scholarly journals Glider-Based Active Acoustic Monitoring of Currents and Turbidity in the Coastal Zone

2020 ◽  
Vol 12 (18) ◽  
pp. 2875
Author(s):  
Mathieu Gentil ◽  
Gaël Many ◽  
Xavier Durrieu de Madron ◽  
Pierre Cauchy ◽  
Ivane Pairaud ◽  
...  
Keyword(s):  
Coastal Zone ◽  
Weather Conditions ◽  
Sediment Dynamics ◽  
Spatial And Temporal Variability ◽  
Geostrophic Balance ◽  
Underwater Gliders ◽  
Suspended Particulate ◽  
River Region ◽  
Optical Turbidity ◽  
Acoustic Doppler Current Profilers

The recent integration of Acoustic Doppler Current Profilers (ADCPs) onto underwater gliders changes the way current and sediment dynamics in the coastal zone can be monitored. Their endurance and ability to measure in all weather conditions increases the probability of capturing sporadic meteorological events, such as storms and floods, which are key elements of sediment dynamics. We used a Slocum glider equipped with a CTD (Conductivity, Temperature, Depth), an optical payload, and an RDI 600 kHz phased array ADCP. Two deployments were carried out during two contrasting periods of the year in the Rhone River region of freshwater influence (ROFI). Coastal absolute currents were reconstructed using the shear method and bottom tracking measurements, and generally appear to be in geostrophic balance. The responses of the acoustic backscatter index and optical turbidity signals appear to be linked to changes of the particle size distribution in the water column. Significantly, this study shows the interest of using a glider-ADCP for coastal zone monitoring. However, the comparison between suspended particulate matter dynamics from satellites and gliders also suggests that a synoptic view of the processes involved requires a multiplatform approach, especially in systems with high spatial and temporal variability, such as the Rhone ROFI area.

scholarly journals Depth-Average Velocity from Spray Underwater Gliders

2018 ◽  
Vol 35 (8) ◽  
pp. 1665-1673 ◽  
Author(s):  
Daniel L. Rudnick ◽  
Jeffrey T. Sherman ◽  
Alexander P. Wu
Keyword(s):  
Average Velocity ◽  
Dead Reckoning ◽  
Water Velocity ◽  
Accurate Estimation ◽  
Underwater Glider ◽  
Underwater Gliders ◽  
Before And After ◽  
The Difference ◽  
Using Data ◽  
Acoustic Doppler Current Profilers

AbstractThe depth-average velocity is routinely calculated using data from underwater gliders. The calculation is a dead reckoning, where the difference between the glider’s velocity over ground and its velocity through water yields the water velocity averaged over the glider’s dive path. Given the accuracy of global positioning system navigation and the typical 3–6-h dive cycle, the accuracy of the depth-average velocity is overwhelmingly dependent on the accurate estimation of the glider’s velocity through water. The calculation of glider velocity through water for the Spray underwater glider is described. The accuracy of this calculation is addressed using a method similar to that used with shipboard acoustic Doppler current profilers, where water velocity is compared before and after turns to determine a gain to apply to glider velocity through water. Differences of this gain from an ideal value of one are used to evaluate accuracy. Sustained glider observations of several years off California and Palau consisted of missions involving repeated straight sections, producing hundreds of turns. The root-mean-square accuracy of depth-average velocity is estimated to be in the range of 0.01–0.02 m s−1, consistent with inferences from the early days of underwater glider design.

scholarly journals An empirical remote sensing algorithm for retrieving total suspended matter in a large estuarine region

2019 ◽  
Vol 83 (1) ◽  
pp. 53
Author(s):  
Martina D. Camiolo ◽  
Ezequiel Cozzolino ◽  
Ana I. Dogliotti ◽  
Claudia G. Simionato ◽  
Carlos A. Lasta
Keyword(s):  
Particulate Matter ◽  
Suspended Particulate Matter ◽  
Pearson Correlation ◽  
Biological Study ◽  
Spatial And Temporal Variability ◽  
Rio De La Plata ◽  
Río De La Plata ◽  
La Plata ◽  
Suspended Particulate ◽  
Southwestern Atlantic Ocean

The Río de la Plata is a large, shallow estuary located at approximately 35°S and flowing into the southwestern Atlantic Ocean. It carries a high amount of nutrients and suspended particulate matter, both organic and inorganic, to the adjacent shelf waters and is considered among the most turbid estuarine systems in the world. Knowledge of the concentration and spatial and temporal variability of these materials is critical for any biological study in the Río de la Plata. In this work, the relationship between suspended particulate matter and turbidity is empirically established in order to derive suspended particulate matter maps from satellite data (MODIS-Aqua) for the Río de la Plata region. A strong correlation between suspended particulate matter and turbidity was found (Pearson correlation coefficient =0.91) and the linear regression (slope =0.76 and intercepts =12.78, R2=0.83) explained 83% of the variance. The validation of the empirical algorithm, using co-located and coincident satellite and in situ measurements, showed good results with a low mean absolute error (14.60%) and a small and positive bias (3.04%), indicating that the estimated suspended particulate matter values tend to slightly overestimate the field values.

