scholarly journals Decennal geomorphic transport from archived time series digital elevation models: a cookbook for tropical and alpine environments.

2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer
Keyword(s):  
Time Series ◽  
Time Scale ◽  
Aerial Images ◽  
Sensor Calibration ◽  
Dense Matching ◽  
Time Period ◽  
Digital Elevation ◽  
Seasonal Time Scale ◽  
Areas Of Interest ◽  
Alpine Environments

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>

scholarly journals Decennal geomorphic transport from archived time series digital elevation models: a cookbook for tropical and alpine environments.

2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer
Keyword(s):  
Time Series ◽  
Time Scale ◽  
Aerial Images ◽  
Sensor Calibration ◽  
Dense Matching ◽  
Time Period ◽  
Digital Elevation ◽  
Seasonal Time Scale ◽  
Areas Of Interest ◽  
Alpine Environments

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>

scholarly journals Decennal geomorphic transport from archived time series digital elevation models: a cookbook for tropical and alpine environments.

2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer
Keyword(s):  
Time Series ◽  
Time Scale ◽  
Aerial Images ◽  
Sensor Calibration ◽  
Dense Matching ◽  
Time Period ◽  
Digital Elevation ◽  
Seasonal Time Scale ◽  
Areas Of Interest ◽  
Alpine Environments

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>

scholarly journals Decennial geomorphic transport from archived time series digital elevation models: a cookbook for tropical and alpine environments

2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer
Keyword(s):  
Time Series ◽  
Time Scale ◽  
Aerial Images ◽  
Sensor Calibration ◽  
Dense Matching ◽  
Time Period ◽  
Digital Elevation ◽  
Seasonal Time Scale ◽  
Areas Of Interest ◽  
Alpine Environments

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>

scholarly journals Decennal geomorphic transport from archived time series digital elevation models: a cookbook for tropical and alpine environments.

2021 ◽  
Author(s):  
Antoine Lucas ◽  
Eric Gayer
Keyword(s):  
Time Series ◽  
Time Scale ◽  
Aerial Images ◽  
Sensor Calibration ◽  
Dense Matching ◽  
Time Period ◽  
Digital Elevation ◽  
Seasonal Time Scale ◽  
Areas Of Interest ◽  
Alpine Environments

<div> <div> <div> <p>On the seasonal time scale, for accessible locations and when manpower is available, direct observations and field survey are the most useful and standard approaches. However very limited studies have been conducted on direct observation at the decennial to century time-scale due to observational constrains. Here, we present an open and reproducible pipeline based on historical aerial images (up to 70 yrs time span) that includes sensor calibration, dense matching and elevation reconstruction over two areas of interest that represent pristine examples for tropical and alpine environments. The Remparts Canyon and Langevin River in Reunion Island, and the Bossons glacier in the French Alps share a limited accessibility (in time and space) that can be overcome only from remote-sensing. We reach a metric to sub-metric resolution close to the nominal images spatial sampling. This provides elevation time series with a better resolution to most recent satellite images such as Pleiades over decennial time period. </p> </div> </div> </div>

Recent changes in boreal aapa mires indicated by CPIsnow model and Landsat time series

2020 ◽  
Author(s):  
Antti Sallinen ◽  
Justice Akanegbu ◽  
Hannu Marttila ◽  
Timo Kumpula ◽  
Teemu Tahvanainen
Keyword(s):  
Time Series ◽  
Aerial Images ◽  
Hydrological Conditions ◽  
Temperature And Precipitation ◽  
Digital Elevation ◽  
Predicted Values ◽  
Peak Runoff ◽  
Elevation Model ◽  
Northern Peatlands ◽  
Boreal Landscape

&lt;p&gt; &lt;span&gt;Patterned fens (aapa mires) are important part of boreal landscape. Their distribution is controlled by climate and local hydrological conditions. In order to assess the changes and stresses climate change and land use may cause in these ecosystems, we modelled the past and future hydrology of twelve aapa mires in different parts of Finland. The study area extends from the southern to northern boreal zone.&lt;br&gt;&lt;br&gt;Mire catchments were delineated with the help of a digital elevation model. Wet minerotrophic areas (flarks) in the centers of aapa mires were traced from aerial images with numerical methods. Runoff modelling was done for the period 1962&amp;#8211;2099 with a conceptual model &amp;#8216;CPI snow&amp;#8217; using gridded temperature and precipitation data from historical weather records as well as predicted values based on climate scenarios.&lt;br&gt;&lt;br&gt;The results clearly indicate changes in hydrological conditions of aapa mires. In particular, timing and volume of spring peak runoff after snowmelt are affected. It is probable that the changes influence aapa mire wetness, vegetation, and eventually survival and distribution. We search for evidence of these changes from remote sensing time series (Landsat) from 1980s to present. Possible implications of changes in northern peatlands include loss of biodiversity and changes in carbon cycle.&lt;/span&gt;&lt;/p&gt;

