Convective Transport of Water Vapor into the Lower Stratosphere Observed During
Double Tropopause Events
Cameron Homeyer National Center for Atmospheric Research AGU Fall Meeting, 10 December 2013 Collaborators: Laura Pan, Teresa Campos & Andy Weinheimer (NCAR) Sam Dorsi & Linnea Avallone (CU-Boulder), Glenn Diskin (NASA) Mark Zondlo, Anthony O’Brien & Josh DiGangi (Princeton), Tom Ryerson (NOAA)
Image Courtesy of Chris Cantrell
Outline • Observations from the Deep Convective Clouds and
Chemistry (DC3) experiment
– May-June 2012
– NSF-NCAR Gulfstream V (GV) & NASA DC-8
– Primary goal was to characterize effect of midlatitude convection on UT composition and chemistry
• Water vapor injection into LS
– May 19-20 (GV)
– May 30-31 (GV & DC-8)
Motivation • Well known: stratosphere-troposphere exchange
modifies UTLS chemistry, radiation budget, and climate • Potential impacts of STE from extratropical convection:
– TST: Increase in stratospheric water vapor • Inorganic chlorine activation and ozone destruction?
(Anderson et al, 2012, Science) – STT: Increase in tropospheric ozone
• Problems? – Convection and associated transport not resolved in global
climate models – Apart from the identification of overshooting extratropical
convection, little is known about the characteristic depth and frequency, large-scale environments conducive to overshooting, and mechanisms responsible for transport
Transport Mechanisms
Wang, 2003, J. Geophys. Res.
Fujita, 1982, J. Meteorol. Soc. Japan
“Jumping Cirrus”
Direct Overshoot
Mixing
19-20 May 2012
Flight Track & Large-Scale Environment
NCEP-GFS Analysis valid 20 May 2012 at 00 UTC 10
12
1212
12
12
1414
1416
16
16
30
30
30 30
30
30
30
30
40
40
4040
Lamont, OK Sounding
� � � � � ��
Temperature (C)
�
5
��
15
��
Altitu
de
(km
)
��
Radar Cross-section (a)
KDDC
LMN
KOUN
A (259.75º E, 35.85º N) B (262.75º E, 35.85º N)
KDDC
LMN
LMN
KOUN
KOUN
A B
(b)
0 15 30 45 60 75
Reflectivity (dB)
0
5
10
15
20
Altitu
de
(km
)
Texas
Oklahoma
Kansas
KDDC
In situ Measurements
00:00 00:05 00:10 00:15 00:20Time (UTC)
10
15
Altit
ude
(km
)
0.00
0.01
0.02
0.03
0.04
IWC
(g m
ï�)
0
50
100
150
200
250
Wat
er V
apor
(ppm
v)
Anvil A
B
0 100 200 300 400 500
Water Vapor (ppmv)
0
200
400
600
Ozone (
ppbv)
ï� ï� 0 1 2
Tropopause Relative (km)
0 50 100 150 200
Carbon Monoxide (ppbv)
0
200
400
600
(a) (b)
A
Anvil
B
Tracer-tracer Relationships
Stratosphere
Tropopause Transition Layer
Troposphere
Conclusions • Observed water vapor mixing ratios up to 200
ppmv above LS background levels (5-10 ppmv) at altitudes 1-2 km above the tropopause – Limited by aircraft ceilings; visual evidence of
transport deeper into the LS • All cases of injection during DC3 are observed
during double tropopause events from poleward Rossby wavebreaking – Unique stability background may facilitate deep
overshooting – Largely devoid of inorganic chlorine
Transport Illustration