River-ice and water velocities using the  Planet optical cubesat constellation

Abstract. The PlanetScope constellation consists of ∼150 optical cubesats that are evenly distributed like strings of pearls on two orbital planes, scanning the Earth's land surface once per day with an approximate spatial image resolution of 3 m. Subsequent cubesats on each of the orbital planes image the Earth surface with a nominal time lag of approximately 90 s between them, which produces near-simultaneous image pairs over the across-track overlaps of the cubesat swaths. We exploit this short time lag between subsequent Planet cubesat images to track river ice floes on northern rivers as indicators of water surface velocities. The method is demonstrated for a 60 km long reach of the Amur River in Siberia, and a 200 km long reach of the Yukon River in Alaska. The accuracy of the estimated horizontal surface velocities is of the order of ±0.01 m s−1. The application of our approach is complicated by cloud cover and low sun angles at high latitudes during the periods where rivers typically carry ice floes, and by the fact that the near-simultaneous swath overlaps, by design, do not cover the complete Earth surface. Still, the approach enables direct remote sensing of river surface velocities for numerous cold-region rivers at a number of locations and occasionally several times per year – which is much more frequent and over much larger areas than currently feasible. We find that freeze-up conditions seem to offer ice floes that are generally more suitable for tracking, and over longer time periods, compared with typical ice break-up conditions. The coverage of river velocities obtained could be particularly useful in combination with satellite measurements of river area, and river surface height and slope.

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River ice and water velocities using the Planet optical cubesat constellation

10.5194/hess-2019-62 ◽

2019 ◽

Cited By ~ 1

Author(s):

Andreas Kääb ◽

Bas Altena ◽

Joseph Mascaro

Keyword(s):

Land Surface ◽

Time Lapse ◽

Image Resolution ◽

River Ice ◽

Earth Surface ◽

Spatial Image ◽

The Amur River ◽

Northern Rivers ◽

Ice Floes ◽

Short Time

Abstract. The PlanetScope constellation consists of ~ 150 optical cubesats that are evenly distributed like strings of pearls in two orbital planes and scan the Earth's land surface once per day with ~ 3 m spatial image resolution. Subsequent cubesats in each of the orbital planes image the Earth surface with a nominal time lapse of ~ 90 s between each other, which produces near-simultaneous pairs of scenes over the across-track overlaps of the cubesat swaths. We exploit this short time lapse between subsequent Planet cubesat images to track river ice floes on Northern rivers as indicators of water surface velocities. The method is demonstrated for a 60 km long reach of the Amur River in Siberia, and a 200 km long reach of the Yukon River, Alaska. The accuracy of the estimated horizontal surface velocities is on the order of ±0.01 m s−1. The application of our approach is complicated by cloud cover and low sun angles at high latitudes during the periods where rivers typically carry ice floes, and by the fact that the near-simultaneous swath overlaps by design do not cover the complete Earth surface. Still, the approach enables direct remote sensing of river surface velocities over many cold-region rivers and several times per year – much more frequent and over much larger areas than feasible so far, if at all. We find that freeze-up conditions seem in general to offer ice floes that are more suitable for tracking, and over longer time periods, compared to typical ice break-up conditions. The coverage of river velocities obtained could be particularly useful in combination with satellite measurements of river area, and river surface height and slope.

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River ice flux and water velocities along a 600 km long reach of Lena River, Siberia, from satellite stereo

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-10-9967-2013 ◽

2013 ◽

Vol 10 (7) ◽

pp. 9967-9997 ◽

Cited By ~ 2

Author(s):

A. Kääb ◽

M. Lamare ◽

M. Abrams

Keyword(s):

