scholarly journals QUAL-NET, a high temporal-resolution eutrophication model for large hydrographic networks

2018 ◽  
Vol 15 (7) ◽  
pp. 2251-2269 ◽  
Author(s):  
Camille Minaudo ◽  
Florence Curie ◽  
Yann Jullian ◽  
Nathalie Gassama ◽  
Florentina Moatar
Keyword(s):  
Climate Change ◽  
Temporal Resolution ◽  
Regional Scale ◽  
High Temporal Resolution ◽  
P Availability ◽  
Model Quality ◽  
Deterministic Models ◽  
Bacterial Dynamics ◽  
Complex Interactions ◽  
Loire River

Abstract. To allow climate change impact assessment of water quality in river systems, the scientific community lacks efficient deterministic models able to simulate hydrological and biogeochemical processes in drainage networks at the regional scale, with high temporal resolution and water temperature explicitly determined. The model QUALity-NETwork (QUAL-NET) was developed and tested on the Middle Loire River Corridor, a sub-catchment of the Loire River in France, prone to eutrophication. Hourly variations computed efficiently by the model helped disentangle the complex interactions existing between hydrological and biological processes across different timescales. Phosphorus (P) availability was the most constraining factor for phytoplankton development in the Loire River, but simulating bacterial dynamics in QUAL-NET surprisingly evidenced large amounts of organic matter recycled within the water column through the microbial loop, which delivered significant fluxes of available P and enhanced phytoplankton growth. This explained why severe blooms still occur in the Loire River despite large P input reductions since 1990. QUAL-NET could be used to study past evolutions or predict future trajectories under climate change and land use scenarios.

scholarly journals QUAL-NET, a high temporal resolution eutrophication model in large hydrographic networks

2017 ◽  
Author(s):  
Camille Minaudo ◽  
Florence Curie ◽  
Yann Jullian ◽  
Nathalie Gassama ◽  
Florentina Moatar
Keyword(s):  
Temporal Resolution ◽  
Regional Scale ◽  
River System ◽  
High Temporal Resolution ◽  
Model Quality ◽  
Deterministic Models ◽  
Time Model ◽  
Complex Interactions ◽  
Drainage Networks ◽  
Loire River

Abstract. To allow climate change impact assessment on river system water quality, the scientific community lacks efficient deterministic models able to simulate hydrological and biogeochemical processes in drainage networks at the regional scale, with a fine temporal resolution and with water temperature explicitly determined. The model QUALity-NETwork (QUAL-NET) was developed and tested on the Middle Loire River Corridor, a sub-catchment of the Loire River (France), prone to eutrophication. Hourly variations computed by the model helped disentangle the complex interactions existing between hydrological and biological processes across different timescales. Phytoplankton variations in the Loire River were governed by phosphorus availability and transit time. Model QUAL-NET showed that a large amount of phytoplankton cells growing in the upper part of the studied corridor was recycled through the microbial loop, which enhanced phytoplankton growth, explaining why severe blooms still occur in the Loire River despite large P input reductions.

Climate change during the past 1000 years: a high-temporal-resolution multiproxy record from a mire in northern Finland

2012 ◽  
Vol 28 (2) ◽  
pp. 152-164 ◽  
Author(s):  
Walter Finsinger ◽  
Kristian Schoning ◽  
Sheila Hicks ◽  
Andreas Lücke ◽  
Tomasz Goslar ◽  
...  
Keyword(s):  
Climate Change ◽  
Temporal Resolution ◽  
High Temporal Resolution ◽  
The Past ◽  
Past 1000 Years

scholarly journals First measurements of continuous δ<sup>18</sup>O-CO<sub>2</sub> with a Fourier Transform InfraRed spectrometer in Heidelberg, Germany

2014 ◽  
Vol 7 (7) ◽  
pp. 6501-6528
Author(s):  
S. N. Vardag ◽  
S. Hammer ◽  
M. Sabasch ◽  
D. W. T. Griffith ◽  
I. Levin
Keyword(s):  
Fourier Transform ◽  
Temporal Resolution ◽  
Regional Scale ◽  
Fourier Transform Infrared ◽  
Ambient Air ◽  
High Temporal Resolution ◽  
Exchange Processes ◽  
Infrared Spectrometer ◽  
Gas Measurements ◽  
The Fourier Transform

