scholarly journals An Ablation Rate for Lake Fryxell, Victoria Land, Antarctica

1966 ◽  
Vol 6 (43) ◽  
pp. 129-133 ◽  
Author(s):  
R. A. Henderson ◽  
W. M. Prebble ◽  
R. A. Hoare ◽  
K. B. Popplewell ◽  
D. A. House ◽  
...  
Keyword(s):  
Ablation Rate ◽  
Ice Cover ◽  
Katabatic Winds ◽  
Taylor Valley ◽  
Victoria Land ◽  
Lake Fryxell ◽  
Novel Method ◽  
The Difference

AbstractThe average yearly net ablation rate on permanently ice-covered Lake Fryxell, Victoria Land, Antarctica, is 30 to 40 cm. This figure was calculated by a novel method utilizing a record of ablation which is incorporated in the ice cover of the lake. These values are higher than those measured on Ross Island 80 km. to the east; the difference in ablation rates for the two areas is attributed to the prevalence of katabatic winds in the climate of Taylor Valley. The Lake Fryxell ablation figure is applied to nearby Canada and Commonwealth Glaciers in the calculation of their ice budgets.

scholarly journals An Ablation Rate for Lake Fryxell, Victoria Land, Antarctica

1966 ◽  
Vol 6 (43) ◽  
pp. 129-133 ◽  
Author(s):  
R. A. Henderson ◽  
W. M. Prebble ◽  
R. A. Hoare ◽  
K. B. Popplewell ◽  
D. A. House ◽  
...  
Keyword(s):  
Ablation Rate ◽  
Ice Cover ◽  
Katabatic Winds ◽  
Taylor Valley ◽  
Victoria Land ◽  
Lake Fryxell ◽  
Novel Method ◽  
The Difference

AbstractThe average yearly net ablation rate on permanently ice-covered Lake Fryxell, Victoria Land, Antarctica, is 30 to 40 cm. This figure was calculated by a novel method utilizing a record of ablation which is incorporated in the ice cover of the lake. These values are higher than those measured on Ross Island 80 km. to the east; the difference in ablation rates for the two areas is attributed to the prevalence of katabatic winds in the climate of Taylor Valley. The Lake Fryxell ablation figure is applied to nearby Canada and Commonwealth Glaciers in the calculation of their ice budgets.

scholarly journals Inorganic carbon-isotope distribution and budget in the Lake Hoare and Lake Fryxell basins, Taylor Valley, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 685-689 ◽  
Author(s):  
Klaus Neumann ◽  
W. Berry Lyons ◽  
David J. Des Marais
Keyword(s):  
Carbon Isotope ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Ice Cover ◽  
Stable Stratification ◽  
High Productivity ◽  
Taylor Valley ◽  
Victoria Land ◽  
Lake Fryxell ◽  
Perennial Ice

One of the unusual features of Lakes Fryxell and Hnare in Taylor Valley, southern Victoria Land, Antarctica, is their perennial ice cover. This ice cover limits gas exchange between the atmosphere and the lake water, and causesa very stable stratification of the lakes. We analyzed a series of water samples from profiles of these lakes and their tributaries for δ13C of the dissolved inorganic carbon (DIC) in order to qualify the carbon flux from the streams into the lakes, and to investigate the carbon cycling with in the lakes. Isotopic values in the uppermost waters (δ13C = +l.3‰ to 5.3‰ in Lake Hoare, +0.4‰ to +3.0‰ in Lake Fryxell) are close to the carbon-isotope values encountered in the streams feeding Lake Fryxell, but distinctively heavier than in streams feeding Lake Hoare (δ13C= — 2.3%n to 1.4%). These ratios are much heavier than ratios found in the moat that forms around the lakes injanuary February (δC = -10.1%). in the oxic photic zones of the lakes, photosynthesis clearly influences the isotopic composition, with layers of high productivity having enriched carbon-isotope signatures δ13C= +2.7‰ to +6.1‰). in both lakes, the isotopic values become lighter with depth, reaching minima of 3.2‰ and 4.0% in Lakes Fryxell and Hoare, respectively. These minima are caused by the microbial remineralization of isotopically light organic carbon. We present DIC flux calculations that help to interpret the isotopic distribution. For example, in Lake Hoare the higher utilization of CO2aq, and a substantially smaller inflow of CO2 from streams cause the heavier observed isotopic ratios. Differences in the hydrology and stream morphologies of the tributaries also greatly influence the carbon budgets of the basins.

