Nonlinear dynamics of hydrostatic internal gravity waves
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Abstract
Stratified hydrostatic fluids have linear internal gravity waves with different phase speeds and vertical profiles. Here a simplified set of partial differential equations (PDE) is derived to represent the nonlinear dynamics of waves with different vertical profiles. The equations are derived by projecting the full nonlinear equations onto the vertical modes of two gravity waves, and the resulting equations are thus referred to here as the two-mode shallow water equations (2MSWE). A key aspect of the nonlinearities of the 2MSWE is that they allow for interactions between a background wind shear and propagating waves. This is important in the tropical atmosphere where horizontally propagating gravity waves interact together with wind shear and have source terms due to convection. It is shown here that the 2MSWE have nonlinear internal bore solutions, and the behavior of the nonlinear waves is investigated for different background wind shears. When a background shear is included, there is an asymmetry between the east- and westward propagating waves. This could be an important effect for the large-scale organization of tropical convection, since the convection is often not isotropic but organized on large scales by waves. An idealized illustration of this asymmetry is given for a background shear from the westerly wind burst phase of the Madden–Julian oscillation; the potential for organized convection is increased to the west of the existing convection by the propagating nonlinear gravity waves, which agrees qualitatively with actual observations. The ideas here should be useful for other physical applications as well. Moreover, the 2MSWE have several interesting mathematical properties: they are a system of nonconservative PDE with a conserved energy, they are conditionally hyperbolic, and they are neither genuinely nonlinear nor linearly degenerate over all of state space. Theory and numerics are developed to illustrate these features, and these features are important in designing the numerical scheme. A numerical method is designed with simplicity and minimal computational cost as the main design principles. Numerical tests demonstrate that no catastrophic effects are introduced when hyperbolicity is lost, and the scheme can represent propagating discontinuities without introducing spurious oscillations.
Keywords
Internal gravity waves Internal bores Stratified fluids Tropical atmospheric dynamics Convectively generated gravity waves Nonconservative PDE Computational methods for nonconservative PDEPACS
47.35.Bb 47.11.−j 92.60.−ePreview
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References
- 1.Majda A.J.: Introduction to PDEs and waves for the atmosphere and ocean, Courant Lecture Notes in Mathematics, vol. 9. American Mathematical Society, Providence (2003)Google Scholar
- 2.Vallis G.: Atmospheric and Oceanic Fluid Dynamics: Fundamentals and Large-scale Circulation. Cambridge University Press, New York (2006)Google Scholar
- 3.Emanuel K.A.: Atmospheric Convection. Oxford University Press, USA (1994)Google Scholar
- 4.Majda A.J.: New multi-scale models and self-similarity in tropical convection. J. Atmos. Sci. 64, 1393–1404 (2007)CrossRefGoogle Scholar
- 5.Baldwin M., Gray L., Dunkerton T., Hamilton K., Haynes P., Randel W., Holton J., Alexander M., Hirota I., Horinouchi T., Jones D., Kinnersly J., Marquardt C., Sato K., Takahashi M.: The quasi-biennial oscillation. Rev. Geophys. 39(2), 179–229 (2001)CrossRefGoogle Scholar
- 6.Zhang, C.: Madden–Julian oscillation. Reviews of Geophysics 43, G2003+ (2005). doi: 10.1029/2004RG000158
- 7.Nakazawa T.: Tropical super clusters within intraseasonal variations over the western Pacific. J. Met. Soc. Japan 66(6), 823–839 (1988)Google Scholar
- 8.Wheeler M., Kiladis G.N.: Convectively coupled equatorial waves: analysis of clouds and temperature in the wavenumber–frequency domain. J. Atmos. Sci. 56(3), 374–399 (1999)CrossRefGoogle Scholar
- 9.Houze, R.A.: Mesoscale convective systems. Rev. Geophys. 42, G4003+ (2004). doi: 10.1029/2004RG000150
