scholarly journals 1.5 years of TROPOMI CO measurements: Comparisons to MOPITT and ATom

2020 ◽  
Author(s):  
Sara Martínez-Alonso ◽  
Merritt Deeter ◽  
Helen Worden ◽  
Tobias Borsdorff ◽  
Ilse Aben ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Near Infrared ◽  
Null Space ◽  
Open Water ◽  
Relative Bias ◽  
Scaled Model ◽  
Space Error ◽  
True Profile ◽  
Cloud Tops ◽  
Bodies Of Water

Abstract. We have analyzed TROPOspheric Monitoring Instrument (TROPOMI) carbon monoxide (CO) data acquired between November 2017 and March 2019 with respect to other satellite (MOPITT, Measurement Of Pollution In The Troposphere) and airborne (ATom, Atmospheric Tomography mission) datasets to understand better TROPOMI’s contribution to the global tropospheric CO record (2000 to present). TROPOMI and MOPITT are currently the only satellite instruments deriving CO from solar reflected radiances. Therefore, it is particularly important to understand how these two datasets compare. Our results indicate that TROPOMI CO retrievals over land show excellent agreement with respect to MOPITT: relative biases and their standard deviation (i.e., accuracy and precision) are on average −3.73 ± 11.51, −2.24 ± 12.38, and −3.22 ± 11.13 %, compared to the MOPITT TIR (thermal infrared), NIR (near infrared), and TIR+NIR (multispectral) products, respectively. TROPOMI and MOPITT data also show good agreement in terms of temporal and spatial patterns. Despite depending on solar reflected radiances for its measurements, TROPOMI can also retrieve CO over bodies of water if clouds are present, by approximating partial columns under cloud tops using scaled, model-based reference CO profiles. We quantify the bias of TROPOMI total column retrievals over bodies of water with respect to colocated in situ ATom CO profiles after smoothing the latter with the TROPOMI column averaging kernels (AK), which account for signal attenuation under clouds (relative bias and its standard deviation = 3.25 ± 11.46 %). In addition, we quantify enull (the null-space error), which accounts for differences between the shape of the TROPOMI reference profile and that of the ATom true profile (enull = 2.16 ± 2.23 %). For comparisons of TROPOMI and MOPITT retrievals over open water, we adopt a simpler approach, since smoothing with TROPOMI AK does not apply for MOPITT retrievals. To this effect, we compare TROPOMI total CO columns (above and below cloud tops) and partial CO columns (above cloud top) to their colocated MOPITT TIR counterparts. (This approximation would be most accurate for optically thick clouds.) We find very small changes in relative bias between TROPOMI and MOPITT TIR retrievals if total columns are considered instead of partial above-cloud-top columns (

scholarly journals 1.5 years of TROPOMI CO measurements: comparisons to MOPITT and ATom

2020 ◽  
Vol 13 (9) ◽  
pp. 4841-4864
Author(s):  
Sara Martínez-Alonso ◽  
Merritt Deeter ◽  
Helen Worden ◽  
Tobias Borsdorff ◽  
Ilse Aben ◽  
...  
Keyword(s):  
Near Infrared ◽  
Null Space ◽  
A Priori ◽  
Open Water ◽  
Relative Bias ◽  
Scaled Model ◽  
Cloud Tops ◽  
Bodies Of Water ◽  
The Impact ◽  
Total Column

