Troposphere

01.11.2012
Stratosphere-Troposphere Exchange
Using a passive tracer to study
deep stratospheric intrusions in COSMO
Stratosphere
Troposphere
Swiss COSMO user workshop November 2012
Bojan Škerlak
Supervision: S. Pfahl, A. Roches, H. Wernli, M. Sprenger, H. Sodemann

Deep stratospheric intrusion affecting Yellowstone NP
• Yellowstone NP spring 2006
• Surface ozone from 50 ppbv to 89 ppbv
PV [pvu]
TP
• Stratospheric (PV > 2 pvu) origin?
Lefohn et al. 2011

COSMO: Stratospheric Tracer
• Initialize tracer to 1 in the Stratosphere
(> 2 pvu or > 380 K) using a
3D-clustering algorithm
Sprenger et al. 2003, Skerlak et al., in preparation
• ECMWF analysis to COSMO
int2lm_trcr_1.18:
S. Pfahl
• Transport of tracer in COSMO
cosmo_trcr_4.23.1:
A. Roches and O. Fuhrer
Tracer = 1
advection (resolved)
turbulence (parametrized)
convection (parametrized)

Stratospheric tracer at lowest model level

Give and Take
• What I can give:
- share first experiences
- 3D-clustering of the atmosphere
- global STE climatology
- plotting scripts in NCL
• What I could profit from:
- interesting scientific questions
- data (ozone, C14, Be10) that
could be influenced by deep STE
=> possible case studies!
bojan.skerlak@env.ethz.ch

• Questions?
Thanks

STE: general overview
TST
STT
Holton et al. 1995, Stohl et al. 2003

3D-Clustering of the atmosphere
1 = Troposphere, 2 = Stratosphere, 3 = Strat. Cutoff in Trop.,
4 = Trop. Cutoff in Strat., 5 = Surface-bound PV anomaly
Sprenger et al. 2003, Skerlak et al., in preparation

STT mass flux averaged 1979-2011 (ERA-Interim)
STT
Skerlak et al., in preparation

Stratospheric tracer at lowest model level

Stratospheric tracer at lowest model level
2 pvu contour
isentropes
S
N

COSMO vs. Measurements at Yellowstone NP