scholarly journals An Automatic Method for Black Margin Elimination of Sentinel-1A Images over Antarctica

2020 ◽  
Vol 12 (7) ◽  
pp. 1175
Author(s):  
Xianwei Wang ◽  
David M. Holland
Keyword(s):  
Automatic Method ◽  
Edge Extraction ◽  
Signal Characteristics ◽  
Standard Level ◽  
Increasing Trend ◽  
Image Center ◽  
Human Interpretation ◽  
Extraction Error ◽  
The Antarctic ◽  
Normal Standard

The Sentinel-1A satellite was launched in April 2014 with a primary C-Band terrain observation with progressive scans synthetic aperture radar (TOPSAR) onboard and has collected plenty of high-quality images for global change studies. However, low magnitude signals around image margins (black margins) does not preserve the normal standard level, influencing the potential usage with these data. Through image analysis, we find that the signal from black margin (BM) is highly dominated by the closest effective signals and the signal in BM shows an increasing trend along the direction from image boundary to image center. An edge detector is developed based on the signal characteristics of BM. Furthermore, an automatic method to discriminate and eliminate BM is designed. Images from both extra wide (EW) and interferometric wide (IW) swath observation modes, covering the land, ocean, and coast of the Antarctic, are taken to verify the robustness of our method. Through comparison with BM edges extracted by human interpretation, our method has the maximum BM edge extraction error of 1.9 ± 3.2 pixels. When considering perimeter (or area) difference along radial direction of BM edge, our method has an averaging extraction accuracy of −0.35 ± 0.11 (or 0.14 ± 1.38) pixels, which suggests that our method is effective and can be potentially used to eliminate BM for multidisciplinary applications of Sentinel-1 data.

Recent and near future climate change in the Antarctic Peninsula

2020 ◽  
Author(s):  
Deniz Bozkurt ◽  
David H. Bromwich ◽  
Roberto Rondanelli
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Antarctic Peninsula ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Change Projections ◽  
Domain Configuration ◽  
Increasing Trend ◽  
The Antarctic ◽  
Near Future

<p>This study assesses the recent (1990-2015) and near future (2020-2045) climate change in the Antarctic Peninsula. For the recent period, we make the use of available observations, ECMWF’s ERA5 and its predecessor ERA-Interim, as well as regional climate model simulations. Given the different climate characteristics at each side of the mountain barrier, we principally assess the results considering the windward and leeward sides. We use hindcast simulations performed with Polar-WRF over the Antarctic Peninsula on a nested domain configuration at 45 km (PWRF-45) and 15 km (PWRF-15) spatial resolutions for the period 1990-2015. In addition, we include hindcast simulations of KNMI-RACMO21P obtained from the CORDEX-Antarctica domain (~ 50 km) for further comparisons. For the near future climate change evaluation, we principally use historical simulations and climate change projections (until 2050s, RCP85) performed with PWRF (forced with NCAR-CESM1) on the same domain configuration of the hindcast simulations. Recent observed trends show contrasts between summer and autumn. Annual warming (cooling) trend is notable on the windward (leeward) coasts of the peninsula. Unlike the reanalysis, numerical simulations indicate a clear pattern of windward warming and leeward cooling at annual time-scale. These temperature changes are accompanied by a decreasing and increasing trend in sea ice on the windward and leeward coasts, respectively. An increasing trend of precipitation is notable on the central and northern peninsula. High resolution climate change projections (PWRF-15, RCP85) indicate that the recent warming trend on the windward coasts tends to continue in the near future (2020-2045) and the projections exhibit an increase in temperature by ~ 1.5°C and 0.5°C on the windward and leeward coasts, respectively. In the same period, the projections show an increase in precipitation over the peninsula (5% to 10%). The more notable warming projected on the windward side causes more increases in surface melting (~ +20% to +80%) and more sea ice loss (-4% to -20%) on this side. Results show that the windward coasts of central and northern Antarctic Peninsula can be considered as "hotspots" with notable increases in temperature, surface melting and sea ice loss.</p>

