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| Titel |
Implementation of a Simple Fire Emission Height Model in ECHAM6-HAM2: Model Evaluation and Potential Climate Impact |
| VerfasserIn |
Andreas Veira, Stiig Wilkenskjeld, Silvia Kloster |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088691
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| Publikation (Nr.) |
 EGU/EGU2014-2831.pdf |
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| Zusammenfassung |
| We use the global circulation model ECHAM6 extended by the aerosol module HAM2
to assess the impact of advanced fire emission height parametrizations in global
climate models. Fire emission heights describe the altitudes at which vegetation
fire smoke plumes release emissions into the atmosphere. In this study prescribed
injection heights in ECHAM6-HAM2 are replaced by an implementation of a simple,
semi-empirical plume model published by M. Sofiev in 2012. The 1-D plume model
predicts maximum emission heights based on ambient meteorological conditions
and fire radiative power (FRP). In a first step, the global model performance is
evaluated against the latest version of the ’MISR Plume Height Project’ data set. Our
results show that the model simulates a largely reasonable global distribution of
emission injection heights. Extra-tropical plume heights are represented slightly
more adequate than tropical plumes, although deep extra-tropical injections are
generally underestimated. By adjustment of the tuning parameters, the bias of the
extra-tropical deep injections can be significantly reduced and thus the modified plume
model offers a reasonable representation of fire emission heights in a global climate
model.
In a second step, we apply the fire activity and emission inventory of the Global
Fire Assimilation System (GFAS) to ECHAM6-HAM2. The assignment of single
fires to a limited number of FRP classes enables a comprehensive and feasible
representation of individual fire intensities within a global climate model. In addition to the
meteorological parameters, the individual FRP values serve as input variable for the 1-D
plume height model. We compare the results of our multi-year simulations based on
this advanced fire emission height representation to standard ECHAM6-HAM2
simulations and discuss the effects of modified emission height distributions on
global aerosol transport and radiative transfer. The changes in first order radiative
aerosol effects turn out to be relatively small, but black carbon concentrations and
deposition rates show significant changes in some regions. Furthermore, modelled
changes in atmospheric aerosol concentrations and aerosol optical properties are
compared to observations. Thus, we evaluate the specific influence of the plume height
model on the overall performance of the global circulation model. In summary, this
study contributes to a better understanding of the importance, the benefits and the
limitations of advanced emission height parametrizations in global circulation models. |
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