Abstract. We have analyzed TROPOspheric Monitoring Instrument (TROPOMI) carbon monoxide (CO) data acquired between November 2017 and March 2019 with respect to other satellite (MOPITT, Measurement Of Pollution In The Troposphere) and airborne (ATom, Atmospheric Tomography mission) datasets to better understand TROPOMI's contribution to the global tropospheric CO record (2000 to present). MOPITT and TROPOMI are two of only a few satellite instruments to ever derive CO from solar-reflected radiances. Therefore, it is particularly important to understand how these two datasets compare. Our results indicate that TROPOMI CO retrievals over land show excellent agreement with respect to MOPITT: relative biases and their SD (i.e., accuracy and precision) are on average -3.73%±11.51%, -2.24%±12.38%, and -3.22%±11.13% compared to the MOPITT TIR (thermal infrared), NIR (near infrared), and TIR + NIR (multispectral) products, respectively. TROPOMI and MOPITT data also show good agreement in terms of temporal and spatial patterns. Despite depending on solar-reflected radiances for its measurements, TROPOMI can also retrieve CO over bodies of water if clouds are present by approximating partial columns under cloud tops using scaled, model-based reference CO profiles. We quantify the bias of TROPOMI total column retrievals over bodies of water with respect to colocated in situ ATom CO profiles after smoothing the latter with the TROPOMI column averaging kernels (AKs), which account for signal attenuation under clouds (relative bias and its SD =3.25%±11.46 %). In addition, we quantify enull (the null-space error), which accounts for differences between the shape of the TROPOMI reference profile and that of the ATom true profile (enull=2.16%±2.23 %). For comparisons of TROPOMI and MOPITT retrievals over open water we compare TROPOMI total CO columns to their colocated MOPITT TIR counterparts. Relative bias and its SD are 2.98 %±15.71 % on average. We investigate the impact of discrepancies between the a priori and reference CO profiles (used by MOPITT and TROPOMI, respectively) on CO retrieval biases by applying a null-space adjustment (based on the MOPITT a priori) to the TROPOMI total column values. The effect of this adjustment on MOPITT and TROPOMI biases is minor, typically 1–2 percentage points.

scholarly journals Ist Wasserbau auch eine Frage der Ästhetik? | Is hydraulic engineering a question of aesthetics?

2008 ◽  
Vol 159 (7) ◽  
pp. 205-208
Author(s):  
Gianni Paravicini
Keyword(s):  
Open Water ◽  
Hydraulic Engineering ◽  
Water Bodies ◽  
Ecological Value ◽  
The Aesthetic ◽  
Bodies Of Water

There is much extended literature about classic technical hydraulic engineering and about the revitalization of bodies of water. This article deals with a third component, which has received little attention by the engineers. The author pleads for more aesthetic in hydraulic engineering, in particular in populated areas where many people use the open water bodies for recreation. It is shown that more aesthetic in hydrologic engineering often also leads to an increased ecological value. With hydraulic constructions in the canton of Lueerne, possible creative elements for the aesthetic and ecological revaluation of the course of creeks are discussed.

Generation of geolocated and radiometrically corrected true reflectance surfaces in the visible portion of the electromagnetic spectrum over large bodies of water using images from a sUAS

2020 ◽  
Vol 8 (3) ◽  
pp. 172-185
Author(s):  
Juan G. Arango ◽  
Brandon K. Holzbauer-Schweitzer ◽  
Robert W. Nairn ◽  
Robert C. Knox
Keyword(s):  
Water Quality ◽  
Near Infrared ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Quality Data ◽  
Electromagnetic Spectrum ◽  
Water Quality Data ◽  
Ground Control Points ◽  
Bodies Of Water

The focus of this study was to develop true reflectance surfaces in the visible portion of the electromagnetic spectrum from small unmanned aerial system (sUAS) images obtained over large bodies of water when no ground control points were available. The goal of the research was to produce true reflectance surfaces from which reflectance values could be extracted and used to estimate optical water quality parameters utilizing limited in-situ water quality analyses. Multispectral imagery was collected using a sUAS equipped with a multispectral sensor, capable of obtaining information in the blue (0.475 μm), green (0.560 μm), red (0.668 μm), red edge (0.717 μm), and near infrared (0.840 μm) portions of the electromagnetic spectrum. To develop a reliable and repeatable protocol, a five-step methodology was implemented: (i) image and water quality data collection, (ii) image processing, (iii) reflectance extraction, (iv) statistical interpolation, and (v) data validation. Results indicate that the created protocol generates geolocated and radiometrically corrected true reflectance surfaces from sUAS missions flown over large bodies of water. Subsequently, relationships between true reflectance values and in-situ water quality parameters were developed.

