scholarly journals Visible and near-infrared digital images for determination of ice velocities and surface elevation during a surge on Osbornebreen, a tidewater glacier in Svalbard

1997 ◽  
Vol 24 ◽  
pp. 255-261 ◽  
Author(s):  
Cecilie Rolstad ◽  
Jostein Amlien ◽  
Jon-Ove Hagen ◽  
Bengt Lundén
Keyword(s):  
Velocity Field ◽  
Near Infrared ◽  
Aerial Photographs ◽  
Correlation Technique ◽  
Digital Elevation ◽  
Compressive Flow ◽  
Tidewater Glacier ◽  
Extension Zone ◽  
Elevation Model ◽  
Cross Correlation Technique

A field of vectors showing the average velocity of the surging glacier Osbornebreen, Svalbard, was determined by comparing sequential SPOT (Système pour l’Observation de la Terre) and Landsat thematic mapper images. Crevasses which developed during the initial phase of the surge in the winter of 1986–87 were tracked using a fast Fourier chip cross-correlation technique. A digital elevation model (DEM) was developed using digital photogrammetry on aerial photographs from 1990. This new DEM was compared with a map drawn in 1966. The velocity field could be almost entirely determined with 1 month separation of the images, but only partly determined with images 1 year apart, due to changes of the crevasse pattern. The velocity field is similar to that found for Kronebreen, a continuously fast-moving tidewater glacier. No distinct zones of compressive flow were present and the data gave no evidence of a compression zone/surge front traveling downstream. The velocity field, the rapid advance of the terminus and the development of transverse crevasses in the upper accumulation area within a 6 month period may indicate that the surge developed as a zone of extension starting near the terminus and propagating quickly upstream. The crevasse pattern in the images is therefore interpreted to be the result of the extension zone traveling upstream, and, as the whole glacier starts to slide, the crevasse pattern alters according to the bedrock topography.

scholarly journals Visible and near-infrared digital images for determination of ice velocities and surface elevation during a surge on Osbornebreen, a tidewater glacier in Svalbard

1997 ◽  
Vol 24 ◽  
pp. 255-261 ◽  
Author(s):  
Cecilie Rolstad ◽  
Jostein Amlien ◽  
Jon-Ove Hagen ◽  
Bengt Lundén
Keyword(s):  
Velocity Field ◽  
Near Infrared ◽  
Aerial Photographs ◽  
Correlation Technique ◽  
Digital Elevation ◽  
Compressive Flow ◽  
Tidewater Glacier ◽  
Extension Zone ◽  
Elevation Model ◽  
Cross Correlation Technique

A field of vectors showing the average velocity of the surging glacier Osbornebreen, Svalbard, was determined by comparing sequential SPOT (Système pour l’Observation de la Terre) and Landsat thematic mapper images. Crevasses which developed during the initial phase of the surge in the winter of 1986–87 were tracked using a fast Fourier chip cross-correlation technique. A digital elevation model (DEM) was developed using digital photogrammetry on aerial photographs from 1990. This new DEM was compared with a map drawn in 1966. The velocity field could be almost entirely determined with 1 month separation of the images, but only partly determined with images 1 year apart, due to changes of the crevasse pattern. The velocity field is similar to that found for Kronebreen, a continuously fast-moving tidewater glacier. No distinct zones of compressive flow were present and the data gave no evidence of a compression zone/surge front traveling downstream. The velocity field, the rapid advance of the terminus and the development of transverse crevasses in the upper accumulation area within a 6 month period may indicate that the surge developed as a zone of extension starting near the terminus and propagating quickly upstream. The crevasse pattern in the images is therefore interpreted to be the result of the extension zone traveling upstream, and, as the whole glacier starts to slide, the crevasse pattern alters according to the bedrock topography.

scholarly journals A new velocity map for Byrd Glacier, East Antarctica, from sequential ASTER satellite imagery

2005 ◽  
Vol 41 ◽  
pp. 71-76 ◽  
Author(s):  
Leigh Stearns ◽  
Gordon Hamilton
Keyword(s):  
Cross Correlation ◽  
Thermal Emission ◽  
East Antarctica ◽  
Correlation Technique ◽  
Main Trunk ◽  
Ice Dynamics ◽  
Digital Elevation ◽  
Stereo Imagery ◽  
Elevation Model ◽  
Cross Correlation Technique

