Variability of springtime transpacific pollution transport during 2000–2006: the INTEX-B mission in the context of previous years

Abstract. We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part B) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and dynamics from changes in source strength. Interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 1/3 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 2/3 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.

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Transpacific pollution transport during INTEX-B: spring 2006 in context to previous years

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-17817-2009 ◽

2009 ◽

Vol 9 (4) ◽

pp. 17817-17849 ◽

Cited By ~ 4

Author(s):

G. G. Pfister ◽

L. K. Emmons ◽

D. P. Edwards ◽

A. Arellano ◽

G. Sachse ◽

...

Keyword(s):

Transport Model ◽

Pollution Transport ◽

Chemistry Transport Model ◽

Pollution Levels ◽

Annual Variability ◽

Source Regions ◽

Time Period ◽

The Pacific ◽

The Us ◽

Transport Experiment

Abstract. We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part B) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and dynamics from changes in source strength. Interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced to (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 1/3 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 2/3 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.

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Influence of the wintertime North Atlantic Oscillation on European tropospheric composition: an observational and modelling study

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-8389-2018 ◽

2018 ◽

Vol 18 (11) ◽

pp. 8389-8408 ◽

Cited By ~ 2

Author(s):

Richard J. Pope ◽

Martyn P. Chipperfield ◽

Stephen R. Arnold ◽

Norbert Glatthor ◽

Wuhu Feng ◽

...

Keyword(s):

North Atlantic Oscillation ◽

North Atlantic ◽

Transport Model ◽

Anthropogenic Source ◽

Chemistry Transport Model ◽

Upper Troposphere ◽

Pollution Levels ◽

Source Regions ◽

Governing Factor ◽

Circulation Patterns

Abstract. We have used satellite observations and a simulation from the TOMCAT chemistry transport model (CTM) to investigate the influence of the well-known wintertime North Atlantic Oscillation (NAO) on European tropospheric composition. Under the positive phase of the NAO (NAO-high), strong westerlies tend to enhance transport of European pollution (e.g. nitrogen oxides, NOx; carbon monoxide, CO) away from anthropogenic source regions. In contrast, during the negative phase of the NAO (NAO-low), more stable meteorological conditions lead to a build-up of pollutants over these regions relative to the wintertime average pollution levels. However, the secondary pollutant ozone shows the opposite signal of larger values during NAO-high. NAO-high introduces Atlantic ozone-enriched air into Europe, while under NAO-low westerly transport of ozone is reduced, yielding lower values over Europe. Furthermore, ozone concentrations are also decreased by chemical loss through the reaction with accumulated primary pollutants such as nitric oxide (NO) in NAO-low. Peroxyacetyl nitrate (PAN) in the upper troposphere–lower stratosphere (UTLS) peaks over Iceland and southern Greenland in NAO-low, between 200 and 100 hPa, consistent with the trapping by an anticyclone at this altitude. Model simulations show that enhanced PAN over Iceland and southern Greenland in NAO-low is associated with vertical transport of polluted air from the mid-troposphere into the UTLS. Overall, this work shows that NAO circulation patterns are an important governing factor for European wintertime composition and air pollution.

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An alternative way to evaluate chemistry-transport model variability

Geoscientific Model Development ◽

10.5194/gmd-10-1199-2017 ◽

2017 ◽

Vol 10 (3) ◽

pp. 1199-1208 ◽

Cited By ~ 1

Author(s):

Laurent Menut ◽

Sylvain Mailler ◽

Bertrand Bessagnet ◽

Guillaume Siour ◽

Augustin Colette ◽

...

Keyword(s):

Transport Model ◽

Model Performance ◽

Error Statistics ◽

Chemistry Transport Model ◽

Temporal Correlations ◽

Time Period ◽

The Difference ◽

Model Variability ◽

Spatial Locations ◽

Statistical Indicators

Abstract. A simple and complementary model evaluation technique for regional chemistry transport is discussed. The methodology is based on the concept that we can learn about model performance by comparing the simulation results with observational data available for time periods other than the period originally targeted. First, the statistical indicators selected in this study (spatial and temporal correlations) are computed for a given time period, using colocated observation and simulation data in time and space. Second, the same indicators are used to calculate scores for several other years while conserving the spatial locations and Julian days of the year. The difference between the results provides useful insights on the model capability to reproduce the observed day-to-day and spatial variability. In order to synthesize the large amount of results, a new indicator is proposed, designed to compare several error statistics between all the years of validation and to quantify whether the period and area being studied were well captured by the model for the correct reasons.