Abstract. The continuous in-situ measurement of δ18O in atmospheric CO2 opens a new door to differentiating between CO2 source and sink components with high temporal resolution. Continuous 13C-CO2 measurement systems have been commercially available already for some time, but until now, only few instruments have been able to provide a continuous measurement of the oxygen isotope ratio in CO2. Besides precise 13C/12C observations, the Fourier Transform InfraRed (FTIR) spectrometer also measures the 18O/16O ratio of CO2, but the precision and accuracy of the measurements has not been evaluated yet. Here we present a first analysis of δ18O-CO2 (and δ13C-CO2) measurements with the FTIR in Heidelberg. We find that our spectrometer measures 18O in CO2 with a reproducibility of better than 0.3‰ at a temporal resolution of less than 10 min, as determined from surveillance gas measurements over a period of ten months. An Allan deviation test shows that the δ18O repeatability reaches 0.15‰ for half-hourly means. The compatibility of our spectroscopic measurements was determined by comparing FTIR measurements of calibration gases and ambient air to mass-spectrometric measurements of flask samples, filled with the cylinder gases or episodically collected over a diurnal cycle (event). We found that direct cylinder gas measurements agree to 0.01 ± 0.04‰ (mean and standard deviation) for δ13C-CO2 and 0.01 ± 0.11‰ for δ18O. Two weekly episodes of recent ambient air measurements, one in winter and one in summer, are discussed in view of the question, which potential insights and new challenges combined highly resolved δ18O-CO2 and δ13C-CO2 records may provide in terms of better understanding regional scale continental carbon exchange processes.

scholarly journals Rainfall intensity bursts and the erosion of soils: an analysis highlighting the need for high temporal resolution rainfall data for research under current and future climates

2019 ◽  
Author(s):  
David L. Dunkerley
Keyword(s):  
Climate Change ◽  
Temporal Resolution ◽  
Rainfall Intensity ◽  
Explanatory Power ◽  
Tropical Climate ◽  
Rainfall Data ◽  
High Temporal Resolution ◽  
Hourly Data ◽  
Rainfall Extremes ◽  
Period Data

Abstract. Many landsurface processes, including splash dislodgment and downslope transport of soil materials, are influenced strongly by short-lived peaks in rainfall intensity but are less well accounted for by longer-term average rates. Specifically, rainfall intensities reached over periods of 10–30 minutes appear to have more explanatory power than hourly or longer-period data. However, most analyses of rainfall, and particularly scenarios of possible future rainfall extremes under climate change, rely on hourly data. Using two Australian pluviograph records with 1 second resolution, one from an arid and one from a wet tropical climate, the nature of short-lived intensity bursts is analysed from the raw inter-tip times of the tipping bucket gauges. Hourly apparent rainfall intensities average just 1.43 mm h−1 at the wet tropical site, and 2.12 mm h−1 at the arid site. At the wet tropical site, intensity bursts of extreme intensity occur frequently, those exceeding 30 mm h−1 occurring on average at intervals of  60 mm h−1 occurring on average at intervals of

scholarly journals First continuous measurements of δ<sup>18</sup>O-CO<sub>2</sub> in air with a Fourier transform infrared spectrometer

2015 ◽  
Vol 8 (2) ◽  
pp. 579-592 ◽  
Author(s):  
S. N. Vardag ◽  
S. Hammer ◽  
M. Sabasch ◽  
D. W. T. Griffith ◽  
I. Levin
Keyword(s):  
Fourier Transform ◽  
Temporal Resolution ◽  
Isotope Ratio ◽  
Regional Scale ◽  
Fourier Transform Infrared ◽  
Ambient Air ◽  
Measurement Precision ◽  
High Temporal Resolution ◽  
Significance Level ◽  
Gas Measurements

Abstract. The continuous in situ measurement of δ18O in atmospheric CO2 opens a new door to differentiating between CO2 source and sink components with high temporal resolution. Continuous 13C–CO2 measurement systems have already been commercially available for some time, but until now, only few instruments have been able to provide a continuous measurement of the oxygen isotope ratio in CO2. Besides precise 13C/12C observations, the Fourier transform infrared (FTIR) spectrometer is also able to measure the 18O / 16O ratio in CO2, but the precision and accuracy of the measurements have not yet been evaluated. Here we present a first analysis of δ18O-CO2 (and δ13C-CO2) measurements with the FTIR analyser in Heidelberg. We used Allan deviation to determine the repeatability of δ18O-CO2 measurements and found that it decreases from 0.25‰ for 10 min averages to about 0.1‰ after 2 h and remains at that value up to 24 h. We evaluated the measurement precision over a 10-month period (intermediate measurement precision) using daily working gas measurements and found that our spectrometer measured δ18O-CO2 to better than 0.3‰ at a temporal resolution of less than 10 min. The compatibility of our FTIR-spectrometric measurements to isotope-ratio mass-spectrometric (IRMS) measurements was determined by comparing FTIR measurements of cylinder gases and ambient air with IRMS measurements of flask samples, filled with gases of the same cylinders or collected from the same ambient air intake. Two-sample t tests revealed that, at the 0.01 significance level, the FTIR and the IRMS measurements do not differ significantly from each other and are thus compatible. We describe two weekly episodes of ambient air measurements, one in winter and one in summer, and discuss what potential insights and new challenges combined highly resolved CO2, δ13C-CO2 and δ18O-CO2 records may provide in terms of better understanding regional scale continental carbon exchange processes.

