Modelling NOx from lightning and its impact on global chemical fields

Abstract We have used a three-dimensional off-line chemical transport model (CTM) to assess the impact of lightning emissions in the free troposphere both on NO x itself and on other chemical species such as O 3 and OH. We have investigated these effects using two lightning emission scenarios. In the first, lightning emissions are coupled in space and time to the convective cloud top height calculated every 6 h by the CTM's moist convection scheme. In the second, lightning emissions are calculated as a constant, monthly mean field. The model's performance against observed profiles of NO x and O 3 in the Atlantic and Pacific ocean improves significantly when lightning emissions are included. With the inclusion of these emissions, the CTM produces a significant increase in the NO x concentrations in the upper troposphere, where the NO x lifetime is long, and a smaller increase in the lower free troposphere, where the surface NO x sources dominate. These changes cause a significant increase in the O 3 production in the upper troposphere and hence higher calculated O 3 there. The model indicates that lightning emissions cause local increases of over 50 parts per 10 12 by volume (pptv) in NO x , 200 pptv in HNO 3 and 20 parts per 10 9 by volume (ppbv) (>40%) in O 3 . In addition, a smaller increase of O 3 in the lower troposphere occurs due to an increase in the downward transport of O 3 . The O 3 change is accompanied by an increase in OH which is more pronounced in the upper troposphere with a corresponding reduction in CO. The method of emission employed in the model does not appear to have a significant effect globally. In the upper troposphere (above about 300 hPa) NO x concentrations are generally lower with monthly mean emissions, because of the de-coupling of emissions from the model's convection scheme, which vents NO x aloft more efficiently in the coupled scheme. Below the local convective outflow altitude, NO x concentrations are larger when using the monthly mean emissions than when coupled to the convection scheme, because the more dilute emissions, and nighttime emissions, lead to a slower NO x destruction rate. Only minor changes are predicted in the monthly average fields of O 3 if we emit lightning as a monthly constant field. However, the method of emission becomes important when we make a direct comparison of model results with time varying data. These differences should be taken into account when a direct comparison of O 3 with measurements collected at particular times and locations is attempted.

[1]  M. Wesely,et al.  SO2, sulfate and HNO3 deposition velocities computed using regional landuse and meteorological data , 1986 .

[2]  D. Rind,et al.  What determines the cloud-to-ground lightning fraction in thunderstorms? , 1993 .

[3]  H. Fuelberg,et al.  A meteorological overview of the TRACE A period , 1996 .

[4]  Jean‐François Müller,et al.  Geographical distribution and seasonal variation of surface emissions and deposition velocities of atmospheric trace gases , 1992 .

[5]  H. Volland,et al.  Handbook of atmospheric electrodynamics , 1995 .

[6]  John A. Pyle,et al.  Implementation of a convective atmospheric boundary layer scheme in a tropospheric chemistry transport model , 1999 .

[7]  Oliver Wild,et al.  The ASAD atmospheric chemistry integration package and chemical reaction database , 1997 .

[8]  M. Tiedtke.  A Comprehensive Mass Flux Scheme for Cumulus Parameterization in Large-Scale Models , 1989 .

[9]  M. Prather.  Numerical advection by conservation of second-order moments. [for trace element spatial distribution and chemical interaction in atmosphere] , 1986 .

[10]  Ø. Hov,et al.  NO x from lightning and the calculated chemical composition of the free troposphere , 1997 .

[11]  P. Kasibhatla,et al.  A global three‐dimensional time‐dependent lightning source of tropospheric NOx , 1996 .

[12]  J. Penner,et al.  NOx from lightning 1. Global distribution based on lightning physics , 1997 .

[13]  Robert Sausen,et al.  Contributions of aircraft emissions to the atmospheric NOx content , 1997 .

[14]  P. Crutzen.  A discussion of the chemistry of some minor constituents in the stratosphere and troposphere , 1973 .

[15]  D. Fahey,et al.  Ozone production in the rural troposphere and the implications for regional and global ozone distributions , 1987 .

[16]  J. Bradshaw,et al.  Asian influence over the western North Pacific during the fall season: Inferences from lead 210, soluble ionic species and ozone , 1996 .