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Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-7055-2017 ◽

2017 ◽

Vol 17 (11) ◽

pp. 7055-7066 ◽

Cited By ~ 20

Author(s):

Felix Ploeger ◽

Paul Konopka ◽

Kaley Walker ◽

Martin Riese

Keyword(s):

Asian Monsoon ◽

Lower Stratosphere ◽

Transport Model ◽

Monsoon Circulation ◽

Pollution Transport ◽

Chemistry Transport Model ◽

Transport Pathways ◽

Air Mass ◽

Mass Fractions ◽

The Tropics

Abstract. Pollution transport from the surface to the stratosphere within the Asian monsoon circulation may cause harmful effects on stratospheric chemistry and climate. Here, we investigate air mass transport from the monsoon anticyclone into the stratosphere using a Lagrangian chemistry transport model. We show how two main transport pathways from the anticyclone emerge: (i) into the tropical stratosphere (tropical pipe), and (ii) into the Northern Hemisphere (NH) extratropical lower stratosphere. Maximum anticyclone air mass fractions reach around 5 % in the tropical pipe and 15 % in the extratropical lowermost stratosphere over the course of a year. The anticyclone air mass fraction correlates well with satellite hydrogen cyanide (HCN) and carbon monoxide (CO) observations, confirming that pollution is transported deep into the tropical stratosphere from the Asian monsoon anticyclone. Cross-tropopause transport occurs in a vertical chimney, but with the pollutants transported quasi-horizontally along isentropes above the tropopause into the tropics and NH.

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Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

10.5194/acp-2017-86 ◽

2017 ◽

Author(s):

Felix Ploeger ◽

Paul Konopka ◽

Kaley Walker ◽

Martin Riese

Keyword(s):

Asian Monsoon ◽

Lower Stratosphere ◽

Transport Model ◽

Monsoon Circulation ◽

Pollution Transport ◽

Chemistry Transport Model ◽

Transport Pathways ◽

Air Mass ◽

Mass Fractions ◽

The Tropics

Abstract. Pollution transport from the surface to the stratosphere within the Asian monsoon circulation may cause harmful effects on stratospheric chemistry and climate. Here, we investigate air mass transport from the monsoon anticyclone into the stratosphere using a Lagrangian chemistry transport model. We show how two main transport pathways from the anticyclone emerge: (i) into the tropical stratosphere (tropical pipe), and (ii) into the Northern hemisphere (NH) extra-tropical lower stratosphere. Maximum anticyclone air mass fractions reach around 5 % in the tropical pipe and 15 % in the extra-tropical lowermost stratosphere over the course of a year. The anticyclone air mass fraction correlates well with satellite hydrogen cyanide (HCN) and carbon monoxide (CO) observations, corroborating that pollution is transported deep into the tropical stratosphere from the Asian monsoon anticyclone. Cross-tropopause transport occurs in a vertical chimney, but with the emissions transported quasi-horizontally along isentropes above the tropopause into the tropics and NH.

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Operational total and tropospheric NO<sub>2</sub> column retrieval for GOME-2

Atmospheric Measurement Techniques ◽

10.5194/amt-4-1491-2011 ◽

2011 ◽

Vol 4 (7) ◽

pp. 1491-1514 ◽

Cited By ~ 83

Author(s):

P. Valks ◽

G. Pinardi ◽

A. Richter ◽

J.-C. Lambert ◽

N. Hao ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Transport Model ◽

Optical Absorption Spectroscopy ◽

Chemistry Transport Model ◽

Air Mass ◽

Cloud Properties ◽

The Pacific ◽

Tropospheric No2 ◽

Data Processor ◽

Radiance Data

Abstract. This paper presents the algorithm for the operational near real time retrieval of total and tropospheric NO2 columns from the Global Ozone Monitoring Experiment (GOME-2). The retrieval is performed with the GOME Data Processor (GDP) version 4.4 as used by the EUMETSAT Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M-SAF). The differential optical absorption spectroscopy (DOAS) method is used to determine NO2 slant columns from GOME-2 (ir)radiance data in the 425–450 nm range. Initial total NO2 columns are computed using stratospheric air mass factors, and GOME-2 derived cloud properties are used to calculate the air mass factors for scenarios in the presence of clouds. To obtain the stratospheric NO2 component, a spatial filtering approach is used, which is shown to be an improvement on the Pacific reference sector method. Tropospheric air mass factors are computed using monthly averaged NO2 profiles from the MOZART-2 chemistry transport model. An error analysis shows that the random error in the GOME-2 NO2 slant columns is approximately 0.45 × 1015 molec cm−2. As a result of the improved quartz diffuser plate used in the GOME-2 instrument, the systematic error in the slant columns is strongly reduced compared to GOME/ERS-2. The estimated uncertainty in the GOME-2 tropospheric NO2 column for polluted conditions ranges from 40 to 80 %. An end-to-end ground-based validation approach for the GOME-2 NO2 columns is illustrated based on multi-axis MAXDOAS measurements at the Observatoire de Haute Provence (OHP). The GOME-2 stratospheric NO2 columns are found to be in good overall agreement with coincident ground-based measurements at OHP. A time series of the MAXDOAS and the GOME-2 tropospheric NO2 columns shows that pollution episodes at OHP are well captured by GOME-2. Monthly mean tropospheric columns are in very good agreement, with differences generally within 0.5 × 1015 molec cm−2.

