scholarly journals Radon activity in the lower troposphere and its impact on ionization rate: a global estimate using different radon emissions

2011 ◽  
Vol 11 (1) ◽  
pp. 3251-3300
Author(s):  
K. Zhang ◽  
J. Feichter ◽  
J. Kazil ◽  
H. Wan ◽  
W. Zhuo ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Radioactive Decay ◽  
Lower Troposphere ◽  
Atmospheric Model ◽  
Ionization Rate ◽  
Aerosol Size Distribution ◽  
Low Latitude ◽  
Near Surface ◽  
Global Estimate ◽  
Global Atmospheric Model

Abstract. The radioactive decay of radon and its progeny can lead to ionization of air molecules and consequently influence aerosol size distribution. In order to provide a global estimate of the radon-related ionization rate, we use the global atmospheric model ECHAM5 to simulate transport and decay processes of the radioactive tracers. A global radon emission map is put together using regional fluxes reported recently in the literature. The near-surface radon concentrations simulated with this new map compare well with measurements. Radon-related ionization rate is calculated and compared to that caused by cosmic rays. The contribution of radon and its progeny clearly exceeds that of the cosmic rays in the mid- and low-latitude land areas in the surface layer. In winter, strong radon-related ionization coincides with low temperature in China, USA, and Russia, providing favorable condition for the formation of aerosol particles. This suggests that it is probably useful to include the radon-induced ionization in global models when investigating the interaction between aerosol and climate.

scholarly journals Radon activity in the lower troposphere and its impact on ionization rate: a global estimate using different radon emissions

2011 ◽  
Vol 11 (15) ◽  
pp. 7817-7838 ◽  
Author(s):  
K. Zhang ◽  
J. Feichter ◽  
J. Kazil ◽  
H. Wan ◽  
W. Zhuo ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Radioactive Decay ◽  
Lower Troposphere ◽  
Atmospheric Model ◽  
Ionization Rate ◽  
Aerosol Size Distribution ◽  
High Concentration ◽  
Near Surface ◽  
Global Estimate ◽  
The Impact

Abstract. The radioactive decay of radon and its progeny can lead to ionization of air molecules and consequently influence aerosol size distribution. In order to provide a global estimate of the radon-related ionization rate, we use the global atmospheric model ECHAM5 to simulate transport and decay processes of the radioactive tracers. A global radon emission map is put together using regional fluxes reported recently in the literature. Near-surface radon concentrations simulated with this new map compare well with measurements. Radon-related ionization rate is calculated and compared to that caused by cosmic rays. The contribution of radon and its progeny clearly exceeds that of the cosmic rays in the mid- and low-latitude land areas in the surface layer. During cold seasons, at locations where high concentration of sulfuric acid gas and low temperature provide potentially favorable conditions for nucleation, the coexistence of high ionization rate may help enhance the particle formation processes. This suggests that it is probably worth investigating the impact of radon-induced ionization on aerosol-climate interaction in global models.

scholarly journals Organic pollutants from Indonesian peatland fires: regional influences and its impact on lower the stratospheric composition

2021 ◽  
Author(s):  
Simon Rosanka ◽  
Bruno Franco ◽  
Lieven Clarisse ◽  
Pierre-François Coheur ◽  
Andreas Wahner ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Lower Troposphere ◽  
Atmospheric Model ◽  
Chemical Production ◽  
Global Atmospheric Model ◽  
Reservoir Species ◽  
Upward Transport ◽  
High Concentrations ◽  
Stratospheric Composition ◽  
The Impact

