Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 26 for “"land surface models"”.
-
Quantifying the Sensitivity of Land-Surface Models to Hydrodynamic Stress Limitations on Transpiration
… heat flux and carbon uptake rates. Current land-surface models couple stomata conductance and soil moisture through empirical relationships. This approach does not take advantage of recent advances in our understanding of water flow and storage in trees or of tree and canopy structure. The …
-
A multi-criteria evaluation of land-surface models and application to semi-arid regions
… errors and that several parameters in the models are insensitive regardless of the input data (i.e., vegetation type). To better understand SVATS performance in semi-arid regions, and to evaluate the various impacts of data on the parameter estimation problem, an intensive calibration and …
-
Trading water for carbon in a changing climate: can optimality theory improve the predictability of land surface models?
… future risk remains a challenge because climate models demonstrate systematic errors in predicting plant function when resources become limiting (e.g., water). To improve predictions of ecosystem resilience, major model weaknesses in the formulation of plant responses to climatic stress must be …
-
The role of rooting strategies on the eco-hydrology of semi-arid regions
… can be critical to their survival. However, land surface models currently prescribe rooting profiles as a function of only the plant functional type of interest with no consideration for the soil texture or rainfall regime of the region being modeled. Additionally, these models do not …
-
On the predictability of land surface fluxes
The land surface is a key component in the earth’s climate system, and is one of the main contributors to uncertainty in climate projections. Fluxes of energy, momentum, water and carbon between the land surface and the atmosphere provide important feedbacks in the climate system. Land surface …
-
Improving parameterization of scalar transport through vegetation in a coupled ecosystem-atmosphere model
Several regional-scale ecosystem models currently parameterize subcanopy scalar transport using a rough-wall boundary eddy diffusivity formulation. This formulation predicts unreasonably high soil evaporation beneath tall, dense forests and low soil evaporation beneath short, sparse grass. This …
-
Estimating evapotranspiration from the Amazon Basin using the atmospheric water balance
… in modeling trees' access to deep soil moisture, land surface models cannot provide reliable estimates of transpiration in the region. From a basin-averaged perspective, it remains uncertain whether transpiration is water-limited, peaking during the basin's wet season, or energy-limited, peaking …
-
Use of global datasets for downscaling soil moisture with the EMT+VS model
Satellite remote sensing and land-surface models provide coarse-resolution (9-40 km) soil moisture estimates, but various applications require fine-resolution (10-30 m) soil moisture patterns. The Equilibrium Moisture from Topography, Vegetation, and Soil (EMT+VS) model downscales soil moisture …
-
Deep-Layer Terrestrial Hydrologic Memory and Mechanisms of Its Influence on the Eco-Climatology of the Biosphere
… of the terrestrial memory is limited to the near-surface soil, and the role of deep-soil reservoir is unknown or has simply been neglected. Observational evidence shows the existence of plant roots much deeper in the soil/rock profile than the depth usually incorporated in existing land surface …
-
Evaluation and Application of the Community Land Model for Simulating Energy and Carbon Exchange in Agricultural Ecosystems
Land surface models (LSMs) serve as important tools for studying the interactions between the atmosphere and ecosystems, understanding biophysical feedback processes, and predicting future climate. Most state-of-the-art LSMs assessed in the fifth phase of the Coupled Model Inter-comparison project …
-
Estimating Soil Moisture and Energy Fluxes Using Assimilation of Remotely Sensed Land Surface State Variables
Soil moisture plays a critical role in the land-atmosphere interactions. Given the approximate model physics representation in the land surface models predicting these fluxes, better predictions can be obtained by assimilating hydrologically relevant remotely sensed data into the predictive models. …
-
Soil moisture dynamics from satellite observations, land surface modeling, and field data
… were well maintained for root zone profile and surface soil moisture time stable characteristics can be used to upper boundary for sub-surface time stability.</p><p>Through inter-comparison analysis, average soil moisture from remotely sensed measurements, ground-based measurements, and land …
-
Characterization of the spatial and temporal variability in pan-Arctic, terrestrial hydrology
… The studies described here focus on quantitative models and methods for predicting the spatial and temporal variability in pan-Arctic hydrology.</p><p>This dissertation discusses pan-Arctic water budgets drawn from a hydrological model which is appropriate for applications across the terrestrial …
-
Exploration of a geometric approach for estimating snow surface roughness
The roughness of a surface that influences atmospheric turbulence is estimated as the aerodynamic roughness length (Z0), and is used to understand the flow of air, temperature, and moisture over a surface. Z0 is a critical variable for estimating latent and sensible fluxes at the surface, but most …
-
Drought tolerance and implications for vegetation-climate interactions in the Amazon forest
… and tree mortality. The majority of climate models predict decreased rainfall in tropical South America over this century. Until recently, land surface models have not included mechanisms of forest resistance to seasonal drought. In some coupled climate models, the inability of tropical …
-
Modeling the impact of land surface feedbacks on post landfall tropical cyclones
<p>The land surface is an important component of numerical models. The land surface models are modules that control energy partitioning, compute surface exchange coefficients and form the only physical boundary in a regional scale numerical model. Thus, an accurate representation of land surface is …
-
Characterizing uncertainty for regional carbon cycle modeling
… from natural processes, disturbance of the land surface and fossil fuel combustion, and the magnitude of accumulated CO2 in the atmosphere as measured by the global flask network indicates that there must be a terrestrial and/or oceanic repository for the unaccounted carbon. The imbalance in …
-
Terrestrial Water Storage Change Over Dryland Regions Using Observational Data and Model Simulations
Drylands occupy a large fraction of global terrestrial areas and are home to around 2.5 billion people. Dryland ecosystems are important constituents of global biodiversity and impact the global carbon cycle. However, drylands typically experience water shortages due to unbalanced atmospheric water …
-
Eddy-covariance measurements as a tool for ecological and hydrological studies on the Tibetan Plateau
… flux measurements were conducted over a lake surface in the same basin. Furthermore, these flux measurements were used to adapt and validate land-surface models to be applied on the TP. Within the experiments a special focus were measurements of latent heat flux during winter conditions on the …
Page 1 of 2