Inertia‐Gravity Waves Revealed in Radiosonde Data at Jang Bogo Station, Antarctica (74°37′S, 164°13′E): 1. Characteristics, Energy, and Momentum Flux

Abstract

Characteristics of inertia-gravity waves (IGWs) at high latitude in Antarctica are investigated using radiosondes launched daily at Jang Bogo Station (74°37 0 S, 164°13 0 E), a new Antarctic station that has been operating since 2014, in the troposphere (z = 2-7 km) and lower stratosphere (z = 15-22 km) for 25 months (December 2014 to December 2016). The vertical propagation of IGWs exhibits strong seasonal variations in the stratosphere, with an enhancement (reduction) in downward (upward)-propagating IGWs from May to mid-October. In the troposphere, both upward-and downward-propagating IGWs have similar occurrence rates without seasonal variations. The intrinsic phase velocity of IGWs mostly direct to the west (isotropic), while the ground-relative phase and group velocities are dominant in the east and southeast (northeast), respectively, in the stratosphere (troposphere). The intrinsic frequency, vertical wavelength, and horizontal wavelength of IGWs averaged in the troposphere (stratosphere) are 3.57f (1.93f; where f is the Coriolis parameter), 1.48 (1.48) km, and 63.06 (221.81) km, respectively. The wave energy in the stratosphere has clear seasonal variations with large values in autumn and spring, while that in the troposphere is smaller without obvious seasonal variations. Zonal and meridional momentum fluxes averaged in the stratosphere (troposphere) are À0.008 (À0.0018) and À0.0005 (0.001) m 2 /s 2 , respectively. The momentum flux of downward-propagating IGWs in the stratosphere is mostly positive in both zonal and meridional directions, whereas the directional preference is not obvious in the troposphere. In Part 2, sources of the observed IGWs in the troposphere and stratosphere will be examined.

Inertia‐Gravity Waves Revealed in Radiosonde Data at Jang Bogo Station, Antarctica (74°37′S, 164°13′E): 2. Potential Sources and Their Relation to Inertia‐Gravity Waves

“…In the present study, the potential sources of the IGWs in the lower stratosphere ( z = 15–22 km) revealed in the radiosonde observations at Jang Bogo Station (JBS; 74°37′S, 164°13′E) are investigated. Analyses are performed using the characteristics of IGWs extracted from 3 years of radiosonde data (December 2014 to November 2017), including the 25‐month (from December 2014 to December 2016) data used in Yoo et al (2018; Part 1). Wave parameters obtained from the 3‐year period radiosonde data exhibit similar values to those reported in Part 1: The average values of the intrinsic frequency, vertical wavelength, and horizontal wavelength are 2.04 f , 1.47 km, and 217 km, respectively, and those of kinetic and potential energies are 3.28 and 1.11 J kg −1 , respectively.…”

“…Recently, Yoo et al (2018, hereafter Part 1) analyzed IGWs in the troposphere and lower stratosphere revealed in radiosonde observations at Jang Bogo Station (JBS; 74°37′S, 164°13′E) for 25 months (December 2014 to December 2016). In Part 1, characteristics, energy, and MF of IGWs have been obtained using the Stokes parameter and rotary spectrum methods.…”

Characteristics of Atmospheric Turbulence Retrieved From High Vertical‐Resolution Radiosonde Data in the United States

“…Radiosondes are launched more than twice a day at approximately 800 stations around the world (Durre et al, 2018;Ingleby et al, 2016). Radiosonde data are arguably the most important and essential data source for numerical weather prediction models and have been used in studies of planetary boundary layer height (Seidel et al, 2010;Sorbjan & Balsley, 2008), tropopause structure (Birner, 2006;Birner et al, 2002;Seidel & Randel, 2006;Sunilkumar et al, 2017), and gravity waves (Allen & Vincent, 1995;Chun et al, 2006;Chun et al, 2007;Hamilton & Vincent, 1995;Ki & Chun, 2010;Sato & Yoshiki, 2008;Wang et al, 2005;Wang & Geller, 2003;Yoo et al, 2018). Although high vertical-resolution radiosonde data (HVRRD) have often been required for these studies, due to telecommunication limitations and data storage costs, only data with a lower resolution than actual observational resolution data have been routinely provided to weather prediction agencies (Ingleby et al, 2016).…”

Statistical Characteristics of Inertial Gravity Waves Over a Tropical Station in the Western Pacific Based on High‐Resolution GPS Radiosonde Soundings

“…The change of momentum flux of GW will lead to the variation of background wind field. As an important factor affecting large‐scale average fluid, the vertical fluxes of zonal momentum () and meridional momentum () per unit mass can be expressed as (Yoo et al., 2018): where denotes the 90° phase shift of the normalized temperature disturbance by using the Hilbert transform, and shows the efficiency of transporting momentum by the low frequency IGWs. Using Equations and , the vertical flux of zonal momentum and meridional momentum in the troposphere (stratosphere) are −0.0046 m 2 /s 2 (0.0072 m 2 /s 2 ) and 0.0003 m 2 /s 2 (−0.0094 m 2 /s 2 ) respectively.…”

“…The altitudinal range below 2 km is not considered in order to avoid error interference caused by strong disturbances near the planetary boundary layer. At present, the extraction of GW background wind and temperature profiles generally adopts second-order (Huang et al, 2018), third-order (Yoo et al, 2018), or fourth-order (Pramitha et al, 2016) by linear, second-order, third-order, or fourth-order polynomial fitting show little difference (Wang & Geller, 2003), considering the more clear changes in the wind profile in tropical regions, here the fourth-order polynomial fitting is adopted to extract the fitted background profile. In order to introduce the method for extracting GW parameters in detail, here we take the radiosonde data on March 3, 2013 as an example for case analysis.…”