Analysis of detailed in-situ soil measurements with ERS C-band radar backscattering data

2003 ◽  
Author(s):  
M. Borgeaud ◽  
M. Davidson ◽  
E. Attema ◽  
J. Louis ◽  
L. Dente ◽  
...  
Keyword(s):  
Radar Backscattering ◽  
Soil Measurements

Sensing the physical and nutritional status of the root environment in the field: a review of progress and opportunities

2005 ◽  
Vol 143 (5) ◽  
pp. 347-358 ◽  
Author(s):  
L. J. CLARK ◽  
D. J. G. GOWING ◽  
R. M. LARK ◽  
P. B. LEEDS-HARRISON ◽  
A. J. MILLER ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Crop Management ◽  
Soil Conditions ◽  
Plant Responses ◽  
Soil Environment ◽  
Soil Factors ◽  
Remote Sensors ◽  
Soil Measurements ◽  
New Strategies

The challenge that faces agriculture at the start of the 21st Century is to provide security of food production in a sustainable way. Achieving this task is difficult enough, but against a background of climate change, it becomes a moving target. However, one certainty is that soil factors that limit crop growth must be taken into account as new strategies for crop management are developed. To achieve this, it is necessary to measure the physical and nutritional status of the root environment in the field. Before considering measurement methods, our understanding of how the plant interacts with its soil environment is reviewed, so that it is clear what needs to be measured. Soil strength due to soil drying is identified as an important stress that limits agricultural productivity. The scope to measure soil factors that directly affect plant growth is reviewed. While in situ sensors are better developed, progress in the development of remote sensors of soil properties are also reviewed. A robust approach is needed to interpret soil measurements at the field scale and here geostatistics has much to offer. The present review takes a forward look and explores how our understanding of plant responses to soil conditions, the newly emerging sensing technologies and geostatistical tools can be drawn together to develop robust tools for soil and crop management. This is not intended to be an exhaustive review. Instead, the authors focus on those aspects that they consider to be most important and where the greatest progress is being made.

Using in situ soil measurements for analysis of a polarimetric SAR-based classification of levee slump slides in the Lower Mississippi River

2014 ◽  
Vol 181 ◽  
pp. 157-168 ◽  
Author(s):  
Sona Sehat ◽  
Farshid Vahedifard ◽  
James V. Aanstoos ◽  
Lalitha Dabbiru ◽  
Khaled Hasan
Keyword(s):  
Mississippi River ◽  
Polarimetric Sar ◽  
Lower Mississippi River ◽  
Soil Measurements

scholarly journals Methane and carbon dioxide emissions from different ecosystems at the end of dry period in South Vietnam

2020 ◽  
Author(s):  
Jiří Dušek ◽  
Vinh Xuan Nguyen ◽  
Thuyen Xuan Le ◽  
Marian Pavelka
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Emissions ◽  
Rain Forest ◽  
Large Variability ◽  
Aerobic Activity ◽  
South Vietnam ◽  
Gas Fluxes ◽  
Soil Measurements ◽  
Chamber Measurements

Abstract The carbon cycle includes important fluxes of methane (CH4) and carbon dioxide (CO2) between the ecosystem and the atmosphere. The fluxes may acquire either positive (release) or negative values (consumption). We calculated these fluxes based on short-campaign in situ chamber measurements from four ecosystems of South Vietnam: intact mountain rain forest, rice field, Melaleuca forest and mangroves (different sites with Avicennia or Rhizophora and a typhoon-disturbed gap). Soil measurements were supplemented by chamber measurements of gas fluxes from the tree stems. Measuring CH4 and CO2 together facilitates the assessment of the ratio between these two gases in connection with current conditions and specificity of individual ecosystems. The highest fluxes of CH4 were recorded in the Melaleuca forest, being within the range from 356.7 to 784.2 mg CH4–C m−2 day−1 accompanied by higher fluxes of CH4 release from Melaleuca tree stems (8.0–262.1 mg CH4–C m−2 day−1). Significant negative soil fluxes of CH4 were recorded in the mountain rain forest, within the range from − 0.3 to − 0.8 mg CH4–C m−2 day−1. Fluxes of CO2 indicate prevailing aerobic activity in the soils of the ecosystems investigated. Quite a large variability of CO2 fluxes was recorded in the soil of the Avicennia mangroves. The in situ measurements of different ecosystems are fundamental for follow-up measurements at different levels such as aerial and satellite gas fluxes observations.

scholarly journals Potential of Sentinel-1 Data for Monitoring Temperate Mixed Forest Phenology

2018 ◽  
Vol 10 (12) ◽  
pp. 2049 ◽  
Author(s):  
Pierre-Louis Frison ◽  
Bénédicte Fruneau ◽  
Syrine Kmiha ◽  
Kamel Soudani ◽  
Eric Dufrêne ◽  
...  
Keyword(s):  
Significant Contribution ◽  
Temporal Frequency ◽  
Mixed Forest ◽  
Optical Data ◽  
Landsat 8 ◽  
Radar Backscattering ◽  
Electromagnetic Models ◽  
Land Surfaces ◽  
Near Future

In this study, the potential of Sentinel-1 data to seasonally monitor temperate forests was investigated by analyzing radar signatures observed from plots in the Fontainebleau Forest of the Ile de France region, France, for the period extending from March 2015 to January 2016. Radar backscattering coefficients, σ0 and the amplitude of temporal interferometric coherence profiles in relation to environmental variables are shown, such as in situ precipitation and air temperature. The high temporal frequency of Sentinel-1 acquisitions (i.e., twelve days, or six, if both Sentinel-1A and B are combined over Europe) and the dual polarization configuration (VV and VH over most land surfaces) made a significant contribution. In particular, the radar backscattering coefficient ratio of VV to VH polarization, σVV0/σVH0, showed a well-pronounced seasonality that was correlated with vegetation phenology, as confirmed in comparison to NDVI profiles derived from Landsat-8 (r=0.77) over stands of deciduous trees. These results illustrate the high potential of Sentinel-1 data for monitoring vegetation, and as these data are not sensitive to the atmosphere, the phenology could be estimated with more accuracy than optical data. These observations will be quantitatively analyzed with the use of electromagnetic models in the near future.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

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