ATTILA 4.0: Lagrangian advective and convective transport of passive tracers within the ECHAM5/MESSy (2.53.0) chemistry–climate model
<p>We have extended ATTILA (Atmospheric Tracer Transport in a LAgrangian model), a Lagrangian tracer transport scheme, which is online coupled to the global ECHAM/MESSy Atmospheric Chemistry (EMAC) model, with a combination of newly developed and modified physical routines and new diagnostic a...
Main Authors: | , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2019-05-01
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Series: | Geoscientific Model Development |
Online Access: | https://www.geosci-model-dev.net/12/1991/2019/gmd-12-1991-2019.pdf |
Summary: | <p>We have extended ATTILA (Atmospheric Tracer Transport in a LAgrangian model),
a Lagrangian tracer transport scheme, which is online coupled to the global
ECHAM/MESSy Atmospheric Chemistry (EMAC) model, with a combination of newly
developed and modified physical routines and new diagnostic and
infrastructure submodels. The new physical routines comprise a
parameterisation for Lagrangian convection, a formulation of diabatic
vertical velocity, and the new grid-point submodel LGTMIX to calculate the
mixing of compounds in Lagrangian representation. The new infrastructure
routines simplify the transformation between grid-point (GP) and Lagrangian
(LG) space in a parallel computing environment. The new submodel LGVFLUX is a
useful diagnostic tool to calculate online vertical mass fluxes through
horizontal surfaces. The submodel DRADON was extended to account for
emissions and changes of <span class="inline-formula"><sup>222</sup></span>Rn on Lagrangian parcels. To evaluate the
new physical routines, two simulations in free-running mode with prescribed
sea surface temperatures were performed with EMAC–ATTILA in T42L47MA
resolution from 1950 to 2010. The results show an improvement of the tracer
transport into and within the stratosphere when the diabatic vertical
velocity is used for vertical advection in ATTILA instead of the standard
kinematic vertical velocity. In particular, the age-of-air distribution is
more in
accordance with observations. The global tropospheric distribution of
<span class="inline-formula"><sup>222</sup></span>Rn, however, is simulated in agreement with available observations
and with the results from EMAC in grid space for both Lagrangian systems.
Additional sensitivity studies reveal an effect of inter-parcel mixing on the
age of air in the tropopause region and the stratosphere, but there is no
significant effect for the troposphere.</p> |
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ISSN: | 1991-959X 1991-9603 |