نتایج جستجو برای: soil moisture

تعداد نتایج: 205538  

2015
Kozue Yuge Kunihiko Hamagami Mitsumasa Anan Kosuke Hamada

The objective of this study was to evaluate the effect of soil moisture condition and irrigation regime on the bioelectric potential of crops with different growth stages. The bioelectric potential of broccoli (Brassica oleracea var. italica) plants at the initial and mid-growth stages was measured under different soil moisture conditions and irrigation regimes using pot experiments. The result...

2010
E. De Keyser H. Lievens H. Vernieuwe J. Álvarez-Mozos B. De Baets

Soil moisture retrieval from SAR images using semi-empirical or physically-based backscatter models requires surface roughness parameters, generally obtained by means of in situ measurements. However, measured roughness parameters often result in inaccurate soil moisture contents. Furthermore, when these retrieved soil moisture contents need to be used in data assimilation schemes, it is import...

2006
J. Parajka V. Naeimi K. Scipal

This paper examines the potential of scatterometer data from ERS satellites for improving hydrological simulations in both gauged and ungauged catchments. We compare the soil moisture dynamics simulated by a semidistributed hydrologic model in 320 Austrian catchments with the soil moisture dynamics inferred from the satellite data. The most apparent differences occur in the Alpine areas. Assimi...

2007
A. J. Teuling R. Uijlenhoet R. Hurkmans O. Merlin R. Panciera J. P. Walker P. A. Troch

[1] Characterization of the space-time variability of soil moisture is important for land surface and climate studies. Here we develop an analytical model to investigate how, at the dry-end of the soil moisture range, the main characteristics of the soil moisture field (spatial mean and variability, steady state distribution) depend on the intermittent character of low intensity rain storms. Ou...

2004
Jeffrey P. Walker Garry R. Willgoose Jetse D. Kalma

A number of automated techniques for point measurement of soil moisture content have been developed to an operational level over the past few decades. While each of those techniques have been individually evaluated by the thermogravimetric (oven drying and weighing) method, typically under laboratory conditions, there have been few studies which have made a direct comparison between the various...

2011
W. Dorigo A. Gruber P. Van Oevelen W. Wagner A. Robock

In situ soil moisture measurements are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. On a worldwide basis the number of meteorological networks measuring soil moisture is still limited and their data lack standardization of technique and protocol. In response to this, the International Soil Moisture Network (ISMN) was initiated to se...

2007
P. J. Steinle

Soil moisture is an important control over atmospheric evolution, since it controls the partition of incoming radiation into latent and sensible heating. To accurately model these land surface fluxes, atmospheric models must ultimately have accurate soil moisture fields. Yet soil moisture is typically initialised indirectly in Numerical Weather Prediction (NWP) models, frequently resulting in u...

2014
C. J. Smith A. Hawdon R. Keen J. Wallace

Field measurement of soil moisture is undertaken traditionally using point based measurement techniques such as neutron probes or time domain reflectrometry (TDR). Recently, a new technique has been developed that can be used to derive soil moisture at larger spatial scales by measuring neutrons that are generated by cosmic rays within the air and soil, and emitted back into the atmosphere. A ...

2009
J. P. Walker

The upcoming Soil Moisture and Ocean Salinity (SMOS) mission of the European Space Agency will be the first satellite dedicated to the measurement of soil moisture. It will measure soil moisture for the top 5 cm at a spatial resolution of 35 to 50 km. Comparison of the soil moisture data from SMOS with insitu monitoring network measurements across areas the size of a SMOS footprint will play a ...

2012
N. Baghdadi

The purpose of this study was to develop an approach to estimate soil surface parameters from C-band polarimetric SAR data in the case of bare agricultural soils. An inversion technique based on multi-layer perceptron (MLP) neural networks was introduced. The neural networks were trained and validated on a noisy simulated dataset generated from the Integral Equation Model (IEM) on a wide range ...

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