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Climatology of the aerosol optical depth by components from the Multiangle Imaging SpectroRadiometer (MISR) and a high-resolution chemistry transport model

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-33897-2015 ◽

2015 ◽

Vol 15 (23) ◽

pp. 33897-33929 ◽

Cited By ~ 1

Author(s):

H. Lee ◽

O. V. Kalashnikova ◽

K. Suzuki ◽

A. Braverman ◽

M. J. Garay ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Transport Model ◽

Radiation Transport ◽

Spectral Radiation ◽

Chemistry Transport Model ◽

Source Regions ◽

Level 3 ◽

Level 2 ◽

Aerosol Type

Abstract. The Multi-angle Imaging SpectroRadiometer (MISR) Joint Aerosol (JOINT_AS) Level 3 product provides a global, descriptive summary of MISR Level 2 aerosol optical depth (AOD) and aerosol type information for each month between March 2000 and the present. Using Version 1 of JOINT_AS, which is based on the operational (Version 22) MISR Level 2 aerosol product, this study analyzes, for the first time, characteristics of observed and simulated distributions of AOD for three broad classes of aerosols: non-absorbing, absorbing, and non-spherical – near or downwind of their major source regions. The statistical moments (means, standard deviations, and skewnesses) and distributions of AOD by components derived from the JOINT_AS are compared with results from the SPectral RadIatioN-TrAnSport (SPRINTARS) model, a chemistry transport model (CTM) with very high spatial and temporal resolution. Overall, the AOD distributions of combined MISR aerosol types show good agreement with those from SPRINTARS. Marginal distributions of AOD for each aerosol type in both MISR and SPRINTARS show considerable high positive skewness, which indicates the importance of including extreme AOD events when comparing satellite retrievals with models. The MISR JOINT_AS product will greatly facilitate comparisons between satellite observations and model simulations of aerosols by type.

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Chemistry and transport of pollution over the Gulf of Mexico and the Pacific: Spring 2006 INTEX-B Campaign overview and first results

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-363-2009 ◽

2009 ◽

Vol 9 (1) ◽

pp. 363-409 ◽

Cited By ~ 13

Author(s):

H. B. Singh ◽

W. H. Brune ◽

J. H. Crawford ◽

F. Flocke ◽

D. J. Jacob

Keyword(s):

Air Quality ◽

Gulf Of Mexico ◽

Transport Model ◽

Chemical Transport ◽

Second Phase ◽

Pollution Transport ◽

Aerosol Composition ◽

Data Set ◽

The Pacific ◽

Two Phases

Abstract. Intercontinental Chemical Transport Experiment-B (INTEX-B) was a major NASA1 led multi-partner atmospheric field campaign completed in the spring of 2006 (http://cloud1.arc.nasa.gov/intex-b/). Its major objectives aimed at (i) investigating the extent and persistence of the outflow of pollution from Mexico; (ii) understanding transport and evolution of Asian pollution and implications for air quality and climate across western North America; and (iii) validating space-borne observations of tropospheric composition. INTEX-B was performed in two phases. In its first phase (1–21 March), INTEX-B operated as part of the MILAGRO campaign with a focus on observations over Mexico and the Gulf of Mexico. In the second phase (17 April–15 May), the main INTEX-B focus was on the trans-Pacific Asian pollution transport. Multiple airborne platforms carrying state of the art chemistry and radiation payloads were flown in concert with satellites and ground stations during the two phases of INTEX-B. Validation of Aura satellite instruments (TES, OMI, MLS, HIRDLS) was a key objective within INTEX-B. Satellite products along with meteorological and 3-D chemical transport model forecasts were integrated into the flight planning process to allow targeted sampling of air parcels. Inter-comparisons were performed among and between aircraft payloads to quantify the accuracy of data and to create a unified data set. Pollution plumes were sampled over the Gulf of Mexico and the Pacific several days after downwind transport from source regions. Signatures of Asian pollution were routinely detected by INTEX-B aircraft, providing a comprehensive data set on gas and aerosol composition to test models and evaluate pathways of pollution transport and their impact on air quality and climate. This overview provides details about campaign implementation and a context within which the present and future INTEX-B/MILAGRO publications can be understood. 1 Acronyms are provided in Appendix A.

