Regional lightning NOx sources during the TROCCINOX experiment C. Mari1, J. P. Chaboureau1, J. P. Pinty1, J. Duron1, P. Mascart1, J. P. Cammas1, F. Gheusi1, T. Fehr2, H. Schlager2, A. Roiger2, M. Lichtenstein2, and P. Stock2 1Laboratoire d'Aérologie, UMR CNRS/UPS, Toulouse, France 2DLR, Institut fuer Physik der Atmosphaere, Oberpfaffenhofen, Wessling, Germany
Abstract. A lightning NOx (LiNOx) source
has been implemented in the deep convection scheme
of the Meso-NH mesoscale model following a
mass-flux formalism coherent with the transport and
scavenging of gases inside the convective scheme.
In this approach the vertical transport of NO inside clouds is calculated by
the parameterization of deep convective transport, thus eliminating the
need for a-priori LiNOx profiles.
Once produced inside
the convective column, NO molecules are redistributed by updrafts and
downdrafts and detrained in the environment when the conditions are
The model was applied to
three particular flights during the Tropical Convection, Cirrus and Nitrogen
campaign over the tropical area around Bauru on 3–4 March 2004.
The convective activity during the three flights was investigated
using brightness temperature at 10.7 μm observed from GOES-12 satellite.
The use of a model-to-satellite approach reveals that the simulation appears
rather realistic compared to the observations.
The diurnal cycle
of the simulated brightness temperature, CAPE, number of IC flashes,
NO entrainment flux are in phase, with a succession of three marked peaks
at 18:00 UTC (15:00 LT). These simulated peaks precede the observed afternoon
one by about three hours.
Comparison of the simulated NOx with observations along the flight
tracks show that the model reproduces well the observed NOx levels when
the LiNOx source is applied.
The budget of entrainment, detrainment and LiNOx convective fluxes shows that
the majority of the NO detrained back to the environment comes from
lightning source inside the convective columns. Entrainment of NO from
the environment and vertical transport from the boundary layer were
not significant during the episode.
The troposphere is impacted by detrainment fluxes of LiNOx from
4 km altitude to
16 km with maximum values around 14 km altitude.
Detrainment fluxes vary between 75 kg(N)/s during nighttime to 400 kg(N)/s
at the times of maximun convective activity.
Extrapolation of the
regional LiNOx source would yield a global LiNOx production around
5.7 Tg(N)/year which
is within the current estimates but should not hide the overestimation of
the number of flash rates by the model.
Citation: Mari, C., Chaboureau, J. P., Pinty, J. P., Duron, J., Mascart, P., Cammas, J. P., Gheusi, F., Fehr, T., Schlager, H., Roiger, A., Lichtenstein, M., and Stock, P.: Regional lightning NOx sources during the TROCCINOX experiment, Atmos. Chem. Phys., 6, 5559-5572, doi:10.5194/acp-6-5559-2006, 2006.