An Analytical Study of Filtered Tropical Flows Using an Improvement of the Longwave Model. Alex O. Gonzalez. Acknowledgements Wayne Schubert, Matt Masarik, Levi Silvers, Jonathan Vigh, CMMAP, and SOARS Program. Overview.
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An Analytical Study of Filtered Tropical Flows Using an Improvement of the Longwave Model
Alex O. Gonzalez
Wayne Schubert, Matt Masarik, Levi Silvers, Jonathan Vigh, CMMAP, and SOARS Program
-Use equatorial wave theory (on beta-plane) to gain insight on atmospheric phenomena such as MJO
-Theoretical studies vital because lack of numerical data in tropics
-Analytical model using different filtering techniques
-4 types of atmospheric waves in equatorial region:
-Inertia gravity, Mixed-Rossby gravity, Rossby, and Kelvin waves
-Most concerned with Rossby and Kelvin waves for MJO
-Filter out inertia-gravity waves
-OLR shows relative importance of wave types for MJO
-Filters out inertia-gravity wave while retaining Kelvin waves
Rossby Dispersion Approximation
-Provides a better approximation of Rossby waves of all wavelengths
Matsuno Primitive Model
-Two important models: Matsuno and Gill
-Want to improve Gill model because it distorts short Rossby waves
Gill Longwave Model
-Shallow-water primitive equations without forcings
-Gill model neglects , we use
Gill Model vs. Filtered Model
Gill model equations
Filtered model equations
Gill Model vs. Filtered Model
-Using Ripa (1994) method of separating and h into Kelvin and non-Kelvin parts
-Can do this because v=0 for Kelvin waves
Gill using Ripa method
Filtered using Ripa method
-Need to solve a master equation for potential function,
-1st order dispersion relation, instead of cubic
-Gill model dispersion relation does not contain
-Not easy to solve shallow-water equations with convective coupling, need to make assumptions
-Follow framework of Ripa (1994)
-Use arguments of PV, Geostrophic Flow, and Divergence
-Learn more about importance of Rossby and Kelvin modes in MJO
Gill, A. E. 1980. Some simple solutions for heat-induced tropical circulation. Quart. J. Roy. Meteor. Soc., 447-462.
Matsuno, T. 1966: Quasi-Geostrophic Motions in the Equatorial Area. J. Meteor. Soc. Japan, 14, 25-42.
Ripa, P. 1994: Horizontal wave propagation in the equatorial waveguide. J. Fluid Mech., 271, 267-284
Schubert, W. H., M. T. Masarik, L. G. Silvers, and A. O. Gonzalez 2008: A Filtered Model of Tropical Wave Motions. Q. J. R. Meteorol. Soc. (2008),134, pp. 1-10.In Progress.
Stevens, P. L., H.-C. Kuo, W. H. Schubert, and P. Ciesielski, 1990: Quasi-balanced
dynamics in the tropics. J. Atmos. Sci., 47, 2262-2273.
Wheeler, M.C., 2002: Tropical Meteorology: Equatorial Waves. In: J. Holton, J. Curry, and J. Pyle (eds), Encyclopedia of Atmospheric Sciences. Academic Press, 2313-2325.