- 10.Mapes B.: Gregarious tropical convection. J. Atmos. Sci. 50(13), 2026–2037 (1993)CrossRefGoogle Scholar
- 11.Tulich S., Mapes B.: Multi-scale convective wave disturbances in the Tropics: Insights from a two-dimensional cloud-resolving model. J. Atmos. Sci. 65(1), 140–155 (2008)CrossRefGoogle Scholar
- 12.Tompkins A.: Organization of tropical convection in low vertical wind shears: the role of cold pools. J. Atmos. Sci. 58(13), 1650–1672 (2001)CrossRefGoogle Scholar
- 13.Gamache J., Houze R. Jr: Mesoscale air motions associated with a tropical squall line. Mon. Weather Rev. 110(2), 118–135 (1982)CrossRefGoogle Scholar
- 14.Mapes B.E., Houze R.A. Jr: Diabatic divergence profiles in western Pacific mesoscale convective systems. J. Atmos. Sci 52, 1807–1828 (1995)CrossRefGoogle Scholar
- 15.Haertel P.T., Kiladis G.N.: Dynamics of 2-day equatorial waves. J. Atmos. Sci. 61, 2707–2721 (2004)CrossRefGoogle Scholar
- 16.Tulich S.N., Randall D., Mapes B.: Vertical-mode and cloud decomposition of large-scale convectively coupled gravity waves in a two-dimensional cloud-resolving model. J. Atmos. Sci. 64, 1210–1229 (2007)CrossRefGoogle Scholar
- 17.Mapes B.E.: Convective inhibition, subgrid-scale triggering energy, and stratiform instability in a toy tropical wave model. J. Atmos. Sci. 57, 1515–1535 (2000)CrossRefGoogle Scholar
- 18.Khouider B., Majda A.J.: A simple multicloud parameterization for convectively coupled tropical waves. Part I. Linear analysis. J. Atmos. Sci. 63, 1308–1323 (2006)CrossRefMathSciNetGoogle Scholar
- 19.Khouider B., Majda A.J.: A simple multicloud parameterization for convectively coupled tropical waves. Part II. Nonlinear simulations. J. Atmos. Sci. 64, 381–400 (2007)CrossRefGoogle Scholar
- 20.Khouider B., Majda A.J.: Model multicloud parameterizations for convectively coupled waves: Detailed nonlinear wave evolution. Dyn. Atmos. Oceans 42, 59–80 (2006)CrossRefGoogle Scholar
- 21.Khouider B., Majda A.J.: Multicloud convective parameterizations with crude vertical structure. Theor. Comput. Fluid Dyn. 20, 351–375 (2006)CrossRefGoogle Scholar
- 22.Khouider B., Majda A.J.: Multicloud models for organized tropical convection: enhanced congestus heating. J. Atmos. Sci. 65(3), 895–914 (2008)CrossRefGoogle Scholar
- 23.Majda A.J., Stechmann S.N., Khouider B.: Madden–Julian oscillation analog and intraseasonal variability in a multicloud model above the equator. Proc. Natl. Acad. Sci. 104(24), 9919–9924 (2007)CrossRefGoogle Scholar
- 24.Moncrieff M., So D.: A hydrodynamical theory of conservative bounded density currents. J. Fluid Mech. 198, 177–197 (1989)MATHCrossRefGoogle Scholar
- 25.Xu Q., Moncrieff M.: Density current circulations in shear flows. J. Atmos. Sci. 51(3), 434–446 (1994)CrossRefGoogle Scholar
- 26.Klemp J., Rotunno R., Skamarock W.: On the dynamics of gravity currents in a channel. J. Fluid Mech. 269, 169–198 (1994)MATHCrossRefMathSciNetGoogle Scholar
- 27.Klemp J., Rotunno R., Skamarock W.: On the propagation of internal bores. J. Fluid Mech. 331, 81–106 (1997)MATHCrossRefGoogle Scholar
- 28.Grabowski W.W., Wu X., Moncrieff M.W.: Cloud-resolving modeling of tropical cloud systems during Phase III of GATE. Part I. Two-dimensional experiments. J. Atmos. Sci. 53, 3684–3709 (1996)CrossRefGoogle Scholar
- 29.LeMone M., Zipser E., Trier S.: The role of environmental shear and thermodynamic conditions in determining the structure and evolution of mesoscale convective systems during TOGA COARE. J. Atmos. Sci. 55(23), 3493–3518 (1998)CrossRefGoogle Scholar
- 30.Xue M.: Density currents in shear flows: Effects of rigid lid and cold-pool internal circulation, and application to squall line dynamics. Quart. J. Roy. Meteor. Soc. 128, 47–73 (2002)CrossRefGoogle Scholar
- 31.Majda A.J., Biello J.A.: The nonlinear interaction of barotropic and equatorial baroclinic Rossby waves. J. Atmos. Sci. 60, 1809–1821 (2003)CrossRefMathSciNetGoogle Scholar
- 32.Khouider B., Majda A.J.: A non-oscillatory balanced scheme for an idealized tropical climate model. Part I. Algorithm and validation. Theor. Comput. Fluid Dyn. 19(5), 331–354 (2005)MATHCrossRefGoogle Scholar
