Radiosonde Observational Study Of Inertia Gravity Waves In The Lower Stratosphere

Atmospheric inertial gravity waves(IGWs)are important waves,which are excited in the lower atmosphere,and due to they propagate upward can saturate and break,with the momentum and energy are deposited into the background atmosphere to transport momentum and energy from the lower atmosphere to the middle atmosphere.Thus,gravity waves have an important influence on the circulation of the middle and upper atmosphere and global atmospheric heat balance.Atmospheric gravity waves have complex excitation mechanisms,propagation and dissipation processes.Many studies have explored GW sources based on observation,modeling,and theoretical derivation.At present,it is believed that the main mechanisms of gravity waves in the lower atmosphere are topography,convection,wind shear and geostrophic adjustment.Gravity waves activity exhibits obviously local characteristics.Their excitation sources are generally different in different latitudes and longitudes and topography.Therefore,in order to understand the effects of global gravity waves activity,it is necessary to extensively study gravity wave activity of different geography and seasons.Radiosonde observations are widely used in the study of tropospheric and low stratospheric inertial gravity waves because of their high vertical resolution and long-term data accumulation.There are a lot of reports about using radiosonde observations to study gravity wave activity in the Antarctic region.Relatively speaking,there are few observation stations and scarce data on radiosonde data in the Arctic region.Therefore,there are few studies on inertial gravity waves in the Arctic.This article uses the observational data of the Arctic Ny-Alesund station(78.9°N,11.9°E)radiosonde during 5 years from 1 April 2012 to 31 March 2017 to analyze the background atmospheric states in the atmospheric region(0?30 km),combined with Lomb-Scargle spectral analysis and the hodograph method to extract quasi-monochromatic inertial gravity waves in the low stratosphere region(15?25 km).Through inertial gravity waves polarization and dispersion relations calculate the characteristic parameters of the gravity wave(wavelength,intrinsic frequency,propagation direction,phase velocity,and wave energy,etc.).The seasonal variation and propagation characteristics of atmospheric inertial gravity waves characteristic parameters were explored through case analysis and statistical studies to reveal the activity characteristics of inertial gravity waves in the low stratosphere over the Arctic.To provide a reference for the construction of a global gravity wave spectrum.The main work results arre summarized as follows:1.Raw data of measured temperature and zonal and meridional winds were processed to have an even height resolution of 5 m by utilizing a linear interpolation,which is helpful in investigating small scale gravity waves.2.Introduced clearly the method used in the analysis process,Lomb-Scargle spectral analysis,sine fitting and hodograph technique.Compared the Lomb-Scargle spectrum with the fast Fourier transform,shows our study results more accurate.3.Through case analysis,detailed description of how to use radiosonde to extract the quasi-monochromatic gravity wave characteristic parameters and statistical study of their seasonal changes.And combined with the results of previous studies in the low-middle latitude,revealed the temporal and spatial changes of inertial gravity waves in the low stratosphere.