Atmospheric transport simulation of ²¹⁰Pb and ⁷Be by the LMDz general circulation model and sensitivity to convection and scavenging parameterization

Heinrich, P.; Jamelot, A.

Atmospheric transport simulation of ²¹⁰Pb and ⁷Be by the LMDz general circulation model and sensitivity to convection and scavenging parameterization

2011

Heinrich, P. | Jamelot, A.

The atmospheric transport of ²¹⁰Pb and ⁷Be is simulated by the Laboratoire de Météorologie Dynamique general circulation model, LMDz, driven by NCEP winds. Simulations are performed for one year (2006) in a regular grid with a resolution of 1.875° in longitude, 1.24° in latitude and 40 vertical levels. ²¹⁰Pb and ⁷Be are two natural radionuclides attached to submicron aerosols and used as inert tracers to evaluate LMDz performance in terms of atmospheric transport, with particular emphasis on the tropics region. Daily averaged concentrations of both radionuclides are compared with available data, which are collected at surface stations with a 24h sampling period. At tropical stations, time series of ⁷Be and ²¹⁰Pb concentrations are not satisfactorily reproduced by the model using a traditional convection scheme. The purpose of this paper is to evaluate a more recently implemented convection scheme and two scavenging representations, in-cloud convective rainout and scavenging in convective updrafts. The former process associated to the new convection scheme, seems to be inappropriate in the tropics, since it tends to exaggerate the release of scavenged aerosols in the atmosphere due to re-evaporation of precipitation. Results suggest that scavenging of aerosols in updrafts could be sufficient to eliminate aerosols under convective regime.

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