In this paper, the nonlinear internal inerntial gravity wave equation is derived by the analysis method of phase plane and is solved by integration method. The results showed that this nonlinear equation not only has ...In this paper, the nonlinear internal inerntial gravity wave equation is derived by the analysis method of phase plane and is solved by integration method. The results showed that this nonlinear equation not only has ordinary solitary wave solution but also has another extra-ordinary solutions, and the form of solution is related to stratification stability, wave velocity and direction of wave motion.展开更多
Characterization of gravity wave （GW） parameters for the stratosphere is critical for global atmospheric circulation models. These parameters are mainly determined from measurements. Here, we investigate variation i...Characterization of gravity wave （GW） parameters for the stratosphere is critical for global atmospheric circulation models. These parameters are mainly determined from measurements. Here, we investigate variation in inertial GW activity with season and latitude in the lower stratosphere （18-25 km） over China, using radiosonde data with a high vertical resolution over a 2-year period. Eight radiosonde stations were selected across China, with a latitudinal range of 22°-49°N. Analyses show that the GW energy in the lower stratosphere over China has obvious seasonal variation and a meridional distribution, similar to other regions of the globe. The GW energy is highest in winter, and lowest in summer; it decreases with increasing latitude. Velocity perturbations with longitude and latitude are almost the same, indicating that GW energy is horizontally isotropic. Typically, 85% of the vertical wavelength distribution is concentrated between elevations of 1 and 3 km, with a mean value of 2 kin; it is almost constant with latitude. Over 80% of all the horizontal wavelengths occur in the range 100-800 km, with a mean value of 450 km; they show a weak decrease with increasing latitude, yielding a difference of about 40 km over the 22°-49°N range. The ratio of horizontal wavelength over vertical wavelength is about 200：1, which implies that inertial GWs in the lower stratosphere propagate along nearly horizontal planes. Ratios of their intrinsic frequency to the Coriolis parameter decrease with increasing latitude; most values are between 1 and 2, with a mean value of 1.5. Study of the propagation directions of GW energy shows that upward fractions account for over 60% at all stations. In contrast, the horizontal propagation direction is significantly anisotropic, and is mainly along prevailing wind directions; this anisotropy weakens with increasing latitude.展开更多
In this paper,by the WKB method the relation between the energy increase of internal inertial gravity waves and heterogeneous atmospheric stratification is derived,and a new generalized wave action is defined and its ...In this paper,by the WKB method the relation between the energy increase of internal inertial gravity waves and heterogeneous atmospheric stratification is derived,and a new generalized wave action is defined and its conservation is proved.展开更多
Observational analysis of the Earth’s stratospheric temperature structure and its dynamical behavior is of great significance for atmospheric dynamics research.In this paper,we present stratospheric temperatures in t...Observational analysis of the Earth’s stratospheric temperature structure and its dynamical behavior is of great significance for atmospheric dynamics research.In this paper,we present stratospheric temperatures in the range of 30–50 km above the Yinchuan observation site,retrieved from diurnal continuous Rayleigh scattering signal observation data collected by a 589 nm lidar throughout a single day.We also present observational studies of atmospheric tides and gravity wave cases.The diurnal temperature background field and perturbation field were obtained from the lidar data using the linear fitting method;these results exhibit good consistency with the temperature perturbation field extracted from ERA5.An obvious quasi-monochromatic inertial gravity wave was detected by application of a two-dimensional Fourier transform to the nighttime observation data with complete height coverage,which revealed these characteristic gravity wave parameters:a vertical wavelength of 8.53 km,a period of 8.46 h,and a downward-propagating vertical phase velocity.A nonlinear least-squares harmonic fitting method was used to extract amplitudes and phases of atmospheric diurnal and semi-diurnal tides in the 30−34 km range,where the diurnal data were relatively complete.The amplitudes increased with height,ranging from 0.6 to 2.5 K(diurnal tide)and 0.3 to 1.9 K(semi-diurnal tide),respectively.The phases showed a decreasing trend with height,indicating that the vertical phase velocity of the tides propagates downward while the energy propagates upward.These results indicate that diurnal 589 nm lidar observations data can provide important reference values for understanding the temperature structure of the stratosphere and the dynamical characteristics of atmospheric gravity waves and tides.展开更多
The breakdown and foundation of geostrophic balance is one of the important movements in the mid-and high-latitude atmosphere and oceans.In the tropical area,the value of Coriolis pa- rameter is so small that it is di...The breakdown and foundation of geostrophic balance is one of the important movements in the mid-and high-latitude atmosphere and oceans.In the tropical area,the value of Coriolis pa- rameter is so small that it is difficult to satisfy the bi-geostrophic equilibrium between the pressure and velocity fields.However,in the tropical area,the zonal velocity of some motions in the atmo- sphere and oceans is large,so the Coriolis force is not small,geostrophic balance can exist in zonal direction,i.e.semi-geostrophic balance.Furthermore,in the dominant area of Hadley circulation in the atmosphere or the area near the ocean meridional boundary,the meridional velocity is large, so geostrophic balance can also exist in meridional direction.In this paper,the process of the dis- persion of inertial gravity wave and the foundation of semi-geostrophic balance are first discussed. Second,the adjustment process between the velocity and pressure fields after adaptation is also viewed,and the scale criterion of the semi-geostrophic adaptation is discussed,i.e.for the motion with meridional scale greater than the equatorial Rossby radius of deformation,the velocity and pressure fields after adaptation change to fit the initial pressure field;on the contrary,the fields change to fit the initial zonal velocity field,and the strength of the fields after adaptation depends on the zonal scale.展开更多
文摘In this paper, the nonlinear internal inerntial gravity wave equation is derived by the analysis method of phase plane and is solved by integration method. The results showed that this nonlinear equation not only has ordinary solitary wave solution but also has another extra-ordinary solutions, and the form of solution is related to stratification stability, wave velocity and direction of wave motion.