The Holocene environmental history of Lake Hoare, Taylor Valley, Antarctica, reconstructed from sediment cores

2011 ◽  
Vol 23 (3) ◽  
pp. 307-319 ◽  
Author(s):  
Bernd Wagner ◽  
Sabrina Ortlepp ◽  
Peter T. Doran ◽  
Fabien Kenig ◽  
Martin Melles ◽  
...  
Keyword(s):  
Environmental History ◽  
Late Holocene ◽  
Sediment Cores ◽  
The Holocene ◽  
Sedimentary Characteristics ◽  
Fine Grained ◽  
Taylor Valley ◽  
Victoria Land ◽  
History Of ◽  
Lake Fryxell

AbstractUp to 2.3 m long sediment sequences were recovered from the deepest part of Lake Hoare in Taylor Valley, southern Victoria Land, Antarctica. Sedimentological, biogeochemical, and mineralogical analyses revealed a high spatial variability of these parameters in Lake Hoare. Five distinct lithological units were recognized. Radiocarbon dating of bulk organic carbon samples from the sediment sequences yielded apparently too old ages and significant age reversals, which prevented the establishment of reliable age-depth models. However, cross correlation of the sedimentary characteristics with those of sediment records from neighbouring Lake Fryxell indicates that the lowermost two units of the Lake Hoare sediment sequences were probably deposited during the final phase of proglacial Lake Washburn, which occupied Taylor Valley during the late Pleistocene and early Holocene. High amounts of angular gravel and the absence of fine-grained material imply a complete desiccation with subaerial conditions in the Lake Hoare basin in the middle of the Holocene. The late Holocene (< c. 3300 calendar yr bp) is characterized by the establishment of environmental conditions similar to those existing today. A late Holocene desiccation event, such as proposed in former studies, is not indicated in the sediment sequences recovered.

scholarly journals Image Anomaly Detection Using Normal Data Only by Latent Space Resampling

2020 ◽  
Vol 10 (23) ◽  
pp. 8660
Author(s):  
Lu Wang ◽  
Dongkai Zhang ◽  
Jiahao Guo ◽  
Yuexing Han
Keyword(s):  
Anomaly Detection ◽  
Normal Distribution ◽  
Autoregressive Model ◽  
Probability Model ◽  
Latent Space ◽  
Industrial Inspection ◽  
Detection Stage ◽  
Novel Method ◽  
The Difference ◽  
Reconstruction Model

Detecting image anomalies automatically in industrial scenarios can improve economic efficiency, but the scarcity of anomalous samples increases the challenge of the task. Recently, autoencoder has been widely used in image anomaly detection without using anomalous images during training. However, it is hard to determine the proper dimensionality of the latent space, and it often leads to unwanted reconstructions of the anomalous parts. To solve this problem, we propose a novel method based on the autoencoder. In this method, the latent space of the autoencoder is estimated using a discrete probability model. With the estimated probability model, the anomalous components in the latent space can be well excluded and undesirable reconstruction of the anomalous parts can be avoided. Specifically, we first adopt VQ-VAE as the reconstruction model to get a discrete latent space of normal samples. Then, PixelSail, a deep autoregressive model, is used to estimate the probability model of the discrete latent space. In the detection stage, the autoregressive model will determine the parts that deviate from the normal distribution in the input latent space. Then, the deviation code will be resampled from the normal distribution and decoded to yield a restored image, which is closest to the anomaly input. The anomaly is then detected by comparing the difference between the restored image and the anomaly image. Our proposed method is evaluated on the high-resolution industrial inspection image datasets MVTec AD which consist of 15 categories. The results show that the AUROC of the model improves by 15% over autoencoder and also yields competitive performance compared with state-of-the-art methods.

scholarly journals Linear traveltime perturbation interpolation: a novel method to compute 3-D traveltimes

2015 ◽  
Vol 203 (1) ◽  
pp. 548-552 ◽  
Author(s):  
Jianzhong Zhang ◽  
Junjie Shi ◽  
Lin-Ping Song ◽  
Hua-wei Zhou
Keyword(s):  
Seismic Waves ◽  
Homogeneous Medium ◽  
Cell Boundary ◽  
Routine Method ◽  
Bilinear Interpolation ◽  
Linear Distribution ◽  
Heterogeneous Model ◽  
Computational Errors ◽  
Novel Method ◽  
The Difference

Abstract The linear traveltime interpolation has been a routine method to compute first arrivals of seismic waves and trace rays in complex media. The method assumes that traveltimes follow a linear distribution on each boundary of cells. The linearity assumption of traveltimes facilitates the numerical implementation but its violation may result in large computational errors. In this paper, we propose a new way to mitigate the potential shortcoming hidden in the linear traveltime interpolation. We use the vertex traveltimes in a calculated cell to introduce an equivalent homogeneous medium that is specific to the cell boundary from a source. Therefore, we can decompose the traveltime at a point on the cell boundary into two parts: (1) a reference traveltime propagating in the equivalent homogeneous medium and (2) a perturbation traveltime that is defined as the difference between the original and reference traveltimes. We now treat that the traveltime perturbation is linear along each boundary of cells instead of the traveltime. With the new assumption, we carry out the bilinear interpolation over traveltime perturbation to complete traveltime computation in a 3-D heterogeneous model. The numerical experiments show that the new method, the linear traveltime perturbation interpolation, is able to achieve much higher accuracy than that based on the linear traveltime interpolation.

