scholarly journals Using remote sensing to enhance modelling of fine sediment dynamics in the Dutch coastal zone

2013 ◽  
Vol 16 (2) ◽  
pp. 458-476 ◽  
Author(s):  
A. M. Y. Kamel ◽  
G. Y. El Serafy ◽  
B. Bhattacharya ◽  
T. van Kessel ◽  
D. P. Solomatine
Keyword(s):  
Remote Sensing ◽  
Temporal Distribution ◽  
Fine Sediment ◽  
In Situ Measurements ◽  
Sediment Dynamics ◽  
Model Parameters ◽  
Imaging Spectrometer ◽  
Suspended Particulate ◽  
Medium Resolution

Modelling fine sediment dynamics, including transport, deposition and re-suspension, is very complex. This led to studies that validate the modelled suspended particulate matter (SPM) based on in-situ measurements. While in-situ measurements are often sparse in time and space, satellite measurements provide us with higher spatial and temporal resolution. This information can be used to validate and enhance the model's capability of predicting the spatial and temporal distribution of SPM. In this paper, the SPM retrieved from the MEdium Resolution Imaging Spectrometer (MERIS) on board European Space Agency's ENVISAT spacecraft is used to carry out a thorough calibration and validation of the SPM description provided by the Delft3DWAQ model of the Southern North Sea for the year 2007. In an uncertainty analysis framework, the key model parameters affecting the SPM distributions were first identified in predefined physical regions. The sensitivity of the model to slight changes in those parameters is tested and the spatial and temporal errors compared to remote sensing images were identified and a new set of parameters has been suggested and further subjected to uncertainty to define prediction intervals of the SPM distribution at a number of locations. The so-called adapted model has been validated against independent data and has shown a decrease in errors, particularly along the Dutch coast.

Investigating suspended particulate matters from multi-wavelength optical and multi-frequency acoustic measurements

2021 ◽  
Author(s):  
Duc Tran ◽  
Matthias Jacquet ◽  
Stuart Pearson ◽  
Romaric Verney
Keyword(s):  
Optical Sensors ◽  
Acoustic Signals ◽  
Fine Sediment ◽  
In Situ Measurements ◽  
Optical Signals ◽  
New Device ◽  
Suspended Particulate ◽  
Multi Wavelength

<p>Long term and high-frequency monitoring of water quality, particularly the suspended particulate matter (SPM) concentration are crucial to decipher the health and sustainable development of marine ecosystems. However, in-situ measurements based on indirect optical or acoustic techniques are often associated with large uncertainties due to the dynamics of natural SPM, especially throughout the land-sea continuum. Therefore, this study aims to improve the accuracy of long term in-situ measurements by quantitatively elucidating the physical mechanisms by which sand and fine sediment respond to multi-wavelength optical and multi-frequency acoustic signals. We <strong>hypothesize</strong> that whilst fine sediment is very sensitive to optical signals, the coarser particles are more sensitive to acoustic signals, and vice versa. We further <strong>hypothesize</strong> that the SPM compositions and variability can be differentiated and derived based on such sensitivities and differences in behaviors of sand and fine sediment under different types of signals, i.e., optical and acoustic. </p><p>Before testing the hypotheses, a novel laboratory device that is capable of 1) generating homogeneous suspended concentration and 2) providing sufficient space for multiple sensors to operate simultaneously must be developed. The new device, DEXMES (dispositive experimental de quantification des matières en suspension), primarily consists of two main components. The upper part is a cylindrical tank with an inner diameter of 0.96 m and 1.4 m high. To break up the large vortexes and mitigate the vortex-induced bubbles (e.g., generated by the impeller), four baffles with dimensions of 0.09 x 1.31 m are evenly attached to the inner side of the tank. The bottom part of the DEXMES device is a convex, elliptical Plexiglas bed. Turbulent flow is generated by an impeller with a diameter of 0.36 m placed approximately 1 m below the water surface. The speed of the impeller, ranging from 0 to 235 rpm, is regulated by a controller box.</p><p>To test the hypotheses, 30 experiments, consisting of 6 concentrations and 5 mixture ratios (by mass) of Bentonite and fine sand (d<sub>50</sub> = 100 µm), i.e., 100/0, 75/25, 50/50, 25/75, and 0/100, were thoroughly investigated using three acoustic sensors (ADV, AQUAscat, LISST-ABS) and three optical sensors (Wetlabs, HydroScat, LISST-100X). On average, each data point is the averaged value of 10 min of recording at 1 or 32 Hz. First, results show logarithmic/linear relationships between concentration and acoustic/optical signals respectively for a given bentonite/sand. Second, the slope of this relation is a function of the Bentonite/sand ratio. Third, the results confirm the hypotheses that coarser particles are more sensitive to acoustic signals and fine sediment is more sensitive to optical signals. Simple regression models were developed for different pairs of acoustic and optical sensors based on their relative sensitivity to SPM characteristics. The correlation coefficient, bias, and RMSE between observed and predicted concentrations then were examined. The results also show that it is possible to use a combination of one acoustic and one optical sensor to infer the concentration and the ratio of fine/coarse sediment in suspension with minimum use of water samples calibration.</p>