<p>In 2015, the particularly strong dry season in Indonesia, caused by an exceptional strong El Niño, led to severe peatland fires. Due to the high carbon content of peatland, these fires are characterised by high volatile organic compound (VOC) biomass burning emissions. The resulting primary and secondary pollutants are efficiently transported to the upper troposphere/lower stratosphere (UTLS) by the developing Asian monsoon anticyclone (ASMA) and the general upward transport in the intertropical convergence zone (ITCZ). In this study, we assess the importance of these VOC emissions for the composition of the lower troposphere and the UTLS by performing multiple chemistry simulations using the global atmospheric model ECHAM/MESSy (EMAC). In a first step, we find that EMAC properly captures the exceptional strength of the Indonesian fires based on the comparison of modelled columns of the biomass burning marker hydrogen cyanide (HCN) to spaceborne measurements from the Infrared Atmospheric Sounding Interferometer (IASI). In the lower troposphere, the increase in VOC levels is higher in Indonesia compared to other biomass burning regions. This directly impacts the oxidation capacity and leads to a high reduction in hydroxyl radicals (OH) and nitrogen oxides (NO<sub>x</sub>). In general, an increase in ozone (O<sub>3</sub>) is predicted close to the peatland fires. However, particular high concentrations of phenols lead to an O<sub>3</sub> depletion in eastern Indonesia. By employing the detailed in-cloud OVOC oxidation scheme Jülich Aqueous-phase Mechanism of Organic Chemistry (JAMOC), we find that the predicted changes are dampened and that by ignoring these processes, global models tend to overestimate the impact of such extreme pollution events. The upward transport in the ASMA and the ITCZ leads to elevated VOC concentrations in the UTLS region. This also results in a depletion of lower stratospheric O<sub>3</sub>. We find that this is caused by a high destruction of O<sub>3</sub> by phenoxy radicals and by the increased formation of NO<sub>x</sub> reservoir species, which dampen the chemical production of O<sub>3</sub>.</p>

scholarly journals Improving the inverse modeling of a trace isotope: how precisely can radium-228 fluxes toward the ocean and submarine groundwater discharge be estimated?

2017 ◽  
Vol 14 (13) ◽  
pp. 3171-3189 ◽  
Author(s):  
Guillaume Le Gland ◽  
Laurent Mémery ◽  
Olivier Aumont ◽  
Laure Resplandy
Keyword(s):  
Ocean Circulation ◽  
Inverse Modeling ◽  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Radioactive Decay ◽  
The Arctic ◽  
Time Data ◽  
Global Estimate ◽  
Submarine Groundwater ◽  
First Time

Abstract. Radium-228 (228Ra), an almost conservative trace isotope in the ocean, supplied from the continental shelves and removed by a known radioactive decay (T1∕2 = 5. 75 years), can be used as a proxy to constrain shelf fluxes of other trace elements, such as nutrients, iron, or rare earth elements. In this study, we perform inverse modeling of a global 228Ra dataset (including GEOSECS, TTO and GEOTRACES programs, and, for the first time, data from the Arctic and around the Kerguelen Islands) to compute the total 228Ra fluxes toward the ocean, using the ocean circulation obtained from the NEMO 3.6 model with a 2° resolution. We optimized the inverse calculation (source regions, cost function) and find a global estimate of the 228Ra fluxes of 8.01–8. 49 × 1023 atoms yr−1, more precise and around 20 % lower than previous estimates. The largest fluxes are in the western North Atlantic, the western Pacific and the Indian Ocean, with roughly two-thirds in the Indo-Pacific Basin. An estimate in the Arctic Ocean is provided for the first time (0.43–0.50  ×  1023 atoms yr−1). Local misfits between model and data in the Arctic, the Gulf Stream and the Kuroshio regions could result from flaws of the ocean circulation in these regions (resolution, atmospheric forcing). As radium is enriched in groundwater, a large part of the 228Ra shelf sources comes from submarine groundwater discharge (SGD), a major but poorly known pathway for terrestrial mineral elements, including nutrients, to the ocean. In contrast to the 228Ra budget, the global estimate of SGD is rather unconstrained, between 1.3 and 14. 7 × 1013 m3 yr−1, due to high uncertainties on the other sources of 228Ra, especially diffusion from continental shelf sediments. Better precision on SGD cannot be reached by inverse modeling until a proper way to separate the contributions of SGD and diffusive release from sediments at a global scale is found.

scholarly journals Uncertainty of the CO<sub>2</sub> threshold for melting a hard Snowball Earth

2010 ◽  
Vol 6 (4) ◽  
pp. 1337-1350 ◽  
Author(s):  
Y. Hu ◽  
J. Yang
Keyword(s):  
Greenhouse Effect ◽  
Atmospheric Model ◽  
Snowball Earth ◽  
Near Surface ◽  
Cloud Forcing ◽  
Clear Sky ◽  
Critical Issues ◽  
Simulation Results ◽  
High Level ◽  
Hadley Cells