基金supported by the National Natural Science Foundation of China(Grant Nos.41175040&91337214)
文摘Characterization of gravity wave （GW） parameters for the stratosphere is critical for global atmospheric circulation models. These parameters are mainly determined from measurements. Here, we investigate variation in inertial GW activity with season and latitude in the lower stratosphere （18-25 km） over China, using radiosonde data with a high vertical resolution over a 2-year period. Eight radiosonde stations were selected across China, with a latitudinal range of 22°-49°N. Analyses show that the GW energy in the lower stratosphere over China has obvious seasonal variation and a meridional distribution, similar to other regions of the globe. The GW energy is highest in winter, and lowest in summer; it decreases with increasing latitude. Velocity perturbations with longitude and latitude are almost the same, indicating that GW energy is horizontally isotropic. Typically, 85% of the vertical wavelength distribution is concentrated between elevations of 1 and 3 km, with a mean value of 2 kin; it is almost constant with latitude. Over 80% of all the horizontal wavelengths occur in the range 100-800 km, with a mean value of 450 km; they show a weak decrease with increasing latitude, yielding a difference of about 40 km over the 22°-49°N range. The ratio of horizontal wavelength over vertical wavelength is about 200：1, which implies that inertial GWs in the lower stratosphere propagate along nearly horizontal planes. Ratios of their intrinsic frequency to the Coriolis parameter decrease with increasing latitude; most values are between 1 and 2, with a mean value of 1.5. Study of the propagation directions of GW energy shows that upward fractions account for over 60% at all stations. In contrast, the horizontal propagation direction is significantly anisotropic, and is mainly along prevailing wind directions; this anisotropy weakens with increasing latitude.
文摘In this paper,by the WKB method the relation between the energy increase of internal inertial gravity waves and heterogeneous atmospheric stratification is derived,and a new generalized wave action is defined and its conservation is proved.
基金supported by the Key Research Program of the Chinese Academy of Sciences(Grant NO.KGFZD-145-23-17)the Specialized Research Fund for State Key Laboratories.
文摘Observational analysis of the Earth’s stratospheric temperature structure and its dynamical behavior is of great significance for atmospheric dynamics research.In this paper,we present stratospheric temperatures in the range of 30–50 km above the Yinchuan observation site,retrieved from diurnal continuous Rayleigh scattering signal observation data collected by a 589 nm lidar throughout a single day.We also present observational studies of atmospheric tides and gravity wave cases.The diurnal temperature background field and perturbation field were obtained from the lidar data using the linear fitting method;these results exhibit good consistency with the temperature perturbation field extracted from ERA5.An obvious quasi-monochromatic inertial gravity wave was detected by application of a two-dimensional Fourier transform to the nighttime observation data with complete height coverage,which revealed these characteristic gravity wave parameters:a vertical wavelength of 8.53 km,a period of 8.46 h,and a downward-propagating vertical phase velocity.A nonlinear least-squares harmonic fitting method was used to extract amplitudes and phases of atmospheric diurnal and semi-diurnal tides in the 30−34 km range,where the diurnal data were relatively complete.The amplitudes increased with height,ranging from 0.6 to 2.5 K(diurnal tide)and 0.3 to 1.9 K(semi-diurnal tide),respectively.The phases showed a decreasing trend with height,indicating that the vertical phase velocity of the tides propagates downward while the energy propagates upward.These results indicate that diurnal 589 nm lidar observations data can provide important reference values for understanding the temperature structure of the stratosphere and the dynamical characteristics of atmospheric gravity waves and tides.
文摘The breakdown and foundation of geostrophic balance is one of the important movements in the mid-and high-latitude atmosphere and oceans.In the tropical area,the value of Coriolis pa- rameter is so small that it is difficult to satisfy the bi-geostrophic equilibrium between the pressure and velocity fields.However,in the tropical area,the zonal velocity of some motions in the atmo- sphere and oceans is large,so the Coriolis force is not small,geostrophic balance can exist in zonal direction,i.e.semi-geostrophic balance.Furthermore,in the dominant area of Hadley circulation in the atmosphere or the area near the ocean meridional boundary,the meridional velocity is large, so geostrophic balance can also exist in meridional direction.In this paper,the process of the dis- persion of inertial gravity wave and the foundation of semi-geostrophic balance are first discussed. Second,the adjustment process between the velocity and pressure fields after adaptation is also viewed,and the scale criterion of the semi-geostrophic adaptation is discussed,i.e.for the motion with meridional scale greater than the equatorial Rossby radius of deformation,the velocity and pressure fields after adaptation change to fit the initial pressure field;on the contrary,the fields change to fit the initial zonal velocity field,and the strength of the fields after adaptation depends on the zonal scale.