River Flow ◽

Thermal Emission ◽

Time Lag ◽

Open Water ◽

Image Resolution ◽

Surface Velocity ◽

River Ice ◽

Data Set ◽

Hazard Management ◽

Lena River

Abstract. Knowledge of water-surface velocities in rivers is useful for understanding a range of river processes. In cold regions, river-ice break up and the related downstream transport of ice debris is often the most important hydrological event of the year, leading to flood levels that typically exceed those for the open-water period and to strong consequences for river infrastructure and ecology. Accurate and complete surface-velocity fields on rivers have rarely been produced. Here, we track river ice debris over a time period of about one minute, which is the typical time lag between the two or more images that form a stereo data set in spaceborne, along-track optical stereo-mapping. Using a series of 9 stereo scenes from the US/Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard the NASA Terra spacecraft with 15 m image resolution, we measure the ice and water velocity field over a 620 km long reach of the lower Lena River, Siberia, just above its entry into the Lena delta. Careful analysis and correction of higher-order image and sensor errors enables an accuracy of ice-debris velocities of up to 0.04 m s−1 from the ASTER data. Maximum ice or water speeds, respectively, reach up to 2.5 m s−1 at the time of data acquisition, 27 May 2011 (03:30 UTC). Speeds show clear along-stream undulations with a wavelength of about 21 km that agree well with variations in channel width and with the location of sand bars along the river reach studied. The methodology and results of this study could be valuable to a number of disciplines requiring detailed information about river flow, such as hydraulics, hydrology, river ecology and natural-hazard management.

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River ice flux and water velocities along a 600 km-long reach of Lena River, Siberia, from satellite stereo

Hydrology and Earth System Sciences ◽

10.5194/hess-17-4671-2013 ◽

2013 ◽

Vol 17 (11) ◽

pp. 4671-4683 ◽

Cited By ~ 11

Author(s):

A. Kääb ◽

M. Lamare ◽

M. Abrams

Keyword(s):

River Flow ◽

Thermal Emission ◽

Time Lag ◽

Open Water ◽

Image Resolution ◽

Surface Velocity ◽

River Ice ◽

Data Set ◽

Hazard Management ◽

Lena River

Abstract. Knowledge of water-surface velocities in rivers is useful for understanding a range of river processes. In cold regions, river-ice break up and the related downstream transport of ice debris is often the most important hydrological event of the year, leading to flood levels that typically exceed those for the open-water period and to strong consequences for river infrastructure and ecology. Accurate and complete surface-velocity fields on rivers have rarely been produced. Here, we track river ice debris over a time period of about one minute, which is the typical time lag between the two or more images that form a stereo data set in spaceborne, along-track optical stereo mapping. Using a series of nine stereo scenes from the US/Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard the NASA Terra spacecraft with 15 m image resolution, we measure the ice and water velocity field over a 620 km-long reach of the lower Lena River, Siberia, just above its entry into the Lena delta. Careful analysis and correction of higher-order image and sensor errors enables an accuracy of ice-debris velocities of up to 0.04 m s−1 from the ASTER data. Maximum ice or water speeds, respectively, reach up to 2.5 m s−1 at the time of data acquisition, 27 May 2011 (03:30 UTC). Speeds show clear along-stream undulations with a wavelength of about 21 km that agree well with variations in channel width and with the location of sand bars along the river reach studied. The methodology and results of this study could be valuable to a number of disciplines requiring detailed information about river flow, such as hydraulics, hydrology, river ecology and natural-hazard management.

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Low-Cost Hardware Implementation of Human Blood Identification Device Using Feed-Forward Artificial Neural Network on FPGA

10.31227/osf.io/dp63x ◽

2018 ◽

Author(s):

Rizki Eka Putri ◽

Denny Darlis

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

Low Cost ◽

Image Resolution ◽

Blood Type ◽

Feed Forward ◽

Testing Facility ◽

System Input ◽

Artificial Neural ◽

Short Time

This article was under review for ICELTICS 2018 -- In the medical world there is still service dissatisfaction caused by lack of blood type testing facility. If the number of tested blood arise, a lot of problems will occur so that electronic devices are needed to determine the blood type accurately and in short time. In this research we implemented an Artificial Neural Network on Xilinx Spartan 3S1000 Field Programable Gate Array using XSA-3S Board to identify the blood type. This research uses blood sample image as system input. VHSIC Hardware Discription Language is the language to describe the algorithm. The algorithm used is feed-forward propagation of backpropagation neural network. There are 3 layers used in design, they are input, hidden1, and output. At hidden1layer has two neurons. In this study the accuracy of detection obtained are 92%, 92%, 92%, 90% and 86% for 32x32, 48x48, 64x64, 80x80, and 96x96 pixel blood image resolution, respectively.