Abstract. One of the critical issues of the Snowball Earth hypothesis is how high level of CO2 is required for triggering the deglaciation. Using Community Atmospheric Model version 3 (CAM3), we study the problem for the CO2 threshold. Our simulations show large differences from previous results (Pierrehumbert, 2004, 2005). At 0.2 bars of CO2, the January maximum near-surface temperature is about 268 K, about 13 K higher than that in Pierrehumbert (2004, 2005), but lower than the value of 270 K for 0.1 bar of CO2 in Le Hir et al. (2007). It is found that the diversity of simulation results is mainly due to model sensitivity of greenhouse effect and longwave cloud forcing to increasing CO2. At 0.2 bar of CO2, CAM3 yields 117 Wm −2 of clear-sky greenhouse effect and 32 Wm−2 of longwave cloud forcing, versus only about 77 Wm−2 and 10.5 Wm−2 in Pierrehumbert (2004, 2005), respectively. CAM3 has comparable clear-sky greenhouse effect to that in Le Hir et al. (2007), but lower longwave cloud forcing. CAM3 also produces much stronger Hadley cells than in Pierrehumbert (2005).

scholarly journals Impact of land–water sensitivity contrast on MOPITT retrievals and trends over a coastal city

2020 ◽  
Vol 13 (7) ◽  
pp. 3521-3542
Author(s):  
Ian Ashpole ◽  
Aldona Wiacek
Keyword(s):  
Transport Model ◽  
Weighted Least Squares ◽  
Temporal Trends ◽  
Lower Troposphere ◽  
Near Surface ◽  
Surface Level ◽  
Coastal City ◽  
Water Sensitivity ◽  
Land Water ◽  
Co Concentrations

Abstract. We compare MOPITT Version 7 (V7) Level 2 (L2) and Level 3 (L3) carbon monoxide (CO) products for the 1∘×1∘ L3 grid box containing the coastal city of Halifax, Canada (longitude −63.58∘, latitude 44.65∘), with a focus on the seasons DJF and JJA, and highlight a limitation in the L3 products that has significant consequences for the temporal trends in near-surface CO identified using those data. Because this grid box straddles the coastline, the MOPITT L3 products are created from the finer spatial resolution L2 products that are retrieved over both land and water, with a greater contribution from retrievals over water because more of the grid box lies over water than land. We create alternative L3 products for this grid box by separately averaging the bounded L2 retrievals over land (L3L) and water (L3W) and demonstrate that profile and total column CO (TCO) concentrations, retrieved at the same time, differ depending on whether the retrieval took place over land or water. These differences (ΔRET) are greatest in the lower troposphere (LT), where mean retrieved volume mixing ratios (VMRs) are greater in L3W than L3L, with maximum mean differences of 11.6 % (14.3 ppbv, p=0.001) at the surface level in JJA. Retrieved CO concentrations are more similar, on average, in the middle and upper troposphere (MT and UT), although large differences (in excess of 40 %) do infrequently occur. TCO is also greater in L3W than L3L in both seasons. By analysing L3L and L3W retrieval averaging kernels and simulations of these retrievals, we demonstrate that, in JJA, ΔRET is strongly influenced by differences in retrieval sensitivity over land and water, especially close to the surface where L3L has significantly greater information content than L3W. In DJF, land–water differences in retrieval sensitivity are much less pronounced and appear to have less of an impact on ΔRET, which analysis of wind directions suggests is more likely to reflect differences in true profile concentrations (i.e. real differences). The original L3 time series for the 1∘×1∘ grid box containing Halifax (L3O) corresponds much more closely to L3W than L3L, owing to the greater contribution from L2 retrievals over water than land. Thus, in JJA, variability in retrieved CO concentrations close to the surface in L3O is suppressed compared to L3L, and a declining trend detected using weighted least squares (WLS) regression analysis is significantly slower in L3O (strongest surface level trend identifiable is −1.35 (±0.35) ppbv yr−1) than L3L (−2.85 (±0.60) ppbv yr−1). This is because contributing L2 retrievals over water are closely tied to a priori CO concentrations used in the retrieval, owing to their lack of near-surface sensitivity in JJA, and these are based on monthly climatological CO profiles from a chemical transport model and therefore have no yearly change (surface level trend in L3W is −0.60 (±0.33) ppbv yr−1). Although our analysis focuses on DJF and JJA, we demonstrate that the findings also apply to MAM and SON. The results that we report here suggest that similar analyses be performed for other coastal cities before using MOPITT surface CO.

scholarly journals Diagnostics for near-surface wind convergence/divergence response to the Gulf Stream in a regional atmospheric model