scholarly journals Methane emissions from a Californian landfill, determined from airborne remote sensing and in situ measurements

2017 ◽  
Vol 10 (9) ◽  
pp. 3429-3452 ◽  
Author(s):  
Sven Krautwurst ◽  
Konstantin Gerilowski ◽  
Haflidi H. Jonsson ◽  
David R. Thompson ◽  
Richard W. Kolyer ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Greenhouse Gas ◽  
Measurement Techniques ◽  
Late Summer ◽  
In Situ Measurements ◽  
Anthropogenic Sources ◽  
Model Parameters ◽  
World Population ◽  
Ch4 Emissions

Abstract. Fugitive emissions from waste disposal sites are important anthropogenic sources of the greenhouse gas methane (CH4). As a result of the growing world population and the recognition of the need to control greenhouse gas emissions, this anthropogenic source of CH4 has received much recent attention. However, the accurate assessment of the CH4 emissions from landfills by modeling and existing measurement techniques is challenging. This is because of inaccurate knowledge of the model parameters and the extent of and limited accessibility to landfill sites. This results in a large uncertainty in our knowledge of the emissions of CH4 from landfills and waste management. In this study, we present results derived from data collected during the research campaign COMEX (CO2 and MEthane eXperiment) in late summer 2014 in the Los Angeles (LA) Basin. One objective of COMEX, which comprised aircraft observations of methane by the remote sensing Methane Airborne MAPper (MAMAP) instrument and a Picarro greenhouse gas in situ analyzer, was the quantitative investigation of CH4 emissions. Enhanced CH4 concentrations or CH4 plumes were detected downwind of landfills by remote sensing aircraft surveys. Subsequent to each remote sensing survey, the detected plume was sampled within the atmospheric boundary layer by in situ measurements of atmospheric parameters such as wind information and dry gas mixing ratios of CH4 and carbon dioxide (CO2) from the same aircraft. This was undertaken to facilitate the independent estimation of the surface fluxes for the validation of the remote sensing estimates. During the COMEX campaign, four landfills in the LA Basin were surveyed. One landfill repeatedly showed a clear emission plume. This landfill, the Olinda Alpha Landfill, was investigated on 4 days during the last week of August and first days of September 2014. Emissions were estimated for all days using a mass balance approach. The derived emissions vary between 11.6 and 17.8 kt CH4 yr−1 with related uncertainties in the range of 14 to 45 %. The comparison of the remote sensing and in situ based CH4 emission rate estimates reveals good agreement within the error bars with an average of the absolute differences of around 2.4 kt CH4 yr−1 (±2. 8 kt CH4 yr−1). The US Environmental Protection Agency (EPA) reported inventory value is 11.5 kt CH4 yr−1 for 2014, on average 2.8 kt CH4 yr−1 (±1. 6 kt CH4 yr−1) lower than our estimates acquired in the afternoon in late summer 2014. This difference may in part be explained by a possible leak located on the southwestern slope of the landfill, which we identified in the observations of the Airborne Visible/Infrared Imaging Spectrometer – Next Generation (AVIRIS-NG) instrument, flown contemporaneously aboard a second aircraft on 1 day.

scholarly journals High resolution NO<sub>2</sub> remote sensing from the Airborne Prism EXperiment (APEX) imaging spectrometer