scholarly journals Surface Albedo of the Antarctic Sea Ice Zone

2005 ◽  
Vol 18 (17) ◽  
pp. 3606-3622 ◽  
Author(s):  
Richard E. Brandt ◽  
Stephen G. Warren ◽  
Anthony P. Worby ◽  
Thomas C. Grenfell
Keyword(s):  
Sea Ice ◽  
Surface Albedo ◽  
Near Infrared ◽  
Field Experiments ◽  
Climate Models ◽  
Solar Spectrum ◽  
Open Water ◽  
Visual Observation ◽  
Antarctic Sea Ice ◽  
The Antarctic

Abstract In three ship-based field experiments, spectral albedos were measured at ultraviolet, visible, and near-infrared wavelengths for open water, grease ice, nilas, young “grey” ice, young grey-white ice, and first-year ice, both with and without snow cover. From the spectral measurements, broadband albedos are computed for clear and cloudy sky, for the total solar spectrum as well as for visible and near-infrared bands used in climate models, and for Advanced Very High Resolution Radiometer (AVHRR) solar channels. The all-wave albedos vary from 0.07 for open water to 0.87 for thick snow-covered ice under cloud. The frequency distribution of ice types and snow coverage in all seasons is available from the project on Antarctic Sea Ice Processes and Climate (ASPeCt). The ASPeCt dataset contains routine hourly visual observations of sea ice from research and supply ships of several nations using a standard protocol. Ten thousand of these observations, separated by a minimum of 6 nautical miles along voyage tracks, are used together with the measured albedos for each ice type to assign an albedo to each visual observation, resulting in “ice-only” albedos as a function of latitude for each of five longitudinal sectors around Antarctica, for each of the four seasons. These ice albedos are combined with 13 yr of ice concentration estimates from satellite passive microwave measurements to obtain the geographical and seasonal variation of average surface albedo. Most of the Antarctic sea ice is snow covered, even in summer, so the main determinant of area-averaged albedo is the fraction of open water within the pack.

Comparison of Commercial near Infrared Transmittance and Reflectance Instruments for Analysis of Whole Grains and Seeds

1993 ◽  
Vol 1 (1) ◽  
pp. 25-32 ◽  
Author(s):  
P. C. Williams ◽  
D.C. Sobering
Keyword(s):  
Standard Deviation ◽  
Wavelength Range ◽  
Standard Error ◽  
Near Infrared ◽  
Original Data ◽  
Whole Grains ◽  
Whole Grain ◽  
Infrared Transmittance

Near infrared transmittance and reflectance instruments were compared for the determination of protein, oil, moisture and some other constituents and parameters in several grains and seeds of commerce. Both approaches were comparable in accuracy and reproducibility. The importance of optimisation of the wavelength range in whole grain analysis is demonstrated for measurements in both the NIR and visible/NlR wavelength ranges. The RPD statistic, which relates the standard error of prediction to the standard deviation of the original data, is illustrated as a method for the evaluation of calibrations. The concept of monitoring the accuracy of analysis using whole grain calibrations with ground grain calibrations is introduced.

Spray overtopping rates for Tarsiut Island: model and field study results

1992 ◽  
Vol 19 (3) ◽  
pp. 469-477 ◽  
Author(s):  
I. Muzik ◽  
A. Kirby
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
Field Data ◽  
Three Dimensional ◽  
Open Water ◽  
Scaled Model ◽  
Model Study ◽  
Study Results ◽  
Intensity Wave ◽  
Height Model

This paper describes a 1:30 three-dimensional Froude scaled model study undertaken to determine the spray overtopping volumes that would result from storms on Tarsiut Island. During the open water season of 1982, spray overtopping data were collected on Tarsiut Island and then compared with the model study results. The Tarsiut field data when compared with the model data were lower by a factor of 3. Some possible reasons for this are scaling errors, physical differences between the model and the prototype, and the model wind speed. The model wind speed used was roughly 3.75 times the Froude scaled wind speed and the literature suggests that a wind speed of twice the Froude scaled wind speed would produce overtopping volumes closer to the field data. The spray overtopping rates landward from the caisson face reduced in an exponential manner, which was substantiated by the literature. Spray overtopping for both the model study and Tarsiut Island was initiated at approximately the same significant wave height. Key words: spray intensity, wave height, model study, field program, artificial island, wind speed.

