scholarly journals Elevation change of Fedchenko Glacier, Pamir Mountains, from GNSS field measurements and TanDEM-X elevation models, with a focus on the upper glacier

2018 ◽  
Vol 64 (246) ◽  
pp. 637-648 ◽  
Author(s):  
A. LAMBRECHT ◽  
C. MAYER ◽  
A. WENDT ◽  
D. FLORICIOIU ◽  
C. VÖLKSEN
Keyword(s):  
Field Measurements ◽  
Global Navigation Satellite Systems ◽  
High Accumulation ◽  
Glacier Surface ◽  
Mean Values ◽  
Satellite Systems ◽  
Pamir Mountains ◽  
Elevation Changes ◽  
Global Navigation Satellite ◽  
Radar Wave

ABSTRACTFedchenko Glacier experienced a large thickness loss since the first scientific investigations in 1928. As the largest glacier in the Pamir Mountains, this glacier plays an important role for the regional glacier mass budget. We use a series of Global Navigation Satellite Systems observations from 2009 to 2016 and TanDEM-X elevation models from 2011 to 2016 to investigate recent elevation changes. Accounting for radar wave penetration minimizes biases in elevation that can otherwise reach up to 6 m in dry snow on Fedchenko Glacier, with mean values of 3–4 m in the high accumulation regions. The seasonal elevation changes reach up to ±5 m. The glacier surface elevation decreased along its entire length over multi-year periods. Thinning rates increased between 2000 and 2016 by a factor of 1.8 compared with 1928–2000, resulting in peak values of 1.5 m a−1. Even the highest accumulation basins above 5000 m elevation have been affected by glacier thinning with change rates between −0.2 and −0.4 m a−1 from 2009 to 2016. The estimated glacier-wide mass-balance rates are −0.27 ± 0.05 m w.e. a−1 for 2000 to 2011 and −0.51 ± 0.04 m w.e. a−1 between 2011 and 2016.

scholarly journals NEW MICROWAVE-BASED MISSIONS APPLICATIONS FOR RAINFED CROPS CHARACTERIZATION

2016 ◽  
Vol XLI-B1 ◽  
pp. 101-107
Author(s):  
N. Sánchez ◽  
J. M. Lopez-Sanchez ◽  
B. Arias-Pérez ◽  
R. Valcarce-Diñeiro ◽  
J. Martínez-Fernández ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Field Measurements ◽  
Global Navigation Satellite Systems ◽  
Radar Signal ◽  
Landsat 8 ◽  
Area Index ◽  
Satellite Systems ◽  
Crop Parameters ◽  
Global Navigation Satellite

A multi-temporal/multi-sensor field experiment was conducted within the Soil Moisture Measurement Stations Network of the University of Salamanca (REMEDHUS) in Spain, in order to retrieve useful information from satellite Synthetic Aperture Radar (SAR) and upcoming Global Navigation Satellite Systems Reflectometry (GNSS-R) missions. The objective of the experiment was first to identify which radar observables are most sensitive to the development of crops, and then to define which crop parameters the most affect the radar signal. A wide set of radar variables (backscattering coefficients and polarimetric indicators) acquired by Radarsat-2 were analyzed and then exploited to determine variables characterizing the crops. Field measurements were fortnightly taken at seven cereals plots between February and July, 2015. This work also tried to optimize the crop characterization through Landsat-8 estimations, testing and validating parameters such as the leaf area index, the fraction of vegetation cover and the vegetation water content, among others. Some of these parameters showed significant and relevant correlation with the Landsat-derived Normalized Difference Vegetation Index (R>0.60). Regarding the radar observables, the parameters the best characterized were biomass and height, which may be explored for inversion using SAR data as an input. Moreover, the differences in the correlations found for the different crops under study types suggested a way to a feasible classification of crops.

scholarly journals NEW MICROWAVE-BASED MISSIONS APPLICATIONS FOR RAINFED CROPS CHARACTERIZATION

