References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-7-697-2007

Characterization of the 222Rn family turbulent transport in the convective atmospheric boundary layer

Vinuesa

J.-F.

¹ Galmarini

European Commission – DG Joint Research Centre, Institute for Environment and Sustainability, Italy

12 02 2007

7 3 697 712

This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

This article is available from http://www.atmos-chem-phys.net/7/697/2007/acp-7-697-2007.html

The full text article is available as a PDF file from http://www.atmos-chem-phys.net/7/697/2007/acp-7-697-2007.pdf

The combined effect of turbulent transport and radioactive decay on the distribution of 222Rn and its progeny in convective atmospheric boundary layers (CBL) is investigated. Large eddy simulation is used to simulate their dispersion in steady state CBL and in unsteady conditions represented by the growth of a CBL within a pre-existing reservoir layer. The exact decomposition of the concentration and flux budget equations under steady state conditions allowed us to determine which processes are responsible for the vertical distribution of 222Rn and its progeny. Their mean concentrations are directly correlated with their half-life, e.g. 222Rn and 210Pb are the most abundant whereas 218Po show the lowest concentrations. 222Rn flux decreases linearly with height and its flux budget is similar to the one of inert emitted scalar, i.e., a balance between on the one hand the gradient and the buoyancy production terms, and on the other hand the pressure and dissipation at smaller scales which tends to destroy the fluxes. While 222Rn exhibits the typical bottom-up behavior, the maximum flux location of the daughters is moving upwards while their rank in the 222Rn progeny is increasing leading to a typical top-down behavior for 210Pb. We also found that the relevant radioactive decaying contributions of 222Rn short-lived daughters (218Po and 214Pb) act as flux sources leading to deviations from the linear flux shape. In addition, while analyzing the vertical distribution of the radioactive decay contributions to the concentrations, e.g. the decaying zone, we found a variation in height of 222Rn daughters' radioactive transformations. Under unsteady conditions, the same behaviors reported under steady state conditions are found: deviation of the fluxes from the linear shape for 218Po, enhanced discrepancy in height of the radioactive transformation contributions for all the daughters. In addition, 222Rn and its progeny concentrations decrease due to the rapid growth of the CBL. The analysis emphasizes the crucial role of turbulent transport in the behavior of 222Rn n morning concentrations, in particular the ventilation at the top of the boundary layer that leads to the dilution of 222Rn by mixing with radon low concentration air.

References 1

Allen, D. J., Rood, R. B., Thompson, A. M., and Hudson R. D.: Three-dimensional radon-222 calculations using assimilated meteorological data and a convective mixing algorithm, J. Geophys. Res., 101, 6871–6881, 1996.

Beck, H. L. and Gogolak C. V.: Time dependent calculation of the vertical distribution of 222Rn and its decay products in the atmosphere, J. Geophys. Res., 84, 3139–3148, 1979.

Butterweck, G., Reineking, A., Kesten, J., and Porstendörfer J.: The use of the natural radioactive noble gases radon and thoron as tracers for the study of the turbulent exchange in the atmospheric boundary layer � case study in and above a wheat field, Atmos. Environ. 28, 1963-1969, 1994.

Clarke, R. H., Dyer, A. J., Brook, R. R., Reid, D. G., and Troup A. J.: The Wangara experiment: boundary layer data, Paper No. 19, Div. Meteorol. Phys., CSIRO, Australia, 1971.

Cuijpers, J W M. and Duynkerke P G.: Large eddy simulations of trade wind with cumulus clouds, J. Atmos. Sci. 50, 3894–3908, 1993.

Cuijpers, J W M. and Holtslag A A M.: Impact of skewness and nonlocal effects on scalar and buoyancy fluxes in convective boundary layers, J. Atmos. Sci., 55, 151–162, 1998.

Damköhler, G.: Influence of turbulence on the velocity flames in gas mixtures, Z. Elektrochem., 46, 601–626, 1940.

Deardorff, J W.: Three-dimensional numerical study of turbulence in an entraining mixed layer, Bound.-Layer Meteorol., 7, 199–226, 1974.

