ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-8-7519-2008 Parameterization of middle atmospheric water vapor photochemistry for high-altitude NWP and data assimilation McCormack J. P. 1 Hoppel K. W. 2 Siskind D. E. 1 Space Science Division, Naval Research Laboratory, Washington DC, USA Remote Sensing Division, Naval Research Laboratory, Washington DC, USA 16 12 2008 8 24 7519 7532 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/8/7519/2008/acp-8-7519-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/7519/2008/acp-8-7519-2008.pdf

This paper describes CHEM2D-H2O, a new parameterization of H<sub>2</sub>O photochemical production and loss based on the CHEM2D photochemical-transport model of the middle atmosphere. This parameterization accounts for the altitude, latitude, and seasonal variations in the photochemical sources and sinks of water vapor over the pressure region from 100–0.001 hPa (~16–90 km altitude). A series of free-running NOGAPS-ALPHA forecast model simulations offers a preliminary assessment of CHEM2D-H2O performance over the June 2007 period. Results indicate that the CHEM2D-H2O parameterization improves global 10-day forecasts of upper mesospheric water vapor compared to forecasts using an existing one-dimensional (altitude only) parameterization. Most of the improvement is seen at high winter latitudes where the one-dimensional parameterization specifies photolytic H<sub>2</sub>O loss year round despite the lack of sunlight in winter. The new CHEM2D-H2O parameterization should provide a better representation of the downwelling of dry mesospheric air into the stratospheric polar vortex in operational analyses that do not assimilate middle atmospheric H<sub>2</sub>O measurements.

 References Brasseur, G. and Solomon, S.: Aeronomy of the Middle Atmosphere, 2nd ed., D. Reidel, Norwell, MA, USA, 452 pp., 1986. Cariolle, D. M. and Dèqué: Southern hemisphere medium-scale waves and total ozone disturbances in a spectral general circulation model, J. Geophys. Res., 91, 10 825–10 846, 1986. Coy, L., Allen, D. R., Eckermann, S. D., McCormack, J. P., Stajner, I., and Hogan, T. F.: Effects of model chemistry and data biases on stratospheric ozone assimilation, Atmos. Chem. Phys., 7, 2917–2935, 2007. Eckermann, S. D., Hoppel, K. W., Coy, L., McCormack, J. P., Siskind, D. E., Nielsen, K., Kochenash, A., Stevens, M. H., and Englert, C. R.: High-altitude data assimilation system experiments for the Northern Hemisphere summer mesosphere season of 2007, J. Atmos. Sol. Terr. Phys., doi:10.1016/j.jastp.2008.09.036, in press, 2008. European Center for Medium-Range Weather Forecasts Integrated Forecast System Documentation Cy31r1, Part IV: Physical Processes, online available at: stylesamehttp://www.ecmwf.int/research/ifsdocs/CY31r1/PHYSICS/IFSPart4.pdf, 2007. Feist, D. G., Geer, A. J., Müller, S., and Kämpfer, N.: Middle atmosphere water vapour and dynamical features in aircraft measurements and ECMWF analyses, Atmos. Chem. Phys., 7, 5291–5307, 2007. Froidevaux, L., Livesey, N. J., Read, W. G., Jiang, Y. B., Jimenez, C., et al.: Early validation analyses of atmospheric profiles from EOS MLS on the Aura satellite, IEEE T. Geosci. Remote Sens., 44, 1106–1121, 2006. Garcia, R. R., Marsh, D. R., Kinnison, D. E., Sassi, F., and Boville, B. A.: Simulation of secular trends in the middle atmosphere, J. Geophys. Res., 112, D09301, doi:10.1029/2006JD007485, 2007. Geer, A. J., Lahoz, W. A., Jackson, D. R., Cariolle, D., and McCormack, J. P.: Evaluation of linear ozone photochemistry parametrizations in a stratosphere-troposphere data assimilation system, Atmos. Chem. Phys., 7, 939–959, 2007. Grooß, J.-U. and Russell, J. M.: Technical note: A stratospheric climatology for O<sub>3</sub>, H<sub>2</sub>O, CH<sub>4</sub>, NO$_x$, HCl and HF derived from HALOE measurements, Atmos. Chem. Phys., 5, 2792–8207, 2005. Harich, S. A., Hwang, D. W. H., Yang, X., Lin, J. J., Yang, X., and Dixon, R. N.: Photodissociation of H2O at 121.6 nm: A state-to-state dynamical picture, J. Chem. Phys., 113, 22, 2000. Hogan, T. and Rosmond, T.: The description of the Navy Operational Global Atmospheric Prediction System's spectral forecast model, Mon. Wea. Rev., 119, 1186–1815, 1991. Hoppel, K. W., Baker, N. L., Coy, L., Eckermann, S. D., McCormack, J. P., Nedoluha, G., and Siskind, D. E.: Assimilation of stratospheric and mesospheric temperatures from MLS and SABER into a global NWP model, Atmos. Chem. Phys., 8, 6103–6116, 2008. Kutepov A. A., Feofilov, A. G., Marshall, B. T., Gordley, L. L., Pesnell,W. D., Goldberg, R. A., and Russell, J. M.:, SABER temperature observations in the summer polar mesosphere and lower thermosphere: Importance of accounting for the CO<sub>2</sub> $\nu_2$ quanta V-V exchange, Geophys. Res. Lett., 33, L21809, doi:10.1029/2006GL026591, 2006. Lambert, A., Read, W. G., Livesey, N. J., Santee, M. L., Manney, G. L., et