2011 ◽  
Vol 13 (1) ◽  
pp. 16-21 ◽  
Author(s):  
Kohei Takatama ◽  
Shoshiro Minobe ◽  
Masaru Inatsu ◽  
R. Justin Small
Keyword(s):  
Gulf Stream ◽  
Surface Wind ◽  
Atmospheric Model ◽  
Near Surface ◽  
Regional Atmospheric Model

scholarly journals Dominant Anomaly Patterns in the Near-Surface Baroclinicity and Accompanying Anomalies in the Atmosphere and Oceans. Part II: North Pacific Basin

2010 ◽  
Vol 23 (24) ◽  
pp. 6445-6467 ◽  
Author(s):  
Mototaka Nakamura ◽  
Shozo Yamane
Keyword(s):  
Heat Flux ◽  
North Pacific ◽  
Spatial Scales ◽  
Baroclinic Instability ◽  
Lower Troposphere ◽  
Pacific Basin ◽  
Mean Flow ◽  
Near Surface ◽  
Eddy Heat Flux ◽  
North Pacific Basin

Abstract Variability in the monthly-mean flow and storm track in the North Pacific basin is examined with a focus on the near-surface baroclinicity. Dominant patterns of anomalous near-surface baroclinicity found from empirical orthogonal function (EOF) analyses generally show mixed patterns of shift and changes in the strength of near-surface baroclinicity. Composited anomalies in the monthly-mean wind at various pressure levels based on the signals in the EOFs show accompanying anomalies in the mean flow up to 50 hPa in the winter and up to 100 hPa in other seasons. Anomalous eddy fields accompanying the anomalous near-surface baroclinicity patterns exhibit, broadly speaking, structures anticipated from simple linear theories of baroclinic instability, and suggest a tendency for anomalous wave fluxes to accelerate–decelerate the surface westerly accordingly. However, the relationship between anomalous eddy fields and anomalous near-surface baroclinicity in the midwinter is not consistent with the simple linear baroclinic instability theories. Composited anomalous sea surface temperature (SST) accompanying anomalous near-surface baroclinicity often exhibits moderate values and large spatial scales in the basin, rather than large values concentrated near the oceanic fronts. In the midsummer and in some cases in cold months, however, large SST anomalies are found around the Kuroshio–Oyashio Extensions. Accompanying anomalies in the net surface heat flux, SST in the preceding and following months, and meridional eddy heat flux in the lower troposphere suggest active roles played by the ocean in generating the concomitant anomalous large-scale atmospheric state in some of these cases.

scholarly journals Evaluation of a Regional Reanalysis and ERA-Interim over East Asia Using In Situ Observations during 2013–14

2017 ◽  
Vol 56 (10) ◽  
pp. 2821-2844 ◽  
Author(s):  
Eun-Gyeong Yang ◽  
Hyun Mee Kim
Keyword(s):  
Relative Humidity ◽  
East Asia ◽  
Geopotential Height ◽  
Spatial Scales ◽  
Weather Prediction ◽  
Surface Wind ◽  
Lower Troposphere ◽  
Near Surface ◽  
Skill Scores ◽  
Regional Reanalysis

AbstractIn this study, the East Asia Regional Reanalysis (EARR) is developed for the period 2013–14 and characteristics of the EARR are examined in comparison with ERA-Interim (ERA-I) reanalysis. The EARR is based on the Unified Model with 12-km horizontal resolution, which has been an operational numerical weather prediction model at the Korea Meteorological Administration since being adopted from the Met Office in 2011. Relative to the ERA-I, in terms of skill scores, the EARR performance for wind, temperature, relative humidity, and geopotential height improves except for mean sea level pressure, the lower-troposphere geopotential height, and the upper-air relative humidity. In a similar way, RMSEs of the EARR are smaller than those of ERA-I for wind, temperature, and relative humidity, except for the upper-air meridional wind and the upper-air relative humidity in January. With respect to the near-surface variables, the triple collocation analysis and the correlation coefficients confirm that EARR provides a much improved representation when compared with ERA-I. In addition, EARR reproduces the finescale features of near-surface variables in greater detail than ERA-I does, and the kinetic energy (KE) spectra of EARR agree more with the canonical atmospheric KE spectra than do the ERA-I KE spectra. On the basis of the fractions skill score, the near-surface wind of EARR is statistically significantly better simulated than that of ERA-I for all thresholds, except for the higher threshold at smaller spatial scales. Therefore, although special care needs to be taken when using the upper-air relative humidity from EARR, the near-surface variables of the EARR that were developed are found to be more accurate than those of ERA-I.

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