Ground-based validation of the MetopA and B GOME-2 OClO measurements

Abstract. This paper reports on ground-based validation of the atmospheric OClO data record produced in the framework of EUMETSAT’s Satellite Application Facility on Atmospheric Chemistry Monitoring (AC SAF) using the GOME2-A and -B instruments over the 2007–2016 and 2013–2016 periods, respectively. OClO slant column densities are compared to correlative measurements collected from 9 NDACC Zenith-Scattered-Light DOAS (ZSL-DOAS) instruments distributed in both the Arctic and Antarctic. Sensitivity tests are performed on the ground-based data to estimate the impact of the different OClO DOAS analysis settings. On this basis, we infer systematic uncertainties of about 25 % between the different ground-based data analysis, reaching total uncertainties ranging from about 26 % to 33 % for the different stations. Time-series at the different sites show good agreement between satellite and ground-based data, both for the inter-annual variability and the overall OClO seasonal behavior. GOME-2A results are found to be nosier than those of GOME-2B, especially after 2011, probably due to instrumental degradation effects. Daily linear regression analysis for OClO activated periods yield correlation coefficients of 0.8 for GOME-2A and 0.87 for GOME-2B, with slopes of 0.64 and 0.72, respectively. Biases are within 8 x 1013 molec/cm2 with some differences between GOME-2A and GOME-2B, depending on the station. Overall, considering all the stations, a median bias of about −2.2 x 1013 molec/cm2 is found for both GOME-2 instruments.

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Dampak Hubungan Karyawan dan Kedisiplinan Kerja terhadap Kinerja Karyawan

Journal of Management and Bussines (JOMB) ◽

10.31539/jomb.v1i2.685 ◽

2019 ◽

Vol 1 (2) ◽

pp. 382-393

Author(s):

Rizki Akbari ◽

Kokom Komariah ◽

Dicky Jhoansyah

Keyword(s):

Employee Performance ◽

Linear Regression Analysis ◽

Correlation Coefficients ◽

Multiple Linear Regression Analysis ◽

Test Reliability ◽

Coefficient Of Determination ◽

Employee Relations ◽

Analysis Technique ◽

Multiple Correlation Coefficients ◽

The Impact

The purpose of this study was to determine the impact of employee relations (variable X1) and Work Discipline (variable X2) on Employee Performance (variable Y). The method used in this research is to use descriptive and associative methods. Data collection techniques used by researchers in this study are through observation, questionnaire interviews, documentation and literature studies. The data analysis technique used is the validity test, reliability test, multiple linear regression analysis, including the test of the coefficient of determination and multiple correlation coefficients. The results of the test of the coefficient of determination seen from the value (Adjusted R2) of 0.531 can be interpreted that the impact of employee relations and working discipline on employee performance is equal to 53.1%. The remaining 46.9% is influenced by other factors outside this study. Conclusion, there is a moderate relationship between employee relations and work discipline with employee performance. Keywords: Employee Relations, Work Discipline, Employee Performance

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Multi-year comparisons of ground-based and space-borne Fourier transform spectrometers in the high Arctic between 2006 and 2013

Atmospheric Measurement Techniques ◽

10.5194/amt-10-3273-2017 ◽

2017 ◽

Vol 10 (9) ◽

pp. 3273-3294 ◽

Cited By ~ 4

Author(s):

Debora Griffin ◽

Kaley A. Walker ◽

Stephanie Conway ◽

Felicia Kolonjari ◽

Kimberly Strong ◽

...

Keyword(s):

