Impact of Transport Schemes on Modeled Dust Concentrations

2009 ◽  
Vol 26 (6) ◽  
pp. 1135-1143 ◽  
Author(s):  
Maria Raffaella Vuolo ◽  
Laurent Menut ◽  
Hélène Chepfer
Keyword(s):  
North Atlantic ◽  
Transport Model ◽  
Surface Concentration ◽  
Sensitivity Study ◽  
Third Order ◽  
Chemistry Transport Model ◽  
Western Africa ◽  
The North ◽  
Dust Modeling ◽  
High Uncertainty

Abstract A sensitivity study is performed with the CHIMERE-DUST chemistry transport model in order to evaluate the modeled mineral dust spread due to the horizontal transport scheme accuracy. Three different schemes are implemented in the model: the simple first-order UPWIND scheme, the second-order Van Leer scheme, and the third-order parabolic piecewise method (PPM) scheme. The results showed that a large part of the uncertainty in dust modeling may be due to the transport scheme only. Compared to the PPM scheme, it is shown that, over a large domain encompassing western Africa and the North Atlantic, a significant increase in the dust plume extension is locally diagnosed (+25% with Van Leer and +48% with UPWIND) and linked to a decrease in the dust maxima (−17% with Van Leer and −32% with UPWIND) to PPM. Far from the sources, hourly surface concentration differences may be up to 30 μg m−3 in Europe, highlighting the high uncertainty of dust modeling for air quality use.

scholarly journals Influence of the North Atlantic oscillation on the atmospheric levels of benzo[a]pyrene over Europe

2021 ◽  
Author(s):  
Pedro Jiménez-Guerrero ◽  
Nuno Ratola
Keyword(s):  
Spatial Pattern ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Transport Model ◽  
Regional Scale ◽  
The South ◽  
Climatic Fluctuations ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

AbstractThe atmospheric concentration of persistent organic pollutants (and of polycyclic aromatic hydrocarbons, PAHs, in particular) is closely related to climate change and climatic fluctuations, which are likely to influence contaminant’s transport pathways and transfer processes. Predicting how climate variability alters PAHs concentrations in the atmosphere still poses an exceptional challenge. In this sense, the main objective of this contribution is to assess the relationship between the North Atlantic Oscillation (NAO) index and the mean concentration of benzo[a]pyrene (BaP, the most studied PAH congener) in a domain covering Europe, with an emphasis on the effect of regional-scale processes. A numerical simulation for a present climate period of 30 years was performed using a regional chemistry transport model with a 25 km spatial resolution (horizontal), higher than those commonly applied. The results show an important seasonal behaviour, with a remarkable spatial pattern of difference between the north and the south of the domain. In winter, higher BaP ground levels are found during the NAO+ phase for the Mediterranean basin, while the spatial pattern of this feature (higher BaP levels during NAO+ phases) moves northwards in summer. These results show deviations up to and sometimes over 100% in the BaP mean concentrations, but statistically significant signals (p<0.1) of lower changes (20–40% variations in the signal) are found for the north of the domain in winter and for the south in summer.

scholarly journals Investigating the impact of Lake Agassiz drainage routes on the 8.2 ka cold event with a climate model

2009 ◽  
Vol 5 (3) ◽  
pp. 471-480 ◽  
Author(s):  
Y.-X. Li ◽  
H. Renssen ◽  
A. P. Wiersma ◽  
T. E. Törnqvist
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Climate Model ◽  
North Atlantic Ocean ◽  
Sensitivity Study ◽  
Meridional Overturning Circulation ◽  
Labrador Sea ◽  
Cold Event ◽  
The North ◽  
The Impact

Abstract. The 8.2 ka event is the most prominent abrupt climate change in the Holocene and is often believed to result from catastrophic drainage of proglacial lakes Agassiz and Ojibway (LAO) that routed through the Hudson Bay and the Labrador Sea into the North Atlantic Ocean, and perturbed Atlantic meridional overturning circulation (MOC). One key assumption of this triggering mechanism is that the LAO freshwater drainage was dispersed over the Labrador Sea. Recent data, however, show no evidence of lowered δ18O values, indicative of low salinity, from the open Labrador Sea around 8.2 ka. Instead, negative δ18O anomalies are found close to the east coast of North America, extending as far south as Cape Hatteras, North Carolina, suggesting that the freshwater drainage may have been confined to a long stretch of continental shelf before fully mixing with North Atlantic Ocean water. Here we conduct a sensitivity study that examines the effects of a southerly drainage route on the 8.2 ka event with the ECBilt-CLIO-VECODE model. Hosing experiments of four routing scenarios, where freshwater was introduced to the Labrador Sea in the northerly route and to three different locations along the southerly route, were performed to investigate the routing effects on model responses. The modeling results show that a southerly drainage route is possible but generally yields reduced climatic consequences in comparison to those of a northerly route. This finding implies that more freshwater would be required for a southerly route than for a northerly route to produce the same climate anomaly. The implicated large amount of LAO drainage for a southerly routing scenario is in line with a recent geophysical modelling study of gravitational effects on sea-level change associated with the 8.2 ka event, which suggests that the volume of drainage might be larger than previously estimated.

