Comparisons of Simulated Radicals and Reservoirs with Observations

1. Comparisons of Simulated Radicals and Reservoirs with Observations Anne Douglass, Peter Connell, Rich Stolarski, Susan Strahan Focus the comparisons on those that provide insight into the forecasts, particularly the differences between them A. Douglass, GMI Irvine

2. Cly - MKIV, HALOE HCl + CLAES ClONO2 (latter courtesy of Andy Dessler) Simulation with FVGCM winds has higher Cly than that with FVDAS winds. Data is “close enough” and simulations are close enough to each other that this does comparison does not discriminate. A. Douglass, GMI Irvine

3. HCl columns from NDSC HCl columns from the two GMI simulations (blue FVGCM; red FVDAS) exhibit the same seasonal behavior as the NDSC data at 46N and at 28 N. In the tropics (19.5N) the seasonal issues in FVDAS appear. The seasonal behavior at Lauder is not as organized as at Jungfrau in either the simulations or the observations. A. Douglass, GMI Irvine

4. HCl columns 1oo - 1 hPa from HALOE Each point is a column calculated from a HALOE profile within the specified latitude range. Neither HALOE nor the simulations show an organized seasonal cycle. The larger column in FVGCM is consistent with higher Cly (and older age of air) in that simulation. A. Douglass, GMI Irvine

5. HCl partial pressure at 46 N from the two GMI Simulations The summer decrease in the HCl column seen in the NDSC data is due to changes in the composition of the middleworld (below 100 hPa). A. Douglass, GMI Irvine

6. ClONO2 Diurnal variation - 40N-50 N 31 hPa 21 hPa 14 hPa 6 hPa 4 hPa 10 hPa ClONO2 agrees better with GMIFVGCM (green) than GMIFVDAS (dark red) in the middle stratosphere. Sunrise drop well simulated in both. Sunset rise not quite right on at lower pressures. A. Douglass, GMI Irvine

7. MLS ClO In the middle latitudes, ClO from GMIFVDAS agrees better with MLS than that from GMIFVGCM. In the tropics, both simulations are too high. A. Douglass, GMI Irvine

8. NOx from sunset HALOE NO + NO2 NOx from GMIFVGCM is lower than that from GMIFVDAS by a few ppbv in the middle latitudes, and falls outside the range of HALOE in the SH. The seasonal behavior is nothing like the data in either simulation. A. Douglass, GMI Irvine

9. NOx from sunset HALOE NO + NO2 (ctd) Simulated NOx is below observations in the SH and in the tropics. NH looks fine. Seasonal character is better here than at 3 hPa. A. Douglass, GMI Irvine

10. GMI total ozone compared with TOMS TOMS - GMIFVGCM is positive most places - also some high latitude “features”; TOMS-GMIFVDAS shows that the simulation is low biased in the tropics (symptom of too much upwelling), and low biased at high latitudes. A. Douglass, GMI Irvine

11. PDF’s of HALOE ozone - Tropics These comparisons show that FOR OZONE the simulations are more similar to each other than you might expect (given the difference sin the radicals). Especially at 10 hPa, agreement with HALOE is good. A. Douglass, GMI Irvine

12. PDF’s of HALOE ozone -45oN summer ozone low in both simulations comp’d with HALOE Simulated annual cycle and variability reflect observations HALOE summer decrease in O3 at 46 hPa far exceeds simulations A. Douglass, GMI Irvine

13. PDF’s of HALOE ozone -45oS The summer most probably value is too low compared to HALOE, making the amplitude of the seasonal cycle too large at 2 hPa. Lower stratosphere shows too little seasonal cycle in both simulations. A. Douglass, GMI Irvine

14. The net chemical loss of ozone GMIFVDAS GMIFVGCM Even though the transport is different, the ozone and the chemical loss of ozone look “the same” in the two simulations A. Douglass, GMI Irvine

15. Losses due to different catalytic cycles 3 hPaGMIFVGCM GMIFVDAS Top two panels are NOX (left) and Clx (right) for each simulation. Obvious that Clx is more important in the GMIFVGCM than in the GMIFVDAS; for NOx the opposite is true. A. Douglass, GMI Irvine

16. Losses due to different catalytic cycles 46 hPaGMIFVGCM GMIFVDAS Losses are more similar in the lower stratosphere; both show an increased importance of NOx processes in the summer high latitudes, but not enough to drive the summer ozone loss observed by HALOE. NOx processes are more important in GMIFVGCM for high latitude summer; HOx processes are more important in GMIFVDAS. The total loss tries to be constant, and neither simulation reproduces the steep summertime fall-off. A. Douglass, GMI Irvine

17. Conclusion • Ozone PDFs comparable to HALOE (similar positive points and deficiencies) • TOMS differences consistent with circulation characteristics • Upper stratospheric NOx differs from HALOE in both simulations; NOx is lower in GMIFVGCM than in GMIFVDAS. • Upper stratospheric ClO from GMIFVDAS is lower than that from GMIFVGCM and looks more like MLS • Total loss similar at 3.4 and 46 hPa • Clx is more important at 3.4 hPa in GMIFVGCM; NOx is more important in GMIFVDAS • NOx is more important at 46 hPa in GMIFVGCM; HOx is more important in GMIFVDAS. • Transport controls these differences - CH4 differences change the partitioning of chlorine reservoirs; NOx transport out of the tropics is insufficient in GMIFVGCM. • Expect different sensitivity to chlorine in the upper stratosphere. A. Douglass, GMI Irvine