[17]  Euan G. Nisbet,et al.  Sensitivity of the CH4 growth rate to changes in CH4 emissions from natural gas and coal , 1996 .

[18]  W. Chameides,et al.  A photochemical theory of tropospheric ozone , 1973 .

[19]  Stephen D. Piccot,et al.  A global inventory of volatile organic compound emissions from anthropogenic sources , 1992 .

[20]  M. Chipperfield,et al.  A tropospheric chemical‐transport model: Development and validation of the model transport schemes , 1999 .

[21]  David John Lary,et al.  A three-dimensional modeling study of trace species in the Arctic lower stratosphere during winter 1989-1990 , 1993 .

[22]  L. Gallardo,et al.  Could cloud‐to‐cloud discharges be as effective as cloud‐to‐ground discharges in producing NOx? , 1996 .

[23]  R. Dickerson,et al.  NOx Production in Lightning , 1977 .

[24]  J. Lamarque,et al.  of the different nitrogen sources in the troposphere , 1996 .

[25]  Dudley E. Shallcross,et al.  Evaluation of modeled O3 using Measurement of Ozone by Airbus In‐Service Aircraft (MOZAIC) data , 1998 .

[26]  S. A. Prentice,et al.  The Ratio of Cloud to Cloud-Ground Lightning Flashes in Thunderstorms , 1977 .

[27]  John A. Pyle,et al.  Modeling trace gas budgets in the troposphere: 1. Ozone and odd nitrogen , 1993 .

[28]  D. E. Proctor,et al.  Regions where lightning flashes began , 1991 .

[29]  D. Stevenson,et al.  Tropospheric Ozone in a Global-Scale Three-Dimensional Lagrangian Model and Its Response to NOX Emission Controls , 1997 .

[30]  D. Ehhalt,et al.  The global tropospheric distribution of NO x estimated by a three‐dimensional chemical tracer model , 1996 .

[31]  Dudley E. Shallcross,et al.  Evaluation of modelled O3 using MOZAIC data , 1998 .

[32]  R. D. Hill,et al.  Atmospheric Nitrogen Fixation by Lightning , 1980 .

[33]  E J Workman,et al.  The Electrical Structure of Thunderstorms , 1942 .

[34]  D. Blake,et al.  Chemical characteristics of tropospheric air over the Pacific Ocean as measured during PEM‐West B: Relationship to Asian outflow and trajectory history , 1997 .

[35]  Anne M. Thompson,et al.  Convective transport of biomass burning emissions over Brazil during TRACE A , 1996 .

[36]  Albert A. M. Holtslag,et al.  Local Versus Nonlocal Boundary-Layer Diffusion in a Global Climate Model , 1993 .

[37]  Donald J. Wuebbles,et al.  Radiative Forcing of Climate Changes in the Vertical Distribution of Ozone , 1990 .

[38]  Richard J. Blakeslee,et al.  The detection of lightning from geostationary orbit , 1989 .

[39]  E. Pierce,et al.  Latitudinal Variation of Lightning Parameters , 1970 .

[40]  D. Rind,et al.  A simple lightning parameterization for calculating global lightning distributions , 1992 .

[41]  Martyn P. Chipperfield,et al.  Validation of an off‐line three‐dimensional chemical transport model using observed radon profiles: 2. Model results , 1998 .

[42]  M. Kritz,et al.  Validation of an off‐line three‐dimensional chemical transport model using observed radon profiles: 1. Observations , 1998 .

[43]  P. Crutzen,et al.  Reactive nitrogen and ozone over the western Pacific: Distribution, partitioning, and sources , 1996 .

[44]  C. Popp,et al.  Nitrogen oxides produced from lightning , 1989 .

[45]  I. Isaksen,et al.  Parameterization of episodical cloud and rainout events in large-scale atmospheric chemistry models , 1992 .

[46]  F. Giorgi,et al.  The rainout parameterization in a photochemical model , 1985 .

[47]  J. Penner,et al.  An evaluation of upper troposphere NO x with two models , 1998 .