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Features of toxic element distribution in the Amur River ice.

Криосфера Земли ◽

10.21782/kz1560-7496-2020-5(3-15) ◽

2020 ◽

Vol XXIV (5) ◽

Keyword(s):

Element Distribution ◽

Toxic Element ◽

River Ice ◽

Amur River ◽

The Amur River

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Reconciling Lagrangian Diffusivity and Effective Diffusivity in Contour-Based Coordinates

Journal of Physical Oceanography ◽

10.1175/jpo-d-18-0251.1 ◽

2019 ◽

Vol 49 (6) ◽

pp. 1521-1539

Author(s):

Yu-Kun Qian ◽

Shiqiu Peng ◽

Chang-Xia Liang

Keyword(s):

Time Lag ◽

Effective Diffusivity ◽

Delta Function ◽

Spreading Rate ◽

Particle Dispersion ◽

Small Scale ◽

Time Lags ◽

Conservative Tracer ◽

Stirring Effect ◽

Short Time

AbstractThe present study reconciles theoretical differences between the Lagrangian diffusivity and effective diffusivity in a transformed spatial coordinate based on the contours of a quasi-conservative tracer. In the transformed coordinate, any adiabatic stirring effect, such as shear-induced dispersion, is naturally isolated from diabatic cross-contour motions. Therefore, Lagrangian particle motions in the transformed coordinate obey a transformed zeroth-order stochastic (i.e., random walk) model with the diffusivity replaced by the effective diffusivity. Such a stochastic model becomes the theoretical foundation on which both diffusivities are exactly unified. In the absence of small-scale diffusion, particles do not disperse at all in the transformed contour coordinate. Besides, the corresponding Lagrangian autocorrelation becomes a delta function and is thus free from pronounced overshoot and negative lobe at short time lags that may be induced by either Rossby waves or mesoscale eddies; that is, particles decorrelate immediately and Lagrangian diffusivity is already asymptotic no matter how small the time lag is. The resulting instantaneous Lagrangian spreading rate is thus conceptually identical to the effective diffusivity that only measures the instantaneous irreversible mixing. In these regards, the present study provides a new look at particle dispersion in contour-based coordinates.

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Short Time Lag of Spark Breakdown

Physical Review ◽

10.1103/physrev.52.652 ◽

1937 ◽

Vol 52 (6) ◽

pp. 652-654 ◽

Cited By ~ 22

Author(s):

Morris Newman

Keyword(s):

Time Lag ◽

Short Time ◽

Spark Breakdown

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Night Thermal Unmixing for the Study of Microscale Surface Urban Heat Islands with TRISHNA-Like Data

Remote Sensing ◽

10.3390/rs11121449 ◽

2019 ◽

Vol 11 (12) ◽

pp. 1449 ◽

Cited By ~ 2

Author(s):

Carlos Granero-Belinchon ◽

Aurelie Michel ◽

Jean-Pierre Lagouarde ◽

Jose A. Sobrino ◽

Xavier Briottet

Keyword(s):

