scholarly journals Supplementary material to "Ozone deposition impact assessments for forest canopies require accurate ozone flux partitioning on diurnal timescales"

2021 ◽  
Author(s):  
Auke J. Visser ◽  
Laurens N. Ganzeveld ◽  
Ignacio Goded ◽  
Maarten C. Krol ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Forest Canopies ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
Flux Partitioning ◽  
Supplementary Material

scholarly journals Evaluation of the flux gradient technique for measurement of ozone surface fluxes over snowpack at Summit, Greenland

2011 ◽  
Vol 4 (1) ◽  
pp. 1021-1059
Author(s):  
F. Bocquet ◽  
D. Helmig ◽  
B. A. Van Dam ◽  
C. W. Fairall
Keyword(s):  
Gradient Method ◽  
Deposition Velocity ◽  
Surface Fluxes ◽  
Sensitivity Threshold ◽  
Lower Sensitivity ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
Gradient Technique ◽  
Measurement Height ◽  
Polar Snow

Abstract. A multi-step procedure for investigating ozone surface fluxes over polar snow by the tower gradient method was developed and evaluated. These measurements were then used to obtain four months of turbulent ozone flux data at the Summit research camp located in the center of the Greenland ice shield. Turbulent fluxes were determined by the aerodynamic gradient method incorporating tower measurements of (a) ozone gradients measured by commercial ultraviolet absorption analyzers, (b) ambient temperature gradients using aspirated thermocouple sensors, and (c) wind speed gradients determined by cup anemometers. All gradient instruments were regularly inter-compared by bringing sensors or inlets to the same measurement height. The developed protocol resulted in an uncertainty on the order of 0.1 ppbv for 30-min averaged ozone gradients that were used for the ozone flux calculations. This protocol facilitated a lower sensitivity threshold for the ozone flux determination of −8 × 10−3 μg m−2 s−1, respectively ~0.01 cm s−1 for the ozone deposition velocity for typical environmental conditions encountered at Summit. Uncertainty in the 30-min ozone exchange measurements (evaluated by the Monte Carlo statistical approach) was on the order of 10−2 cm s−1. This uncertainty typically accounted to ~20–100% of the ozone exchange velocities that were determined. These measurements are among the most sensitive ozone deposition determinations reported to date. This flux experiment, deployed at Summit for a period of four months, allowed for measurements of the relatively low ozone uptake rates encountered for polar snow, and thereby the study of their environmental and seasonal dependencies.

scholarly journals Ozone deposition impact assessments for forest canopies require accurate ozone flux partitioning on diurnal timescales

2021 ◽  
Vol 21 (24) ◽  
pp. 18393-18411
Author(s):  
Auke J. Visser ◽  
Laurens N. Ganzeveld ◽  
Ignacio Goded ◽  
Maarten C. Krol ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Land Surface ◽  
Large Scale ◽  
Crop Yields ◽  
Carbon Sink ◽  
Surface Ozone ◽  
Ozone Uptake ◽  
Ozone Deposition ◽  
Ozone Flux

Abstract. Dry deposition is an important sink of tropospheric ozone that affects surface concentrations and impacts crop yields, the land carbon sink, and the terrestrial water cycle. Dry deposition pathways include plant uptake via stomata and non-stomatal removal by soils, leaf surfaces, and chemical reactions. Observational studies indicate that ozone deposition exhibits substantial temporal variability that is not reproduced by atmospheric chemistry models due to a simplified representation of vegetation uptake processes in these models. In this study, we explore the importance of stomatal and non-stomatal uptake processes in driving ozone dry deposition variability on diurnal to seasonal timescales. Specifically, we compare two land surface ozone uptake parameterizations – a commonly applied big leaf parameterization (W89; Wesely, 1989) and a multi-layer model (MLC-CHEM) constrained with observations – to multi-year ozone flux observations at two European measurement sites (Ispra, Italy, and Hyytiälä, Finland). We find that W89 cannot reproduce the diurnal cycle in ozone deposition due to a misrepresentation of stomatal and non-stomatal sinks at our two study sites, while MLC-CHEM accurately reproduces the different sink pathways. Evaluation of non-stomatal uptake further corroborates the previously found important roles of wet leaf uptake in the morning under humid conditions and soil uptake during warm conditions. The misrepresentation of stomatal versus non-stomatal uptake in W89 results in an overestimation of growing season cumulative ozone uptake (CUO), a metric for assessments of vegetation ozone damage, by 18 % (Ispra) and 28 % (Hyytiälä), while MLC-CHEM reproduces CUO within 7 % of the observation-inferred values. Our results indicate the need to accurately describe the partitioning of the ozone atmosphere–biosphere flux over the in-canopy stomatal and non-stomatal loss pathways to provide more confidence in atmospheric chemistry model simulations of surface ozone mixing ratios and deposition fluxes for large-scale vegetation ozone impact assessments.