- 33.Khouider B., Majda A.J.: A non-oscillatory balanced scheme for an idealized tropical climate model. Part II. Nonlinear coupling and moisture effects. Theor. Comput. Fluid Dyn. 19(5), 355–375 (2005)MATHCrossRefGoogle Scholar
- 34.Abgrall, R., Karni, S.: Two-layer shallow water systems: a relaxation approach. Submitted to SIAM J. Sci. Comput. (2007)Google Scholar
- 35.Ripa P.: On improving a one-layer ocean model with thermodynamics. J. Fluid Mech. 303, 169–201 (1995)MATHCrossRefMathSciNetGoogle Scholar
- 36.Schwendeman D., Wahle C., Kapila A.: The Riemann problem and a high-resolution Godunov method for a model of compressible two-phase flow. J. Comput. Phys. 212(2), 490–526 (2006)MATHCrossRefMathSciNetGoogle Scholar
- 37.Deledicque V., Papalexandris M.: An exact Riemann solver for compressible two-phase flow models containing non-conservative products. J. Comput. Phys. 222(1), 217–245 (2007)MATHCrossRefMathSciNetGoogle Scholar
- 38.Evans L.: Partial Differential Equations. American Mathematical Society, USA (1998)MATHGoogle Scholar
- 39.LeVeque R.J.: Finite Volume Methods for Hyperbolic Problems. Cambridge University Press, London (2002)MATHGoogle Scholar
- 40.Dal Maso G., LeFloch P., Murat F.: Definition and weak stability of nonconservative products. J. Math. Pure Appl. 74(6), 483–548 (1995)MATHMathSciNetGoogle Scholar
- 41.LeFloch, P.G., Tzavaras, A.E.: Representation of weak limits and definition of nonconservative products. SIAM J. Math. Anal. 30(6), 1309–1342 (1999). doi: 10.1137/S0036141098341794. http://link.aip.org/link/?SJM/30/1309/1
- 42.Crasta G., LeFloch P.: Existence result for a class of nonconservative and nonstrictly hyperbolic systems. Commun. Pure Appl. Anal. 1, 1–18 (2002)MathSciNetGoogle Scholar
- 43.Bianchini S.: On the Riemann problem for non-conservative hyperbolic systems. Arc. Ration. Mech. Anal. 166(1), 1–26 (2003)MATHCrossRefMathSciNetGoogle Scholar
- 44.Toumi I.: A weak formulation of Roe’s approximate Riemann solver. J. Comput. Phys. 102(2), 360–373 (1992)MATHCrossRefMathSciNetGoogle Scholar
- 45.Pares C.: Numerical methods for nonconservative hyperbolic systems: a theoretical framework. SIAM J. Numer. Anal. 44(1), 300–321 (2006)MATHCrossRefMathSciNetGoogle Scholar
- 46.Nessyahu H., Tadmor E.: Non-oscillatory central differencing for hyperbolic conservation laws. J. Comput. Phys. 87(2), 408–463 (1990)MATHCrossRefMathSciNetGoogle Scholar
- 47.Jiang G.S., Tadmor E.: Nonoscillatory central schemes for multidimensional hyperbolic conservation laws. SIAM J. Sci. Comput. 19(6), 1892–1917 (1998). doi: 10.1137/S106482759631041X MATHCrossRefMathSciNetGoogle Scholar
- 48.Strang G.: On the construction and comparison of difference schemes. SIAM J. Numer. Anal. 5, 506–517 (1968)MATHCrossRefMathSciNetGoogle Scholar
- 49.Charney J.G., Eliassen A.: On the growth of the hurricane depression. J. Atmos. Sci. 21, 68–75 (1964)CrossRefGoogle Scholar
- 50.Majda A.: Compressible fluid flow and systems of conservation laws in several space variables, Applied Mathematical Sciences, vol. 53. Springer, New York (1984)Google Scholar
- 51.Lax P.D.: Hyperbolic systems of conservation laws II. Comm. Pure Appl. Math. 10, 537–566 (1957)MATHCrossRefMathSciNetGoogle Scholar
- 52.Bretherton C.S., Smolarkiewicz P.K.: Gravity waves, compensating subsidence and detrainment around cumulus clouds. J. Atmos. Sci. 46(6), 740–759 (1989)CrossRefGoogle Scholar
- 53.Nicholls M., Pielke R., Cotton W.: Thermally forced gravity waves in an atmosphere at rest. J. Atmos. Sci. 48(16), 1869–1884 (1991)CrossRefGoogle Scholar
- 54.Pandya R., Durran D., Bretherton C.: Comments on “thermally forced gravity waves in an atmosphere at rest. J. Atmos. Sci. 50(24), 4097–4101 (1993)CrossRefGoogle Scholar
- 55.Lac C., Lafore J., Redelsperger J.: Role of gravity waves in triggering deep convection during TOGA COARE. J. Atmos. Sci. 59(8), 1293–1316 (2002)CrossRefGoogle Scholar
- 56.Lin X., Johnson R.H.: Kinematic and thermodynamic characteristics of the flow over the western Pacific warm pool during TOGA COARE. J. Atmos. Sci. 53, 695–715 (1996)CrossRefGoogle Scholar
- 57.Wu X., LeMone M.: Fine structure of cloud patterns within the intraseasonal oscillation during toga coare. Mon. Weather Rev. 127(10), 2503–2513 (1999)CrossRefGoogle Scholar