Spatio-temporal effects of vegetated windbreaks on wind erosion and microclimate as basis for model development

2021 ◽  
Author(s):  
Thomas Weninger ◽  
Simon Scheper ◽  
Nathan King ◽  
Karl Gartner ◽  
Barbara Kitzler ◽  
...  
Keyword(s):  
Soil Water ◽  
Wind Erosion ◽  
Arable Land ◽  
Model Development ◽  
Weather Conditions ◽  
Bare Soil ◽  
Sediment Traps ◽  
Spatial And Temporal Variability ◽  
Regional Modelling ◽  
Erosion Rates

<p>Wind erosion of arable soil is considered a risk factor for Austrian fields, but direct measurements of soil loss are not available until now. Despite this uncertainty, vegetated windbreaks have been established to minimize adverse wind impacts on arable land. The study addresses these questions: i) How relevant is wind erosion as a factor of soil degradation? ii) How important is the protective effect of vegetated windbreaks? iii) Are systematic patterns of spatial and temporal variability of wind erosion rates detectable in response to weather conditions? </p><p>Two experimental fields adjacent to windbreaks were equipped with sediment traps, soil moisture sensors, and meteorological measurement equipment for microclimatic patterns. Sediment traps were arranged in high spatial resolution from next to the windbreak to a distance of ten times the windbreak height. Beginning in January 2020, the amount of trapped sediment was analyzed every three weeks. The highest wind erosion rates on bare soil were observed in June and July. For unprotected fields with bare soil, upscaled annual erosion rates were as high as 0.8 tons per hectare, and sediment trapped increased in a linear fashion with distance from the windbreak. Soil water content near the surface (5 cm depth) was three percent higher at a distance of two times the height of the windbreak than at a distance of six times the height. For the same respective distances from the windbreak, we observed 29 days of soil water contents below the wilting point compared with 60 days.</p><p>The preliminary outcomes confirmed the expected effects of windbreaks on soil erosion and microclimate in agricultural fields. Prospective results from multiple vegetation periods will be used in an upscaling approach to gain informations for the whole basin. That is meant to be done by a combination with a soil wind erosion model which was so far used for regional modelling of wind erosion susceptibility.</p>

scholarly journals Overview of the HI-SCALE Field Campaign: A New Perspective on Shallow Convective Clouds

2019 ◽  
Vol 100 (5) ◽  
pp. 821-840 ◽  
Author(s):  
Jerome D. Fast ◽  
Larry K. Berg ◽  
Lizbeth Alexander ◽  
David Bell ◽  
Emma D’Ambro ◽  
...  
Keyword(s):  
Great Plains ◽  
Deep Convection ◽  
Weather Conditions ◽  
Radiation Budget ◽  
Atmospheric Radiation ◽  
Spatial And Temporal Variability ◽  
Convective Clouds ◽  
Microphysical Properties ◽  
Shallow Clouds ◽  
Improved Model

AbstractShallow convective clouds are common, occurring over many areas of the world, and are an important component in the atmospheric radiation budget. In addition to synoptic and mesoscale meteorological conditions, land–atmosphere interactions and aerosol–radiation–cloud interactions can influence the formation of shallow clouds and their properties. These processes exhibit large spatial and temporal variability and occur at the subgrid scale for all current climate, operational forecast, and cloud-system-resolving models; therefore, they must be represented by parameterizations. Uncertainties in shallow cloud parameterization predictions arise from many sources, including insufficient coincident data needed to adequately represent the coupling of cloud macrophysical and microphysical properties with inhomogeneity in the surface-layer, boundary layer, and aerosol properties. Predictions of the transition of shallow to deep convection and the onset of precipitation are also affected by errors in simulated shallow clouds. Coincident data are a key factor needed to achieve a more complete understanding of the life cycle of shallow convective clouds and to develop improved model parameterizations. To address these issues, the Holistic Interactions of Shallow Clouds, Aerosols and Land Ecosystems (HI-SCALE) campaign was conducted near the Atmospheric Radiation Measurement (ARM) Southern Great Plains site in north-central Oklahoma during the spring and summer of 2016. We describe the scientific objectives of HI-SCALE as well as the experimental approach, overall weather conditions during the campaign, and preliminary findings from the measurements. Finally, we discuss scientific gaps in our understanding of shallow clouds that can be addressed by analysis and modeling studies that use HI-SCALE data.

scholarly journals Is the Polish Smog a New Type of Smog?

2019 ◽  
Vol 26 (3) ◽  
pp. 465-474 ◽  
Author(s):  
Justyna Czerwińska ◽  
Grzegorz Wielgosiński ◽  
Olga Szymańska
Keyword(s):  
Particulate Matter ◽  
Suspended Particulate Matter ◽  
Polyaromatic Hydrocarbons ◽  
Common Factor ◽  
Ground Level ◽  
Weather Conditions ◽  
Air Masses ◽  
Suspended Particulate ◽  
New Type ◽  
Sunny Weather

Abstract In recent years, every winter we face the problem of excessive air pollution in the cities in Poland. This phenomenon is usually called smog and is associated with the concept of acidic smog of London type. However, there is a fundamental difference between the Great Smog of London known from the literature and winter smog episodes in Poland. While in 1952 in London the smog occurred at low atmospheric pressure, in foggy and windless weather conditions, in Poland smog episodes occur most often at the influx of cold, high-pressure air masses from the east in sunny weather. There are also various harmful components of smog - in London it was dust (suspended particulate matter), sulfur dioxide and carbon monoxide, while in Poland it is suspended particulate matter and polyaromatic hydrocarbons, especially benzo(a)pyrene. A common factor is the inversion of temperature in the ground level of the atmosphere. The chemical composition of the “Polish smog” is analyzed in the study justifying the need to distinguish the two types of smog described.

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