Annual cycle of ozone at and above the tropical tropopause: observations versus simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) 1Forschungszentrum Jülich (ICG-1: Stratosphere), Jülich, Germany
2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
Received: 10 Jul 2009 – Published in Atmos. Chem. Phys. Discuss.: 01 Sep 2009 Abstract. Multi-annual simulations with the Chemical Lagrangian Model of the Stratosphere
(CLaMS) were conducted to study the seasonality of O3 within the
stratospheric part of the tropical tropopause layer (TTL),
i.e. above θ=360 K potential temperature level.
In agreement with satellite (HALOE) and in-situ observations (SHADOZ),
CLaMS simulations show a pronounced annual cycle in O3,
at and above θ=380 K, with the highest mixing ratios in the late
boreal summer. Within the model, this cycle is driven by the seasonality of
both upwelling and in-mixing. The latter process occurs through enhanced
horizontal transport from the extratropics into the TTL that is mainly
driven by the meridional, isentropic winds.
The strongest in-mixing occurs during the late boreal summer from the
Northern Hemisphere in the potential temperature range between 370 and
420 K. Complementary, the strongest upwelling occurs in winter
reducing O3 to the lowest values in early spring.
Both CLaMS simulations and Aura MLS O3 observations consistently
show that enhanced in-mixing in summer is mainly driven by the
Asian monsoon anticyclone.
Revised: 09 Dec 2009 – Accepted: 14 Dec 2009 – Published: 11 Jan 2010
Citation: Konopka, P., Grooß, J.-U., Günther, G., Ploeger, F., Pommrich, R., Müller, R., and Livesey, N.: Annual cycle of ozone at and above the tropical tropopause: observations versus simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS), Atmos. Chem. Phys., 10, 121-132, doi:10.5194/acp-10-121-2010, 2010.