Model-based and in-situ observations of high-frequency (10s–100s kHz) acoustic scattering from multiple targets

Abstract The feasibility of using high-frequency acoustic scattering techniques to map the extent and evolution of the diffusive regime of double-diffusive convection in the ocean is explored. A scattering model developed to describe acoustic scattering from double-diffusive interfaces in the laboratory, which accounted for much of the measured scattering in the frequency range from 200 to 600 kHz, is used in conjunction with published in situ observations of diffusive-convection interfaces to make predictions of acoustic scattering from oceanic double-diffusive interfaces. Detectable levels of acoustic scattering are predicted for a range of different locations in the world’s oceans. To corroborate these results, thin acoustic layers detected near the western Antarctic Peninsula using a multifrequency acoustic backscattering system are shown to be consistent with scattering from diffusive-convection interfaces.

Download Full-text

Assessment of Four Model-Based Surface Soil Temperature Products Unsing Global Dense in Situ Observations

10.1109/igarss47720.2021.9554151 ◽

2021 ◽

Author(s):

Hongliang Ma ◽

Jiangyuan Zeng ◽

Jean-Pierre Wigneron ◽

Xiang Zhang ◽

Nengcheng Chen ◽

...

Keyword(s):

Soil Temperature ◽

Surface Soil ◽

Model Based ◽

Surface Soil Temperature ◽

In Situ Observations

Download Full-text

Evaluation of Remotely-Sensed and Model-Based Soil Moisture Products According to Different Soil Type, Vegetation Cover and Climate Regime Using Station-Based Observations over Turkey

Remote Sensing ◽

10.3390/rs11161875 ◽

2019 ◽

Vol 11 (16) ◽

pp. 1875 ◽

Cited By ~ 2

Author(s):

Burak Bulut ◽

M. Tugrul Yilmaz ◽

Mehdi H. Afshar ◽

A. Ünal Şorman ◽

İsmail Yücel ◽

...

Keyword(s):

Soil Moisture ◽

Root Mean Square ◽

Soil Type ◽

Vegetation Cover ◽

Remotely Sensed ◽

Mean Square ◽

Climate Regime ◽

Model Based ◽

In Situ Observations

This study evaluates the performance of widely-used remotely sensed- and model-based soil moisture products, including: The Advanced Scatterometer (ASCAT), the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E), the European Space Agency Climate Change Initiative (ESA-CCI), the Antecedent Precipitation Index (API), and the Global Land Data Assimilation System (GLDAS-NOAH). Evaluations are performed between 2008 and 2011 against the calibrated station-based soil moisture observations collected by the General Directorate of Meteorology of Turkey. The calibration of soil moisture observing sensors with respect to the soil type, correction of the soil moisture for the soil temperature, and the quality control of the collected measurements are performed prior to the evaluation of the products. Evaluation of remotely sensed- and model-based soil moisture products is performed considering different characteristics of the time series (i.e., seasonality and anomaly components) and the study region (i.e., soil type, vegetation cover, soil wetness and climate regime). The systematic bias between soil moisture products and in situ measurements is eliminated by using a linear rescaling method. Correlations between the soil moisture products and the in situ observations vary between 0.57 and 0.87, while the root mean square errors of the products versus the in situ observations vary between 0.028 and 0.043 m3 m−3. Overall, according to the correlation and root mean square error values obtained in all evaluation categories, NOAH and ESA-CCI soil moisture products perform better than all the other model- and remotely sensed-based soil moisture products. These results are valid for the entire study time period and all of the sub-categories under soil type, vegetation cover, soil wetness and climate regime.

Download Full-text

Extreme heat events heighten soil respiration

Scientific Reports ◽

10.1038/s41598-021-85764-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Hassan Anjileli ◽

Laurie S. Huning ◽

Hamed Moftakhari ◽

Samaneh Ashraf ◽

Ata Akbari Asanjan ◽

...

Keyword(s):

Soil Respiration ◽

Carbon Cycle ◽

High Frequency ◽

The Past ◽

Extreme Heat Events ◽

In Situ Observations ◽

Terrestrial Feedback ◽

The Relationship ◽

Heat Events

AbstractIn the wake of climate change, extreme events such as heatwaves are considered to be key players in the terrestrial biosphere. In the past decades, the frequency and severity of heatwaves have risen substantially, and they are projected to continue to intensify in the future. One key question is therefore: how do changes in extreme heatwaves affect the carbon cycle? Although soil respiration (Rs) is the second largest contributor to the carbon cycle, the impacts of heatwaves on Rs have not been fully understood. Using a unique set of continuous high frequency in-situ measurements from our field site, we characterize the relationship between Rs and heatwaves. We further compare the Rs response to heatwaves across ten additional sites spanning the contiguous United States (CONUS). Applying a probabilistic framework, we conclude that during heatwaves Rs rates increase significantly, on average, by ~ 26% relative to that of non-heatwave conditions over the CONUS. Since previous in-situ observations have not measured the Rs response to heatwaves (e.g., rate, amount) at the high frequency that we present here, the terrestrial feedback to the carbon cycle may be underestimated without capturing these high frequency extreme heatwave events.

Download Full-text

Extreme event occurrences and impacts in coastal waters of western Europe

10.5194/egusphere-egu2020-14936 ◽

2020 ◽

Author(s):

Coline Poppeschi ◽

Maximilian Unterberger ◽

Guillaume Charria ◽

Peggy Rimmelin-Maury ◽

Eric Goberville ◽

...

