HEPPA-II model-measurement intercomparison project: EPP indirect effects during the dynamically perturbed NH winter 2008-2009
Artikel i vetenskaplig tidskrift, 2017

We compare simulations from three high-top (with upper lid above 120 km) and five medium-top (with upper lid around 80 km) atmospheric models with observations of odd nitrogen (NOx D NO+NO2), temperature, and carbon monoxide from seven satellite instruments (ACE-FTS on SciSat, GOMOS, MIPAS, and SCIAMACHY on Envisat, MLS on Aura, SABER on TIMED, and SMR on Odin) during the Northern Hemisphere (NH) polar winter 2008/2009. The models included in the comparison are the 3-D chemistry transport model 3dCTM, the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMO-NIA), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA), the modelling tools for SOlar Climate Ozone Links studies (SOCOL and CAO-SOCOL), and the Whole Atmosphere Community Climate Model (WACCM4). The comparison focuses on the energetic particle precipitation (EPP) indirect effect, that is, the polar winter descent of NOx largely produced by EPP in the mesosphere and lower thermosphere. A particular emphasis is given to the impact of the sudden stratospheric warming (SSW) in January 2009 and the subsequent elevated stratopause (ES) event associated with enhanced descent of mesospheric air. The chemistry climate model simulations have been nudged toward reanalysis data in the troposphere and stratosphere while being unconstrained above. An odd nitrogen upper boundary condition obtained from MIPAS observations has further been applied to medium-top models. Most models provide a good representation of the mesospheric tracer descent in general, and the EPP indirect effect in particular, during the unperturbed (pre-SSW) period of the NH winter 2008/2009. The observed NOx descent into the lower mesosphere and stratosphere is generally reproduced within 20 %. Larger discrepancies of a few model simulations could be traced back either to the impact of the models' gravity wave drag scheme on the polar wintertime meridional circulation or to a combination of prescribed NOx mixing ratio at the uppermost model layer and low vertical resolution. In March-April, after the ES event, however, modelled mesospheric and stratospheric NOx distributions deviate significantly from the observations. The too-fast and early downward propagation of the NO x tongue, encountered in most simulations, coincides with a temperature high bias in the lower mesosphere (0.2-0.05 hPa), likely caused by an overestimation of descent velocities. In contrast, upper-mesospheric temperatures (at 0.05-0.001 hPa) are generally underestimated by the high-top models after the onset of the ES event, being indicative for too-slow descent and hence too-low NOx fluxes. As a consequence, the magnitude of the simulated NOx tongue is generally underestimated by these models. Descending NOx amounts simulated with mediumtop models are on average closer to the observations but show a large spread of up to several hundred percent. This is primarily attributed to the different vertical model domains in which the NOx upper boundary condition is applied. In general, the intercomparison demonstrates the ability of state-of- the-art atmospheric models to reproduce the EPP indirect effect in dynamically and geomagnetically quiescent NH winter conditions. The encountered differences between observed and simulated NOx, CO, and temperature distributions during the perturbed phase of the 2009 NH winter, however, emphasize the need for model improvements in the dynamical representation of elevated stratopause events in order to allow for a better description of the EPP indirect effect under these particular conditions.

Författare

B. Funke

CSIC - Instituto de Astrofísica de Andalucía (IAA)

W. Ball

Physikalisch-Meteorologisches Observatorium Davos World Radiation Center

Stefan Bender

Karlsruher Institut für Technologie (KIT)

A. Gardini

CSIC - Instituto de Astrofísica de Andalucía (IAA)

V. L. Harvey

University of Colorado at Boulder

A. Lambert

Jet Propulsion Laboratory, California Institute of Technology

M. Lopez-Puertas

CSIC - Instituto de Astrofísica de Andalucía (IAA)

D. R. Marsh

National Center for Atmospheric Research

K. Meraner

Max Planck-institutet

H. Nieder

Karlsruher Institut für Technologie (KIT)

S. M. Paivarinta

Finnish Meteorological Institute

Helsingin Yliopisto

Kristell Perot

Chalmers, Rymd- och geovetenskap, Global miljömätteknik och modellering

C. E. Randall

University of Colorado at Boulder

T. Reddmann

Karlsruher Institut für Technologie (KIT)

E. Rozanov

Physikalisch-Meteorologisches Observatorium Davos World Radiation Center

Eidgenössische Technische Hochschule Zürich (ETH)

H. Schmidt

Max Planck-institutet

A. Seppala

Finnish Meteorological Institute

M. Sinnhuber

Karlsruher Institut für Technologie (KIT)

T. Sukhodolov

Physikalisch-Meteorologisches Observatorium Davos World Radiation Center

G. P. Stiller

Karlsruher Institut für Technologie (KIT)

N. D. Tsvetkova

Central Aerological Observatory

P. T. Verronen

Finnish Meteorological Institute

S. Versick

Karlsruher Institut für Technologie (KIT)

T. von Clarmann

Karlsruher Institut für Technologie (KIT)

K. A. Walker

University of Toronto

V. Yushkov

Central Aerological Observatory

Atmospheric Chemistry and Physics

1680-7316 (ISSN) 1680-7324 (eISSN)

Vol. 17 5 3573-3604

Ämneskategorier

Geovetenskap och miljövetenskap

DOI

10.5194/acp-17-3573-2017