scholarly journals Modelling the wintertime response to upper tropospheric and lower stratospheric ozone anomalies over the North Atlantic and Europe

2003 ◽  
Vol 21 (10) ◽  
pp. 2107-2118 ◽  
Author(s):  
I. Kirchner ◽  
D. Peters
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Initial Conditions ◽  
Stratospheric Ozone ◽  
Circulation Model ◽  
Sensitivity Study ◽  
Boreal Winter ◽  
Radiative Processes ◽  
The North ◽  
The North Atlantic

Abstract. During boreal winter months, mean longitude-dependent ozone changes in the upper troposphere and lower stratosphere are mainly caused by different ozone transport by planetary waves. The response to radiative perturbation induced by these ozone changes near the tropopause on the circulation is unclear. This response is investigated with the ECHAM4 general circulation model in a sensitivity study. In the simulation two different mean January realizations of the ozone field are implemented in ECHAM4. Both ozone fields are estimated on the basis of the observed mean January planetary wave structure of the 1980s. The first field represents a 14-year average (reference, 1979–1992) and the second one represents the mean ozone field change (anomaly, 1988–92) in boreal extra-tropics during the end of the 1980s. The model runs were carried out pairwise, with identical initial conditions for both ozone fields. Five statistically independent experiments were performed, forced with the observed sea surface temperatures for the period 1988 to 1992. The results support the hypothesis that the zonally asymmetric ozone changes of the 80s triggered a systematic alteration of the circulation over the North Atlantic – European region. It is suggested that this feedback process is important for the understanding of the decadal coupling between troposphere and stratosphere, as well as between subtropics and extra-tropics in winter.Key words. Meteorology and atmospheric dynamics (general circulation; radiative processes; synoptic-scale meteorology)

Peasants and Danes: The Danish National Identity and Political Culture

1992 ◽  
Vol 34 (1) ◽  
pp. 3-27 ◽  
Author(s):  
Uffe Østergård
Keyword(s):  
National Identity ◽  
Political Culture ◽  
North Atlantic ◽  
West Indies ◽  
North Atlantic Ocean ◽  
Sociological Perspective ◽  
The West ◽  
Western Africa ◽  
The North ◽  
Rare Situation

From a cultural and historical-sociological perspective, the Danish nationstate of today represents a rare situation of virtual identity between state, nation, and society, which is a more recent phenomenon than normally assumed in Denmark and abroad. Though one of the oldest European monarchies, whose flag came ‘tumbling down from heaven in 1219’—ironically enough an event that happened in present-day Estonia—Denmark's present national identity is of recent vintage. Until 1814 the word, Denmark, denominated a typical European, plurinational or multinational, absolutist state, second only to such powers as France, Great Britain, Austria, Russia, and perhaps Prussia. The state had succeeded in reforming itself in a revolution from above in the late eighteenth century and ended as one of the few really “enlightened absolutisms” of the day (Horstbøll and østergård 1990; østergård 1990). It consisted of four main parts and several subsidiaries in the North Atlantic Ocean, plus some colonies in Western Africa, India, and the West Indies. The main parts were the kingdoms of Denmark proper and Norway, plus the duchies of Schleswig and Holstein. How this particular state came about need not bother us here.

scholarly journals Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer

2010 ◽  
Vol 10 (21) ◽  
pp. 10223-10236 ◽  
Author(s):  
J. B. Gilman ◽  
J. F. Burkhart ◽  
B. M. Lerner ◽  
E. J. Williams ◽  
W. C. Kuster ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Transport Model ◽  
Arctic Basin ◽  
The Arctic ◽  
Arctic Boundary Layer ◽  
Air Masses ◽  
The North ◽  
The North Atlantic

Abstract. The influence of halogen oxidation on the variabilities of ozone (O3) and volatile organic compounds (VOCs) within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68° N) was observed between the acetylene to benzene ratio, used as a marker for chlorine and bromine oxidation, and O3 signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O3 variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O3-poor air masses from the Arctic Basin to latitudes as far south as 52° N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI), multi-year ice (MYI), and total ICE (FYI+MYI). O3 anti-correlated with the modeled total ICE tracer (r = −0.86) indicating that up to 73% of the O3 variability measured in the Arctic marine boundary layer could be related to sea ice exposure.

scholarly journals Representing the effects of stratosphere–troposphere exchange on 3-D O<sub>3</sub> distributions in chemistry transport models using a potential vorticity-based parameterization