Fourier Transform ◽

Atmospheric Chemistry ◽

Trace Gases ◽

Correlation Coefficients ◽

High Arctic ◽

Atmospheric Research ◽

Time Period ◽

Experiment Validation ◽

Mean Differences ◽

Good Agreement

Abstract. This paper presents 8 years (2006–2013) of measurements obtained from Fourier transform spectrometers (FTSs) in the high Arctic at the Polar Environment Atmospheric Research Laboratory (PEARL; 80.05° N, 86.42° W). These measurements were taken as part of the Canadian Arctic ACE (Atmospheric Chemistry Experiment) validation campaigns that have been carried out since 2004 during the polar sunrise period (from mid-February to mid-April). Each spring, two ground-based FTSs were used to measure total and partial columns of HF, O3, and trace gases that impact O3 depletion, namely, HCl and HNO3. Additionally, some tropospheric greenhouse gases and pollutant species were measured, namely CH4, N2O, CO, and C2H6. During the same time period, the satellite-based ACE-FTS made measurements near Eureka and provided profiles of the same trace gases. Comparisons have been carried out between the measurements from the Portable Atmospheric Research Interferometric Spectrometer for the InfraRed (PARIS-IR) and the co-located high-resolution Bruker 125HR FTS, as well as with the latest version of the ACE-FTS retrievals (v3.5). The total column comparison between the two co-located ground-based FTSs, PARIS-IR and Bruker 125HR, found very good agreement for most of these species (except HF), with differences well below the estimated uncertainties ( ≤ 6 %) and with high correlations (R ≥ 0. 8). Partial columns have been used for the ground-based to space-borne comparison, with coincident measurements selected based on time, distance, and scaled potential vorticity (sPV). The comparisons of the ground-based measurements with ACE-FTS show good agreement in the partial columns for most species within 6  % (except for C2H6 and PARIS-IR HF), which is consistent with the total retrieval uncertainty of the ground-based instruments. The correlation coefficients (R) of the partial column comparisons for all eight species range from approximately 0.75 to 0.95. The comparisons show no notable increases of the mean differences over these 8 years, indicating the consistency of these datasets and suggesting that the space-borne ACE-FTS measurements have been stable over this period. In addition, changes in the amounts of these trace gases during springtime between 2006 and 2013 are presented and discussed. Increased O3 (0. 9 % yr−1), HCl (1. 7 % yr−1), HF (3. 8 % yr−1), CH4 (0.5  % yr−1), and C2H6 (2. 3 % yr−1, 2009–2013) have been found with the PARIS-IR dataset, the longer of the two ground-based records.

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Exploring ice core sea ice proxies through process-based modelling

10.5194/egusphere-egu2020-9013 ◽

2020 ◽

Author(s):

Rachael Rhodes ◽

Xin Yang ◽

Eric Wolff

Keyword(s):

Sea Ice ◽

Atmospheric Chemistry ◽

Ice Core ◽

Ice Cores ◽

Sea Salt ◽

Atmospheric Composition ◽

The Arctic ◽

Sea Salt Aerosol ◽

Aerosol Emission ◽

The Impact

It is important to understand the magnitude and rate of past sea ice changes, as well as their timing relative to abrupt shifts in other components of Earth&#8217;s climate system. Furthermore, records of past sea ice over the last few centuries are urgently needed to assess the scale of natural (internal) variability over decadal timescales. By continuously recording past atmospheric composition, polar ice cores have the potential to document changing sea ice conditions if atmospheric chemistry is altered. &#160;Sea salt aerosol, specifically sodium (Na), and bromine enrichment (Brenr, Br/Na enriched relative to seawater ratio) are two ice core sea ice proxies suggested following this premise.Here we aim to move beyond a conceptual understanding of the controls on Na and Brenr in ice cores by using process-based modelling to test hypotheses. We present results of experiments using a 3D global chemical transport model (p-TOMCAT) that represents marine aerosol emission, transport and deposition. Critically, the complex atmospheric chemistry of bromine is also included. Three fundamental issues will be examined: 1) the partitioning of Br between gas and aerosol phases, 2) sea salt aerosol production from first-year versus multi-year sea ice, and 3) the impact of increased acidity in the atmosphere due to human activity in the Arctic.

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Denitrification by large NAT particles: the impact of reduced settling velocities and hints on particle characteristics

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-11525-2014 ◽

2014 ◽

Vol 14 (20) ◽

pp. 11525-11544 ◽

Cited By ~ 8

Author(s):

W. Woiwode ◽

J.-U. Grooß ◽

H. Oelhaf ◽

S. Molleker ◽

S. Borrmann ◽

...