Dial Instrument Calibration by both Automatic and Half-Automatic Methods

2012 ◽  
Vol 157-158 ◽  
pp. 581-588
Author(s):  
Zhen Long Bai ◽  
Xiang Li
Keyword(s):  
Video Processing ◽  
Processing Technique ◽  
Automatic Calibration ◽  
Automatic Method ◽  
Edge Extraction ◽  
Calibration System ◽  
Practical Application ◽  
Instrument Calibration ◽  
Different Types ◽  
Automatic Methods

This paper presents a calibration system by video processing technique. The system can calibrate large number of different types of dial instruments. The system is composed of an automatic recog-nition approach and a half-automatic approach. Both the automatic calibration and half-automatic calibration include four steps: 1st, dial plane circle edge extraction and center identification; 2nd, pointer extraction; 3rd, scale start and end position identification; 4th, result reading. For half-automatic method, the 1st step and 3rd step are manually indentified. By experiments and practical application in industry, it proves that our calibration system is effective for more than hundreds of different types of dial instruments.

scholarly journals Assessing the Financial Statement (Ratios) of Anglogold-Ashanti Limited, Ghana

2020 ◽  
pp. 45-55 ◽  
Author(s):  
Regina Wompakeah Bagina
Keyword(s):  
Time Series Data ◽  
Financial Statement ◽  
Series Data ◽  
Gross Margin ◽  
Return On Equity ◽  
Financial Ratio ◽  
Standard Tool ◽  
Increasing Trend ◽  
Acid Test ◽  
Normal Standard

This study assessed the financial position of Anglogold –Ashanti ltd, Ghana by conducting various financial ratio analyses. The study used time series data for a period of 7 years (2008/09 to 2013/14) of Anglogold Ashanti Limited. The data was analysed using standard tool ratio analysis. This was applied to evaluating the financial performance. Among the ratios used are the Liquidity ratio, current or acid test ration, profitability ratio, gross margin, return on equity, debt to equity. Tables were used in the data presentation.  The study findings revealed that both current and the quick ratios has a fluctuating trend of continues increase for the study period (2009-2011), that is (1.68, 1.93, 1.33, 1.77, 0.53, 0.53) and (0.90, 0.89, 0.62, 1.06, 0.65, 0.67 0.84). Also, the higher the ratio the more solvent the business is. Although, the company’s ratio was high it did not always imply that there was solvency but also indicated that the company was holding excess liquid funds. The quick ratio was also in a fluctuating trend throughout the period 2008 – 14. The company liquidity position was not far from the normal standard; to some extent it was satisfactory. The total assets turnover ratio also indicated an increasing trend from the year 2008 – 14(0.56, 0.62, 0.73, 0.54, 0.56, 0.49 and 0.39. Based on the findings, the study concluded that, the company’s overall position is not at a good position, particularly the last year under review due to decreased profit level from the previous year. It is better for the organization not to diversify the funds to different sectors in the present market scenario. The study recommended the need for the company to increase its sales by more promotions and by quick movements of the finished goods.

scholarly journals The Characteristics of Surface Albedo Change Trends over the Antarctic Sea Ice Region during Recent Decades

2019 ◽  
Vol 11 (7) ◽  
pp. 821 ◽  
Author(s):  
Chunxia Zhou ◽  
Teng Zhang ◽  
Lei Zheng
Keyword(s):  
Spatial Distribution ◽  
Sea Ice ◽  
Transition Point ◽  
Surface Albedo ◽  
Weddell Sea ◽  
West Antarctica ◽  
Stable Level ◽  
Antarctic Sea Ice ◽  
Increasing Trend ◽  
The Antarctic