scholarly journals Improving the monitoring of deciduous broadleaf phenology using the Geostationary Operational Environmental Satellite (GOES) 16 and 17

2020 ◽  
Author(s):  
Kathryn I. Wheeler ◽  
Michael C. Dietze
Keyword(s):  
Climate Change ◽  
Temporal Resolution ◽  
Ecosystem Processes ◽  
Western Hemisphere ◽  
High Temporal Resolution ◽  
P Values ◽  
Modis Ndvi ◽  
Remotely Sense ◽  
Limited Coverage ◽  
Lower Temporal Resolution

Abstract. Monitoring leaf phenology allows for tracking the progression of climate change and seasonal variations in a variety of organismal and ecosystem processes. Networks of finite-scale remote sensing, such as the PhenoCam Network, provide valuable information on phenological state at high temporal resolution, but have limited coverage. To more broadly remotely sense phenology, satellite-based data that has lower temporal resolution has primarily been used (e.g., 16-day MODIS NDVI product). Recent versions of the Geostationary Operational Environmental Satellites (GOES-16 and -17) allow the monitoring of NDVI at temporal scales comparable to that of PhenoCam throughout most of the western hemisphere. Here we examine the current capacity of this new data to measure the phenology of deciduous broadleaf forests for the first two full calendar years of data (2018 and 2019) by fitting double-logistic Bayesian models and comparing the start, middle, and end of season transition dates to those obtained from PhenoCam and MODIS 16-day NDVI and EVI products. Compared to the MODIS indices, GOES was more correlated with PhenoCam at the start and middle of spring, but had a larger bias (3.35 &amp;pm; 0.03 days later than PhenoCam) at the end of spring. Satellite-based autumn transition dates were mostly uncorrelated with those of PhenoCam. PhenoCam data produced significantly more certain (all p-values 

Regional seismic velocity changes following the 2019 Mw7.1 Ridgecrest California earthquake from autocorrelations and P/S converted waves

2021 ◽  
Author(s):  
Y Lu ◽  
Y Ben-Zion
Keyword(s):  
Temporal Resolution ◽  
Seismic Velocity ◽  
Time Windows ◽  
Regional Scale ◽  
Early Period ◽  
Temporal Changes ◽  
High Temporal Resolution ◽  
Seismic Velocities ◽  
Seismic Velocity Changes ◽  
Velocity Changes

Summary We examine regional transient changes of seismic velocities generated by the Mw 7.1 2019 Ridgecrest earthquake in California, using autocorrelations of moving time windows in continuous waveforms recorded at regional stations. We focus on travel time differences in a prominent phase generated by an interface around 2 km depth, associated with transmitted Pp waves and converted Ps waves from the ongoing microseismicity. Synthetic tests demonstrate the feasibility of the method for monitoring seismic velocity changes. Taking advantage of the numerous aftershocks in the early period following the mainshock, we obtain a temporal resolution of velocity changes up to 20 min in the early post-mainshock period. The results reveal regional coseismic velocity drops in the top 1–3 km with an average value of ∼2 per cent over distances up to 100 km from the Ridgecrest event. These average velocity drops are likely dominated by larger changes in the shallow materials, and are followed by rapid recoveries on timescales of days. Around the north end of the Ridgecrest rupture and the nearby Coso geothermal region, the observed coseismic velocity drops are up to ∼8 per cent. The method allows monitoring temporal changes of seismic velocities with high temporal resolution, fast computation, and precise spatial mapping of changes. The results suggest that significant temporal changes of seismic velocities of shallow materials are commonly generated on a regional scale by large events.

Multidetector-row Computed Tomography in the Assessment of Coronary Artery Disease – New Techniques and Insights

2010 ◽  
Vol 6 (2) ◽  
pp. 43 ◽  
Author(s):  
Andreas H Mahnken ◽  
Keyword(s):  
Computed Tomography ◽  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Data Acquisition ◽  
Temporal Resolution ◽  
High Temporal Resolution ◽  
Multidetector Row ◽  
Ct Scanners ◽  
Artery Disease ◽  
Cardiac Mdct

Over the last decade, cardiac computed tomography (CT) technology has experienced revolutionary changes and gained broad clinical acceptance in the work-up of patients suffering from coronary artery disease (CAD). Since cardiac multidetector-row CT (MDCT) was introduced in 1998, acquisition time, number of detector rows and spatial and temporal resolution have improved tremendously. Current developments in cardiac CT are focusing on low-dose cardiac scanning at ultra-high temporal resolution. Technically, there are two major approaches to achieving these goals: rapid data acquisition using dual-source CT scanners with high temporal resolution or volumetric data acquisition with 256/320-slice CT scanners. While each approach has specific advantages and disadvantages, both technologies foster the extension of cardiac MDCT beyond morphological imaging towards the functional assessment of CAD. This article examines current trends in the development of cardiac MDCT.

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