scholarly journals Evaluation of the flux gradient technique for measurement of ozone surface fluxes over snowpack at Summit, Greenland

2011 ◽  
Vol 4 (10) ◽  
pp. 2305-2321 ◽  
Author(s):  
F. Bocquet ◽  
D. Helmig ◽  
B. A. Van Dam ◽  
C. W. Fairall
Keyword(s):  
Gradient Method ◽  
Deposition Velocity ◽  
Surface Fluxes ◽  
Sensitivity Threshold ◽  
Lower Sensitivity ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
Gradient Technique ◽  
Measurement Height ◽  
Polar Snow

Abstract. A multi-step procedure for investigating ozone surface fluxes over polar snow by the tower gradient method was developed and evaluated. These measurements were then used to obtain five months (April–August 2004) of turbulent ozone flux data at the Summit research camp located in the center of the Greenland ice shield. Turbulent fluxes were determined by the gradient method incorporating tower measurements of (a) ozone gradients measured by commercial ultraviolet absorption analyzers, (b) ambient temperature gradients using aspirated thermocouple sensors, and (c) wind speed gradients determined by cup anemometers. All gradient instruments were regularly inter-compared by bringing sensors or inlets to the same measurement height. The developed protocol resulted in an uncertainty on the order of 0.1 ppbv for 30-min averaged ozone gradients that were used for the ozone flux calculations. This protocol facilitated a lower sensitivity threshold for the ozone flux determination of ∼8 × 10−3μg m−2 s−1, respectively ∼0.01 cm s−1 for the ozone deposition velocity for typical environmental conditions encountered at Summit. Uncertainty in the 30-min ozone exchange measurements (evaluated by the Monte Carlo statistical approach) was on the order of 10−2 cm s−1. This uncertainty typically accounted to ~20–100% of the ozone exchange velocities that were determined. These measurements are among the most sensitive ozone deposition determinations reported to date. This flux experiment allowed for measurements of the relatively low ozone uptake rates encountered for polar snow, and thereby the study of their environmental and spring-versus-summer dependencies.

Ozone flux and ozone deposition in a mountain spruce forest are modulated by sky conditions

2019 ◽  
Vol 672 ◽  
pp. 296-304 ◽  
Author(s):  
Stanislav Juráň ◽  
Ladislav Šigut ◽  
Petr Holub ◽  
Silvano Fares ◽  
Karel Klem ◽  
...  
Keyword(s):  
Spruce Forest ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
Sky Conditions

scholarly journals Determination of oceanic ozone deposition by ship-borne eddy covariance flux measurements

2010 ◽  
Vol 3 (2) ◽  
pp. 441-455 ◽  
Author(s):  
L. Bariteau ◽  
D. Helmig ◽  
C. W. Fairall ◽  
J. E. Hare ◽  
J. Hueber ◽  
...  
Keyword(s):  
Time Lag ◽  
Fast Response ◽  
Ozone Deposition ◽  
Ozone Flux ◽  
The North ◽  
Flux System ◽  
Deposition Velocities ◽  
Flux Measurements ◽  
Chemical Analyzer

Abstract. A fast response ozone analyzer based on the ozone-nitric oxide chemiluminescence method was integrated into the NOAA-ESRL flux system to achieve the first ship-borne, direct ozone flux measurements over the open ocean. Air was collected from an inlet at 18 m height over the ocean surface mounted to the bow-jackstaff and via a 30 m-long sampling line to the ozone instrument on the ship deck. A "puff" system was used for accurate and regular determination of the sample transport time (lag) between the inlet and the chemical analyzer. A Nafion-membrane dryer facilitated removal of fast water vapor fluctuations, which eliminated the need for quenching and density correction of the ozone signal. The sampling-analyzer system was found to have a ~0.25–0.40 s response time at a sensitivity of ~2800 counts s−1 per ppbv of ozone. Quality control and data filtering procedures for eliminating data that did not meet measurement requirements were critically evaluated. The new ozone flux system was deployed aboard the NOAA Ship Ronald H. Brown, and evaluated using results obtained during several research cruises off the coasts of the North and South America continents, yielding ozone deposition velocities (mean ± standard error) ranging from 0.009±0.001 cm s−1 to 0.24±0.020 cm s−1.

