نتایج جستجو برای: soil moisture
تعداد نتایج: 205538 فیلتر نتایج به سال:
Soil moisture is one of the most important climatic parameters playing an important role in the global climate system. Soil moisture can be derived from in-situ measurements as well as remotely sensed observations. However, these measurements typically lack the spatial and/or temporal resolutions necessary for modeling and applications. Land surface models (LSM) can be used to simulate the land...
This paper reports a study of algorithm development and testing for soil moisture retrieval for bare fields using L-band SAR imagery. First-order surface scattering models predict that the co-polarization ratio is sensitive to soil moisture but not to surface roughness. Our previous study indicated that the measurement of (Jvv / (Jhh at L-band is proportional to soil moisture. In this study, th...
The carbon isotopic composition (delta(13)C) of recently assimilated plant carbon is known to depend on water-stress, caused either by low soil moisture or by low atmospheric humidity. Air humidity has also been shown to correlate with the delta(13)C of soil respiration, which suggests indirectly that recently fixed photosynthates comprise a substantial component of substrates consumed by soil ...
Land aridity has been projected to increase with global warming. Such projections are mostly based on off-line aridity and drought metrics applied to climate model outputs but also are supported by climate-model projections of decreased surface soil moisture. Here we comprehensively analyze soil moisture projections from the Coupled Model Intercomparison Project phase 5, including surface, tota...
Land surface model validation at distributed scales is important for model improvements. Recent advances in satellite technology provide an opportunity for distributed calibration and validation of land surface models. In the past years, a number of active and passive microwave soil moisture products have become available. While passive microwave soil moisture is the preferred approach for soil...
Radar-based surface soil moisture retrieval has been subject of intense research during the last decades. However, several difficulties hamper the operational estimation of soil moisture based on currently available spaceborne sensors. The main difficulty experienced so far results from the strong influence of other surface characteristics, mainly roughness, on the backscattering coefficient, w...
The high spatio-temporal variability of soil moisture is the result of atmosphericforcing and redistribution processes related to terrain, soil, and vegetation characteristics.Despite this high variability, many field studies have shown that in the temporal domainsoil moisture measured at specific locations is correlated to the mean soil moisture contentover an area. Since the measurements take...
Soil moisture is a critical hydrological variable that links the terrestrial water, energy and carbon cycles. Global and regional observations of soil moisture are needed to estimate the water and energy fluxes at the land surface, to quantify the net carbon flux in boreal landscapes, to enhance weather and climate forecast skill and to develop improved flood prediction and drought monitoring c...
For more than a decade, the European Centre for Medium-Range Weather Forecasts (ECMWF) has used in-situ observations of 2 m temperature and 2 m relative humidity to operationally constrain the temporal evolution of model soil moisture. These observations are not available everywhere and they are indirectly linked to the state of the surface, so under various circumstances, such as weak radiativ...
Recent studies [Bourgeau-Chavez, L.L., Kasischke, E.S., Riordan, K., Brunzell, S.M., Nolan, M., Hyer, E.J., Slawski, J.J., Medvecz, M., Walters, T., and Ames, S. (in press). Remote monitoring of spatial and temporal surface soil moisture in fire disturbed boreal forest ecosystems with ERS SAR imagery. Int. J. Rem. Sens.] demonstrated that ERS SAR imagery can be used to estimate surface soil moi...
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