A 50-Year Sr/Ca Time Series from an Enclosed, Shallow-Water Guam Coral: In situ Monitoring and Extraction of a Temperature Trend, Annual Cycle, and ENSO and PDO Signals

<p>Large rock slopes instabilities form over long timescales through progressive rock mass strength weakening of initially stable slopes. Progressive rock mass damage is driven by environmental loads and is thus strongly dependent on the local setting and environmental conditions of the rock slope, which can vary over time. It is often assumed that the strong variations of the thermal and hydraulic boundary conditions during deglaciation in combination with unloading due to ice downwasting cause enhanced rates of rock mass damage. However, in-situ observations to quantify deformation, damage and the relevance of different drivers in such environments are rare. This presentation is related to the contribution of Oestreicher et al., presenting in the same session, addressing similar questions, but at different scales and based on different field data and analysis.</p><p>In this contribution we analyze continuous pore pressure, temperature and micrometer-scale deformation time series from a subsurface monitoring system comprised of three, 50 m deep, highly instrumented boreholes in a crystalline rock slope which is located beside the rapidly retreating glacier tongue of the Great Aletsch Glacier (Switzerland). We compare high-resolution reversible and irreversible deformation signals with potential drivers, including locally measured pore pressure fluctuation, rock temperature variations, and nearby earthquakes. We show that shallow (10 - 15 m deep) deformations in our rock slope are dominated by thermo-mechanical forcing, whereas deformation measured below this depth is mainly driven by hydro-mechanical effects related to pore pressure fluctuations. Both reversible deformation and irreversible damage events occur more frequently during the snow-free summer season, when we observe higher dynamics in thermal and hydraulic boundary conditions. In our 2.5 years long time series, we do not find any significant deformation event coinciding with a nearby earthquake. Additionally, we discuss differences in the deformation signal with respect to the stability state and the rock mass quality at the different monitoring locations. Also, we assess longer term impacts of glacier retreat and ice downwasting on rock slope deformation and damage. Such information is critical for an improved understanding and quantification of factors contributing to the formation of paraglacial rock slope instabilities.</p>

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SONIC LAYER DEPTH VARIATION ANALYSIS UTILIZING BIDE (BANDA ITF DYNAMIC EXPERIMENT) ARGO FLOAT IN SITU OBSERVATION FOR UNDERSEA WARFARE TACTICAL ENVIRONMENT SUPPORT

JOURNAL ASRO ◽

10.37875/asro.v9i1.60 ◽

2018 ◽

Vol 9 (1) ◽

pp. 62

Author(s):

D Armansyah ◽

N B Sukoco ◽

W S Pranowo

Keyword(s):

Time Series ◽

Annual Cycle ◽

Series Data ◽

Variation Analysis ◽

Dynamic Experiment ◽

Layer Depth ◽

Depth Variation ◽

Argo Float ◽

Cycle Variation

ABSTRACT Sonic Layer Depth is the vertical distance from surface to the depth where the speed of sound reach it’s local maximum. Global Navy as well as Indonesan Navy operates in this kind of layers on a daily basis, wether it be in an anti submarine warfare operation through its ships and aircrafts or in an anti-surface warfare operation waged by its submarines. For the navy, the importance of knowing the exact value of the SLD is because it determines the minimum cut off frequency and sound wave propagation above which sound tends to be trapped and below which a shadow zone exist. This has a direct impact on where the navy operates its sensors and places its platforms in the water column. The best way to estimate SLD is by performing own measurement on the ocean using instrument such as expendable bathytermographs, which can be relatively expensive and time consuming for an operational navy ships, furthermore such measurement may be impractical in the case of mission planning or emergencies. Dedicated oceanography survey for the purpose of science and defense is relatively scarce due to prioritization concerning to the budget available resulting lack of time series in situ CTD observation which cover full annual cycle variation in Indonesia waters. Banda Indonesia Through Flow Dynamic Experiment (BIDE) is multi institution and bilateral oceanography experiment led by Indonesian scientist which utilizes argo float to perform in situ CTD measurement in Banda Sea to get an adequate time series data that cover full annual cycle variation. The dataset is publicly available so defense community as well may utilize the data for defense interest such as sonic layer depth variation analysis in Banda Sea. Keyword : sonic layer depth, BIDE, argo float, undersea warfare, tactical environment

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Potential of Synthetic Aperture Radar Sentinel-1 time series for the monitoring of phenological cycles in a deciduous forest

10.1101/2021.02.04.429811 ◽

2021 ◽

Author(s):

Kamel Soudani ◽

Nicolas Delpierre ◽

Daniel Berveiller ◽

Gabriel Hmimina ◽

Gaëlle Vincent ◽

...