scholarly journals An extended time-series (2000–2018) of global NPP-VIIRS-like nighttime light data from a cross-sensor calibration

2020 ◽  
Author(s):  
Zuoqi Chen ◽  
Bailang Yu ◽  
Chengshu Yang ◽  
Yuyu Zhou ◽  
Xingjian Qian ◽  
...  
Keyword(s):  
Time Series ◽  
Infrared Imaging ◽  
Sensor Calibration ◽  
Temporal Consistency ◽  
Extended Time ◽  
Economic Activities ◽  
Time Period ◽  
Nighttime Light Data ◽  
Nighttime Light ◽  
The Difference

Abstract. The nighttime light (NTL) satellite data have been widely used to investigate urbanization process. The Defense Meteorological Satellite Program-Operational Linescan System (DMSP-OLS) stable nighttime light data and Suomi National Polar-Orbiting Partnership-Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) nighttime light data are two widely used NTL datasets. However, the difference of their spatial resolutions and sensor design makes it difficult to directly use these two datasets together for a long-term analysis of urbanization. To solve this issue, an extended time-series (2000–2018) of NPP-VIIRS-like NTL data were proposed in this study through a cross-sensor calibration from DMSP-OLS NTL data (2000–2012) and a composition of monthly NPP-VIIRS NTL data (2013–2018). Compared with the annual composited NPP-VIIRS NTL data in 2012, our product of extended NPP-VIIRS-like NTL data shows a good consistency at the pixel and city levels with R2 of 0.87 and 0.95, respectively. We also found that our product has a good accuracy by comparing with DMSP-OLS radiance calibrated NTL (RNTL) data in 2000, 2004, 2006, and 2010. Generally, our extended NPP-VIIRS-like NTL data (2000–2018) have a good spatial pattern and temporal consistency, which are similar to the composited NPP-VIIRS NTL data. In addition, the resulting product could be easily updated and provide a useful proxy to monitor the dynamics of demographic and socio-economic activities for a longer time period compared to existing products. The extended time-series (2000–2018) of nighttime light data are freely accessible at https://doi.org/10.7910/DVN/YGIVCD (Chen et al., 2020).

scholarly journals InSAR Monitoring of Landslide Activity in Dominica

2021 ◽  
Vol 13 (4) ◽  
pp. 815
Author(s):  
Mary-Anne Fobert ◽  
Vern Singhroy ◽  
John G. Spray
Keyword(s):  
Risk Mitigation ◽  
Disaster Mitigation ◽  
Aerial Images ◽  
Landslide Inventory ◽  
Landslide Risk ◽  
Susceptibility Map ◽  
Interferometric Synthetic Aperture Radar ◽  
Rainfall Events ◽  
Susceptibility Maps ◽  
Digital Elevation

Dominica is a geologically young, volcanic island in the eastern Caribbean. Due to its rugged terrain, substantial rainfall, and distinct soil characteristics, it is highly vulnerable to landslides. The dominant triggers of these landslides are hurricanes, tropical storms, and heavy prolonged rainfall events. These events frequently lead to loss of life and the need for a growing portion of the island’s annual budget to cover the considerable cost of reconstruction and recovery. For disaster risk mitigation and landslide risk assessment, landslide inventory and susceptibility maps are essential. Landslide inventory maps record existing landslides and include details on their type, location, spatial extent, and time of occurrence. These data are integrated (when possible) with the landslide trigger and pre-failure slope conditions to generate or validate a susceptibility map. The susceptibility map is used to identify the level of potential landslide risk (low, moderate, or high). In Dominica, these maps are produced using optical satellite and aerial images, digital elevation models, and historic landslide inventory data. This study illustrates the benefits of using satellite Interferometric Synthetic Aperture Radar (InSAR) to refine these maps. Our study shows that when using continuous high-resolution InSAR data, active slopes can be identified and monitored. This information can be used to highlight areas most at risk (for use in validating and updating the susceptibility map), and can constrain the time of occurrence of when the landslide was initiated (for use in landslide inventory mapping). Our study shows that InSAR can be used to assist in the investigation of pre-failure slope conditions. For instance, our initial findings suggest there is more land motion prior to failure on clay soils with gentler slopes than on those with steeper slopes. A greater understanding of pre-failure slope conditions will support the generation of a more dependable susceptibility map. Our study also discusses the integration of InSAR deformation-rate maps and time-series analysis with rainfall data in support of the development of rainfall thresholds for different terrains. The information provided by InSAR can enhance inventory and susceptibility mapping, which will better assist with the island’s current disaster mitigation and resiliency efforts.

