.0.1.0.0)

2015 ◽  
Vol 8 (7) ◽  
pp. 5809-5871 ◽  
Author(s):  
Y. Kim ◽  
P. R. Moorcroft ◽  
I. Aleinov ◽  
M. J. Puma ◽  
N. Y. Kiang
Keyword(s):  
Soil Moisture ◽  
Leaf Area ◽  
Land Surface ◽  
Surface Hydrology ◽  
Terrestrial Biosphere ◽  
Dynamic Global Vegetation Model ◽  
Area Index ◽  
Frost Hardening ◽  
Land Surface Hydrology ◽  
Biosphere Model

Abstract. The Ent Terrestrial Biosphere Model (Ent TBM) is a mixed-canopy dynamic global vegetation model developed specifically for coupling with land surface hydrology and general circulation models (GCMs). This study describes the leaf phenology submodel implemented in the Ent TBM version 1.0.1.0.0, coupled to the carbon allocation scheme of the Ecosystem Demography (ED) model. The phenology submodel adopts a combination of responses to temperature (growing degree days and frost-hardening), soil moisture (linearity of stress with relative saturation), and radiation (light length). Growth of leaves, sapwood, fine roots, stem wood, and coarse roots is updated on a daily basis. We evaluate the performance in reproducing observed leaf seasonal growth as well as water and carbon fluxes for four plant functional types at five Fluxnet sites, with both observed and prognostic hydrology, and observed and prognostic seasonal leaf area index. The phenology submodel is able to capture the timing and magnitude of leafout and senescence for temperate broadleaf deciduous forest (Harvard Forest and Morgan–Monroe State Forest, US), C3 annual grassland (Vaira Ranch, US), and California oak savanna (Tonzi Ranch, US). For evergreen needleleaf forest (Hyytiäla, Finland), the phenology submodel captures the effect of frost-hardening of photosynthetic capacity on seasonal fluxes and leaf area. We address the importance of customizing parameter sets of vegetation soil moisture stress response to the particular land surface hydrology scheme. We identify model deficiencies that reveal important dynamics and parameter needs.

Exploring the effects of the land surface on tropical precipitation

2021 ◽  
Author(s):  
Marianne Pietschnig ◽  
Abigail L. S. Swann ◽  
Ruth Geen ◽  
F. Hugo Lambert ◽  
Geoffrey K. Vallis
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Amazon Basin ◽  
Earth System ◽  
Maritime Continent ◽  
Surface Hydrology ◽  
System Models ◽  
Tropical Precipitation ◽  
Land Surface Hydrology ◽  
Earth System Models

&lt;p&gt;Projected precipitation changes over tropical land tend to be enhanced by vegetation responses to CO&lt;sub&gt;2&lt;/sub&gt; forcing in Earth System Models. Projected decreases in rainfall over the Amazon basin and increases over the Maritime Continent are both stronger when plant physiological changes are modelled than if these changes are neglected, but the reasons for this amplification remain unclear. The responses of vegetation to increasing CO&lt;sub&gt;2 &lt;/sub&gt;levels are complex and uncertain, but changes in stomatal conductance likely dominate the evapotranspiration response in Earth System Models.&lt;/p&gt;&lt;p&gt;We investigate why vegetation changes cause precipitation to increase more strongly over the Maritime Continent while decreasing more strongly over the Amazon basin. We employ an idealized Atmospheric General Circulation Model with a simplified vegetation scheme that captures CO&lt;sub&gt;2&lt;/sub&gt;-driven stomatal closure.&lt;/p&gt;&lt;p&gt;We find that &amp;#8211; counter-intuitively &amp;#8211; rainfall is enhanced over a narrow rectangular island when terrestrial evaporation falls to zero with high CO&lt;sub&gt;2&lt;/sub&gt;. Strong heating and ascent over the island trigger moisture advection from the surrounding ocean. In contrast, over larger continents rainfall depends on continental moisture recycling.&lt;/p&gt;&lt;p&gt;Simulations with two large rectangular continents representing South America and Africa reveal that the stronger decrease in rainfall over the Amazon basin is due to a combination of local and remote effects:&lt;/p&gt;&lt;p&gt;Finally, we investigate the impact of land-surface hydrology on continental rainfall on seasonal timescales. Using our idealized model and realistic continents, we study the strength of the South East Asian monsoon for different continental evaporation schemes. Surprisingly, when terrestrial evapotranspiration is unlimited (i.e. does not depend on soil moisture availability), monsoon precipitation is much weaker than when terrestrial evapotranspiration is limited by soil moisture. In order to explain this behavior, we compare the atmospheric energy budgets and circulation between the simulations.&lt;/p&gt;&lt;p&gt;Our results show that the land-surface hydrology plays an important role in modifying tropical precipitation and atmospheric dynamics on seasonal timescales and in the long-term under climate change, and that further investigation into the topic is called for.&lt;/p&gt;

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