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Dynamically controlled ozone decline in the tropical mid-stratosphere observed by SCIAMACHY

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-767-2019 ◽

2019 ◽

Vol 19 (2) ◽

pp. 767-783 ◽

Cited By ~ 7

Author(s):

Evgenia Galytska ◽

Alexey Rozanov ◽

Martyn P. Chipperfield ◽

Sandip. S. Dhomse ◽

Mark Weber ◽

...

Keyword(s):

Residence Time ◽

Transport Model ◽

Stratospheric Ozone ◽

Satellite Measurements ◽

Linear Change ◽

Chemistry Transport Model ◽

Negative Change ◽

Time Period ◽

Scanning Imaging ◽

Odd Nitrogen

Abstract. Despite the recently reported beginning of a recovery in global stratospheric ozone (O3), an unexpected O3 decline in the tropical mid-stratosphere (around 30–35 km altitude) was observed in satellite measurements during the first decade of the 21st century. We use SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) measurements for the period 2004–2012 to confirm the significant O3 decline. The SCIAMACHY observations show that the decrease in O3 is accompanied by an increase in NO2. To reveal the causes of these observed O3 and NO2 changes, we performed simulations with the TOMCAT 3-D chemistry-transport model (CTM) using different chemical and dynamical forcings. For the 2004–2012 time period, the TOMCAT simulations reproduce the SCIAMACHY-observed O3 decrease and NO2 increase in the tropical mid-stratosphere. The simulations suggest that the positive changes in NO2 (around 7 % decade−1) are due to similar positive changes in reactive odd nitrogen (NOy), which are a result of a longer residence time of the source gas N2O and increased production via N2O + O(1D). The model simulations show a negative change of 10 % decade−1 in N2O that is most likely due to variations in the deep branch of the Brewer–Dobson Circulation (BDC). Interestingly, modelled annual mean “age of air” (AoA) does not show any significant changes in transport in the tropical mid-stratosphere during 2004–2012. However, further analysis of model results demonstrates significant seasonal variations. During the autumn months (September–October) there are positive AoA changes that imply transport slowdown and a longer residence time of N2O allowing for more conversion to NOy, which enhances O3 loss. During winter months (January–February) there are negative AoA changes, indicating faster N2O transport and less NOy production. Although the variations in AoA over a year result in a statistically insignificant linear change, non-linearities in the chemistry–transport interactions lead to a statistically significant negative N2O change.

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Shipborne MAX-DOAS measurements for validation of TROPOMI NO<sub>2</sub> products

Atmospheric Measurement Techniques ◽

10.5194/amt-13-1413-2020 ◽

2020 ◽

Vol 13 (3) ◽

pp. 1413-1426 ◽

Cited By ~ 3

Author(s):

Ping Wang ◽

Ankie Piters ◽

Jos van Geffen ◽

Olaf Tuinder ◽

Piet Stammes ◽

...

Keyword(s):

Column Density ◽

Transport Model ◽

Massively Parallel ◽

Optical Absorption Spectroscopy ◽

Vertical Column ◽

Chemistry Transport Model ◽

The Pacific ◽

Tropospheric No2 ◽

Vertical Column Density ◽

Good Agreement

Abstract. Tropospheric NO2 and stratospheric NO2 vertical column densities are important TROPOspheric Monitoring Instrument (TROPOMI) data products. In order to validate the TROPOMI NO2 products, KNMI Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instruments have measured NO2 on ship cruises over the Atlantic and the Pacific oceans. The MAX-DOAS instruments have participated in five cruises on board RV Sonne (in 2017 and 2019) and RV Maria S. Merian (in 2018). The MAX-DOAS measurements were acquired over 7 months and spanned about 90∘ in latitude and 300∘ in longitude. During the cruises aerosol measurements from Microtops sun photometers were also taken. The MAX-DOAS measured stratospheric NO2 columns between 1.5×1015 and 3.5×1015 molec cm−2 and tropospheric NO2 up to 0.6×1015 molec cm−2. The MAX-DOAS stratospheric NO2 vertical column densities have been compared with TROPOMI stratospheric NO2 vertical column densities and the stratospheric NO2 vertical column densities simulated by the global chemistry Transport Model, version 5, Massively Parallel model (TM5-MP). Good correlation is found between the MAX-DOAS and TROPOMI and TM5 stratospheric NO2 vertical column densities, with a correlation coefficient of 0.93 or larger. The TROPOMI and TM5 stratospheric NO2 vertical column densities are about 0.4×1015 molec cm−2 (19 %) higher than the MAX-DOAS measurements. The TROPOMI tropospheric NO2 also has good agreement with the MAX-DOAS measurements. The tropospheric NO2 vertical column density is as low as 0.5×1015 molec cm−2 over remote oceans.

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