Updating long-range transport model predictions using real-time monitoring data in case of nuclear accidents with release to the atmosphere

Abstract. The reconstruction of the Chernobyl accident source term has been previously carried out using core inventories, but also back and forth confrontations between model simulations and activity concentration or deposited activity measurements. The approach presented in this paper is based on inverse modelling techniques. It relies both on the activity concentration measurements and on the adjoint of a chemistry-transport model. The location of the release is assumed to be known, and one is looking for a source term available for long-range transport that depends both on time and altitude. The method relies on the maximum entropy on the mean principle and exploits source positivity. The inversion results are mainly sensitive to two tuning parameters, a mass scale and the scale of the prior errors in the inversion. To overcome this hardship, we resort to the statistical L-curve method to estimate balanced values for these two parameters. Once this is done, many of the retrieved features of the source are robust within a reasonable range of parameter values. Our results favour the acknowledged three-step scenario, with a strong initial release (26 to 27 April), followed by a weak emission period of four days (28 April–1 May) and again a release, longer but less intense than the initial one (2 May–6 May). The retrieved quantities of iodine-131, caesium-134 and caesium-137 that have been released are in good agreement with the latest reported estimations. Yet, a stronger apportionment of the total released activity is ascribed to the first period and less to the third one. Finer chronological details are obtained, such as a sequence of eruptive episodes in the first two days, likely related to the modulation of the boundary layer diurnal cycle. In addition, the first two-day release surges are found to have effectively reached an altitude up to the top of the domain (5000 m).

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Systematic analysis of tropospheric NO<sub>2</sub> long-range transport events detected in GOME-2 satellite data

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-7367-2014 ◽

2014 ◽

Vol 14 (14) ◽

pp. 7367-7396 ◽

Cited By ~ 19

Author(s):

A. W. Zien ◽

A. Richter ◽

A. Hilboll ◽

A.-M. Blechschmidt ◽

J. P. Burrows

Keyword(s):

Long Range ◽

Transport Model ◽

Meteorological Data ◽

Long Range Transport ◽

Emission Region ◽

Systematic Analysis ◽

Range Transport ◽

Tropospheric No2 ◽

High Emission ◽

Autumn And Winter

Abstract. Intercontinental long-range transport (LRT) events of NO2 relocate the effects of air pollution from emission regions to remote, pristine regions. We detect transported plumes in tropospheric NO2 columns measured by the GOME-2/MetOp-A instrument with a specialized algorithm and trace the plumes to their sources using the HYSPLIT Lagrangian transport model. With this algorithm we find 3808 LRT events over the ocean for the period 2007 to 2011. LRT events occur frequently in the mid-latitudes, emerging usually from coastal high-emission regions. In the free troposphere, plumes of NO2 can travel for several days to the polar oceanic atmosphere or to other continents. They travel along characteristic routes and originate from both continuous anthropogenic emission and emission events such as bush fires. Most NO2 LRT events occur during autumn and winter months, when meteorological conditions and emissions are most favorable. The evaluation of meteorological data shows that the observed NO2 LRT is often linked to cyclones passing over an emission region.

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A statistical long-range transport model for simulation of wet sulphate deposition

Canadian Journal of Civil Engineering ◽

10.1139/l89-051 ◽

1989 ◽

Vol 16 (3) ◽

pp. 258-266 ◽

Cited By ~ 1

Author(s):

J. M. Byrne ◽

E. A. McBean ◽

K. B. Shipley ◽

G. J. Farquhar

Keyword(s):

Long Range ◽

Transport Model ◽

Long Range Transport ◽

Central Processor ◽

Central Processor Unit ◽

Range Transport ◽

Sulphate Deposition ◽

Time Requirements ◽

Processor Unit ◽

Relative Errors

A statistical long-range transport of air pollutants model (UW-LRT) is utilized to simulate wet SO4 deposition in eastern North America in 1980. Model results compare favorably to an analyzed deposition field. In a comparison of the relative errors associated with four long-range transport models, the UW-LRT model demonstrates the lowest variation from recorded, analyzed deposition data. The UW-LRT model has modest data input and central processor unit time requirements. Key words: acid rain, long-range transport, spatial deposition, mathematical models.