Quantitative Determination of Epoxidized Soybean Oil Using Near-Infrared Spectroscopy and Multivariate Calibration

2002 ◽  
Vol 56 (12) ◽  
pp. 1607-1614 ◽  
Author(s):  
Thais F. Parreira ◽  
Márcia M. C. Ferreira ◽  
Henrique J. S. Sales ◽  
Wanderson B. De Almeida
Keyword(s):  
Standard Deviation ◽  
Soybean Oil ◽  
Near Infrared ◽  
Multivariate Calibration ◽  
Hydrogen Bromide ◽  
External Validation ◽  
Water Levels ◽  
Epoxidized Soybean Oil ◽  
Epoxide Ring ◽  
Statistical Parameters

The quality of epoxidized soybean oil (ESO), industrially used as a plasticizer and heat stabilizer for PVC films, is given by the degree of epoxidation (EI), the number of double bonds expressed as the iodine index (II), and the water percentage in the final product. In this work, near-infrared (NIR) spectra recorded off line at the chemical industry during the epoxidation process, combined with the multivariate regression method partial least squares (PLS), was used for the quantification of EI, II, and water percentage in the ESO. The water levels were determined by the Karl Fischer titration. The content of iodine was determined by iodometry. The epoxide index was obtained by the hydrogen bromide reaction with the epoxide ring. On average, 50 samples were used to model each analyte and 10 were used for external validation. The results, expressed in terms of the statistical parameters RPD (ratio of standard deviation of experimental concentrations to the standard deviation of the residuals) and RER (ratio error range), were excellent for the EI (26.02 and 80.70, respectively). For the water % and II, the obtained results were fairly good. Good correlations between predicted and real concentrations were attained (0.984, 0.966 and 0.974 for water %, II, and EI, respectively). It is shown in this work that the use of NIRS combined with chemometric methods are of great importance, especially for industrial purposes.

scholarly journals ΑΞΙΟΛΟΓΗΣΗ TOY ΔΕΙΚΤΗ ΒΛΑΣΤΗΣΗΣ TVI ME ΤΗ ΣΥΝΔΡΟΜΗ ΤΗΣ ΘΕΩΡΙΑΣ ΠΙΘΑΝΟΤΗΤΩΝ

2004 ◽  
Vol 36 (3) ◽  
pp. 1338
Author(s):  
Γ. Αιμ. Σκιάνης ◽  
Δ. Βαϊόπουλος ◽  
Κ. Νικολακόπουλος
Keyword(s):  
Probability Theory ◽  
Standard Deviation ◽  
Vegetation Index ◽  
Near Infrared ◽  
Normalized Difference Vegetation Index ◽  
Environmental Research ◽  
Theoretical Predictions ◽  
Landsat 7 ◽  
The Right ◽  
Western Greece

In the present paper the statistical behaviour of the Transformed Vegetation Index TVI is studied. TVI is defined by: (equation No1) - or, alternatively, by: (equation No2) u is the numerical value of the vegetation index, χ and y are the brightness values of the near infrared and red zones, respectively. Relation (1) defines the vegetation index TVI. Relation (2) defines the vegetation index TVI'. Using appropriate distributions to describe the histograms of χ and y channels, and taking into account certain theorems from probability theory, the expressions for the distributions of TVI and TVI' values are deduced. According to these expressions, the standard deviation of TVI image is larger than that of TVI', as well as NDVI (Normalized Difference Vegetation Index). The prevailing value of the TVI' histogram is located at the right part of the tonality range. Therefore, according to the mathematical analysis, the TVI image has a better contrast than that of the NDVI and TVI' images. The TVI' has a diffuse luminance. The theoretical predictions were tested with a Landsat 7 ETM image of Zakynthos Island (western Greece) and they were found to be in accordance with the satellite data. It was also observed that lineaments with a dark tonality are expressed more clearly in the TVI image than in the TVI' image. The general conclusion is that the TVI vegetation index is preferable from TVI', since the former produces images with a larger standard deviation and a better contrast than the latter. The results and conclusions of this paper may be useful in geological and environmental research , for mapping regions with a different vegetation cover.

