The Circulation Response to Resolved Versus Parametrized Orographic Drag Over Complex Mountain Terrains

Abstract

The accuracy with which parametrizations of orographic blocking and orographic gravity wave drag (OGWD) are able to reproduce the explicitly resolved impacts on flow over complex terrain is investigated in two models: the Met Office Unified Model (MetUM) and the European Centre for Medium-Range Weather Forecasts Integrated Forecasting System (ECMWF IFS). To this end, global and limited area short-range forecast experiments across a range of horizontal resolutions, and their model errors relative to analyses, are assessed over two complex mountainous regions: the Himalayas and the Middle East. The impact of resolved orography on the circulation is deduced by taking the difference between high-resolution experiments with a high (4 to 9 km) and low-resolution (125 to 150 km) orography. This is then compared with the impact of parametrized orographic drag, deduced from global low-resolution experiments with and without parametrized orographic drag. At resolutions ranging from tens to hundreds of kilometres, both the MetUM and ECMWF IFS exhibit too strong zonal winds relative to analyses in the lower stratosphere in the region of maximum resolved orographic gravity wave breaking, indicative of some deficiency in the parametrization of OGWD. Diagnosis of the parametrized physics and resolved dynamics tendencies across a range of OGWD parameter values reveal that this error is partly due to the manner in which the resolved dynamics interacts with the parametrized OGWD. This work introduces a method for quantifying the impacts of resolved versus parametrized orographic drag in models and highlights the importance of physics-dynamics interactions.

References Beljaars, A. C. M., Brown, A. R., & Wood, N. (2004). A new parametrization of turbulent orographic form drag. Quarterly Journal of the Royal Meteorological Society, 130(599), 1327–1347. https://doi.org/10.1256/qj.03.73 Bougeault, P., Benech, B., Bessemoulin, P., Carissimo, B., Clar, A. J., Pelon, J., Petitdidier, M., Richard, E., Bougeault, P., Benech, B., Bessemoulin, P., Carissimo, B., Clar, A. J., Pelon, J., Petitdidier, M., Richard, E. (1997). PYREX: A summary of findings. Bulletin of the American Meteorological Society, 78(4), 637–650. https://doi.org/10.1175/1520-0477(1997)078<0637:PASOF>2.0.CO;2 Boyer, D. L., & Davies, P. A. (2000). Laboratory studies of orographic effects in rotating and stratified flows. Annual Review of Fluid Mechanics, 32(1), 165–202. https://doi.org/10.1146/annurev.fluid.32.1.165 Carissimo, B. C., Pierrehumbert, R. T., & Pham, H. L. (1988). An estimate of mountain drag during ALPEX for comparison with numerical models. Journal of the Atmospheric Sciences, 45(13), 1949–1960. https://doi.org/10.1175/1520-0469(1988)045<1949:AEOMDD>2.0.CO;2 Charney, J. G., & Eliassen, A. (1949). A numerical nethod for predicting the perturbations of the middle latitude westerlies. Tellus, 1(2), 38–54. https://doi.org/10.3402/tellusa.v1i2.8500 Chen, C.-C., Hakim, G. J., & Durran, D. R. (2007). Transient mountain waves and their interaction with large scales. Journal of the Atmospheric Sciences, 64(7), 2378–2400. https://doi.org/10.1175/JAS3972.1 Clayton, A. M., Lorenc, A. C., & Barker, D. M. (2013). Operational implementation of a hybrid ensemble/4d-var global data assimilation system at the met office. Quarterly Journal of the Royal Meteorological Society, 139(675), 1445–1461. https://doi.org/10.1002/qj.2054 Cohen, N. Y., Gerber, E. P., & Bühler, O. (2013). Compensation between resolved and unresolved wave driving in the stratosphere: Implications for downward control. Journal of the Atmospheric Sciences, 70(12), 3780–3798. https://doi.org/10.1175/JAS-D-12-0346.1 Denis, B., Laprise, R., Caya, D., & Côté, J. (2002). Downscaling ability of one-way nested regional climate models: The big-brother experiment. Climate Dynamics, 18(8), 627–646. https://doi.org/10.1007/s00382-001-0201-0 ECMWF (2017a). Part III: Dynamics and numerical procedures, IFS Documentation (pp. 1–31). England: ECMWF. ECMWF (2017b). Part II: Data assimilation, IFS Documentation (pp. 1–103). England:ECMWF. ECMWF (2017c). Part IV: Physical processes, IFS Documentation (176 pp.). England: ECMWF. Elvidge, A. D., Vosper, S. B., Wells, H., Cheung, J. C. H., Derbyshire, S. H., & Turp, D. (2017). Moving towards a waveresolved approach to forecasting mountain wave induced clear air turbulence. Meteorological Applications, 24, 540–550. Georgelin, M., Bougeault, P., Black, T., Brzovic, N., Buzzi, A., Calvo, J., Casse, V., Desgagné, M., El-Khatib, R., Geleyn, J.-F. (2000). The second COMPARE exercise: A model intercomparison using a case of a typical mesoscale orographic flow, the PYREX IOP3. Quarterly Journal of the Royal Meteorological Society, 126(564), 991–1029. Hastings, D. A., & Dunbar, P. K. (1998). Development and assessment of the global land one-km base elevation digital elevation model (globe). ISPRS Archives, 32(4), 218–221. Jackson, D. R., Gadian, A., Hindley, N. P., Hoffmann, L., Hughes, J., King, J., Moffat-Griffin, T., Moss, A. C., Ross, A. N., Vosper, S. B., Wright, C. J., Mitchell, N. J.(2017). The South Georgia Wave Experiment (SG-WEX)—A means for improved analysis of gravity waves and low-level wind impacts generated from mountainous islands. Bulletin of the American Meteorological Society, 99, 1027–1040. https://doi.org/10.1175/BAMS-D-16-0151.1 Kim, Y.-J., & Arakawa, A. (1995). Improvement of orographic gravity wave parameterization using a mesoscale gravity wave model. Journal of the Atmospheric Sciences, 52(11), 1875–1902. https://doi.org/10.1175/1520-0469(1995)052<1875:IOOGWP>2.0.CO;2 Lott, F., & Miller, M. J. (1997). A new subgrid-scale orographic drag parametrization: Its formulation and testing. Quarterly Journal of the Royal Meteorological Society, 123(537), 101–127. https://doi.org/10.1002/qj.49712353704 Malardel, S., Wedi, N., Deconinck, W., Diamantakis, M., Kuehnlein, C., Mozdzynski, G., Hamrud, M., Smolarkiewicz, P. (2016). A new grid for the ifs. ECMWF Newsletter, 146, 23–28. https://doi.org/10.21957/zwdu9u5i McFarlane, N. A. (1987). The effect of orographically excited gravity wave drag on the general circulation of the lower stratosphere and troposphere. Journal of Atmospheric Science, 44, 1775–1800. https://doi.org/10.1175/1520-0469(1987)044<1775:TEOOEG>2.0.CO;2 McLandress, C., & McFarlane, N. A. (1993). Interactions between orographic gravity wave drag and forced stationary planetary waves in the winter northern hemisphere middle atmosphere. Journal of the Atmospheric Sciences, 50(13), 1966–1990. https://doi.org/10.1175/1520-0469(1993)050<1966:IBOGWD>2.0.CO;2 Palmer, T. N., Shutts, G. J., & Swinbank, R. (1986). Alleviation of a systematic westerly bias in general circulation and numerical weather prediction models through an orographic gravity wave drag parametrization. Quarterly Journal of the Royal Meteorological Society, 112(474), 1001–1039. https://doi.org/10.1002/qj.49711247406 Phillips, D. S. (1984). Analytical surface pressure and drag for linear hydrostatic flow over three-dimensional elliptical mountains. Journal of the Atmospheric Sciences, 41(6), 1073–1084. https://doi.org/10.1175/1520-0469(1984)041<1073:ASPADF>2.0.CO;2 Pithan, F., Shepherd, T. G., Zappa, G., & Sandu, I. (2016). Climate model biases in jet streams, blocking and storm tracks resulting from missing orographic drag. Geophysical Research Letters, 43, 7231–7240. https://doi.org/10.1002/2016GL069551 Rossby, C.