Deardorff, J W.: Prediction of convective mixed-layer entrainment for realistic capping inversion structure, J. Atmos. Sci., 36, 424–436, 1979.

Dentener, F., Feichter, J., and Jeuken A.: Simulation of the transport of Rn-222 using on-line and off-line global models at different horizontal resolutions: a detailed comparison with measurements, Tellus 51B, 573–602, 1999.

Druilhet, A. and Fontan J.: Détermination des coefficients de diffusion verticale entre 0 et 100 m à l�aide du radon et du ThB, Bound.-Layer Meteorol., 3, 468-498, 1973a.

Druilhet, A. and Fontan J.: Utilisation du thoron pour la détermination du coefficient vertical de diffusion turbulante près de sol, Tellus 25, 199-212, 1973b.

Fontan, J., Guedalia, D., Druilhet, A., and Lopez A.: Une méthode de mesure de la stabilité verticale de l�atmosphère près du sol, Bound.-Layer Meteorol., 17, 3–14, 1979.

Fujinami, N. and Esaka S.: Variations in Radon 222 daughter concentrations in surface air with atmospheric stability, J. Geophys. Res., 92, 1041–1043, 1987.

Fujinami, N. and Esaka S.: A simple model for estimating the mixing depth from the diurnal variation of atmospheric 222Rn concentration, Rad. Prot. Dos., 24, 88–91, 1988.

Galmarini, S.: One year of 222-Rn concentration in the atmospheric surface layer, Atmos. Chem. Phys. 6, 2865–2887, 2006.

Gao, W. and Wesely M L.: Numerical modelling of the turbulent fluxes of chemically reactive trace gases in the atmospheric boundary layer, J. Appl. Meteorol., 33, 835–847, 1994.

Guedalia, D., Allet, C., Fontan, J., Druilhet, A., and Assaf, G.: Lead-212, Rn, and vertical mixing in the lower atmosphere (100-2000 m), Tellus, 25, 381-385, 1973.

Guedalia, D., Allet, C., and Fontan J.: Vertical exchange measurements in the lower troposphere using ThB (212Pb) and radon (222Rn), J. Appl. Meteorol., 13, 27-39, 1974.

Guedalia, D., N�Tsila, A., Druilhet, A., and Fontan J.: Monitoring of the atmospheric stability above an urban and suburban site using rodar and radon measurements, J. Appl. Meteorol., 19, 839-848, 1980.

Gaudry, A., Polian, G., Ardouin, B., and Lambert G.:Radon-calibrated emissions of CO2 from South Africa, Tellus, 42B, 9-19, 1990.

Genthon, C. and Armengaud A.: Radon-222 as a comparative tracer of transport and mixing in 2 general-circulation models of the atmosphere, J. Geophys. Res., 100, 2849–2866, 1995.

Ikebe, Y.: Variation of radon and thoron concentrations in relation to the wind speed, J. Meteorol. Soc. Jpn., 48, 461-467, 1970.

Ikebe, Y. and Shimo M.: Estimation of the vertical turbulent diffusivity from thoron profiles, Tellus, 24, 29-37, 1972.

Jacob, D. J. and Prather M. J.: Radon-222 as a test of convective transport in a general circulation model, Tellus, 42B, 118-134, 1990.

Jacob, D. J., Prather, M. J., Rasch, P. J., Shia, R. L., Balkanski, Y. J., Beagley, S. R., Bergmann, D. J., Blackshear, W. T., Brown, M., Chiba, M., Chipperfield, M. P., deGrandpre, J., Dignon, J. E., Feichter, J., Genthon, C., Grose, W. L., Kasibhatla, P. S., Kohler, I., Kritz, M. A., Law, K., Penner, J. E., Ramonet, M., Reeves, C. E., Rotman, D. A., Stockwell, D. Z., VanVelthoven, P. F. J., Verver, G., Wild, O., Yang, H., and Zimmermann P.: Evaluation and intercomparison of global atmospheric transport models using Rn-222 and other short-lived tracers, J. Geophys. Res., 102, 5953–5970, 1997.

