Introduction GWs are mostly generated on the troposphere and - - PowerPoint PPT Presentation

ANGWIN – 4TH ANTARTIC GRAVITY WAVE INSTRUMENT NETWORK

24 - 26 April 2018, São José dos Campos, Brazil.

CHARACTERIZATION OF THE EFFECTS OF GRAVITY

WAVES IN THE IONOSPHERE USING VLF

Luís T. M. Raunheitte1, Emília Correia1,2

[1] Center for Radio Astronomy and Astrophysics at Mackenzie (CRAAM), Engineering School, Mackenzie Presbyterian University, São Paulo, Brasil [2] National Institute for Space Research - INPE

• GWs are mostly generated on the troposphere and propagates in ascendant

direction, affecting all the atmospheric layers, with periods of minutes to hours and spatial scale from a few to hundreds of kilometers. GWs are known for interfere with the atmosphere circulation affecting the electron density on the ionosphere base.

• Under the influence of the GWs the electron density, thus the conductivity, of the

lower ionosphere changes and affects the reflection conditions of the very low frequency (VLF) radio signal. Variations in the conductivity are detected as fluctuations in the amplitude of VLF signals;

• Here we will investigate the influence of GW on the base of ionosphere, D-region,

using VLF measurements done at Brazilian Antarctic Station Comandante Ferraz (EACF) on King George Island during 2007.

Introduction

Materials and Methods

• To evaluate the effect and the propagation of GW in the lower ionosphere we will use

the amplitude of VLF signals propagating in two paths EACF – USA (NPM on Hawaii e NAA on the east coast), obtained with VLF station operated at EACF. These paths were chosen because they cross the Drake Passage region, where the GW activity are strong.

• Python routines;
• Obtain the GW

characteristics with Wavelet Analysis;

Wu et al, 2002.

Preliminary Results

Date Period (min)

18/08/07 05:50-05:59 UT 13,14±0,2 Period: 13 min.

Bageston, 2009.

Preliminary Results

Date Period (min)

12/06/07 00:23-00:25 UT 17,7±2,5 Period: 18 min.

Bageston, 2009.

Discussion

• The preliminary results shows the high potentiality of using VLF as a

tool to observe GWs in the ionosphere base to obtain GWs characteristics as period, propagation direction and amplitude;

• The two studied cases show signs of GW interfering on the base of

ionosphere, the properties of these appear similar to the ones obtained with airglow observations of the atmosphere;

• VLF tool has some advantages over the other methods because it’s

possible to observe 24hs a day, showing a more detailed timeline of the events, and it’s capable of covering a much larger area;

• To complete these study the investigation will be done for all 2007 to

characterize it’s seasonal influence in the ionosphere;

Thanks

• 4th ANGWIN Organizing Committee;
• CNPQ PROANTAR;
• CAPES Master Degree Scholarship;