2012 ◽  
Vol 5 (2) ◽  
pp. 2449-2486 ◽  
Author(s):  
C. Popp ◽  
D. Brunner ◽  
A. Damm ◽  
M. Van Roozendael ◽  
C. Fayt ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Air Quality ◽  
Spatial Resolution ◽  
In Situ Measurements ◽  
High Signal ◽  
Waste Incinerator ◽  
Imaging Spectrometer ◽  
Airborne Measurements ◽  
Spectrometer Data

Abstract. We present and evaluate the retrieval of high spatial resolution maps of NO2 vertical column densities (VCD) from the Airborne Prism EXperiment (APEX) imaging spectrometer. APEX is a novel instrument providing airborne measurements of unique spectral and spatial resolution and coverage as well as high signal stability. In this study, we use spectrometer data acquired over Zurich, Switzerland, in the morning and late afternoon during a flight campaign on a cloud-free summer day in June 2010. NO2 VCD are derived with a two-step approach usually applied to satellite NO2 retrievals, i.e. a DOAS analysis followed by air mass factor calculations based on radiative transfer computations. Our analysis demonstrates that APEX is clearly sensitive to NO2 VCD above typical European tropospheric background abundances (>1 × 1015 molec cm−2). The two-dimensional maps of NO2 VCD reveal a very plausible spatial distribution with strong gradients around major NOx sources (e.g. Zurich airport, waste incinerator, motorways) and low NO2 in remote areas. The morning overflights resulted in generally higher NO2 VCD and a more distinct pattern than the afternoon overflights which can be attributed to the meteorological conditions prevailing during that day (development of the boundary layer and increased wind speed in the afternoon) as well as to photochemical loss of NO2. The remotely sensed NO2 VCD are also highly correlated with ground-based in-situ measurements from local and national air quality networks (R=0.73). Airborne NO2 remote sensing using APEX will be valuable to detect NO2 emission sources, to provide input for NO2 emission modeling, and to establish links between in-situ measurements, air quality models, and satellite NO2 products.

scholarly journals Methane emissions from a Californian landfill, determined from airborne remote sensing and in-situ measurements

2016 ◽  
Author(s):  
Sven Krautwurst ◽  
Konstantin Gerilowski ◽  
Haflidi H. Jonsson ◽  
David R. Thompson ◽  
Richard W. Kolyer ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Greenhouse Gas ◽  
Late Summer ◽  
In Situ Measurements ◽  
Anthropogenic Sources ◽  
Absolute Difference ◽  
Model Parameters ◽  
World Population ◽  
Ch4 Emissions

Abstract. Fugitive emissions from waste disposal sites are important anthropogenic sources of the greenhouse gas methane (CH4). As a result of the growing world population and the recognition of the need to control greenhouse gas emissions, this anthropogenic source of CH4 has received much recent attention. However, the accurate assessment of the CH4 emissions from landfills by modeling and existing measurement techniques is challenging. This is because of inaccurate knowledge of the model parameters and the extent of and limited accessibility to landfill sites. This results in a large uncertainty in our knowledge of the emissions of CH4 from landfills and waste management. In this study, we present results derived from data collected during the research campaign COMEX (CO2 and Methane EXperiement) in late summer 2014 in the Los Angeles (LA) Basin. The objective of COMEX, which comprised aircraft observations of methane by the remote sensing Methane Airborne MAPper (MAMAP) instrument and a Picarro greenhouse gas in-situ analyser, was the quantitative investigation of CH4 emissions. Enhanced CH4 concentrations or "CH4 plumes" were detected downwind of landfills by remote sensing aircraft surveys. Subsequent to each remote sensing survey, the detected plume was sampled within the atmospheric boundary layer by in-situ measurements of atmospheric parameters such as wind information and dry gas mixing ratios of CH4 and carbon dioxide (CO2) from the same aircraft. This was undertaken to facilitate the independent estimation of the surface fluxes for the validation of the remote sensing estimates. During the COMEX campaign, four landfills in the LA Basin were surveyed. One landfill has repeatedly shown a clear emission plume. This landfill, the Olinda Alpha Landfill, was observed on four days during the last week of August and first days of September 2014. Emissions were estimated for all days using a mass balance approach. The derived emissions are between 13.0 and 18.2 kt CH4/yr with related uncertainties in the range of 17 % to 46 %. The comparison of the remote sensing and in-situ based CH4 emission rate estimates reveals good agreement within the error bars with an average absolute difference of around 2.3 kt CH4/yr. The US Environmental Protection Agency (EPA) reported inventory value is 11.5 kt CH4/yr in 2014, on average 3.0 kt CH4/yr (±1.5 kt CH4/yr) lower than our estimates acquired in late Summer 2014. This difference may in part be explained by a possible leak located on the south-western slope of the landfill, which we identified in the observations of the Airborne Visible/Infrared Imaging Spectrometer – Next Generation (AVIRIS-NG) instrument, flown contemporaneously aboard a second aircraft on one day.