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Long range transport of mercury to the Arctic and across Canada

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-4673-2010 ◽

2010 ◽

Vol 10 (2) ◽

pp. 4673-4717 ◽

Cited By ~ 3

Author(s):

D. Durnford ◽

A. Dastoor ◽

D. Figueras-Nieto ◽

A. Ryjkov

Keyword(s):

North America ◽

Long Range ◽

Transport Model ◽

Extensive Study ◽

Atmospheric Mercury ◽

The Arctic ◽

Long Range Transport ◽

Chemical Transport Model ◽

Transport Pathways ◽

Range Transport

Abstract. This study is the most extensive study to date on the transport of mercury to the Arctic. Moreover, it is the first such study to use a fully-coupled, online chemical transport model, Environment Canada's Global/Regional Atmospheric Heavy Metals model (GRAHM), where the meteorology and mercury processes are fully integrated. It is also the only study to date on the transport of mercury across Canada. We determined source attribution from Asia, North America, Russia and Europe at six arctic verification stations, as well as three subarctic and eight midlatitude Canadian stations. We have found that Asia, despite having transport efficiencies that were almost always lower than those of North America and often lower than those of Russia, was the dominant source of gaseous atmospheric mercury at all verification stations: it contributed the most mercury (29–37% at all stations, seasons and levels considered), its concentrations frequently explained nearly 100% of the variability in the concentrations produced by the simulation performed with full global emissions, particularly in the absence of local sources, and it generated the most long range transport (LRT) events, causing 43%, 67% and 75% of the events at the arctic, subarctic and midlatitude stations, respectively. For the Arctic, Russian transport efficiencies tended to be the strongest, as expected, while European and Asian efficiencies were lower and higher, respectively, than those found in the literature. This disagreement is likely produced by mercury's long lifetime relative to that of other pollutants. The accepted springtime preference for the trans-Pacific transport of Asian pollution was evident only in the midlatitude group of stations, being masked in the arctic and subarctic groups by the occurrence of atmospheric mercury depletion events. Some neighbouring arctic stations recorded dissimilar numbers of LRT events; despite their proximity, the behaviour of mercury at these stations was governed by different dynamics and transport pathways. The column burden of GEM in the lowest 5 km of the Northern Hemisphere was largest in summer from Asia, North America and Russia, but in winter from Europe. In the vertical, transport of mercury from all source regions occurred principally in the mid-troposphere.

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Interannual variability of long-range transport as seen at the Mt. Bachelor Observatory

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-16335-2008 ◽

2008 ◽

Vol 8 (4) ◽

pp. 16335-16379 ◽

Cited By ~ 3

Author(s):

D. R. Reidmiller ◽

D. A. Jaffe ◽

D. Chand ◽

S. Strode ◽

P. Swartzendruber ◽

...

Keyword(s):

Southeast Asia ◽

Interannual Variability ◽

Long Range ◽

Biomass Burning ◽

Transport Model ◽

Long Range Transport ◽

Naval Research ◽

Chemical Transport Model ◽

Northeast Pacific ◽

Range Transport

Abstract. Interannual variations in background tropospheric trace gases (such as carbon monoxide, CO) are largely driven by variations in emissions (especially wildfires), transport pathways and tropospheric oxidizing capacity. Understanding this variability is essential to quantify the intercontinental contribution to US air quality. We investigate the interannual variability of long-range transport of Asian pollutants to the Northeast Pacific via measurements from the Mt. Bachelor Observatory (MBO: 43.98° N, 121.69° W; 2.7 km above sea level) and GEOS-Chem chemical transport model simulations in spring 2005 vs. the INTEX-B campaign during spring 2006. Measurements of CO at MBO were significantly enhanced during spring 2005 relative to the same time in 2006 (the INTEX-B study period); a monthly mean decline in CO of 41 ppbv was observed between April 2005 and April 2006. Meteorological indices show that long-range transport of CO from the heavily industrialized region of East Asia was significantly greater in 2005 than in 2006. In addition, spring 2005 was an anomalously strong biomass burning season in Southeast Asia. Data presented by Yurganov et al. (2008) using MOPITT satellite retrievals from this area reveal an average CO burden anomaly (referenced to March 2000–February 2002 mean values) between October 2004 through April 2005 of 2.6 Tg CO vs. 0.6 Tg CO for the same period a year later. The Naval Research Laboratory's global aerosol transport model shows that emissions from these fires were efficiently transported to MBO throughout April 2005. Asian dust transport, however, was substantially greater in 2006 than 2005, particularly in May. Monthly mean aerosol light scattering coefficient at 532 nm (σsp) at MBO more than doubled from 2.7 Mm−1 in May 2005 to 6.2 Mm−1 in May 2006. We also evaluate CO interannual variability throughout the western US via Earth System Research Laboratory ground site data and throughout the Northern Hemisphere via MOPITT and TES satellite observations. Both in the Northeast Pacific and on larger scales, we reveal a significant decrease (from 2–21%) in springtime maximum CO between 2005 and 2006, evident in all platforms and the GEOS-Chem model. We attribute this to (a) anomalously strong biomass burning in Southeast Asia during winter 2004 through spring 2005, and (b) the transport pattern in 2006 which limited the inflow of Asian pollution to the lower free troposphere over western North America.

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