Based on a long-time series (1982–2015) of remote sensing data, we analyzed the change in surface albedo (SAL) during summer (from December to the following February) for the entire Antarctic Sea Ice Region (ASIR) and five longitudinal sectors around Antarctica: (1). the Weddell Sea (WS), (2). Indian Ocean, (3). Pacific Ocean (PO), (4). Ross Sea, and (5). Bellingshausen–Amundsen Sea (BS). Empirical mode decomposition was used to extract the trend of the original signal, and then a slope test method was utilized to identify a transition point. The SAL provided by the CM SAF cloud, Albedo, and Surface Radiation dataset from AVHRR data-Second Edition was validated at Neumayer station. Sea ice concentration (SIC) and sea surface temperature (SST) were also analyzed. The trend of the SAL/SIC was positive during summer over the ASIR and five longitudinal sectors, except for the BS (−2.926% and −4.596% per decade for SAL and SIC, correspondingly). Moreover, the largest increasing trend of SAL and SIC appeared in the PO at approximately 3.781% and 3.358% per decade, respectively. However, the decreasing trend of SAL/SIC in the BS slowed down, and the increasing trend of SAL/SIC in the PO accelerated. The trend curves of the SST exhibited a crest around 2000–2005; thus, the slope lines of the SST showed an increasing–decreasing type for the ASIR and the five longitudinal sectors. The evolution of summer albedo decreased rapidly in the early summer and then maintained a relatively stable level for the whole ASIR. The change of it mainly depended on the early melt of sea ice during the entire summer. The change of sea ice albedo had a narrow range when compared with composite albedo and SIC over the five longitudinal sectors and reached a stable level earlier. The transition point of SAL/SIC in several sectors appeared around the year 2000, whereas that of the SST for the entire ASIR occurred in 2003–2005. A high value of SAL/SIC and a low value of the SST existed in the WS which can be displayed by the spatial distribution of pixel average. In addition, the lower the latitude was, the lower the SAL/SIC and the higher the SST would be. A transition point of SAL appeared in 2001 in most areas of West Antarctica. This transition point could be illustrated by anomaly maps. The spatial distribution of the pixel-based trend of SAL demonstrated that the change in SAL in East Antarctica has exhibited a positive trend in recent decades. However, in West Antarctica, the change of SAL presented a decreasing trend before 2001 and transformed into an increasing trend afterward, especially in the east of the Antarctic Peninsula.

scholarly journals Patterns of relationship between PM10 from air monitoring quality station and AOT data from MODIS sensor onboard of Terra satellite

2021 ◽  
Vol 30 (2) ◽  
pp. 236-249
Author(s):  
Winai Suriya ◽  
Poramate Chunpang ◽  
Teerawong Laosuwan
Keyword(s):  
Northern Region ◽  
Meteorological Conditions ◽  
Monitoring Station ◽  
Spatial Changes ◽  
Standard Level ◽  
Terra Satellite ◽  
Ground Monitoring ◽  
Monitoring Quality ◽  
Normal Standard

Thailand, especially in the northern region, often encounters the problem of having PM10 exceeding the normal standard level, which could do harm to people’s health. Mostly, such problem is caused by the burning of forest area and open area; this is clearly seen during January–April of every year. Also, the problem as mentioned is caused by the meteorological conditions and the terrains in the northern region that make it easy for PM10 to be accumulated. The aim of this study was to analyze the patterns of relationship between PM10 measured from the ground monitoring station and AOT data received from MODIS sensor onboard of Terra satellite in Phrae Province located in the northern region of Thailand. The method performed was by analyzing the correlation between PM10 data obtained from the ground monitoring station and the AOT data received from the MODIS sensor onboard of Terra satellite during January–April 2018. It was found from the study that the change of the intensity of PM10 and AOT in the climate was highly related; it appeared that the correlation coefficient (r) in January–April was 0.92, 0.91, 0.91 and 0.92, respectively. This research pointed out that during February– –April, the areas of Phrae Province had the level of PM10 that affected health. Besides, from the method in this research, it revealed AOT data received from MODIS sensor onboard of Terra satellite could be applied in order to follow up, monitor, and notify the spatial changes of PM10 efficiently.