Jacobi, W. and Andre K.: The vertical distribution of 222Rn, 220Rn and their decay products in the atmosphere, J. Geophys. Res., 68, 3799–3814, 1963.

Jonker, H. J. J., Vilà -Guerau de Arellano, J., and Duynkerke P. G.: Characteristic length scales of reactive species in a convective boundary layer, J. Atmos. Sci., 61, 41–56, 2004.

Kataoka, T., Yunoki, E., Shimizu, M., Mori, T., Tsukamoto, O., Ohhashi, Y., Sahashi, K., Maitani, T., Miyashita, K., Fujikawa, Y., and Kudo A.: Diurnal variation in radon concentration and mixing-layer gepth, Bound.-Layer Meteorol., 89, 225-250, 1998.

Kataoka, T., Yunoki, E., Shimizu, M.,Mori, T., Tsukamoto, O., Ohhashi, Y., Sahashi, K., Maitani, T.,Miyashita, K., Iwata, T., Fujikawa, Y., Kudo, A., and Shaw R. H.: A study of the atmospheric boundary layer using raon and air pollutants as tracers, Bound.-Layer Meteorol., 101, 131-155, 2001.

Krol, M C., Molemaker, M J., and Vilà-Guerau de Arellano J.: Effects of turbulence and heterogeneous emissions on photochemically active species in the convective boundary layer, J. Geophys. Res., 105, 6871–6884, 2000.

Larson, R. E., Lamontagne, R. A., and Wittmann W. I.: Radon-222, CO, CH4 and continental dust over the greenland and norwegian seas, Nature, 240, 345-347, 1972.

Li, Y. H. and Chang J. S.: A three-dimensional global episodic tracer transport model. 1. Evaluation of its processes by radon 222 simulations, J. Geophys. Res., 101, 25 931–25 947, 1996.

Lopez, A., Guedalia, D., Servant, J., and Fontan J.: Advantages of the use of radioactive tracers 222Rn and 212Pb for the study of aitken nuclei within the lower troposphere, J. Geophys. Res., 79, 1243-1252, 1974.

Mahowald, N. M., Rasch, P. J., Eaton, B. E., Whittlestone, S., and Prinn R. G.: Transport of (222)radon to the remote troposphere using the model of atmospheric transport and chemistry and assimilated winds from ECMWF and the National Center for Environmental Prediction NCAR, J. Geophys. Res., 102, 28 139-28 151, 1997.

Moeng, C H. and Wyngaard J C.: Statistics of conservative scalars in the convective boundary layer, J. Atmos. Sci., 41, 3161–3169, 1984.

Molemaker, M J. and Vilà-Guerau de Arellano J.: Turbulent control of chemical reactions in the convective boundary layer, J. Atmos. Sci., 55, 568–579, 1998.

Moses, H., Lucus Jr., H. F., and Zerbe G. A.: The Effect of Meteorological Variables upon Radon concentration three feet above the ground, J. Air Pollut. Control. Assoc., 13, 12-19, 1963.

Patton, E G., Davis, K J., Barth, M C., and Sullivan P P. : Decaying scalars emitted by a forest canopy: a numerical study, Bound.-Layer Meteorol., 100, 91–129, 2001.

Pearson, J. E. and Moses H.: Atmospheric Radon-222 concentration variation with height and time, J. Appl. Meteorol. 5, 175-181, 1966.

Petersen, A C. and Holtslag A A M.: A first-order closure for covariances and fluxes of reactive species in the convective boundary layer, J. Appl. Meteorol., 38, 1758–1776, 1999.

Petersen, A C., Beets, C., van Dop, H., and Duynkerke P G.: Mass-flux schemes for transport of non-reactive and reactive scalars in the convective boundary layer, J. Atmos. Sci., 56, 37–56, 1999.

Petersen, A C.: The impact of chemistry on flux estimates in the convective boundary layer, J. Atmos. Sci., 57, 3398–3405, 2000.

