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Radia%veInfluencesofNaturalVariabilityinTropicalLowerStratosphericWaterVaporandOzoneDanielM.Gilford([email protected])andSusanSolomon
Mo8va8on
January2016
Acknowledgements
DepartmentofEarth,Atmospheric,andPlanetarySciences,MIT
This work was supported by NASA Headquarters under the NASA Earth and Space Science Fellowship
Program - Grant NNX14AK83H. It was also supported by NSF Grant AGS-1342810 and 1461517.
SelectedReferences
Methods
SeasonalCycleResults QBOResults
Conclusions
• Mote,P.W.,andcoauthors,1996.J.Geophy.Res.,101,3989–4006.• Conley,A.J.,J.-F.Lamarque,F.ViW,W.D.Collin,andJ.Kiehl,2013.Geosci.ModelDev.,6,469–476.• Folkins,I.,P.Bernath,C.Boone,G.Lesins,N.Livesey,A.M.Thompson,K.Walker,andJ.C.WiWe,2006.Geophys.Res.LeB.,
33,doi:10.1029/2006GL026602.• FreeUniversityofBerlin,2015.[Availableat:hWp://www.geo.fu-berlin.de/en/met/ag/strat/produkte/qbo/]• Fueglistaler,S.,P.H.Haynes,andP.M.Forster,2011.Atmos.Chem.Phys.,11,3701–3711,doi:10.5194/acp-11-3701-2011.• Gilford,D.M.,S.Solomon,andR.W.Portmann,inpress.J.Climate,doi:10.1175/JCLI-D-15-0167.1.• Livesey,N.J.,andcoauthors,2011.JetPropulsionLaboratory,Pasadena,California.[Availableat:
hWp://mls.jpl.nasa.gov/data/v3-3_data_quality_document.pdf]
1 2 3 4 5 6 7 8 9 10 11 12
12 17 26 38 56 82121177261
Press
ure (
hPa)
Month (Jan−Dec)
−5−4−3−2−1012345
12 17 26 38 56 82121177261
−25
−20
−15
−10
−5
0
5
10
−25−20−15−10−50510152025
12 17 26 38 56 82121177261
Press
ure (
hPa)
1 2 3 4 5 6 7 8 9 10 11 12Month (Jan−Dec)
1 2 3 4 5 6 7 8 9 10 11 12Month (Jan−Dec)
T (K) H2O (%) O3 (%)
0 1 2 3 4 5 6 7 8 9 10 11Lag (months)
O3/QBO β values at each Level/Lag
−1−0.8−0.6−0.4−0.200.20.40.60.81
0 1 2 3 4 5 6 7 8 9 10 11
12 17 26 38 56 82
121177261
Lag (months)
Press
ure (
hPa)
H2O/QBO β values at each Level/Lag
2006 2008 2010 2012
12 17 26 38 56 82121177261
Time
Press
ure (
hPa)
QBO O3 Regression (%)
−10
−5
0
5
10
2006 2008 2010 2012
12 17 26 38 56 82121177261
Time
Press
ure (
hPa)
QBO H2O Tape Recorder (%)
−15
−10
−5
0
5
10
15
1 2 3 4 5 6 7 8 9 10 11 12
23
53
85118163226313
O3 Low QBO Tadj (K)
Hybr
id Sig
ma/P
ressu
re
Month (Jan−Dec)
−0.75−0.6−0.45−0.3−0.1500.150.30.450.60.75
1 2 3 4 5 6 7 8 9 10 11 12
23
53
85118163226313
H2O Low QBO Tadj (K)
Month (Jan−Dec)
−0.15−0.12−0.09−0.06−0.0300.030.060.090.120.15
Hybr
id Sig
ma/P
ressu
re
1 2 3 4 5 6 7 8 9 10 11 12
23
53
85118163226
Ozone Radiative Seasonal Cycle (K), Tadj
Month (Jan−Dec)
−1.25−1−0.75−0.5−0.2500.250.50.7511.25
Hybr
id Sig
ma/P
ressu
re
1 2 3 4 5 6 7 8 9 10 11 12
23
53
85118163226
Water Vapor Radiative Seasonal Cycle (K), Tadj
Month (Jan−Dec)
−0.5−0.4−0.3−0.2−0.100.10.20.30.40.5
Hybr
id Sig
ma/P
ressu
re
Aura Microwave Limb Sounder (MLS), version 3.3 [Livesey et al. 2011] • H2O, O3, and Temperature measurements, over 20S – 20N. • 5° x 5°, 316–0.02 hPa, 39 vertical levels QBO Index: Normalized 50hPa Singapore Winds [Free University of
Berlin 2015]
How do tropical lower stratospheric H2O/O3 seasonal cycles and QBO structures radiatively impact temperatures in the
upper troposphere and lower stratosphere (UTLS)?
