Upper Tropospheric Ozone and Relative Humidity with respect to Ice: Seasonal Inter-comparison between GEOS CCM, MOZAIC and MLS Richard Damoah 1, H. B. Selkirk 1, Q. Liang 1, M. Manyin 2, L. Oman 3, L. Ott 3, A. R. Douglass 3, S. Pawson 3, and R. Stolarski 4 1 Universities Space Research Association (GESTAR/NASA), Greenbelt MD 2 System Science and Applications, Inc. Lanham, MD 3 NASA Goddard Space Flight Center, Greenbelt, MD 4 Johns Hopkins University, Baltimore, MD Scatter plot of MLS ozone versus the model’s ozone at 147 hPa for the MLS and 150 hPa level for the model in northern mid- latitude (30N-60N). Similarly, the red shows the scatter for January while black shows that for July. Here the points are compact even at 600 ppbv. Overall, the model predicts higher ozone in both seasons compared with the MLS with July (black) showing a slight better agreement than January (red). Global distribution of MLS ozone climatology and GEOS CCM ozone output. The upper row show the MLS distribution at 147 hPa. The second row show that for the model at 150 hPa and the bottom row showing the absolute difference between them. The left column is for January and right July. There is fairly good agreement between the MLS and the model especially in January. The model over estimates the ozone of more than 300 ppbv at northern high latitudes. MOZAIC (upper row) and GEOS CCM (middle row) ozone at 250 hPa. The bottom row shows the absolute difference between the model and the observation. Left panel show January comparison while right panel show that for July. The model shows a reasonable agreement (+ and – 70 ppbv) with MOZAIC especially in January. At high northern latitudes in July the model over estimates the ozone up to about 200 ppbv. Model and MOZAIC relative humidity with respect to ice at 250 hPa. The model has been sampled to spatially coincide with MOZAIC locations. January and July distributions are shown in the left and right panels, respectively. Again the best agreement between the model and MOZIAC with respective to relative humidity ice is seen in January. The model shows over estimation at high latitudes up to about 50% with various patches of negative values within the region. MLS relative humidity ice (147 hPa) versus the model’s relative ice (150 hPa) in northern mid-latitude (30N-60N). Again MLS with the model show a compact distribution and close to the one to one line than shown in the MOZAIC versus the model above. MOZAIC AND MLS We have used 15 years of observational data set from the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOAZIC) to test the model’s predictability of upper tropospheric ozone and relative humidity with respect to ice. We also constructed 6 years seasonal climatology of ozone and relative humidity derived from the Microwave Limb Sounder (MLS) measurements for comparison with the model output. MODEL The Goddard Earth Observing System Chemistry Climate Model (GEOS CCM ) was used to simulate 16 years of ensemble runs in sequence using 2005 trace-gas emissions and historical SSTs. Simulations with (perturbed) and without (control) aircraft emissions were initiated. The perturbed run used AEDT 2006 aircraft emissions. For the purpose of this poster, we have compared the seasonal climatology of upper tropospheric ozone and relative humidity with respect to ice derived from the perturbed simulations, with observational data. Scatter plot of MOZAIC ozone versus the model’s ozone at 250 hPa level. Red shows the scatter for January while black shows that for July. In both seasons MOAZIC and the model show a compact distribution up to about 150 ppbv, and a distribution over wide region at values greater than 150 ppbv. MOZAIC relative humidity with respect to ice versus relative humidity ice predicted by the model at 250 hPa. Blue and black points show January and July distributions, respectively. The points show a spread over wide area. Relative humidity with respect to ice from MLS and the model. Left and right columns show January and July distributions, respectively. The upper row show the MLS RHI at147 hPa and middle row the model’s RHI at 150 hPa. The bottom row show the absolute difference between. Qualitatively, the model’s distribution agrees fairly well with the MLS distributions especially in January. The CCM predicts higher values in the tropics up to 60%. However, for July in the southern polar region the model underestimate the relative humidity ice more than 80% compared with the MLS. CONCLUSION We have compared a seasonal climatology of upper tropospheric ozone and relative humidity with respect to ice derived from 16 years of ensemble simulations with the Goddard Earth Observing System Chemistry Climate Model (GEOS CCM), 6 years of observations from the Aura’s Microwave Limb Sounder (MLS) and a 15-year data set from the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOAZIC) project. The model showed fairly good agreement with the observations especially in the January season. Difference between the model (over estimates) and MOZAIC ranges between +70 and -70 ppbv in January and +250 to - 70 ppbv in July for ozone. With MLS at 147 hPa level the difference is between and – 50 ppbv in January and between +300 and – 50 ppbv in July. The model over estimates the RHI up to 60% in the tropics, however, in parts of the Antarctic region the MLS over estimates the RHI more than 80%.