Keyword(s):

Stratospheric Ozone ◽

Spherical Particles ◽

Lagrangian Model ◽

The Arctic ◽

Reference Scenario ◽

Climate Interactions ◽

Stratospheric Clouds ◽

The Impact ◽

Good Agreement

Abstract. Vertical redistribution of HNO3 through large HNO3-containing particles associated with polar stratospheric clouds (PSCs) plays an important role in the chemistry of the Arctic winter stratosphere. During the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) campaign, apparently very large NAT (nitric acid trihydrate) particles were observed by the airborne in situ probe FSSP-100 (Molleker et al., 2014). Our analysis shows that the FSSP-100 observations associated with the flight on 25 January 2010 cannot easily be explained assuming compact spherical NAT particles due to much too short growing time at temperatures below the existence temperature of NAT (TNAT). State-of-the-art simulations using CLaMS (Chemical Lagrangian Model of the Stratosphere; Grooß et al., 2014) suggest considerably smaller particles. We consider the hypothesis that the simulation reproduces the NAT particle masses in a realistic way, but that real NAT particles may have larger apparent sizes compared to compact spherical particles, e.g. due to non-compact morphology or aspheric shape. Our study focuses on the consequence that such particles would have reduced settling velocities compared to compact spheres, altering the vertical redistribution of HNO3. Utilising CLaMS simulations, we investigate the impact of reduced settling velocities of NAT particles on vertical HNO3 redistribution and compare the results with observations of gas-phase HNO3 by the airborne Fourier transform spectrometer MIPAS-STR associated with two RECONCILE flights. The MIPAS-STR observations confirm conditions consistent with denitrification by NAT particles for the flight on 25 January 2010 and show good agreement with the simulations within the limitations of the comparison. Best agreement is found if settling velocities between 100 and 50% relative to compact spherical particles are considered (slight preference for the 70% scenario). In contrast, relative settling velocities of 30% result in too weak vertical HNO3 redistribution. Sensitivity simulations considering temperature biases of ±1 K and multiplying the simulated nucleation rates by factors of 0.5 and 2.0 affect the comparisons to a similar extent, but result in no effective improvement compared to the reference scenario. Our results show that an accurate knowledge of the settling velocities of NAT particles is important for quantitative simulations of vertical HNO3 redistribution.

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Multi-year comparisons of ground-based and space-borne Fourier Transform Spectrometers in the high Arctic between 2006 and 2013

10.5194/amt-2016-272 ◽

2016 ◽

Author(s):

Debora Griffin ◽

Kaley A. Walker ◽

Stephanie Conway ◽

Felicia Kolonjari ◽

Kimberly Strong ◽

...

Keyword(s):

Fourier Transform ◽

Atmospheric Chemistry ◽

Trace Gases ◽

Correlation Coefficients ◽

High Arctic ◽

Atmospheric Research ◽

Time Period ◽

Experiment Validation ◽

Mean Differences ◽

Good Agreement

Abstract. This paper presents eight years (2006–2013) of measurements obtained from Fourier Transform Spectrometers (FTSs) in the high Arctic at the Polar Environment Atmospheric Research Laboratory (PEARL, 80.05° N, 86.42° W). These measurements were taken as part of the Canadian Arctic ACE (Atmospheric Chemistry Experiment) Validation Campaigns that have been carried out since 2004 during the polar sunrise period (from mid-February to mid-April). Each spring, two ground-based FTSs were used to measure total and partial columns of HF, O3, and trace gases that impact O3 depletion, namely, HCl, and HNO3. Additionally, some tropospheric greenhouse gases and pollutant species were measured, namely CH4, N2O, CO, and C2H6. During the same time period, the satellite-based ACE-FTS made measurements near Eureka and provided profiles of the same trace gases. Comparisons have been carried out between the measurements from PARIS-IR and the co-located high-resolution Bruker 125HR FTS, as well as with the latest version of the ACE-FTS retrievals (v3.5). The total column comparison between the two co-located ground-based FTSs, PARIS-IR and Bruker 125HR, found very good agreement for most of these species (except HF), with differences well below the estimated uncertainties (~ 6 %) and with high correlations (R ≥ 0.8). Partial columns have been used for the ground-based to space-borne comparison, with coincident measurements selected based on time, distance and scaled potential vorticity (sPV). The comparisons of the ground-based measurements with ACE-FTS show good agreement in the partial columns for most species within 6 % (except for C2H6 and PARIS-IR HF), which are consistent with the total retrieval uncertainty of the ground-based instruments. The correlation coefficients (R) of the partial column comparisons for all eight species range from approximately 0.75 to 0.95. The comparisons show no significant increase in the mean differences over these eight years, indicating the consistency of these datasets and suggesting that the space-borne ACE-FTS measurements have been stable over this period. In addition, changes in the amounts of these trace gases during springtime between 2006 and 2013 are presented and discussed. Increased O3 (0.9 % yr−1), HCl (1.7 % yr−1), HF (3.8 % yr−1), CH4 (0.5 % yr−1) and C2H6 (2.3 % yr−1, 2009–2013) have been found near PEARL from the Portable Atmospheric Research Interferometric Spectrometer for the InfraRed (PARIS-IR) dataset.