Polian, G., Lambert, G., Ardouin, B., and Jegou A.: Long-range transport of continental radon in subantarctic and antarctic areas, Tellus, 38B, 178-189, 1986.

Porstendörfer, J.: Properties and behaviour of radon and thoron and their decay products in the air, J. Atmos. Sci., 25, 219–263, 1994.

Ramonet, M., Le Roulley, J. C., Bousquet, P., and Monfray P.: Radon-222 measurements during the Tropoz II campaign and comparison with a global atmospheric transport model, J. Atmos. Chem., 23, 107-136, 1996.

Robé, M. C., Rannou, A., and Le Bronec J. Radon measurement in the environment in France, Rad. Prot. Dos., 45, 455-457, 1992.

Schumann, U.: Large-eddy simulation of turbulent diffusion with chemical reactions in the convective boundary layer, Atmos. Environ., 23, 1713–1729, 1989.

Sykes, R I., Parker, S F., Henn, D S., and Lewellen W S.: Turbulent mixing with chemical reactions in the planetary boundary layer, J. Appl. Meteorol., 33, 825–834, 1994.

Sesana, L., Barbieri, L., Facchini, U., and Marcazzan G.M.: 222Rn as a tracer of atmospheric motions: a study in Milan, Rad. Prot. Dos., 78, 65–71, 1998.

Sesana, L., Ottobrini, B., Polla, G., and Facchini U.: 222Rn as indicator of atmospheric turbulence: measurements at Lake Maggiore and on the pre-Alps, J. Env. Rad., 86, 271–288, 2006.

Siebesma, A P. and Cuijpers J W M.: Evaluation of parametric assumptions for shallow cumulus convection, J. Atmos. Sci., 52, 650–666, 1995.

Stockwell, D. Z., Kritz, M. A., Chipperfield, M. P., and Pyle J. A.: Validation of an off-line three dimensional chemical transport model using observed radon profiles – 2. Model results, J. Geophys. Res., 103, 8433-8445, 1998.

van Zanten, M., Duynkerke, P. G., and Cuijpers J. W. M.: Entrainment parameterizations in convective boundary layers, J. Atmos. Sci., 56, 813-828, 1999.

Verver, G. H L., van Dop, H., and Holtslag A A M.: Turbulent mixing of reactive gases in the convective boundary layer, Bound.-Layer Meteorol., 85, 197–222, 1997.

Vilà-Guerau de Arellano, J., and Cuijpers J W M.: The chemistry of a dry cloud: the effects of radiation and turbulence, J. Atmos. Sci. 57, 1573–1584, 2000.

Vilà-Guerau de Arellano J.: Bridging the gap between atmospheric physics and chemistry in studies of small-scale turbulence, Bull. Amer. Meteor. Soc., 84, 51–56, 2003.

Vinod Kumar, A., Sitaraman, V., Oza, R. B., and Krishamoorthy T. M.: Application of a numerical model for the planetary boundary layer to the vertical distribution of radon and its daughter products, Atmos. Environ., 33, 4717–4726, 1999.

Vinuesa, J.-F. and Vilà -Guerau de Arellano J.: Fluxes and (co-)variances of reacting scalars in the convective boundary layer, Tellus, 55B, 935-949, 2003.

Vinuesa, J.-F. and Vilà -Guerau de Arellano J.: Introducing effective reaction rates to account for the inefficient mixing of the convective boundary layer, Atmos. Environ., 39, 445–461, 2005.

Wilkening M. H.: Radon 222 concentrations in the convective patterns of a mountain environment, J. Geophys. Res., 75, 1733–1740, 1970.

Wyngaard, J C. and Brost R A.: Top-down and bottom-up diffusion of a scalar in the convective boundary layer, J. Atmos. Sci., 41, 102–112, 1984.

Wyngaard J C.: Structure of the planetary boundary layer and implications for its modeling, J. Clim. App. Meteorol., 24, 1131–1142, 1985.

Zahorowski, W., Chambers, S. D., and Henderson-Sellers, A.: Ground based radon-222 observations and their application to atmospheric studies, J. Env. Rad., 76, 3-33, 2004.