scholarly journals Deceptive Jamming Detection for SAR Based on Cross-Track Interferometry

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2265 ◽  
Author(s):  
Qingqing Feng ◽  
Huaping Xu ◽  
Zhefeng Wu ◽  
Wei Liu
Keyword(s):  
Sar Interferometry ◽  
Synthetic Aperture ◽  
Sar Image ◽  
Frequency Detection ◽  
Interferometric Phase ◽  
Deceptive Jamming ◽  
Jamming Detection ◽  
Novel Method ◽  
The Difference ◽  
Cross Track

Deceptive jamming against synthetic aperture radar (SAR) can create false targets or deceptive scenes in the image effectively. Based on the difference in interferometric phase between the target and deceptive jamming signals, a novel method for detecting deceptive jamming using cross-track interferometry is proposed, where the echoes with deceptive jamming are received by two SAR antennas simultaneously and the false targets are identified through SAR interferometry. Since the derived false phase is close to a constant in interferogram, it is extracted through phase filtering and frequency detection. Finally, the false targets in the SAR image are obtained according to the detected false part in the interferogram. The effectiveness of the proposed method is validated by simulation results based on the TanDEM-X system.

scholarly journals A NOVEL METHOD OF CLOUD AND SHADOW EXTRACTION WITH MULTI-TEMPORAL LANDSAT8 OLI IMAGES

2017 ◽  
Vol XLII-2/W7 ◽  
pp. 1301-1305
Author(s):  
Y. Ni ◽  
G. He ◽  
W. Jiang
Keyword(s):  
Remote Sensing ◽  
Large Change ◽  
Remote Sensing Image ◽  
Image Process ◽  
Actual Application ◽  
Significant Step ◽  
Multi Temporal ◽  
Ground Object ◽  
Novel Method ◽  
The Difference

Cloud and Shadow removal is a significant step in remote sensing image process. As we all know, the ground object coverage type of the same area of the remote sensing image has little change in the short term. But for cloud and shadow coverage areas, the ground object coverage type has large change. Therefore, according to the difference between the two Landsat / OLI images caused by changes in the cover, this paper presents a method of extracting clouds and shadows based on differences in luminance values. This method selects two thresholds for the difference of brightness values, and extracts the clouds and shadows respectively, and validates them with random point method, which can obtain high precision of extracting cloud and shadow and satisfy the actual application needs.

Novel Method of Assessing Practical Intelligence Acquired in Mechatronics Laboratory Classes

2015 ◽  
pp. 895-928
Author(s):  
Zol Bahri Razali
Keyword(s):  
Engineering Education ◽  
Engineering Students ◽  
Explicit Knowledge ◽  
Assessment Instruments ◽  
Practical Intelligence ◽  
Work Related ◽  
Novel Method ◽  
The Difference ◽  
Representative Work ◽  
Method Of Assessment

Practical intelligence is often referred to as the ability of a person to solve practical challenges in a given domain. The lack of practical intelligence may be due to the way in which explicit knowledge is valued and subsequently assessed in engineering education, namely via examinations, tests, laboratory reports, and tutorial exercises. The lack of effective assessments on practical intelligence indicates implicit devaluation, which can significantly impair engineering students' ability to acquire practical intelligence. To solve this problem, the authors propose a new method of assessment for measuring practical intelligence acquired by engineering students after performing engineering laboratory classes. The novices-experts approach is used in designing the assessment instruments, based on the behaviors' of novices/experts observed and novices/experts representative work-related situations. The practical intelligence can be measured by calculating the difference between participants' and the experts' ratings; the closer the novices to experts, the higher the practical intelligence acquired.

Orographic clouds in north Victoria Land from AVHRR images

Polar Record ◽  
1996 ◽  
Vol 32 (183) ◽  
pp. 317-324 ◽  
Author(s):  
Giuseppe Zibordi ◽  
Massimo Frezzotti
Keyword(s):  
High Resolution ◽  
Satellite Imagery ◽  
Meteorological Data ◽  
Spectral Features ◽  
Katabatic Winds ◽  
Victoria Land ◽  
Avhrr Data ◽  
Orographic Clouds ◽  
Temporal Occurrence ◽  
Very High

ABSTRACTOrographic clouds over north Victoria Land, East Antarctica, have been observed in Advanced Very High Resolution Radiometer (AVHRR) satellite imagery. These occasional clouds are discussed through analysis of their spectral features in AVHRR data. Temporal occurrence, spatial extension, and direction of the clouds are also discussed in relation to meteorological data for two periods characterised by katabatic winds, in December 1992 and January 1993.

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