Why is this important? • Increase understanding of UTLS radiative controls • Predictability and model representations of variability • Upper tropospheric stability (convection and hurricanes) • Stratospheric H2O important for surface climate and very
sensitive to temperatures • Further applications exploring UTLS trends
Wave-driving and temperatures
vary seasonally and with QBO
Associated vertical structure in H2O and O3
anomalies
Radiative impact on UTLS
temperatures
Parallel Offline Radiative Transfer (PORT) model [Conley et al. 2013] • 10° x 15°, 992–3.5 hPa, 26 Hybrid vertical levels • Seasonally Evolving Fixed Dynamical Heating (SEFDH) assumption,
Q à Heating Rates, T à Temperature, c à Constituents, t à Time: • Tadj = T – Tp à Radiative Temperature Adjustment from Perturbation (p) • One-year simulations with 4 month spin-up time (16 months total)
dTadjdt
=Q(T,c)−Q(Tp,cp )
Data
Model
Runs
MLS Observed Seasonal Cycles:
Temperature Adjustments (Tadj):
Lag Correlations (β) between H2O / O3 and QBO:
QBO-Regressed Anomalies at Optimal Lag:
Associated Tadj:
For the Seasonal Cycle and QBO, we perform the following calculations to test the importance of anomaly vertical structures: • Full runs − Perturbations applied
everywhere above tropopause
• Cutoff runs − Perturbations applied at and below the cutoff pressure level and above the tropopause
Determine H2O and O3
perturbations
Apply perturbations to PORT
background
Run PORT with SEFDH
Analyze resulting Temperature Adjustments
Seasonal Temperature Range (K) H2O Full Structure
O3 Full Structure
H2O Cutoff ~85hPa
O3 Cutoff ~85hPa
H2O Cutoff ~53hPa
O3 Cutoff ~53hPa
85 hPa 0.50* 1.77 0.41* 0.94 0.48* 1.48
118 hPa 0.44 0.51 0.48 0.15 0.44 0.36
Tropopause
• Lower stratosphere: H2O Tadj offset seasonal cycle; O3 Tadj amplify the cycle
• Upper troposphere: H2O and O3 Tadj constructively amplify/positively shift the seasonal cycle
• H2O Tadj ~insensitive to cutoff altitude. Nearly all radiative influences due to local lower stratospheric anomalies
• Lower stratospheric O3 Tadj strongly depends on nonlocal radiative influences. ~46% of 85hPa Tadj and ~66% of 118hPa Tadj due to O3 anomalies above 85hPa
• UTLS Tadj lag H2O / O3 anomalies by 2-3 months
Fig. 1: Example H2O profile to illustrate run methodology
• A “tape recorder” signal is apparent in H2O lag correlations; significant in lower stratosphere
• O3 lag correlations follow QBO signal; significant at higher altitudes
• Structures are consistent with correlations; a “low” QBO period ( ) is selected for radiative runs
• QBO-related Tadj much smaller than seasonal cycle, especially below tropopause
• O3 impacts are strong locally—away from tropopause—inconsistent with weaker H2O signal
Fig. 4: Seasonal cycles of H2O and O3 Tadj on 85, 118hPa hybrid surfaces
Table 1: Seasonal cycle temperature ranges for radiative Tadj. (*) indicates cycle offsets sign of the observed temperature cycle
Fig. 3: Mean tropical seasonal cycles of Tadj for H2O and O3 vs. pressure level. Black dashed curves are the levels analyzed below.
Fig. 2: Mean tropical seasonal cycles of Temperature, H2O and O3 vs. pressure level
Fig. 5: Pearson Correlation coefficients, hatching indicates >90% confidence
Fig. 6: Regression time series at each pressure level’s optimal lag
Fig. 7: Mean tropical QBO signals of Tadj for H2O and O3 vs. pressure level.
1. Stratospheric seasonal cycles of H2O and O3 act to radiatively cool the upper troposphere in the boreal spring, and warm it in the boreal fall
2. Anomalies very close to the tropopause (~85hpa) dominate the H2O radiative signal, with little influence from the overlying structure
3. About half of the O3 radiative influences in the UTLS result from anomalies above the
lowermost stratosphere (p<85hPa)
4. QBO-related H2O anomalies result in UTLS radiative influences smaller than those of the seasonal cycle; O3 influences are larger, but primarily focused at higher altitudes
−40 −30 −20 −10 0 10 20
313846566882
100121146
Anomaly (%)
Press
ure (
hPa)
Full StructureCutoff 82hPaCutoff 56hPa
1 2 3 4 5 6 7 8 9 10 11 12−0.25−0.15−0.050.050.150.250.35
Tadj
(K)
Month (Jan−Dec)
1 2 3 4 5 6 7 8 9 10 11 12−0.75−0.5
−0.250
0.250.5
0.751
1.25
Tadj
(K)
Month (Jan−Dec)
118 hPa (Below Tropopause)
85 hPa (Above Tropopause)
H2O FullO3 FullH2O Cutoff ~85hPaH2O Cutoff ~70hPaH2O Cutoff ~53hPaO3 Cutoff ~85hPaO3 Cutoff ~70hPaO3 Cutoff ~53hPa
H2O FullO3 FullH2O Cutoff ~85hPaH2O Cutoff ~70hPaH2O Cutoff ~53hPaO3 Cutoff ~85hPaO3 Cutoff ~70hPaO3 Cutoff ~53hPa
How do the anomalies at higher levels affect temperatures below?
Tropopause