2016 ◽  
Vol XLI-B1 ◽  
pp. 101-107
Author(s):  
N. Sánchez ◽  
J. M. Lopez-Sanchez ◽  
B. Arias-Pérez ◽  
R. Valcarce-Diñeiro ◽  
J. Martínez-Fernández ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Field Measurements ◽  
Global Navigation Satellite Systems ◽  
Radar Signal ◽  
Landsat 8 ◽  
Area Index ◽  
Satellite Systems ◽  
Crop Parameters ◽  
Global Navigation Satellite

A multi-temporal/multi-sensor field experiment was conducted within the Soil Moisture Measurement Stations Network of the University of Salamanca (REMEDHUS) in Spain, in order to retrieve useful information from satellite Synthetic Aperture Radar (SAR) and upcoming Global Navigation Satellite Systems Reflectometry (GNSS-R) missions. The objective of the experiment was first to identify which radar observables are most sensitive to the development of crops, and then to define which crop parameters the most affect the radar signal. A wide set of radar variables (backscattering coefficients and polarimetric indicators) acquired by Radarsat-2 were analyzed and then exploited to determine variables characterizing the crops. Field measurements were fortnightly taken at seven cereals plots between February and July, 2015. This work also tried to optimize the crop characterization through Landsat-8 estimations, testing and validating parameters such as the leaf area index, the fraction of vegetation cover and the vegetation water content, among others. Some of these parameters showed significant and relevant correlation with the Landsat-derived Normalized Difference Vegetation Index (R>0.60). Regarding the radar observables, the parameters the best characterized were biomass and height, which may be explored for inversion using SAR data as an input. Moreover, the differences in the correlations found for the different crops under study types suggested a way to a feasible classification of crops.

scholarly journals Spatial uncertainty of a geoid undulation model in Guayaquil, Ecuador

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
E.G. Chicaiza ◽  
C.A. Leiva ◽  
J.J. Arranz ◽  
X.E. Buenańo
Keyword(s):  
Estimation Error ◽  
Model Fitting ◽  
Field Measurements ◽  
Geoid Undulation ◽  
Spatial Uncertainty ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Estimation Uncertainty ◽  
Geostatistical Approach ◽  
Global Navigation Satellite

AbstractGeostatistics is a discipline that deals with the statistical analysis of regionalized variables. In this case study, geostatistics is used to estimate geoid undulation in the rural area of Guayaquil town in Ecuador. The geostatistical approach was chosen because the estimation error of prediction map is getting. Open source statistical software R and mainly geoR, gstat and RGeostats libraries were used. Exploratory data analysis (EDA), trend and structural analysis were carried out. An automatic model fitting by Iterative Least Squares and other fitting procedures were employed to fit the variogram. Finally, Kriging using gravity anomaly of Bouguer as external drift and Universal Kriging were used to get a detailed map of geoid undulation. The estimation uncertainty was reached in the interval [-0.5; +0.5] m for errors and a maximum estimation standard deviation of 2 mm in relation with the method of interpolation applied. The error distribution of the geoid undulation map obtained in this study provides a better result than Earth gravitational models publicly available for the study area according the comparison with independent validation points. The main goal of this paper is to confirm the feasibility to use geoid undulations from Global Navigation Satellite Systems and leveling field measurements and geostatistical techniques methods in order to use them in high-accuracy engineering projects.

Modelling of the reference STARs procedures in the context of RPAS integration in non-segregated airspace

2020 ◽  
Vol 92 (9) ◽  
pp. 1385-1392
Author(s):  
Daniel Lichoń
Keyword(s):  
Traffic Management ◽  
Design Guidelines ◽  
Global Navigation Satellite Systems ◽  
Civil Aviation ◽  
Very High Frequency ◽  
Content Type ◽  
Mean Values ◽  
Satellite Systems ◽  
Reference Shape ◽  
Global Navigation Satellite