scholarly journals Locally and Remotely Forced Subtropical AMOC Variability: A Matter of Time Scales

2020 ◽  
Vol 33 (12) ◽  
pp. 5155-5172
Author(s):  
Quentin Jamet ◽  
William K. Dewar ◽  
Nicolas Wienders ◽  
Bruno Deremble ◽  
Sally Close ◽  
...  
Keyword(s):  
Time Series ◽  
Time Scales ◽  
North Atlantic ◽  
Time Scale ◽  
Low Frequency ◽  
Meridional Overturning Circulation ◽  
Open Boundary ◽  
Overturning Circulation ◽  
Decadal Scale ◽  
Meridional Overturning

AbstractMechanisms driving the North Atlantic meridional overturning circulation (AMOC) variability at low frequency are of central interest for accurate climate predictions. Although the subpolar gyre region has been identified as a preferred place for generating climate time-scale signals, their southward propagation remains under consideration, complicating the interpretation of the observed time series provided by the Rapid Climate Change–Meridional Overturning Circulation and Heatflux Array–Western Boundary Time Series (RAPID–MOCHA–WBTS) program. In this study, we aim at disentangling the respective contribution of the local atmospheric forcing from signals of remote origin for the subtropical low-frequency AMOC variability. We analyze for this a set of four ensembles of a regional (20°S–55°N), eddy-resolving (1/12°) North Atlantic oceanic configuration, where surface forcing and open boundary conditions are alternatively permuted from fully varying (realistic) to yearly repeating signals. Their analysis reveals the predominance of local, atmospherically forced signal at interannual time scales (2–10 years), whereas signals imposed by the boundaries are responsible for the decadal (10–30 years) part of the spectrum. Due to this marked time-scale separation, we show that, although the intergyre region exhibits peculiarities, most of the subtropical AMOC variability can be understood as a linear superposition of these two signals. Finally, we find that the decadal-scale, boundary-forced AMOC variability has both northern and southern origins, although the former dominates over the latter, including at the site of the RAPID array (26.5°N).

scholarly journals Complexity traits and synchrony of cryptocurrencies price dynamics

2021 ◽  
Author(s):  
Davide Provenzano ◽  
Rodolfo Baggio
Keyword(s):  
Time Series ◽  
Complex Network ◽  
Complex Structures ◽  
Slope Parameter ◽  
Exponential Distributions ◽  
Horizontal Visibility ◽  
Time Period ◽  
Before And After ◽  
Visibility Algorithm ◽  
Similar Complex

AbstractIn this study, we characterized the dynamics and analyzed the degree of synchronization of the time series of daily closing prices and volumes in US$ of three cryptocurrencies, Bitcoin, Ethereum, and Litecoin, over the period September 1,2015–March 31, 2020. Time series were first mapped into a complex network by the horizontal visibility algorithm in order to revel the structure of their temporal characters and dynamics. Then, the synchrony of the time series was investigated to determine the possibility that the cryptocurrencies under study co-bubble simultaneously. Findings reveal similar complex structures for the three virtual currencies in terms of number and internal composition of communities. To the aim of our analysis, such result proves that price and volume dynamics of the cryptocurrencies were characterized by cyclical patterns of similar wavelength and amplitude over the time period considered. Yet, the value of the slope parameter associated with the exponential distributions fitted to the data suggests a higher stability and predictability for Bitcoin and Litecoin than for Ethereum. The study of synchrony between the time series investigated displayed a different degree of synchronization between the three cryptocurrencies before and after a collapse event. These results could be of interest for investors who might prefer to switch from one cryptocurrency to another to exploit the potential opportunities of profit generated by the dynamics of price and volumes in the market of virtual currencies.

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