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MELISSA studies of equatorial spread- F irregularities Gebreab K. Zewdie 1 Fabiano S. Rodrigues 1 and Eurico R. de Paula 2 1. UT Dallas 2. INPE, Brazil gkz130030@utdallas.edu May 10, 2015 Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 1

SLIDE 1

MELISSA studies of equatorial spread-F irregularities

Gebreab K. Zewdie1 Fabiano S. Rodrigues 1 and Eurico R. de Paula2

1. UT Dallas
2. INPE, Brazil

gkz130030@utdallas.edu

May 10, 2015

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 1 / 11

SLIDE 2

Objectives

Develop software tools for spectral analyses Apply the software tools to new measurements made by MELISSA

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 2 / 11

SLIDE 3

Outline

1

Introduction

2

Radar Observations

3

Estimated ESF Parameters

4

Summary

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 3 / 11

SLIDE 4

Equatorial Spread F

Spread F irregularities are perturbations in the ionospheric electron density. They adversely affect radio propagations.

Sources: Hysell et. al (2006), www.nasa.gov, www.cpi.com

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 4 / 11

SLIDE 5

Radar Observations

−150 −100 −50 50 100 150 −80 −60 −40 −20 20 40 60 80 SANYA EAR JICAMARCA SAO LUIS GADANKI Bahir Dar Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 5 / 11

SLIDE 6

MELISSA (Measurement of Equatorial and Low-latitude Ionospheric irregularities over Sao Luis, South America)

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 6 / 11

SLIDE 7

Radar Parameters

Summary of Radar parameters for the 2014 Observations

Parameter Value Radar Frequency 30MHz Peak power 16kW Lowest height sampled 90km Highest height sampled 1222.8km Baud length 2.4km Number of FFT points 64 Number of FFT spectra averaged 25

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SLIDE 8

Examples of Measurements

19 19.5 20 20.5 21 21.5 22 22.5 23 23.5 24 200 400 600 800 1000

200 397.2 km 19:45 LT

200 394.8 km 19:45 LT Doppler Vel. [m/s]

200 392.4 km 19:45 LT

200 637.2 km 20:07 LT

200 634.8 km 20:07 LT Doppler Vel. [m/s]

200 632.4 km 20:07 LT

200 447.6 km 20:45 LT

200 445.2 km 20:45 LT Doppler Vel. [m/s]

200 442.8 km 20:45 LT

200 397.2 km 22:03 LT

200 394.8 km 22:03 LT Doppler Vel. [m/s]

200 392.4 km 22:03 LT

Observations made by the MELISSA radar on March 22, 2014. The top panel shows the RTI map. The bottom panels show examples of spectra estimated.

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 8 / 11

SLIDE 9

Examples of Measurements

Height [km] 22−Mar−2014 − SNR [dB] 19:00 20:00 21:00 22:00 23:00 200 400 600 800 1000 −20 −15 −10 −5 5 10 15 Height [km] Mean Doppler Velocity [m/s + Up] 19:00 20:00 21:00 22:00 23:00 200 400 600 800 1000 −100 −50 50 100 Height [km] Local Time Spectral Witdh [m/s] 19:00 20:00 21:00 22:00 23:00 200 400 600 800 1000 20 40 60 80 100

Examples of parameters derived using the MELISSA radar on March 22, 2014. SNR (top panel), vertical velocity (middle panel) and spectral width (bottom) panel.

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 9 / 11

SLIDE 10

Histograms

Mean Doppler Vel. [m/s, + Up]

100 200 300 Occurrence Rate 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 22-Mar-2014 - SNR > 0 dB Spectral Width [m/s] 50 100 150 200 250 300 Occurrence Rate 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

Histograms of mean Doppler velocities (+ upward) and spectral widths estimated from the observations made by MELISSA on March 22, 2014.

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 10 / 11

SLIDE 11

Summary and Conclusion

We implemented tools that calculate spectral parameters: Doppler velocity, spectral width, and power Doppler velocities fall within ±100m/s Spectral width values fall below 100m/s We have not yet observed supersonic velocities of Spread F irregularities commonly observed by Jicamarca [e.g. Hysell et al. (2004) ].

Gebreab K. Zewdie (UTD) Equatorial SF May 10, 2015 11 / 11