Keyword(s):

Extreme Events ◽

Coastal Waters ◽

High Frequency ◽

Western Europe ◽

Extreme Event ◽

Low Frequency ◽

In Situ Observations ◽

Bay Of Brest ◽

The Relationship

Extreme event occurrences and impacts in coastal waters of western Europe&#160;Coline Poppeschi1, Maximilian Unterberger1, Guillaume Charria1, Peggy Rimmelin-Maury2, Eric Goberville3, Nicolas Barrier5, Emilie Grossteffan2, Michel Repecaud6, Loi&#776;c Quemener6, Se&#769;bastien Theetten1, S&#233;bastien Petton7, Jean-Fran&#231;ois Le Roux1, Paul Tre&#769;guer4&#160;1 Ifremer, Univ. Brest, CNRS, IRD, Laboratoire d'Oc&#233;anographie Physique et Spatiale (LOPS), IUEM, 29280 Brest, France.2 OSU-Institut Universitaire Europe&#769;en de la Mer (IUEM), UMS3113, F-29280, Plouzane&#769;, France.3 Muse&#769;um National d&#8217;Histoire Naturelle, UMR 7208 BOREA, Sorbonne Universite&#769;, CNRS, UCN, UA, IRD, Paris, France.4 IUEM, UMR-CNRS 6539 Laboratoire de l&#8217;Environnement Marin (LEMAR), OSU IUEM, F-29280, Plouzane&#769;, France.5 MARBEC, Universite&#769; de Montpellier, Centre National de la Recherche Scientifique (CNRS), Ifremer, Institut de Recherche pour le De&#769;veloppement (IRD), F-34203 Se&#768;te, France.6 Ifremer, Centre de Brest, REM/RDT/DCM, F-29280, Plouzane&#769;, France.7 Ifremer, Centre de Brest, RBE/PFOM/LPI, F-29840, Argenton en Landunvez, France.&#160;Abstract&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; The occurrence and the impact of the atmospheric extreme events in coastal waters of western Europe is evolving. Responses of the coastal environment to those events and evolutions need to be explored and explained. In this framework, the hydrodynamical and biogeochemical processes driven by extreme events in the bay of Brest are studied to better estimate their impacts on the local ecosystem. We are analyzing long-term in situ observations (since 2000), sampled at high and low frequencies, from the COAST-HF and SOMLIT network sites, located at the entrance to the bay of Brest. This study is divided into two main parts: the detection and characterization of extreme events, followed by the analysis of a realistic numerical simulation of these events to understand the underlying ocean processes. We focus on freshwater events during the winter months (December, January, February and March), considering the season with most of extreme event occurrence. The relationship between local extreme events and variability at larger scales, considering climate indices such as the North Atlantic Oscillation (NAO), is detailed. A comparison between the low frequency data from the SOMLIT network and the high frequency data from the COAST-HF network is carried out, highlighting the potential of high frequency measurements for the detection of extreme events. A comparison between in situ data and two numerical simulations of different resolutions is also performed over salinity time series. The interannual variability of extreme event occurrences and features in a context of climate change is also discussed. The link between these extreme low salinity events and the winter nitrate levels in the bay of Brest is shown. Then, we investigate the relationship between extreme events and biology in the coastal environment.&#160;Keywords In-situ observations, High and low frequency measurements, Extreme events, Numerical simulations, Bay of Brest, Weather regimes.

Download Full-text

A 24-year record of high-frequency, in situ, observations of hydrogen at the Atmospheric Research Station at Mace Head, Ireland

Atmospheric Environment ◽

10.1016/j.atmosenv.2019.01.050 ◽

2019 ◽

Vol 203 ◽

pp. 28-34 ◽

Cited By ~ 2

Author(s):

Richard G. Derwent ◽

Peter G. Simmonds ◽

Simon J. O'Doherty ◽

Alistair J. Manning ◽

T. Gerard Spain

Keyword(s):

High Frequency ◽

Research Station ◽

Atmospheric Research ◽

In Situ Observations

Download Full-text

In situ observations of velocity changes in response to tidal deformation from analysis of the high-frequency ambient wavefield

Journal of Geophysical Research Solid Earth ◽

10.1002/2014jb011318 ◽

2015 ◽

Vol 120 (1) ◽

pp. 210-225 ◽

Cited By ~ 26

Author(s):

G. Hillers ◽

L. Retailleau ◽

M. Campillo ◽

A. Inbal ◽

J.-P. Ampuero ◽

...

Keyword(s):

High Frequency ◽

Tidal Deformation ◽

In Situ Observations ◽

Velocity Changes

Download Full-text

In situ observations of electromigration induced void behavior

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137598 ◽

1995 ◽

Vol 53 ◽

pp. 244-245

Author(s):

T. Marieb ◽

J. C. Bravman ◽

P. Flinn ◽

D. Gardner ◽

M. Madden

Keyword(s):

Electron Microscopy ◽

Void Nucleation ◽

Plan View ◽

Transmission Electron ◽

Nucleation Sites ◽

Microelectronics Industry ◽

In Situ Observations ◽

Backscatter Electron Detector ◽

Voltage Scanning

Electromigration and stress voiding have been active areas of research in the microelectronics industry for many years. While accelerated testing of these phenomena has been performed for the last 25 years[1-2], only recently has the introduction of high voltage scanning electron microscopy (HVSEM) made possible in situ testing of realistic, passivated, full thickness samples at high resolution.With a combination of in situ HVSEM and post-testing transmission electron microscopy (TEM) , electromigration void nucleation sites in both normal polycrystalline and near-bamboo pure Al were investigated. The effect of the microstructure of the lines on the void motion was also studied.The HVSEM used was a slightly modified JEOL 1200 EX II scanning TEM with a backscatter electron detector placed above the sample[3]. To observe electromigration in situ the sample was heated and the line had current supplied to it to accelerate the voiding process. After testing lines were prepared for TEM by employing the plan-view wedge technique [6].

Download Full-text