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 H 2 O (troposphere) Ozone H 2 O(stratosphere)

40-year long control run for present day conditions: Monthly SST/SI prescribed from AMIPII ( ) Lower boundary conditions for the source gases : 1995 CO2=356 ppm Initial distributions for meteorological quantities are from MA-ECHAM4 and gas mixing ratios from 8-year SCTM (Rozanov et al., 1999) C limatological data sets used for model validation. Data source Time period used Upper level UKMO (8 years) 0.3hPa CPC (20 years) 1 hPa NCEP (21 years) 10hPa ERA (15 years) 10hPa URAP (8 years) 0.01hPa Discrepancies among data sets  difficult to conclude about model performance One 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

Comparison of SOCOL total ozone with observations and other similar models October, Southern Hemispher ensemble mean (40-year long run) OBSERVATIONSUMETRACUIUC CCSR/NIESMAECHAM/CHEMECHAM/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 Max UV+VIS Solar rotation Completed experiments of the sensitivity study Solar Max Only VIS Solar Max Only UV

Experimental 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: HR SMA = HR SMI + HR * SMA HR * SMA is the parameterized heating rate due to O 2 and O 3 absorption.

Tropical temperature response (23S-23N averaged) Black:ensemble averaged two 1-year long runs: Red :with UV absorption Blue :without UV absorption

Solar signal in ozone UV +Visible Red – observations Blue - simulated

Visible onlyUV only Solar signal in ozone

Solar signal in temperature UV +Visible SOCOL [Egorova et al, 2004] SSU/MSU [Hood and Soukharev, 2000] CPC [Hood, 2004] NCEP [Labitzke, 2002] MAECHAM/CHEM [Tourpali et al., 2003]

Visible onlyUV only Solar signal in temperature

Solar signal in zonal wind UV +VisibleVisible onlyUV only

UV +Visible Visible onlyUV only Thomson & Wallace (GRL,1998) Solar 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 Solar flux variability during 27-day solar rotation cycle and atmosphere

Sensitivity of tropical ozone to UV changes SBUV MLS Ensemble. mean

Sensitivity of tropical T to UV changes MLS SAMS Ensemble mean

Conclusions 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 (H 2 O, CH 4, N 2 O, HCl, F12, HNO 3, OH, HO 2, ClO, NO 2 ) 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