Presentation on theme: "Institut für Atmosphäre und Umwelt Andreas Engel Institut für Atmosphäre und Umwelt J.W. Gotehe Universität Frankfurt Mean age as a diagnostic of stratospheric."— Presentation transcript:
Institut für Atmosphäre und Umwelt Andreas Engel Institut für Atmosphäre und Umwelt J.W. Gotehe Universität Frankfurt Mean age as a diagnostic of stratospheric transport Determination of mean age Mean age trends – model and measurement TTL and stratospheric Halogen budget, incl. Br from VSLS Possible contributions Variability and long term change in atmospheric transport time scales and the halogen budget
Stratosphärische (Ballon) und troposphärische SF 6 Messungen:Bestimmung des mittleren Alters Bei linearem Anstieg:
Institut für Atmosphäre und Umwelt Vertical profiles of CO 2 derived mean age for mid latitudes. For the trend analysis only data above the 30 hPa level (shown by the red line) are used. Data obtained since 1995 which have a higher precision are shown as large bold symbols. Vertical profiles of CO 2 derived mean age for high latitudes. For the trend analysis only data above the 80 hPa level (shown by the blue line) are used. Data obtained since1995 which have a higher precision are shown as large bold symbols. Vertical profiles of mean age derived from CO 2 observations
Institut für Atmosphäre und Umwelt Figure 3: Correlation between CO2 derived mean age and normalized methane. For the trend analysis only data with normalised CH4 levels below 0.7 (shown by the green line) are used. High latitude data are shown in blue, mid latitude data in red. Data obtained since 1995 which have a higher precision are shown as large bold symbols.
Institut für Atmosphäre und Umwelt Temporal evolution of mean age derived from CO 2 observations. The data have been filtered based on the pressure criterium (above 30 hPa for mid latitudes, above 80 hPa for high latitudes). The systematic error is included at 1.0 years prior to 1990 and 0.3 years since 1990. Linear regression yields a slope of - 0.016 (+/- 0.018) years of mean age per year. The small symbols show the individual observations, color coded based on their distance relative to the selection criterium. Temporal evolution of mean age above 30/80 hpa at mid and high latitudes from balloon-borne observations
Institut für Atmosphäre und Umwelt Model calculation of mean age Austin et al., JGR, in press, 2006
Institut für Atmosphäre und Umwelt Model set up in Austin et al., 2006 Austin et al., JGR, in press, 2006
Institut für Atmosphäre und Umwelt VSLS species in the tropopause region New GC/MS system set up in late 2005 Measurable VSLS include: CHBr 3, CH 2 Br 2, CH 2 Br 2, CH 3 I, CH 2 Cl 2, CHCl 3, C 2 H 5 Cl, CH 2 ClCH 2 Cl, C 2 Cl 4, C 2 HCl 3. Measurements of VSLS species in TTL and lower tropical stratosphere performed in 2005 (2 balloon flights) Mid latitude Flight in October 2006 with measurements of VSLS; new sampler shows good sample stability. Next flight planned in October 2007 in Teresina 5°S, Brazil). In-situ GC/MS measurements planned for HALO missions in 2009/2010.
Institut für Atmosphäre und Umwelt Tropical bromine budget – June 2005, prel. Some things we do and do not understand Total Br measured in the TTL is about 17 ppt, incl. Contributions from 4 Halons, CH 3 Br, CH 2 Br 2, CH 2 BrCl, CHCl 2 Br. There was no Bromoform up there, but even traces (about 0.1 ppt) of CH 3 I (which is shorter lived) Br y derived from BrO measurements is about 21 ppt What brings the extra Br up there (if not Bromoform)??
Institut für Atmosphäre und Umwelt Possible contributions to G-Sparc Age is the best possible diagnostic of the strength of the Brewer- Dobson circulation. Changes in the Brewer Dobson circulation are of prime interest, as they are a direct effect of climate change. Regular mean age observations in the stratosphere up to 30 km are needed in order to assess if such a change is occuring. Organic Halogen budget can be measured simultaneously. Satellite observations (MIPAS-ENV) have improved very much lately. Regular geophysical validation is needed in order to ensure the data quality. Averaging is needed in order to derive mean age. Balloon-borne spot observations are still the only reliable way of getting mean age and Halogen budget information above 20 km. Continuation proposal for CAWSES submitted; should allow funding of mean age activities until mid 2009 (if granted). Activity would fit very well in SPARC, co-operation with modellers needed.
Institut für Atmosphäre und Umwelt Possible contributions to G-Sparc One profile observation per year should – due to the high precision - be sufficient to get a picture of long term mean age and halogen evolution. Global variability, seasonal effects etc. are better covered by satellite data (allthough it is not clear yet, if MIPAS can measure SF 6 in the reduced resolution mode). CO 2 with the neccesary precision and accuracy is not possible from space yet. Mini-sampler with 26 sample bottles has been develloped and tested at our institute. Total payload weight 100 kg. Can be flown with rather small balloons, which can be launched quite easily. Measurements of age tracers and complete halogen budgets possible, incl. VSLS. Develop chemical ionisation GC/MS method for selective bromine screening method, to get better detection limits (below 0.1 ppt, compared to about 0.2- 0.5 ppt now) and to allow measurements of mixed bromo-chlorocarbons.
Institut für Atmosphäre und Umwelt Proposal and discussion Proposal: –maintain data base of stratospheric age tracer measurements (incl. Satellite data and other observations); maintain tropospheric reference time series; update time series with a flight on a yearly basis; provide time series to global modellers. –Maintain and improve data base on halogen budget, including VSLS species, improve analytical system. Suggestion for Discussion: –Prepare a HALO mission with emphasis on transport into and in the TTL and the chemical budget of the TTL??? Such a mission could be done in 2010 or 2011. Funding of flight hours from DFG HALO budget possible. Co-ordination with one or 2 balloon flights for information on altitude above 15 km and MIPAS/Sciamachy satellite observations?
Institut für Atmosphäre und Umwelt Required measurements for TTL mission Age tracers CO 2, SF 6, CF 4, C 2 F 6 … Water vapour Ozone Long lived tracers (N 2 O, CH 4 ).. Short lived tracers (Acetone, VSLS etc.) Inorganic Br and Cl species, incl. what could be on aerosols (PGI!) Aersols, incl. their chemical composition (PGI) NO x, NO y, HCl Red: could be measured from balloon also