Seasonal Amplification of the 2-Day Wave: Relationship between Normal Mode and Instability

Abstract The 2-day wave is a prominent feature of the middle and upper atmosphere, amplifying twice-yearly around solstice. Its period, structure, and reproducibility have led to its association with the gravest planetary normal mode of zonal wavenumber 3, the so-called Rossby-gravity mode. On the other hand, its amplification around solstice has also led to its association with baroclinic instability of summer easterlies. To explore the relationship between the Rossby-gravity mode and instability, calculations are performed with the linearized primitive equations that have been generalized to account for that mode's interaction with a generally unstable mean flow u. The mode's eigenfrequency is then complex, the imaginary component representing amplification and decay. For mean states representative of solstice and equinox, the normal mode is calculated and then compared to observed behavior in terms of its period, structure, and amplification. The behavior recovered, including structural differences bet...

[1]  B. Boville,et al.  A Numerical Simulation of the Two-Day Wave near the Stratopause , 2000 .

[2]  R. Lieberman.  Eliassen–Palm Fluxes of the 2-Day Wave , 1999 .

[3]  R. Roble,et al.  TIME‐GCM results for the quasi‐two‐day wave , 1998 .

[4]  J. Thuburn,et al.  The two‐day wave in a middle atmosphere GCM , 1996 .

[5]  W. Read,et al.  Excitation and evolution of the quasi-2-day wave observed in UARS/MLS temperature measurements , 1996 .

[6]  W. Randel.  Observations of the 2-day wave in NMC stratospheric analyses , 1994 .

[7]  D. Ortland,et al.  Observations of the quasi 2‐day wave from the High Resolution Doppler Imager on Uars , 1993 .

[8]  J. Forbes,et al.  Numerical investigation of the propagation of the quasi-two-day wave into the lower thermosphere , 1993 .

[9]  E. Manzini,et al.  Middle Atmospheric Traveling Waves Forced by Latent and Convective Heating , 1993 .

[10]  R. Vincent,et al.  The quasi‐two‐day wave observed in the equatorial middle atmosphere , 1993 .

[11]  William J. Randel,et al.  Global atmospheric circulation statistics, 1000-1 mb , 1992 .

[12]  William H. Press,et al.  Numerical recipes , 1990 .

[13]  T. Tsuda,et al.  Long period wind oscillations observed by the Kyoto meteor radar and comparison of the quasi-2-day wave with Adelaide HF radar observations , 1988 .

[14]  R. Garcia,et al.  Transient Response to Localized Episodic Heating in the Tropics. Part II: Far-Field Behavior. , 1987 .

[15]  R. Garcia,et al.  Theory and observations of the short‐period normal mode oscillations of the atmosphere , 1986 .

[16]  L. Pfister.  Baroclinic instability of easterly jets with applications to the summer mesosphere , 1985 .

[17]  M. Salby.  Survey of planetary-scale traveling waves: the state of theory and observations , 1984 .

[18]  H. G. Muller,et al.  Simultaneous observations of the quasi 2-day wave in the northern and southern hemispheres , 1983 .

[19]  A. E. Gill.  Atmosphere-Ocean Dynamics , 1982 .

[20]  B. Hunt.  The 2-day wave in the middle atmosphere as simulated in a general circulation model extending from the surface to 100 km , 1981 .

[21]  M. Salby.  The 2‐day wave in the middle atmosphere: Observations and theory , 1981 .

[22]  A. Prata,et al.  Evidence for a traveling two‐day wave in the middle atmosphere , 1981 .

[23]  R. Garcia,et al.  Stochastic Forcing of Small-Amplitude Oscillations in the Stratosphere. , 1981 .

[24]  M. Salby.  Rossby Normal Modes in Nonuniform Background Configurations. Part II. Equinox and Solstice Conditions , 1981 .

[25]  M. Salby.  The Influence of Realistic Dissipation on Planetary Normal Structures , 1980 .

[26]  R. Vincent,et al.  The quasi 2-day wave in the Southern Hemisphere mesosphere , 1980, Nature.

[27]  A. Kasahara.  Effect of Zonal Flows on the Free Oscillations of a Barotropic Atmosphere , 1980 .

[28]  R. A. Madden,et al.  Observations of large‐scale traveling Rossby waves , 1979 .

[29]  H. G. Muller,et al.  A travelling quasi 2-day wave in the meteor region , 1978 .

[30]  A. Spizzichino,et al.  Comparison and interpretation of the results of simultaneous wind measurements in the lower thermosphere at Garchy (France) and Obninsk (U.S.S.R.) by meteor radar technique , 1975 .

[31]  H. G. Muller,et al.  On the scale sizes of wind systems in the meteor zone , 1974 .

[32]  R. Dickinson,et al.  Numerical Study of an Interacting Rossby Wave and Barotropic Zonal Flow Near a Critical Level , 1974 .

[33]  R. Dickinson.  Baroclinic Instability of an Unbounded Zonal Shear Flow in a Compressible Atmosphere , 1973 .

[34]  R. A. Madden,et al.  Further Evidence of Global-Scale 5-Day Pressure Waves , 1972 .

[35]  H. Muller,et al.  A discussion on D and E region winds over Europe - Long-period meteor wind oscillations , 1972, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[36]  T. Broadbent,et al.  Survey of Applicable Mathematics , 1970, The Mathematical Gazette.

[37]  R. A. Plumb.  Baroclinic Instability of the Summer Mesosphere: A Mechanism for the Quasi-Two-Day Wave? , 1983 .

[38]  M. Salby,et al.  Long-Period Oscillations in the Meteor Region , 1980 .