-G. (1939). Relation between variations in the intensity of the zonal circulation of the atmosphere and the displacements of the semi-permanent centers of action. Journal of Marine Research, 2(1), 38–55. https://doi.org/10.1357/002224039806649023 Sandu, I., Bechtold, P., Beljaars, A., Bozzo, A., Pithan, F., Shepherd, T. G., & Zadra, A. (2016). Impacts of parameterized orographic drag on the northern hemisphere winter circulation. Journal of Advances in Modeling Earth Systems, 8, 196–211. https://doi.org/10.1002/2015MS000564 Smith, R. B. (1980). Linear theory of stratified hydrostatic flow past an isolated mountain. Tellus, 32(4), 348–364. https://doi.org/10.1111/j.2153-3490.1980.tb00962.x Stein, J. (1992). Investigation of the regime diagram of hydrostatic flow over a mountain with a primitive equation model. Part I: Two-dimensional flows. Monthly Weather Review, 120(12), 2962–2976. https://doi.org/10.1175/1520-0493(1992)120<2962:IOTRDO>2.0.CO;2 Teixeira, M. A. C. (2014). The physics of orographic gravity wave drag. Frontiers in Physics, 2(July), 1–24. https://doi.org/10.3389/fphy.2014.00043 Tibaldi, S. (1986). Envelope orography and maintenance of the quasi-stationary circulation in the ECMWF global models. Advances in Geophysics, 29, 339–374. https://doi.org/10.1016/S0065-2687(08)60045-X van Niekerk, A., Scinocca, J. F., & Shepherd, T. G. (2017). The modulation of stationary waves, and their response to climate change, by parameterized orographic drag. Journal of the Atmospheric Sciences, 74(8), 2557–2574. https://doi.org/10.1175/JAS-D-17-0085.1 van Niekerk, A., Shepherd, T. G., Vosper, S. B., & Webster, S. (2016). Sensitivity of resolved and parametrized surface drag to changes in resolution and parametrization. Quarterly Journal of the Royal Meteorological Society, 142(699), 2300–2313. https://doi.org/10.1002/qj.2821 van Zyl, J. J. (2001). The shuttle radar topography mission (srtm): A breakthrough in remote sensing of topography. Acta Astronautica, 48(5), 559–565. https://doi.org/10.1016/S0094-5765(01)00020-0 Vosper, S. B. (2015). Mountain waves and wakes generated by South Georgia: Implications for drag parametrization. Quarterly Journal of the Royal Meteorological Society, 141(692), 2813–2827. https://doi.org/10.1002/qj.2566 Vosper, S. B., Brown, A. R., & Webster, S. (2016). Orographic drag on islands in the NWP mountain grey zone. Quarterly Journal of the Royal Meteorological Society, 142, 3128–3137. https://doi.org/10.1002/qj.2894 Wallace, N. M., Tibaldi, S., & Simmons, A. J. (1983). Reduction of systematic forecast errors in the ECMWF model through the introduction of an envelope orography. Quarterly Journal of the Royal Meteorological Society, 109, 683–717. Walters, D., Boutle, I., Brooks, M., Melvin, T., Stratton, R., Vosper, S., Wells, H., Williams, K., Wood, N., Allen, T., Bushell, A., Copsey, D., Earnshaw, P., Edwards, J., Gross, M., Hardiman, S., Harris, C., Heming, J., Klingaman, N., Levine, R., Manners, J., Martin, G., Milton, S., Mittermaier, M., Morcrette, C., Riddick, T., Roberts, M., Sanchez, C., Selwood, P., Stirling, A., Smith, C., Suri, D., Tennant, W., Vidale, P. L., Wilkinson, J., Willett, M., Woolnough, S., Xavier, P. (2017). The met office unified model global atmosphere 6.0/6.1 and jules global land 6.0/6.1 configurations. Geoscientific Model Development, 10(4), 1487–1520. https://doi.org/10.5194/gmd-10-1487-2017 Wood, N., Brown, A. R., & Hewer, F. E. (2001). Parametrizing the effects of orography on the boundary layer: An alternative to effective roughness lengths. Quarterly Journal of the Royal Meteorological Society, 127(573), 759–777. https://doi.org/10.1002/qj.49712757303 Wood, N., & Mason, P. (1993). The pressure force induced by neutral, turbulent flow over hills. Quarterly Journal of the Royal Meteorological Society, 119(514), 1233–1267. https://doi.org/10.1002/qj.49711951402 Wood, N., Staniforth, A., White, A., Allen, T., Diamantakis, M., Gross, M., Melvin, T., Smith, C., Vosper, S., Zerroukat, M., Thuburn, J. (2014). An inherently mass-conserving semi-implicit semi-lagrangian discretization of the deep-atmosphere global non-hydrostatic equations. Quarterly Journal of the Royal Meteorological Society, 140(682), 1505–1520. https://doi.org/10.1002/qj.2235 Zadra, A., Bacmeister, J., Bouyssel, F., Brown, A., Lock, A., Figueroa, S. N., Innocentini, V., Nakagawa, M., Roff, G., Tolstykh, M. (2013). WGNE Drag Project. Retrieved from http://collaboration.cmc.ec.gc.ca/science/rpn/drag_project/.