AbstractNew ice-velocity measurements are obtained for the main trunk of Byrd Glacier, East Antarctica, using recently acquired Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery. The velocities are derived from the application of a cross-correlation technique to sequential images acquired in 2000 and 2001. Images were co-registered and ortho-rectified with the aid of a digital elevation model (DEM) generated from ASTER stereo imagery. This paper outlines the process of DEM generation, image co-registration and correction, and the application of the cross-correlation technique to obtain ice velocities. Comparison of the new velocity map with earlier measurements of velocity from 1978 indicates that the glacier has undergone a substantial deceleration between observations. Portions of the glacier flowing at speeds of ~850ma–1 in 1978/79 were flowing at ~650ma–1 in 2000/01. The cause of this change in ice dynamics is not known, but the observation shows that East Antarctic outlet glaciers can undergo substantial changes on relatively short timescales.

scholarly journals The emergence of the red sequence at z~2 seen through galaxy clustering in the UKIDSS UDS

2012 ◽  
Vol 8 (S295) ◽  
pp. 105-108
Author(s):  
William G. Hartley ◽  
Omar Almaini ◽  
Alice Mortlock ◽  
Chris Conselice ◽  
Keyword(s):  
Dark Matter ◽  
Cross Correlation ◽  
Near Infrared ◽  
Correlation Technique ◽  
Dark Matter Halos ◽  
Star Forming ◽  
Deep Survey ◽  
Cross Correlation Technique ◽  
Infrared Survey

AbstractWe use the UKIDSS Ultra-Deep Survey, the deepest degree-scale near-infrared survey to date, to investigate the clustering of star-forming and passive galaxies to z ~ 3.5. Our new measurements include the first determination of the clustering for passive galaxies at z > 2, which we achieve using a cross-correlation technique. We find that passive galaxies are the most strongly clustered, typically hosted by massive dark matter halos with Mhalo > 1013 M⊙ irrespective of redshift or stellar mass. Our findings are consistent with models in which a critical halo mass determines the transition from star-forming to passive galaxies.

scholarly journals SuperCLASS – I. The super cluster assisted shear survey: Project overview and data release 1

2020 ◽  
Vol 495 (2) ◽  
pp. 1706-1723 ◽  
Author(s):  
Richard A Battye ◽  
Michael L Brown ◽  
Caitlin M Casey ◽  
Ian Harrison ◽  
Neal J Jackson ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Near Infrared ◽  
Correlation Technique ◽  
Large Array ◽  
Photometric Redshifts ◽  
Very Large Array ◽  
Infrared Observations ◽  
Data Release ◽  
L Band ◽  
Cross Correlation Technique

ABSTRACT The SuperCLuster Assisted Shear Survey (SuperCLASS) is a legacy programme using the e-MERLIN interferometric array. The aim is to observe the sky at L-band (1.4 GHz) to a r.m.s. of $7\, \mu {\rm Jy}\,$beam−1 over an area of $\sim 1\, {\rm deg}^2$ centred on the Abell 981 supercluster. The main scientific objectives of the project are: (i) to detect the effects of weak lensing in the radio in preparation for similar measurements with the Square Kilometre Array (SKA); (ii) an extinction free census of star formation and AGN activity out to z ∼ 1. In this paper we give an overview of the project including the science goals and multiwavelength coverage before presenting the first data release. We have analysed around 400 h of e-MERLIN data allowing us to create a Data Release 1 (DR1) mosaic of $\sim 0.26\, {\rm deg}^2$ to the full depth. These observations have been supplemented with complementary radio observations from the Karl G. Jansky Very Large Array (VLA) and optical/near infrared observations taken with the Subaru, Canada-France-Hawaii, and Spitzer Telescopes. The main data product is a catalogue of 887 sources detected by the VLA, of which 395 are detected by e-MERLIN and 197 of these are resolved. We have investigated the size, flux, and spectral index properties of these sources finding them compatible with previous studies. Preliminary photometric redshifts, and an assessment of galaxy shapes measured in the radio data, combined with a radio-optical cross-correlation technique probing cosmic shear in a supercluster environment, are presented in companion papers.

scholarly journals Potential of Sentinel-2 Images for Estimating of Soil Resistivity over Agricultural Fields

Proceedings ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 18
Author(s):  
Remy Fieuzal ◽  
Vincent Bustillo ◽  
David Collado ◽  
Gerard Dedieu
Keyword(s):  
Electrical Resistivity ◽  
Near Infrared ◽  
Soil Layers ◽  
Digital Elevation ◽  
Combined Use ◽  
Input Variables ◽  
Elevation Model ◽  
High Level ◽  
Sentinel 2 ◽  
Soil Electrical Resistivity

The aim of this study is to assess the possibilities of the VNIR (Visible and Near InfraRed) and SWIR (Short Wavelength InfraRed) satellite data for estimating intra-plot patterns of soil electrical resistivity consistent with ground measurements. The methodology is based on optical reflectances that constitute the input variables of random forest, alone or in combination with parameters derived from a digital elevation model (DEM). Over a field located in southwestern France, the results show high level of accuracy for the 0–50 and 0–100 cm soil layers (with R² of 0.69 and 0.59, and a relative RMSE of 18% and 16%, respectively), the performances being lower for the 0–170 cm layer (R² of 0.39, relative RMSE of 20%). The combined use of optical reflectances with parameters derived from the DEM slightly improves the performances, whatever the considered layer. The influence of each reflectance on soil electrical resistivity estimates is finally analyzed, showing that the wavelengths acquired in the SWIR have a relative higher importance than VNIR reflectance.