Keyword(s):

Time Series ◽

Synthetic Aperture Radar ◽

Leaf Senescence ◽

Temporal Dynamics ◽

Deciduous Forest ◽

In Situ Monitoring ◽

Synthetic Aperture ◽

Cross Polarization ◽

Aperture Radar

AbstractAnnual time-series of the two satellites C-band SAR (Synthetic Aperture Radar) Sentinel-1 A and B data over five years were used to characterize the phenological cycle of a temperate deciduous forest. Six phenological markers of the start, middle and end of budburst and leaf expansion stage in spring and the leaf senescence in autumn were extracted from time-series of the ratio (VV/VH) of backscattering at co-polarization VV (vertical-vertical) and at cross polarization VH (vertical-horizontal). These markers were compared to field phenological observations, and to phenological dates derived from various proxies (Normalized Difference Vegetation Index NDVI time-series from Sentinel-2 A and B images, in situ NDVI measurements, Leaf Area Index LAI and litterfall temporal dynamics). We observe a decrease in the backscattering coefficient (σ0) at VH cross polarization during the leaf development and expansion phase in spring and an increase during the senescence phase, contrary to what is usually observed on various types of crops. In vertical polarization, σ0VV shows very little variation throughout the year. S-1 time series of VV/VH ratio provides a good description of the seasonal vegetation cycle allowing the estimation of spring and autumn phenological markers. Estimates provided by VV/VH of budburst dates differ by approximately 8 days on average from phenological observations. During senescence phase, estimates are positively shifted (later) and deviate by about 20 days from phenological observations of leaf senescence while the differences are of the order of 2 to 4 days between the phenological observations and estimates based on in situ NDVI and LAI time-series, respectively. A deviation of about 7 days, comparable to that observed during budburst, is obtained between the estimates of senescence from S-1 and those determined from the in situ monitoring of litterfall. While in spring, leaf emergence and expansion described by LAI or NDVI explains the increase of VV/VH (or the decrease of σ0VH), during senescence, S-1 VV/VH is decorrelated from LAI or NDVI and is better explained by litterfall temporal dynamics. This behavior resulted in a hysteresis phenomenon observed on the relationships between VV/VH and NDVI or LAI. For the same LAI or NDVI, the response of VV/VH is different depending on the phenological phase considered. This study shows the high potential offered by Sentinel-1 SAR C-band time series for the detection of forest phenology for the first time, thus overcoming the limitations caused by cloud cover in optical remote sensing of vegetation phenology.HighlightsWe study S-1 C-band dual polarized data potential to predict forest phenologySeasonal phenological transitions were accurately described by S-1 time-seriesBudburst and senescence dates from S-1 differ from direct observations by one weekTime-series of S-1 VV/VH, NDVI, LAI and litterfall were also comparedRelationships VV/VH vs NDVI and LAI show a hysteresis according to the season

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CHARACTERIZATION OF THE FROST HEAVE DEFORMATIONS IN HIGH LATITUDE AND DEEP SEASONALLY FROZEN SOIL OF INNER MONGOLIA WITH SENTINEL-1 INSAR OBSERVATIONS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xliii-b3-2020-887-2020 ◽

2020 ◽

Vol XLIII-B3-2020 ◽

pp. 887-891

Author(s):

T. Qu ◽

H. Zhang ◽

F. Niu ◽

X. Shi ◽

Z. Li

Keyword(s):

Time Series ◽

High Latitude ◽

Inner Mongolia ◽

Hydrothermal Process ◽

Frozen Soil ◽

In Situ Monitoring ◽

Frost Heave ◽

Permafrost Degradation

Abstract. Global warming in recent years led to significant permafrost degradation worldwide. Accurate monitoring and comprehensive characterization of the deformation process in seasonally frozen soil is of great importance for constructions in cold regions in China. This work concentrates on the deformation laws and spatio-temporal characteristics of frost heave in high latitude and seasonally frozen soil of Inner Mongolia with time series InSAR observations. With 101 Sentinel-1 descending scenes that covered more than three freeze-thaw cycles for the study area along Shiwei-Labudalin Highway, this study realized the characterization of the frost heave deformations in seasonally frozen soil, and the analysis of the influencing factors of the hydrothermal process with the help of temperature and moisture data from in-situ monitoring. Time series InSAR observations show that most parts of the highway show obvious deformation with a displacement rate of around 30–60 mm/yr. Especially, the deformation evolution in this seasonally frozen soil region changes with seasons, demonstrating a notable annual cyclical characteristic and seasonal activity. Moreover, time series in-situ monitoring data in deep underground boreholes not only further explains the deformation kinematics from InSAR observations, but also provide a better supplement for a more comprehensive mechanism understanding of frost heave deformations.

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