scholarly journals Hydrodynamic characteristics of marine composite propeller blade using a numerical approach

2021 ◽  
Vol 10 (1) ◽  
pp. 20
Author(s):  
M L P Kishore ◽  
Vijay K Singh ◽  
R K Behra ◽  
Chandra S Saran ◽  
Manikant Paswan ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Research Work ◽  
Open Water ◽  
Numerical Approach ◽  
Series Data ◽  
Hydrodynamic Characteristics ◽  
Propeller Blade ◽  
Scaled Model ◽  
Fluent Simulation ◽  
Thrust And Torque

<p>The aim of the present research work is to investigate the hydrodynamic characteristics (pressure distribution, rotational speed, thrust and torque) of the conventional B-series composite propeller blade. The open water efficiency for the scaled model of composite propeller blade is computed using computational fluid dynamics (CFD) fluent simulation tool. The obtained numerical results show that the propeller will operate at optimum efficiency for the given speed condition and perform with reduced efficiency at other operational speeds. The computed responses are also validated with the standard B-series data which verifies the accuracy and robustness of the present numerical approach in analyzing the performance characteristics of propellers. The deviation in solution ranges from 5 to 15% in the case of thrust, 10-20% in case of torque. Pressure estimation is usually quite accurate with a 5-8% variation. The tabular data of pressure distribution over the propeller blade may be used for further structural analysis</p>

scholarly journals Fiberoptic monitoring of central venous oxygen saturation (PediaSat) in small children undergoing cardiac surgery: continuous is not continuous

F1000Research ◽  
2014 ◽  
Vol 3 ◽  
pp. 23 ◽  
Author(s):  
Francesca G. Iodice ◽  
Zaccaria Ricci ◽  
Roberta Haiberger ◽  
Isabella Favia ◽  
Paola Cogo
Keyword(s):  
Cardiac Surgery ◽  
Standard Deviation ◽  
Repeated Measures ◽  
Near Infrared ◽  
Superior Vena ◽  
Vena Cava ◽  
Poor Correlation ◽  
Average Difference ◽  
Limits Of Agreement ◽  
Median Percentage

Background: Monitoring of superior vena cava saturation (ScvO2) has become routine in the management of pediatric patients undergoing cardiac surgery. The objective of our study was to evaluate the correlation between continuous ScvO2 by the application of a fiber-optic oximetry catheter (PediaSat) and intermittent ScvO2 by using standard blood gas measurements. These results were compared to those obtained by cerebral near infrared spectroscopy (cNIRS).Setting: Tertiary pediatric cardiac intensive care unit (PCICU).Methods and main results: A retrospective study was conducted in consecutive patients who were monitored with a 4.5 or 5.5 F PediaSat catheter into the right internal jugular vein. An in vivo calibration was performed once the patient was transferred to the PCICU and re-calibration took place every 24 hours thereafter. Each patient had a NIRS placed on the forehead. Saturations were collected every 4 hours until extubation. Ten patients with a median age of 2.2 (0.13-8.5) years and a weight of 12.4 (3.9-24) kg were enrolled. Median sampling time was 32 (19-44) hours: 64 pairs of PediaSat and ScVO2 saturations showed a poor correlation (r=0.62, 95% CI 44-75; p<0.0001) and Bland Altman analysis for repeated measures showed an average difference of 0.34 with a standard deviation of 7,9 and 95% limits of agreement from -15 to 16. Thirty-six pairs of cNIRS and ScVO2 saturations showed a fair correlation (r=0.79, 95% CI 0.60-0.89; p<0.0001) an average difference of -1.4 with a standard deviation of 6 and 95% limits of agreement from -13 to 10. Analysis of median percentage differences between PediaSat and ScvO2 saturation over time revealed that, although not statistically significant, the change in percentage saturation differences was clinically relevant after the 8th hour from calibration (from -100 to +100%).Conclusion: PediaSat catheters showed unreliable performance in our cohort. It should be further investigated whether repeating calibrations every 8 hours may improve the accuracy of this system. CNIRS may provide similar results with a lower invasiveness.

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