Purpose This work presents the part of the research in the integration of the remotely piloted aircraft systems (RPAS) in non-segregated airspace. The purpose of this study is to elaborate the reference shape of the Standard Instrument Arrivals (STARs) procedures of controlled airports. The STARs parameters are unique for the aerodromes and depend on navigational aids (NAVAIDs), manoeuvres and aircraft categories. Therefore, the elaboration of reference shapes was advisable in the context of RPAS integration research. Design/methodology/approach The models were based on the procedure design guidelines by International Civil Aviation Organization. The statistics of existing STARs were prepared using Aeronautical Information Publications to determine the representative procedural parameters. Construction of procedural shapes required to define the nominal flight path and tolerance areas. Findings In statistics, the standard deviation of distances was below the determined reference mean values, thus the models were convergent with existing procedures. Research limitations/implications The modelling was limited to initial, intermediate, final and missed approach segments. Arrival segment was not modelled. NAVAIDs include Instrument Landing System Category 1 (in final and missed approach) and very high-frequency omni-directional ranging or global navigation satellite systems (in initial and intermediate approach segments). Practical implications Prepared models may be used in research in the integration of the new types of aerial vehicles in existing air traffic management systems. Originality/value The reference STARs possess commonly used procedural manoeuvres (straight-in, turn, racetrack and base turn) and different NAVAIDs. The parameters of approach segments were determined as representative of the existing procedures. Moreover, the models are suitable to place at arbitrary origin and runway axis bearing.

scholarly journals MULTISENSOR EXPERIMENTS OVER VINEYARD: NEW CHALLENGES FOR THE GNSS-R TECHNIQUE

2015 ◽  
Vol XL-7/W3 ◽  
pp. 1299-1303 ◽  
Author(s):  
N. Sánchez ◽  
A. Alonso-Arroyo ◽  
J. Martínez-Fernández ◽  
A. Camps ◽  
A. González-Zamora ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Field Measurements ◽  
Climatic Conditions ◽  
Global Navigation Satellite Systems ◽  
Landsat 8 ◽  
Spectral Measurements ◽  
Satellite Systems ◽  
Vegetation Parameters ◽  
Global Navigation Satellite ◽  
Different Sources

An airborne campaign was performed during August, 2014 in an agricultural area in the Duero basin (Spain) in order to appraise the synergy between very different sources of Earth Observation imagery, and very different instruments for soil moisture retrieval. During the flight, an intensive field campaign comprising soil, plant and spectral measurements was carried out. An innovative sensor based on the Global Navigation Satellite Systems Reflectometry (GNSS-R) was on board the manned vehicle, the Light Airborne Reflectometer for GNSS-R Observations (LARGO) engineered by the Universitat Politècnica de Catalunya. While the synergy between thermal, optical and passive microwave spectra observations is well known for vegetation parameters and soil moisture retrievals, the experiment aimed to evaluate the synergy of GNSS-R reflectivity with a time-collocated Landsat 8 imagery for soil moisture retrieval under semiarid climatic conditions. LARGO estimates, field measurements, and optical, NIR, SWIR and thermal bands from Landsat 8 were compared. Results showed that the joint use of GNSS-R reflectivity with vegetation and water indices together with thermal maps from Landsat 8 thoroughly improved the soil moisture estimation.

scholarly journals Ground-based gravimetry for measuring small spatial-scale mass changes on glaciers

2009 ◽  
Vol 50 (50) ◽  
pp. 141-147 ◽  
Author(s):  
Kristian Breili ◽  
Cecilie Rolstad
Keyword(s):  
Mass Density ◽  
Vertical Gradient ◽  
Gravity Change ◽  
Global Navigation Satellite Systems ◽  
Glacier Surface ◽  
Satellite Systems ◽  
Gravity Measurements ◽  
Global Navigation Satellite ◽  
Vertical Gradient Of Gravity ◽  
Snow And Ice

AbstractGravity change on a glacier surface is a composite of several effects (e.g. melting and accumulation of snow and ice, redistribution of mass with depth by refreezing of meltwater and height and thickness changes of the snow and ice layers). Models and equations necessary to estimate the measured gravity change due to different effects are presented, and the propagation of observational errors is evaluated. The paper presents experiences with ground-based gravity measurements carried out on Hardangerjøkulen, Norway, in spring and autumn 2007. It was found that the vertical gradient of gravity contributes most to the uncertainty in the determined mass change. With present instrumentation, gravity can be measured with the required accuracy to determine the mass loss to ∼10% of the loss determined by conventional mass-balance measurements. Improvements in field procedures to achieve the required accuracy for measuring the mass/density changes directly, combining gravity measurements and GNSS (Global Navigation Satellite Systems), are discussed.

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