scholarly journals High-resolution NO<sub>2</sub> remote sensing from the Airborne Prism EXperiment (APEX) imaging spectrometer

2012 ◽  
Vol 5 (9) ◽  
pp. 2211-2225 ◽  
Author(s):  
C. Popp ◽  
D. Brunner ◽  
A. Damm ◽  
M. Van Roozendael ◽  
C. Fayt ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Air Quality ◽  
Spatial Resolution ◽  
In Situ Measurements ◽  
High Signal ◽  
Waste Incinerator ◽  
Imaging Spectrometer ◽  
Airborne Measurements ◽  
Spectrometer Data

Abstract. We present and evaluate the retrieval of high spatial resolution maps of NO2 vertical column densities (VCD) from the Airborne Prism EXperiment (APEX) imaging spectrometer. APEX is a novel instrument providing airborne measurements of unique spectral and spatial resolution and coverage as well as high signal stability. In this study, we use spectrometer data acquired over Zurich, Switzerland, in the morning and late afternoon during a flight campaign on a cloud-free summer day in June 2010. NO2 VCD are derived with a two-step approach usually applied to satellite NO2 retrievals, i.e. a DOAS analysis followed by air mass factor calculations based on radiative transfer computations. Our analysis demonstrates that APEX is clearly sensitive to NO2 VCD above typical European tropospheric background abundances (>1 × 1015 molec cm−2). The two-dimensional maps of NO2 VCD reveal a very convincing spatial distribution with strong gradients around major NOx sources (e.g. Zurich airport, waste incinerator, motorways) and low NO2 in remote areas. The morning overflights resulted in generally higher NO2 VCD and a more distinct pattern than the afternoon overflights which can be attributed to the meteorological conditions prevailing during that day with stronger winds and hence larger dilution in the afternoon. The remotely sensed NO2 VCD are also in reasonably good agreement with ground-based in-situ measurements from air quality networks considering the limitations of comparing column integrals with point measurements. Airborne NO2 remote sensing using APEX will be valuable to detect NO2 emission sources, to provide input for NO2 emission modelling, and to establish links between in-situ measurements, air quality models, and satellite NO2 products.

Particulate matter variability in Kathmandu based on in-situ measurements, remote sensing, and reanalysis data

2021 ◽  
pp. 105623
Author(s):  
Stefan Becker ◽  
Ramesh Prasad Sapkota ◽  
Binod Pokharel ◽  
Loknath Adhikari ◽  
Rudra Prasad Pokhrel ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Particulate Matter ◽  
Reanalysis Data ◽  
In Situ Measurements

scholarly journals Aerosol optical and microphysical retrievals from a hybrid multiwavelength lidar data set – DISCOVER-AQ 2011

2014 ◽  
Vol 7 (9) ◽  
pp. 3095-3112 ◽  
Author(s):  
P. Sawamura ◽  
D. Müller ◽  
R. M. Hoff ◽  
C. A. Hostetler ◽  
R. A. Ferrare ◽  
...  
Keyword(s):  
Remote Sensing ◽  
In Situ Measurements ◽  
Index Of Refraction ◽  
High Spectral Resolution ◽  
Lidar Data ◽  
Data Set ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
Multiwavelength Lidar

Abstract. Retrievals of aerosol microphysical properties (effective radius, volume and surface-area concentrations) and aerosol optical properties (complex index of refraction and single-scattering albedo) were obtained from a hybrid multiwavelength lidar data set for the first time. In July 2011, in the Baltimore–Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne (in situ and remote sensing) and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar data set combines ground-based elastic backscatter lidar measurements at 355 nm with airborne High-Spectral-Resolution Lidar (HSRL) measurements at 532 nm and elastic backscatter lidar measurements at 1064 nm that were obtained less than 5 km apart from each other. This was the first study in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in situ measurements for 11 cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor in such discrepancies.

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