Surface Temperature ◽

Land Surface ◽

Image Resolution ◽

Urban Heat Islands ◽

Land Uses ◽

Regression Kriging ◽

Heat Islands ◽

Urban Heat ◽

Land Covers ◽

The City

Urban Heat Islands (UHIs) at the surface and canopy levels are major issues in urban planification and development. For this reason, the comprehension and quantification of the influence that the different land-uses/land-covers have on UHIs is of particular importance. In order to perform a detailed thermal characterisation of the city, measures covering the whole scenario (city and surroundings) and with a recurrent revisit are needed. In addition, a resolution of tens of meters is needed to characterise the urban heterogeneities. Spaceborne remote sensing meets the first and the second requirements but the Land Surface Temperature (LST) resolutions remain too rough compared to the urban object scale. Thermal unmixing techniques have been developed in recent years, allowing LST images during day at the desired scales. However, while LST gives information of surface urban heat islands (SUHIs), canopy UHIs and SUHIs are more correlated during the night, hence the development of thermal unmixing methods for night LSTs is necessary. This article proposes to adapt four empirical unmixing methods of the literature, Disaggregation of radiometric surface Temperature (DisTrad), High-resolution Urban Thermal Sharpener (HUTS), Area-To-Point Regression Kriging (ATPRK), and Adaptive Area-To-Point Regression Kriging (AATPRK), to unmix night LSTs. These methods are based on given relationships between LST and reflective indices, and on invariance hypotheses of these relationships across resolutions. Then, a comparative study of the performances of the different techniques is carried out on TRISHNA synthesized images of Madrid. Since TRISHNA is a mission in preparation, the synthesis of the images has been done according to the planned specification of the satellite and from initial Aircraft Hyperspectral Scanner (AHS) data of the city obtained during the DESIREX 2008 capaign. Thus, the coarse initial resolution is 60 m and the finer post-unmixing one is 20 m. In this article, we show that: (1) AATPRK is the most performant unmixing technique when applied on night LST, with the other three techniques being undesirable for night applications at TRISHNA resolutions. This can be explained by the local application of AATPRK. (2) ATPRK and DisTrad do not improve significantly the LST image resolution. (3) HUTS, which depends on albedo measures, misestimates the LST, leading to the worst temperature unmixing. (4) The two main factors explaining the obtained performances are the local/global application of the method and the reflective indices used in the LST-index relationship.

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Responding to Bioterror Concerns by Increasing Milk Pasteurization Temperature Would Increase Estimated Annual Deaths from Listeriosis

Journal of Food Protection ◽

10.4315/0362-028x.jfp-13-191 ◽

2014 ◽

Vol 77 (5) ◽

pp. 696-705 ◽

Cited By ~ 5

Author(s):

MATTHEW J. STASIEWICZ ◽

NICOLE MARTIN ◽

SHELLEY LAUE ◽

YRJO T. GRÖHN ◽

KATHRYN J. BOOR ◽

...

Keyword(s):

Public Health ◽

High Temperature ◽

Time Lag ◽

Fold Increase ◽

Quantitative Microbial Risk Assessment ◽

The Public ◽

High Temperature Short Time ◽

Increased Risk ◽

Short Time ◽

Fluid Milk

In a 2005 analysis of a potential bioterror attack on the food supply involving a botulinum toxin release into the milk supply, the authors recommended adopting a toxin inactivation step during milk processing. In response, some dairy processors increased the times and temperatures of pasteurization well above the legal minimum for high temperature, short time pasteurization (72°C for 15 s), with unknown implications for public health. The present study was conducted to determine whether an increase in high temperature, short time pasteurization temperature would affect the growth of Listeria monocytogenes, a potentially lethal foodborne pathogen normally eliminated with proper pasteurization but of concern when milk is contaminated postpasteurization. L. monocytogenes growth during refrigerated storage was higher in milk pasteurized at 82°C than in milk pasteurized at 72°C. Specifically, the time lag before exponential growth was decreased and the maximum population density was increased. The public health impact of this change in pasteurization was evaluated using a quantitative microbial risk assessment of deaths from listeriosis attributable to consumption of pasteurized fluid milk that was contaminated postprocessing. Conservative estimates of the effect of pasteurizing all fluid milk at 82°C rather than 72°C are that annual listeriosis deaths from consumption of this milk would increase from 18 to 670, a 38-fold increase (8.7- to 96-fold increase, 5th and 95th percentiles). These results exemplify a situation in which response to a rare bioterror threat may have the unintended consequence of putting the public at increased risk of a known, yet severe harm and illustrate the need for a paradigm shift toward multioutcome risk benefit analyses when proposing changes to established food safety practices.

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