Stratospheric Temperature Trends in GFDL model runs

• SKYHI

• AM2 --- New model, atmosphere with specified SSTs.

• CM2 --- New model, coupled ocean

• (CM2.1 --- New model, coupled ocean,

finite volume dynamical core)

• SKYHI simulations [see the B-set which employs a more realistic background ozone] global-annual-mean; zonal-annual-mean; zonal-seasonal-mean.

• Fixed SSTs; prognostic clouds based on Manabe-Wetherald scheme.

• Equilibrium simulations for (a) 1979 and (b) 1997. • WMGGs (IPCC, WMO).• Ozone (Randel-Wu trend data).• One calculation with H2O trend estimate (based

on Haigh and co-workers).• Temperature trend (Randel; Austin; Berlin).• B1 (ozone-only); B2 (ozone+WMGGs).• Model stat. sig. based on “unforced” runs.

Ramaswamy and Schwarzkopf (2002)Model’s unforced

variability

Model simulation (trace gas changes)

}Obs.

Ramaswamy and Schwarzkopf (GRL, 2002)

S-R (GRL,2002)

‘filled’ Stat. sig. in

model

• SKYHI simulations….continued

• Transient (“trns”} integrations [1979-1997]; 4-member ensemble.

• Ozone change specified as a linear variable at each grid-box and in each month.

• Results compared with “B1-equilibrium” solution and MSU4.

• Simulations with GFDL AM2 [Anderson et al., 2004]. Top at ~5 mb {lower top and stratos. resolution than SKYHI}.

• Prescribed SSTs [Hurrell, 1981-2000].• Transient 4-member ensemble runs [1981-2000]. • Temporal (3D monthly-means) forcings: WMGGs (IPCC,

WMO); Strat. O3 (Randel); Volcanic (Stenchikov data blended with Sato et al.); Solar (Lean); Trop. aerosol direct effect (sea-salt and dust held fixed; sulfate, black and organic carbon vary with time) and ozone (varies with time) from MOZART2 CTM runs.

• Runs with SSTs-only and with subsets of forcings.• Temperature obs. (Randel; LKS; Austin; Soden).• Trend is difference of the end-year values.

Solar included in wmgg+o3, wmgg+o3+aero.

Solar included in wmgg+o3, wmgg+o3+aero

• Simulations with GFDL CM2 [Delworth et al., 2004]. Same atmosphere as in AM2.

• 1860-2000 simulations.• 3-member ensemble runs [CM2.0]; 4-member

ensemble runs [CM2.1]. • Temporal (3D monthly-means) forcings: WMGGs

(IPCC, WMO); Strat. O3 (Randel); Volcanic (Stenchikov data blended with Sato et al.); Solar (Lean); Trop. aerosol direct effect (sea-salt and dust held fixed; sulfate, black and organic carbon vary with time) and ozone (varies with time) from MOZART2 CTM runs.

• Temperature obs. (Randel; LKS; Austin; Soden).• Trend is difference of the end-year values.

WMGhgO3 = WMGG + StratO3 + TropO3Anthro = WMGhgO3 + Trop. Aerosol

Natural = Solar + volcanic aero.

Global Mean Stratospheric Temperature Trends: Global Mean Stratospheric Temperature Trends: MSU MSU vsvs GFDL GCM (AM2p13)GFDL GCM (AM2p13)

Global Mean Stratospheric Temperature Trends: Global Mean Stratospheric Temperature Trends: MSU MSU vsvs GFDL GCM (CM2p0)GFDL GCM (CM2p0)

Global Mean Stratospheric Temperature Trends: Global Mean Stratospheric Temperature Trends: MSU MSU vsvs GFDL GCM (CM2p1)GFDL GCM (CM2p1)

Contributions from

J. AustinL. HorowitzK.LabitzkeJ. LanzanteJ. LeanV. RamaswamyW. RandelD. SchwarzkopfB. SodenG. Stenchikov