Structure factor refinement by least-squares inversion of 2D convergent-beam patterns

1993 ◽  
Vol 51 ◽  
pp. 682-683
Author(s):  
K. Marthinsen ◽  
R. Holmestad ◽  
R. Høier
Keyword(s):  
Least Squares ◽  
Structure Factor ◽  
Convergent Beam Electron Diffraction ◽  
Alternative Methods ◽  
Automatic Method ◽  
Beam Electron ◽  
Structure Information ◽  
Increasing Trend ◽  
Convergent Beam ◽  
Beam Patterns

While electron microscopy and diffraction for decades mainly have been a qualitative tool, there has been an increasing trend over the last years for more quantitative work. This trend applies in particular to convergent beam electron diffraction (CBED) where different methods for the retrieval of quantitative structure information from CBED intensities have been proposed. In our group we have aimed at developing a general and automatic method based on the strong parameter dependencies that govern the complicated two-dimensional (2-D) intensity variations in the CBED-disks particularly in the nonsystematic many-beam case. The method is based on least squares fitting between digitized experimental and computed patterns. The advantage of this method as compared with alternative methods is many turning points in the intensity variations, which should give a high parameter sensitivity, and the fact that non-systematic many-beam effects are particularly sensitive to structure factor phases, which should make the method especially suitable to non-centric crystals.

Nonlinear influence of the Earth’s rotation on iceberg melting

2018 ◽  
Vol 858 ◽  
pp. 832-851
Author(s):  
Agostino N. Meroni ◽  
Craig D. McConnochie ◽  
Claudia Cenedese ◽  
Bruce Sutherland ◽  
Kate Snow
Keyword(s):  
Free Stream ◽  
Gravity Current ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
Earth’S Rotation ◽  
Local Circulation ◽  
Earth's Rotation ◽  
Flow Acceleration ◽  
Increasing Trend ◽  
The Antarctic

The calving of icebergs accounts for a significant fraction of the mass loss from both the Antarctic and Greenland ice sheets. Iceberg melting affects the water properties impacting sea ice formation, local circulation and biological activity. Laboratory experiments have investigated the effects of the Earth’s rotation on iceberg melting and the possible formation of Taylor columns (TCs) underneath icebergs. It is found that at high Rossby number, $Ro$, when rotation is weak compared to advection, iceberg melting is unaffected by the background rotation. As $Ro$ decreases, the melt rate shows an increasing trend, which is expected to reverse for very low $Ro$. This behaviour is explained by considering the integrated horizontal velocity at the base of the iceberg. For moderate $Ro$, a partial TC is formed and its effective blocking accelerates the flow under the remainder of the iceberg, which increases the melt rate since the melting is proportional to the flow velocity. It is expected that for very low $Ro$ the melt rate decreases because, with the expansion of the TC, the region of flow acceleration occurs away from the base of the iceberg. For low free stream velocity the freshwater produced by the ice melting introduces another dynamical effect. It is observed that there is a threshold free stream velocity below which the melt rate is constant. This is explained with the formation of a gravity current at the base of the iceberg that insulates it from the free flow and controls its melting.

Automatic measurement of SAED patterns from asbestos minerals

1988 ◽  
Vol 46 ◽  
pp. 846-847
Author(s):  
J. C. Russ ◽  
T. Taguchi ◽  
P. M. Peters ◽  
E. Chatfield ◽  
J. C. Russ ◽  
...  
Keyword(s):  
Diffraction Pattern ◽  
High Precision ◽  
Diffraction Data ◽  
Automatic Measurement ◽  
Automatic Method ◽  
Important Method ◽  
X Ray ◽  
Integrated Intensity ◽  
Asbestiform Minerals ◽  
True Center

Conventional SAD patterns as obtained in the TEM present difficulties for identification of materials such as asbestiform minerals, although diffraction data is considered to be an important method for making this purpose. The preferred orientation of the fibers and the spotty patterns that are obtained do not readily lend themselves to measurement of the integrated intensity values for each d-spacing, and even the d-spacings may be hard to determine precisely because the true center location for the broken rings requires estimation. We have implemented an automatic method for diffraction pattern measurement to overcome these problems. It automatically locates the center of patterns with high precision, measures the radius of each ring of spots in the pattern, and integrates the density of spots in that ring. The resulting spectrum of intensity vs. radius is then used just as a conventional X-ray diffractometer scan would be, to locate peaks and produce a list of d,I values suitable for search/match comparison to known or expected phases.

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