al.: Validation of the Aura Microwave Limb Sounder middle atmospheric water vapor and nitrous oxide measurements, J. Geophys. Res., 112, D24S36, doi:10.1029/2007JD008724, 2007. Lahoz, W. A., Errera, Q., Swinbank, R., and Fonteyn, D.: Data assimilation of stratospheric constituents: A review, Atmos. Chem. Phys., 7, 5745–5773, 2007. Lean, J., Rottman, G., Kyle, H., Woods, T., Hickey, J., and Puga, L.: Detection and parameterization of variations in solar mid- and near-ultraviolet radiation (200–400 nm): J. Geophys. Res., 102, 29 939–29 956, 1997. Lewis, B. R., Vardava, I. M., and Carver, J. H.: The aeronomic dissociation of water vapor by solar H Lyman a radiation, J. Geophys. Res., 88, A6, 4935–4940, 1983. LeTexier, H., Solomon, S., and Garcia, R. R.: the role of molecular hydrogen and methane oxidation in the water vapour budget of the stratosphere, Q. J. R. Meteorol. Soc., 114, 281–295, 1988. MacKenzie, I. A. and Harwood, R. S.: Middle atmospheric response to a future increase in humidity arising from increased methane abundance, J. Geophys. Res., 109, D02107, doi:10.1029/2003JD003590, 2004. McCormack, J. P., Eckermann, S. D., Coy, L., et al.: NOGAPS-ALPHA model simulations of stratospheric ozone during the SOLVE2 campaign, Atmos. Chem. Phys., 4, 2401–2423, 2004. McCormack, J. P., S. D. Eckermann, D. E. Siskind, and T. J. McGee, CHEM2D-OPP: A new linearized gas-phase ozone photochemistry parameterization for high-altitude NWP and climate models, Atmos. Chem. Phys., 6, 4943–4972, 2006. McCormack, J. P., Siskind, D. E., and Hood, L. L.: Solar-QBO interaction and its impact on stratospheric ozone in a zonally averaged photochemical transport model of the middle atmosphere, J. Geophys. Res., 112, D16109, doi:10.1029/2006JD008369, 2007. Minschwaner, K., Salawitch, R. J., and McElroy, M. B.: Absorption of solar radiation by O<sub>2</sub>: Implications for O<sub>3</sub> and lifetimes of N<sub>2</sub>O, CFCCl3, and CF2Cl2, J. Geophys. Res., 98, 10 543–10 561, 1993. Nedoluha, G., Bevilacqua, R., Gomez, R., Siskind, D., Hicks, B., Russell, J., and Connor, B., Increases in middle atmospheric water vapor as observed by the Halogen Occultation Experiment and the ground-based Water Vapor Millimeter-wave Spectrometer from 1991-1997, J. Geophys. Res., 103, D3, 3531–3543, 1998. Peng, M. S., Ridout, J. A., and Hogan, T. F.: Recent modifications of the Emanuel convective scheme in the Navy Operational Global Atmospheric Prediction System, Mon. Weather Rev., 132, 1254–1268, 2004. Randel, W. J., Wu, F., Russel, J. M., Roche, A., and Waters, J. W.: Seasonal cycles and QBO variations in stratospheric CH<sub>4</sub> and H<sub>2</sub>O observed in UARS HALOE data, J. Atmos. Sci., 55, 163–185, 1998. Randel, W. J., Wu, F., Russell, J. M., and Waters, J.: Space-time patterns of trends in stratospheric constituents derived from UARS measurements, J. Geophys. Res., 104, D3, 3711–3727, 1999. Sander, S. P., Friedl, R. R., Ravishankara, A. R., et al.: Chemical kinetics and photochemical data for use in atmospheric studies, Evaluation No. 14, Jet Propulsion Laboratory, Pasadena, CA, USA, 334 pp., 2003. Siskind, D. E., Eckermann, S. D., McCormack, J. P., et al.: Hemispheric differences in the temperature of the summertime stratosphere and mesosphere, J. Geophys. Res., 108(D2), 4051, doi:10.1029/2002JD002095, 2003. Siskind, D. E., Minschwaner, K., and Eckman, R. S.: Photodissociation of O2 and H2O in the middle atmosphere: Comparison of numerical methods and impact on model O<sub>3</sub> and OH, Geophys. Res. Lett., 21(10), 863–866, 1994. Slingo, J. M.: The development and verification of a cloud prediction scheme in the ECMWF model, Q. J. R. Meteorol. Soc., 113, 899–927, 1987. Stief, L., J., Payne, W. A., and Klemm, R. B.: A flash photolysis-resonance fluorescence study of the formation of O(1D) in the photolysis of water and the reaction of O(1D) with H2, Ar, and He, J. Chem. Phys., 62(10), 4000–4008, 1975. Summers, M. E., Siskind, D. E., Bacmeister, J. T., Conway, R. R., Zasadil, S. E., and Strobel, D. F.: Seasonal variation of middle atmospheric CH<sub>4</sub> and H<sub>2</sub>O with a new chemical-dynamical model, J. Geophys. Res., 102, 3503–3526, 1997. Teixeira, J. and Hogan, T.:, Boundary layer clouds in a global atmospheric model: Simple cloud cover parameterization, J. Climate, 15, 1261–1276, 2002. Tiedtke, M.: The sensitivity of the time-scale flow to cumulus convection in the ECMWF model, Proceedings from the Workshop on Large-Scale Numerical Models, European Centre for Medium-Range Weather Forecasts, Reading, UK, 28 November–1 December 1983, 297–316, 1984. Untch, A. and Simmons, A. J.: Increased stratospheric resolution in the ECMWF forecasting system, ECMWF Newsletter No. 82, online available at: stylesamehttp://www.ecmwf.int/publications/newsletters/pdf/82.pdf, 1999.