scholarly journals Ozone deposition impact assessments for forest canopies require accurate ozone flux partitioning on diurnal timescales

2021 ◽  
Author(s):  
Auke J. Visser ◽  
Laurens N. Ganzeveld ◽  
Ignacio Goded ◽  
Maarten C. Krol ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Land Surface ◽  
Large Scale ◽  
Crop Yields ◽  
Carbon Sink ◽  
Surface Ozone ◽  
Ozone Uptake ◽  
Ozone Deposition ◽  
Ozone Flux

Abstract. Dry deposition is an important sink of tropospheric ozone that affects surface concentrations, and impacts crop yields, the land carbon sink and the terrestrial water cycle. Dry deposition pathways include plant uptake via stomata and nonstomatal removal by soils, leaf surfaces and chemical reactions. Observational studies indicate that ozone deposition exhibits substantial temporal variability that is not reproduced by atmospheric chemistry models due to a simplified representation of vegetation uptake processes in these models. In this study, we explore the importance of stomatal and non-stomatal uptake processes in driving ozone dry deposition variability on diurnal to seasonal timescales. Specifically, we compare two land surface ozone uptake parameterizations – a commonly applied ’big leaf’ parameterization (W89; Wesely, 1989) and a multi-layer model (MLC-CHEM) constrained with observations – to multi-year ozone flux observations at two European measurement sites (Ispra, Italy, and Hyytiälä, Finland). We find that W89 cannot reproduce the diurnal cycle in ozone deposition due to a mis-representation of stomatal and non-stomatal sinks at our two study sites, while MLC-CHEM accurately reproduces the different sink pathways. Evaluation of non-stomatal uptake further corroborates the previously found important roles of wet leaf uptake in the morning under humid conditions, and soil uptake during warm conditions. The misrepresentation of stomatal versus non-stomatal uptake in W89 results in an overestimation of growing-season cumulative ozone uptake (CUO), a metric for assessments of vegetation ozone damage, by 18 % (Ispra) and 28 % (Hyytiälä), while MLC-CHEM reproduces CUO within 7 % of the observation-inferred values. Our results indicate the need to accurately describe the partitioning of the ozone atmosphere-biosphere flux over the in-canopy stomatal and non-stomatal loss pathways to provide more confidence in atmospheric chemistry model simulations of surface ozone mixing ratios and deposition fluxes for large-scale vegetation ozone impact assessments.

Supplementary material to "Synthetic ozone deposition and stomatal uptake at flux tower sites"

2018 ◽  
Author(s):  
Jason A. Ducker ◽  
Christopher D. Holmes ◽  
Trevor F. Keenan ◽  
Silvano Fares ◽  
Allen H. Goldstein ◽  
...  
Keyword(s):  
Flux Tower ◽  
Ozone Deposition ◽  
Supplementary Material

Designing Workbook for Teaching Writing Descriptive Text Based on Scientific Approach

2019 ◽  
Vol 1 (2) ◽  
pp. 59
Author(s):  
Indah Pratiwi ◽  
Yanti Sri Rezeki
Keyword(s):  
Teaching Writing ◽  
English Teacher ◽  
Design Development ◽  
Seventh Grade ◽  
Internal Evaluation ◽  
Writing Ability ◽  
Good Book ◽  
Scientific Approach ◽  
Supplementary Material ◽  
Analysis Design

This research aims to design workbook based on the scientific approach for teaching writing descriptive text. This research was conducted on the seventh-grade students of SMPN 24 Pontianak. The method of this research is ADDIE (Analysis, Design, Development, Implementation, and Evaluation) with the exclusion of Implementation and Evaluation phases. This material was designed as supplementary material to support the course book used especially in teaching writing of descriptive text. The respondents in this research were the seventh-grade students and an English teacher at SMPN 24 Pontianak. In this research, the researchers found that workbook based on scientific approach fulfilled the criteria of the good book to teach writing descriptive text. The researchers conducted an internal evaluation to see the usability and the feasibility of the workbook. The result of the evaluation is 89%. It showed that the workbook is feasible to be used by students as the supplementary material to support the main course book and help the students improve their writing ability in descriptive text.

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