2016 ◽  
Vol 16 (17) ◽  
pp. 10865-10877 ◽  
Author(s):  
Jia Xing ◽  
Rohit Mathur ◽  
Jonathan Pleim ◽  
Christian Hogrefe ◽  
Jiandong Wang ◽  
...  
Keyword(s):  
Potential Vorticity ◽  
Transport Model ◽  
Model Performance ◽  
Surface Concentration ◽  
Weather Research And Forecasting ◽  
Regional Models ◽  
Transport Models ◽  
Reference Case ◽  
Chemistry Transport Model ◽  
Spatially Varying

Abstract. Downward transport of ozone (O3) from the stratosphere can be a significant contributor to tropospheric O3 background levels. However, this process often is not well represented in current regional models. In this study, we develop a seasonally and spatially varying potential vorticity (PV)-based function to parameterize upper tropospheric and/or lower stratospheric (UTLS) O3 in a chemistry transport model. This dynamic O3–PV function is developed based on 21-year ozonesonde records from World Ozone and Ultraviolet Radiation Data Centre (WOUDC) with corresponding PV values from a 21-year Weather Research and Forecasting (WRF) simulation across the Northern Hemisphere from 1990 to 2010. The result suggests strong spatial and seasonal variations of O3 ∕ PV ratios which exhibits large values in the upper layers and in high-latitude regions, with highest values in spring and the lowest values in autumn over an annual cycle. The newly developed O3 ∕ PV function was then applied in the Community Multiscale Air Quality (CMAQ) model for an annual simulation of the year 2006. The simulated UTLS O3 agrees much better with observations in both magnitude and seasonality after the implementation of the new parameterization. Considerable impacts on surface O3 model performance were found in the comparison with observations from three observational networks, i.e., EMEP, CASTNET and WDCGG. With the new parameterization, the negative bias in spring is reduced from −20 to −15 % in the reference case to −9 to −1 %, while the positive bias in autumn is increased from 1 to 15 % in the reference case to 5 to 22 %. Therefore, the downward transport of O3 from upper layers has large impacts on surface concentration and needs to be properly represented in regional models.

scholarly journals The impact of shipping emissions on air pollution in the greater North Sea region – Part 2: Scenarios for 2030

2016 ◽  
Vol 16 (2) ◽  
pp. 759-776 ◽  
Author(s):  
V. Matthias ◽  
A. Aulinger ◽  
A. Backes ◽  
J. Bieser ◽  
B. Geyer ◽  
...  
Keyword(s):  
North Sea ◽  
Transport Model ◽  
So2 Emissions ◽  
Chemistry Transport Model ◽  
The North ◽  
International Regulations ◽  
The North Sea ◽  
Sea Area ◽  
The Impact ◽  
Ship Fuels

Abstract. Scenarios for future shipping emissions in the North Sea have been developed in the framework of the Clean North Sea Shipping project. The effects of changing NOx and SO2 emissions were investigated with the CMAQ chemistry transport model for the year 2030 in the North Sea area. It has been found that, compared to today, the contribution of shipping to the NO2 and O3 concentrations will increase due to the expected enhanced traffic by more than 20 and 5 %, respectively, by 2030 if no regulation for further emission reductions is implemented in the North Sea area. PM2.5 will decrease slightly because the sulfur contents in ship fuels will be reduced as international regulations foresee. The effects differ largely between regions, seasons and date of the implementation of stricter regulations for NOx emissions from newly built ships.

scholarly journals Application of the Gaussian anamorphosis to assimilation in a 3-D coupled physical-ecosystem model of the North Atlantic with the EnKF: a twin experiment

2009 ◽  
Vol 6 (1) ◽  
pp. 617-652 ◽  
Author(s):  
E. Simon ◽  
L. Bertino
Keyword(s):  
North Atlantic ◽  
Coupled Model ◽  
Surface Concentration ◽  
Ecosystem Model ◽  
Concentration Data ◽  
Linear Change ◽  
The North ◽  
Change Of Variables ◽  
Non Linear ◽  
Non Gaussian

Abstract. We consider the application of the Ensemble Kalman Filter (EnKF) to a coupled ocean ecosystem model (HYCOM-NORWECOM). Such models, especially the ecosystem models, are characterized by strongly non-linear interactions active in ocean blooms and present important limitations for the use of data assimilation methods based on linear statistical analysis. Besides the non-linearity of the model, one is confronted with physical/biological limitations, the analysis state having to be consistent with the model, especially with the constraints of positiveness of some variables. Furthermore the non-Gaussian distributions of the biogeochemical variables break an important assumption of the linear analysis, leading to a loss of optimality of the filter. We present an extension of the EnKF dealing with these limitations by introducing a non-linear change of variables (anamorphosis function) in order to execute the analysis step in a Gaussian space. We present also the initial results of the application of this non-Gaussian extension of the EnKF to the assimilation of simulated chlorophyll surface concentration data in a North Atlantic configuration of the HYCOM NORWECOM coupled model.