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Retrieval of MetOp-A/IASI CO profiles and validation with MOZAIC data

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-5-3271-2012 ◽

2012 ◽

Vol 5 (3) ◽

pp. 3271-3301

Author(s):

E. De Wachter ◽

B. Barret ◽

E. Le Flochmoën ◽

E. Pavelin ◽

M. Matricardi ◽

...

Keyword(s):

Lower Troposphere ◽

Correlation Coefficients ◽

Global Scale ◽

Upper Troposphere ◽

Retrieval Algorithms ◽

Good Reproduction ◽

The Impact ◽

Good Agreement ◽

Limited Sensitivity

Abstract. The IASI nadir looking thermal infrared sounder onboard MetOp-A enables the monitoring of atmospheric constituents on a global scale. This paper presents a quality assessment of IASI CO profiles retrieved by the two different retrieval algorithms SOFRID and FORLI, by an intercomparison with airborne in-situ CO profiles from the MOZAIC program. A statistical analysis shows a very good agreement between the two retrieval algorithms and smoothed MOZAIC data for the lower troposphere (surface-480 hPa) with correlation coefficients r ~ 0.8, and a good agreement in the upper troposphere (480–225 hPa) with r ~ 0.7. Closer investigation of the temporal variation of the CO profiles at the airports of Frankfurt and Windhoek demonstrates that on the overall a very good agreement is found between the IASI products and smoothed MOZAIC data in terms of seasonal variability. At Frankfurt SOFRID (resp. FORLI) is positively biased by 10.5% (resp. 13.0%) compared to smoothed MOZAIC in the upper (resp. lower) troposphere, and the limited sensitivity of the IASI instrument to the boundary layer when thermal contrast is low is identified. At Windhoek, we find a good reproduction of the impact of the vegetation fires in Southern Africa from July to November by both SOFRID and FORLI, with an overestimation of the CO background values (resp. fire maxima) by SOFRID (resp. FORLI) by 12.8% (resp. ~10%). Profile comparisons at Frankfurt and Windhoek identify a reduced performance of the nighttime retrievals of both products compared to daytime retrievals.

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Nitrogen oxides and PAN in plumes from boreal fires during ARCTAS-B and their impact on ozone: an integrated analysis of aircraft and satellite observations

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-9739-2010 ◽

2010 ◽

Vol 10 (20) ◽

pp. 9739-9760 ◽

Cited By ~ 167

Author(s):

M. J. Alvarado ◽

J. A. Logan ◽

J. Mao ◽

E. Apel ◽

D. Riemer ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Dry Matter ◽

Satellite Observations ◽

The Arctic ◽

Integrated Analysis ◽

Fire Emissions ◽

Ozone Profile ◽

Smoke Plumes ◽

The Impact ◽

Aircraft Data

Abstract. We determine enhancement ratios for NOx, PAN, and other NOy species from boreal biomass burning using aircraft data obtained during the ARCTAS-B campaign and examine the impact of these emissions on tropospheric ozone in the Arctic. We find an initial emission factor for NOx of 1.06 g NO per kg dry matter (DM) burned, much lower than previous observations of boreal plumes, and also one third the value recommended for extratropical fires. Our analysis provides the first observational confirmation of rapid PAN formation in a boreal smoke plume, with 40% of the initial NOx emissions being converted to PAN in the first few hours after emission. We find little clear evidence for ozone formation in the boreal smoke plumes during ARCTAS-B in either aircraft or satellite observations, or in model simulations. Only a third of the smoke plumes observed by the NASA DC8 showed a correlation between ozone and CO, and ozone was depleted in the plumes as often as it was enhanced. Special observations from the Tropospheric Emission Spectrometer (TES) also show little evidence for enhanced ozone in boreal smoke plumes between 15 June and 15 July 2008. Of the 22 plumes observed by TES, only 4 showed ozone increasing within the smoke plumes, and even in those cases it was unclear that the increase was caused by fire emissions. Using the GEOS-Chem atmospheric chemistry model, we show that boreal fires during ARCTAS-B had little impact on the median ozone profile measured over Canada, and had little impact on ozone within the smoke plumes observed by TES.

