Discovery And Research Of Antarctic Gravity Wave QBO Modulation Based On All-time Lidar Observations

Gravity waves transport energy and momentum both vertically and horizontally,making significant contributions to the complex coupling among stratified layers from troposphere to thermosphere,between the northern and southern hemispheres,and crossing over the polar,middle,and equatorial regions.Meanwhile as the most puzzling elements in modern general circulation and chemical climate models,our understanding of gravity waves is still limited due to their small scales and wide spectra.Lidar has been utilized as an unique technology in atmosphere science,especially in gravity waves observation,it can provide lots of atmosphere parameters which help to derive gravity wave activities with unprecedented temporal and spatial resolutions compare with other instruments.The observation of gravity waves is one of the major applications of Lidar.Daytime observation has always been the major limitation for Lidar system,in this work,an ultra-narrow band-pass filter which combining FPI with interference filter is used to eliminates background photocounts,improving the capability of Lidar daytime observation.In this dissertation,we aim to combine Lidar data with model simulations to establish a ground work that link the tropical QBO to extratropical waves via investigating Antarctica stratosphere gravity wave potential energy density interannual variations,polar vortex edge,and polar night jet.With Lidar observation data,gravity waves induced temperature perturbations can be subtracted to calculate the stratospheric gravity wave potential energy density,MERRA-2 data provide large scale information to identify tropical QBO signal,polar vortex edge and polar night jet.The tropical QBO modulate the polar vortex to expand or contract in mid-winter during different QBO phase year.Expanding or contracting polar vortex will push the polar night jet to shift toward or away from equator.As a barrier,polar night jet can create a quite background wind field for polar region with less critical level filtering.When polar night jet moving towards equator,polar region is deep inside the polar vortex and experience a quite winter.Less critical level filtering will allow more gravity waves propagate into stratosphere and higher latitude,when polar night jet moving towards pole,polar region is close to the edge of polar vortex,background wind will change more randomly,more gravity waves will be absorbed by the background.This process leads to the interannual variations of Lidar observed gravity wave potential energy density have clear QBO signals.