IAC ETH, 26 October 2004

Sub-project:

Effects of Solar irradiance variability on the atmosphere(steady-state sensitivity study)

Progress report(final)

Poly Project: “Variability of the Sun and Global Climate”

Goals of the sub-project:

- development of the chemistry-climate model and its validation against available observations

- study of global chemistry and climate response to solar irradiance variability

SOCOL : modeling tool to study SOlar-Climate-Ozone Links

General Circulation component : MA-ECHAM4 (Manzini & McFarlane, 1998)Chemistry/transport component : MEZON (Rozanov et al., 1999, Egorova et al., 2003)

Horizontal grid ~3.75ºx3.75º(T30); 39 levels in vertical; model top at ~80 km

Ported on PC: 10 years of integration takes ~ 40 days of wall-clock time

GCM CTM

•Winds and temperature•H2O (troposphere)

•Ozone•H2O(stratosphere)

40-year long control run for present day conditions:

Monthly SST/SI prescribed from AMIPII (1979-1996)Lower boundary conditions for the source gases : 1995CO2=356 ppmInitial distributions for meteorological quantities are from MA-ECHAM4 and gas mixing ratios

from 8-year SCTM (Rozanov et al., 1999)

Climatological data sets used for model validation.Data source Time period used Upper level UKMO 1992-1999 (8 years) 0.3hPaCPC 1979-1998 (20 years) 1 hPaNCEP 1979-1999 (21 years) 10hPaERA-15 1979-1999 (15 years) 10hPaURAP 1992-1999 (8 years) 0.01hPa

Discrepancies among data sets difficult to conclude about model performanceOne data set has been produced: 64 years, climatology of T and U and standart deviation:

interannual variability and variability due to differences in the data sets.

 

Validation of SOCOL

Difference between simulated and observed climatology

Temperature “hot” spots

Latitude Latitude

Comparison of SOCOL total ozone with observations and other similar models

October, Southern Hemispher ensemble mean

(40-year long run)

OBSERVATIONS UMETRAC UIUC

CCSR/NIES MAECHAM/CHEM ECHAM/CHEM/DLR

SOCOLCMAMULAQ

Austin et al.,2003

Conclusions

• Overall performance of SOCOL is reasonable and many futures of the atmosphere are simulated rather well.

• SOCOL shows good wall-clock performance.

• CCM SOCOL can be used for climate studies

Solar Min

Solar MaxUV+VIS

Solar rotation

Completed experiments of the sensitivity studyCompleted experiments of the sensitivity study

Solar MaxOnly VIS

Solar MaxOnly UV

Experimental designExperimental design

• Prescribed SST/SI, GHG, ODS (mid 90-ies), 20-year long runs

• Two observed by SUSIM (UARS) solar spectral fluxes for maximum and minimum of the solar activity from 1992 to 1998 have been used for photolysis rates, radiation fluxes and heating rates calculations

• Parameterization for the heating rate changes for the solar maximum case due to absorption in Ly-, Schumann-Runge bands, Herzberg continuum, Hartley band (based on Strobel formalism [1978] and detailed radiation code).

Additional heating due to oxygen and ozone absorption has been calculated only for the Solar maximum case as:

HRSMA = HRSMI + HR*SMA

HR*SMA is the parameterized heating rate due to O2 and O3 absorption.

Tropical temperature response (23S-23N averaged)

Black:ensemble averagedtwo 1-year long runs:Red :with UV absorptionBlue :without UV absorption

Solar signal in ozoneSolar signal in ozone

UV +VisibleRed – observationsBlue - simulated

Visible only UV only

Solar signal in ozoneSolar signal in ozone

Solar signal in temperatureSolar signal in temperature

UV +VisibleSOCOL [Egorova et al, 2004]

SSU/MSU [Hood and Soukharev, 2000]

CPC [Hood, 2004]

NCEP [Labitzke, 2002]

MAECHAM/CHEM [Tourpali et al., 2003]

Visible only UV only

Solar signal in temperatureSolar signal in temperature

Solar signal in zonal windSolar signal in zonal wind

UV +Visible Visible only UV only

UV +Visible Visible only UV only

Thomson & Wallace (GRL,1998)

Solar signal in surface air temperatureSolar signal in surface air temperature

Conclusions

1. Introducing of observed solar spectral flux variations into the model produced not only changes in the stratosphere but also changes in the troposphere and near the surface.

2. The obtained solar signal in surface air temperature resembles pattern of positive phase of AO. UV and VIS radiation both play a role in surface air temperature changes due to 11-year solar irradiance variability.

3. Simulated solar signal disagrees with the solar signal derived from satellite measurements.

4. The next step is to understand the mechanisms by which solar-induced circulation anomalies propagate poleward and downward to the troposphere. The crucial idea in current theory is that changes in thermal structure will change the wave-propagation properties in the lower stratosphere.

Motivation:

Why the steady-state run results are not in a reasonably good agreement with “observations”:

- Forcing/response are not right (“bad” models)?

- Experimental set-up is wrong (transient)?

- Short time-series (“bad” observations)?

- Do we have other possibilities to check? – Yes, 27-day cycle.

Experimental set up:

- Solar maximum for 1992,

- nine 1-year long runs

- with prescribed SST/SI, GHG,ODS

- daily SUSIM spectral UV fluxes for 1992

SolarSolar flux variability during 2 flux variability during 277-day-daysolar rotation cycle and atmospheresolar rotation cycle and atmosphere

Sensitivity of tropical ozone to UV changesSensitivity of tropical ozone to UV changes

SBUV

MLS

Ensemble. mean

Sensitivity of tropical T to UV changesSensitivity of tropical T to UV changes

MLS

SAMS

Ensemble mean

ConclusionsConclusions

• nine 1-year long runs with “SOCOL” have been completed

• Ozone sensitivity is robust and in reasonable agreement with observations

• Temperature sensitivity is not robust and deviates from the observations

• We need more data and quantities to compare with observations (HALOE, ENVISAT?)

General conclusions

• Goals of the sub-project are fulfilled: the model has been developed and experiments have been performed and analyzed.

• UV does play a role in surface air temperature.

• Analysis of the solar signal in several source gases, reservoirs and radicals (H2O, CH4, N2O, HCl, F12, HNO3, OH, HO2, ClO, NO2) has been performed and revealed agreement with theoretical expectations. Analysis of the solar signal for some species has no precedents.

• The solar signal extracted from the transient runs might be different from the steady-state and closer to the observations.

• Papers: - published in GRL: analysis of annual mean solar signal; - several papers in preparation (validation, chemical analysis, extended

analysis of the steady-state runs and 27-day rotation cycle).

End of the presentation