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Predicting Impact Sensitivity of Heterocyclic Nitroarenes from Molecular Structures Selected by Genetic Algorithm

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.535-537.2550 ◽

2012 ◽

Vol 535-537 ◽

pp. 2550-2553

Author(s):

Rui Wang ◽

Yong Gu Wang ◽

Hui Liu

Keyword(s):

Genetic Algorithm ◽

Cross Validation ◽

Correlation Coefficients ◽

Molecular Structures ◽

Impact Sensitivity ◽

Optimal Subset ◽

Leave One Out ◽

The Impact ◽

Prediction Capability ◽

Good Agreement

A novel theoretical model was constructed to predict the impact sensitivity of 44 heterocyclic nitroarenes. The optimal subset of the molecular structures descriptors were selected by genetic algorithm (GA). The multiple linear regression (MLR) was then applied to build a prediction model of impact sensitivity for the 44 compounds. The correlation coefficients (R2) together with correlation coefficient of the leave-one-out cross validation (Q2CV) of the model is 0.928 and 0.865, respectively. The new model is highly statistically significant, and the robustness as well as internal prediction capability of which is satisfactory. The predicted impact sensitivity values are in good agreement with the experimental data.

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Nitrogen oxides and PAN in plumes from boreal fires during ARCTAS-B and their impact on ozone: an integrated analysis of aircraft and satellite observations

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-15325-2010 ◽

2010 ◽

Vol 10 (6) ◽

pp. 15325-15377 ◽

Cited By ~ 2

Author(s):

M. J. Alvarado ◽

J. A. Logan ◽

J. Mao ◽

E. Apel ◽

D. Riemer ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Dry Matter ◽

Satellite Observations ◽

The Arctic ◽

Integrated Analysis ◽

Fire Emissions ◽

Ozone Profile ◽

Smoke Plumes ◽

The Impact ◽

Aircraft Data

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Long-term Time-series of Arctic Tropospheric BrO derived from UV-VIS Satellite Remote Sensing and its Relation to First Year Sea Ice

10.5194/acp-2020-116 ◽

2020 ◽

Author(s):

Ilias Bougoudis ◽

Anne-Marlene Blechschmidt ◽

Andreas Richter ◽

Sora Seo ◽

John Philip Burrows ◽

...

Keyword(s):

Time Series ◽

Sea Ice ◽

Ice Age ◽

The Arctic ◽

First Year ◽

Arctic Amplification ◽

Vertical Column ◽

The Impact ◽

Good Agreement

Abstract. Arctic Amplification describes the rapid increase of the air temperature in the past three decades in the Arctic, which impacts on physicochemical conditions, the ecosystem and biogeochemistry. Every polar spring, the BrO explosion, a series of chemical reactions that release bromine molecules to the troposphere occurs over sea ice covered regions. This autocatalytic mechanism depletes boundary layer and tropospheric ozone, thereby changes the oxidizing capacity of the atmosphere and facilitates the deposition of metals (e.g. Hg). In this study, we present a 22 year consolidated and consistent tropospheric BrO dataset, derived from four different UV-VIS satellite instruments and investigate the BrO evolution under the impact of Arctic Amplification. The retrieval data products from the different sensors are compared during periods of overlap and show good agreement. By studying the sensor merged time-series of tropospheric BrO vertical column densities, we find an increase in the magnitude of BrO explosion events under the impact of Arctic Amplification with an upward trend of about 1.5 % per year. Furthermore, the areas where BrO plumes frequently appear have changed, extending over larger regions in the Arctic during more recent years. Comparison to sea ice age data suggests that the reported changes in tropospheric BrO are linked in a complex way to the increase of first-year ice extent in the Arctic.

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