scholarly journals Soil Moisture Mapping Based on Multi-Source Fusion of Optical, Near-Infrared, Thermal Infrared, and Digital Elevation Model Data via the Bayesian Maximum Entropy Framework

2020 ◽  
Vol 12 (23) ◽  
pp. 3916
Author(s):  
Leran Han ◽  
Chunmei Wang ◽  
Qiyue Liu ◽  
Gengke Wang ◽  
Tao Yu ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Maximum Entropy ◽  
Near Infrared ◽  
Bayesian Maximum Entropy ◽  
General Knowledge ◽  
Combined Approach ◽  
Soft Data ◽  
Digital Elevation ◽  
Source Data ◽  
Elevation Model

This paper proposes a combined approach wherein the optical, near-infrared, and thermal infrared data from the Landsat 8 satellite and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global digital elevation model (GDEM) data are fused for soil moisture mapping under sparse sampling conditions, based on the Bayesian maximum entropy (BME) framework. The study was conducted in three stages. First, based on the maximum entropy principle of the information theory, a Lagrange multiplier was introduced to construct general knowledge, representing prior knowledge. Second, a principal component analysis (PCA) was conducted to extract three principal components from the multi-source data mentioned above, and an innovative and operable discrete probability method based on a fuzzy probability matrix was used to approximate the probability relationship. Thereafter, soft data were generated on the basis of the weight coefficients and coordinates of the soft data points. Finally, by combining the general knowledge with the prior information, hard data (HD), and soft data (SD), we completed the soil moisture mapping based on the Bayesian conditioning rule. To verify the feasibility of the combined approach, the ordinary kriging (OK) method was taken as a comparison. The results confirmed the superiority of the soil moisture map obtained using the BME framework. The map revealed more detailed information, and the accuracies of the quantitative indicators were higher compared with that for the OK method (the root mean squared error (RMSE) = 0.0423 cm3/cm3, mean absolute error (MAE) = 0.0399 cm3/cm3, and Pearson correlation coefficient (PCC) = 0.7846), while largely overcoming the overestimation issue in the range of low values and the underestimation issue in the range of high values. The proposed approach effectively fused inexpensive and easily available multi-source data with uncertainties and obtained a satisfactory mapping accuracy, thus demonstrating the potential of the BME framework for soil moisture mapping using multi-source data.

scholarly journals Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978–1987

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Niels J. Korsgaard ◽  
Christopher Nuth ◽  
Shfaqat A. Khan ◽  
Kristian K. Kjeldsen ◽  
Anders A. Bjørk ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Aerial Photographs ◽  
Digital Elevation ◽  
Elevation Model

scholarly journals Characterization and verification of ACAM slit functions for trace-gas retrievals during the 2011 DISCOVER-AQ flight campaign

2015 ◽  
Vol 8 (2) ◽  
pp. 751-759 ◽  
Author(s):  
C. Liu ◽  
X. Liu ◽  
M. G. Kowalewski ◽  
S. J. Janz ◽  
G. González Abad ◽  
...  
Keyword(s):  
Air Quality ◽  
Cross Correlation ◽  
Near Infrared ◽  
Gas Absorption ◽  
Trace Gas ◽  
Correlation Technique ◽  
Reference Spectrum ◽  
Infrared Spectrometer ◽  
Cross Correlation Technique ◽  
Near Infrared Spectrometer

Abstract. The Airborne Compact Atmospheric Mapper (ACAM), an ultraviolet/visible/near-infrared spectrometer, has been flown on board the NASA UC-12 aircraft during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaigns to provide remote sensing observations of tropospheric and boundary-layer pollutants from its radiance measurements. To assure the trace-gas retrieval from ACAM measurements we perform detailed characterization and verification of ACAM slit functions. The wavelengths and slit functions of ACAM measurements are characterized for the air-quality channel (~304–500 nm) through cross-correlation with a high-resolution solar irradiance reference spectrum after necessarily accounting for atmospheric gas absorption and the ring effect in the calibration process. The derived slit functions, assuming a hybrid combination of asymmetric Gaussian and top-hat slit functions, agree very well with the laboratory-measured slit functions. Comparisons of trace-gas retrievals between using derived and measured slit functions demonstrate that the cross-correlation technique can be reliably used to characterize slit functions for trace-gas retrievals.

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