Air pollution and cloud-interaction over Europe in 1985 and today

2020 ◽  
Author(s):  
Roland Schrödner ◽  
Christa Genz ◽  
Bernd Heinold ◽  
Holger Baars ◽  
Silvia Henning ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Transport Model ◽  
Cloud Droplet ◽  
Forecast Model ◽  
Sensitivity Study ◽  
High Definition ◽  
Chemistry Transport Model ◽  
Meteorological Model ◽  
Cloud Properties ◽  
Aerosol Mass

&lt;p&gt;Aerosol concentrations over Europe and Germany were simulated for the years 1985 and 2013 using the aerosol-chemistry transport model COSMO-MUSCAT. The aerosol fields from the two simulations were used in a high-resolution meteorological model for a sensitivity study on cloud properties. The modelled aerosol and cloud variables were compared to a variety of available observations, including satellites, remote sensing and in-situ observations. Finally, the radiative forcing of the aerosol could be estimated from the different sensitivity simulations.&lt;/p&gt;&lt;p&gt;Due to reduction of emissions the ambient aerosol mass and number in Europe was strongly decreased since the 1980s. Hence, today&amp;#8217;s number of particles in the CCN size range is smaller. The HD(CP)&lt;sup&gt;2&lt;/sup&gt; (High Definition Clouds and Precipitation for Climate Prediction) project amongst others aimed at analysing the effect of the emission reduction on cloud properties.&lt;/p&gt;&lt;p&gt;As a pre-requiste, the aerosol mass, number, and composition over Germany were simulated for 1985 and 2013 using the regional chemistry-transport-model COSMO-MUSCAT. The EDGAR emission inventory was used for both years.&lt;/p&gt;&lt;p&gt;The model results were compared to observations from the two HD(CP)&lt;sup&gt;2&lt;/sup&gt; campaigns that took place in 2013 (HOPE, HOPE-Melpitz) as well as the AVHRR aerosol optical thickness product, which is available from 1981 onwards. Despite the fact, that emissions of the 1980s are very uncertain, the modelled AOD is in good agreement with observations. The modelled mean CCN number concentration in 1985 is a factor of 2-4 higher than in 2013.&lt;/p&gt;&lt;p&gt;Within HD(CP)&lt;sup&gt;2&lt;/sup&gt;, the ICON weather forecast model was applied in a configuration allowing for large-eddy simulations. In these simulations, the time-varying CCN fields for the year 1985 and 2013 calculated with COSMO-MUSCAT were used as input for ICON-LEM. In the present-day simulation, the cloud droplet number agrees with observations, whereas the perturbed (1985) simulation does not with droplet numbers about twice as high as in 2013. Also, for other cloud variables systematic changes between the two scenarios were observed.&lt;/p&gt;

scholarly journals Free-troposphere ozone and carbon monoxide over the North Atlantic for 2001–2011

2013 ◽  
Vol 13 (24) ◽  
pp. 12537-12547 ◽  
Author(s):  
A. Kumar ◽  
S. Wu ◽  
M. F. Weise ◽  
R. Honrath ◽  
R. C. Owen ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
North Atlantic ◽  
Transport Model ◽  
Measurement Data ◽  
Free Troposphere ◽  
Chemical Transport Model ◽  
Significance Level ◽  
The Past ◽  
The North ◽  
The North Atlantic

Abstract. In situ measurements of carbon monoxide (CO) and ozone (O3) at the Pico Mountain Observatory (PMO) located in the Azores, Portugal, are analyzed together with results from an atmospheric chemical transport model (GEOS-Chem) and satellite remote sensing data (AIRS (Atmospheric Infrared Sounder) for CO, and TES (Tropospheric Emission Spectrometer) for O3) to examine the evolution of free-troposphere CO and O3 over the North Atlantic for 2001–2011. GEOS-Chem captured the seasonal cycles for CO and O3 well but significantly underestimated the mixing ratios of CO, particularly in spring. Statistically significant (using a significance level of 0.05) decreasing trends were found for both CO and O3 based on harmonic regression analysis of the measurement data. The best estimates of the possible trends for CO and O3 measurements are −0.31 ± 0.30 (2-σ) ppbv yr−1 and −0.21 ± 0.11 (2-σ) ppbv yr−1, respectively. Similar decreasing trends for both species were obtained with GEOS-Chem simulation results. The most important factor contributing to the decreases in CO and O3 at PMO over the past decade is the decline in anthropogenic emissions from North America, which more than compensate for the impacts from increasing Asian emissions. It is likely that climate change in the past decade has also affected the intercontinental transport of O3.

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