Haris Haralambous

84
Exploiting Space and Earth-based Instrumentation for Atmospheric Studies in Cyprus Haris Haralambous Department of Electrical Engineering Frederick University “Cyprus Embraces Space 2016” Conference Wednesday, 18th May 2016 European University Cyprus

Transcript of Haris Haralambous

Exploiting Space and Earth-based Instrumentation for

Atmospheric Studies in Cyprus

Haris Haralambous

Department of Electrical Engineering

Frederick University

“Cyprus Embraces Space 2016” Conference

Wednesday, 18th May 2016

European University Cyprus

Outline

• INTRODUCTION

• THE IONOSPHERE

• THE SUN AS THE MAIN SPACE WEATHER

DRIVER

• SPACE WEATHER

• IONOSPHERIC EFFECTS ON RADIO

SYSTEMS

• IONOSPHERIC MONITORING

• IONOSPHERIC RESEARCH AT FREDERICK

• The ionosphere is the uppermost part of the atmosphere and is ionized by solar radiation.

• Ionization is the conversion of atoms or molecules into an ion by light (heating up or charging) from the sun on the upper atmosphere.

• Ionization also creates a horizontal set of stratum (layer) where each has a peak density and a definable width or profile that influences radio propagation.

IONOSPHERE

D region: (60÷90 km) mainly responsible

for the radiowave absorption.

E region: (90÷150 km) reflects the long

and medium radiowaves (λ>100 m).

F region: (150÷400 km ) reflects the short

radiowaves.

F region: (150÷400 km ) reflects the short

radiowaves.

IONOSPHERE

This means that people who broadcast from

the Earth using HF frequencies can use the

ionosphere like a mirror (an electromagnetic

mirror) to bounce their signals anywhere in the world.

The ionosphere can distort radio

signals from satellites.

High Frequency (HF, 3-30 MHz)

or short-wave radio signals can be reflected by the ionosphere.

IONOSPHERE

THE SOLAR CYCLE

SOLAR CYCLE VARIATION OF IONOSPHERIC CHARACTERISTICS

The main causes of large scale variations in ionospheric layers are related to the 11-year

solar cycle. The last solar cycle peak occurred in 2000-2001. The current cycle peak is

progressing through its maximum phase.

SATCOM OUTAGE REGIONS

IONOSPHERIC STRUCTURE IN SPACE

IONOSPHERE-THERMOSPHERE PROCESSES

MULTIPLE DAY SPACE WEATHER EVENT BY SOHO

(Solar and Heliospheric Observatory)

ANIMATED SPACE WEATHER EVENT

A coronal mass ejection (CME) is an ejection of material from the solar corona..The ejected

material is a plasma consisting primarily of electrons and protons. When the ejection reaches the

Earth, it may disrupt the Earth's magnetosphere. When the magnetosphere reconnects on the

nightside, it creates trillions of watts of power which is directed back toward the Earth's upper

atmosphere.

THE SKYLAB CRASH

•Track and identify active payloads and debris (DOD)

•Collision avoidance and re-entry prediction (NASA)

•Study the atmosphere’s density and temperature profile (Science)

Skylab, 1978

April 9, 1979

CYPRUS DIGITAL IONOSONDE (digisonde)

More than 15 ground-based ionosondes are currently available covering European

ionosphere. The recently started Nicosia DPS-4D ionosonde station is expected to

introduce new opportunities for real-time ground based ionospheric operations in

the Mediterranean area.

Rome (41.8°N, 12.5°E)

Ebro (40.8°N, 0.3°E )

Athens (38.0°N, 23.5°E)

Nicosia (35.1°N, 33.3°E)

Gibilmana (37.9°N, 14.0°E)

El Arenosillo (37.1°N, 353.3°E )

CYPRUS DIGITAL IONOSONDE INSTALLATION IN 2008

The increase of electron density of ionosphere can be monitored and displayed by ionosondes. Ionosondes are radars that measure the electron density of the ionosphere up to the maximum electron density by means of bottom-side radio sounding. Regular radio sounding are made from Nicosia station since 2009. The data is open for public access via Digital Ionogram DataBase (DIDBase) and Digital Drift DataBase (DriftBase) Web Portals. Our ionosonde data provides 5 minute values in automatically scaled form.

IONOSONDE OPERATION

THE IONOGRAM

The ionogram is the record produced by the ionosonde which shows the time delay

between the trasmission time and the received echo from the ionospheric layer

(proportional to the altitude) as function of the radio frequency.

A SPACE WEATHER EVENT DETECTED OVER CYPRUS

foF2 and vTEC variations at Nicosia during 9-15 October 2008

SOLAR FLARE EVENTS IN 2015

The practical significance of the increase in D-region electron density caused by solar flares lies on the

increase of signal absorption that it produces causing limited window of operating frequencies for HF

communications.

QUIET TIME FLARE TIME

RESULTS

A SOLAR FLARE EVENT DETECTED OVER CYPRUS

………………………..the nature of ionosphere is highly variable and can make it difficult to find and maintain a frequency to communicate.

Although ionospheric global models represent a valid tool to plan HF links,

ionospheric regional models can be important to catch some features that may

be easily neglected by global models.

Cyprus Ionospheric Forecasting Service

CYPRUS IONOSPHERIC FORECASTING SERVICE (CIFS)

fplot Nicosia station http://ionos.ingv.it/cyprus/fplot.htm

CYPRUS IONOSPHERIC FORECASTING SERVICE (CIFS)

foF2 nowcasting maps http://ionos.ingv.it/cyprus/fof2_nowcasting.htm

CYPRUS IONOSPHERIC FORECASTING SERVICE (CIFS)

foF2 long-term maps http://ionos.ingv.it/cyprus/fof2_long_term.htm

CYPRUS IONOSPHERIC FORECASTING SERVICE (CIFS)

MUF nowcasting maps http://ionos.ingv.it/cyprus/muf_nowcasting.htm

f<12MHz

CYPRUS IONOSPHERIC FORECASTING SERVICE (CIFS)

EFFECT OF SPORADIC-E

The presence of a Es layer which does not allow for ionosonde signals to reach F2

region altitudes does not allow a useful ionogram to be obtained and therefore gaps in

the data series of foF2 are formed. These gaps have to be interpolated in a way to

preserve the inherent variability of foF2 data.

0

2

4

6

8

4/18/2009 4/19/2009 4/20/2009 4/21/2009

Date

foF

2 (

MH

z)

0

2

4

6

8

5/13/2009 5/14/2009 5/15/2009 5/16/2009

Date

foF

2 (

MH

z)

No Es

Es

EFFECT OF SPORADIC-E LAYER OVER CYPRUS

INTERMEDIATE DESCENDING LAYERS OF METEOR ORIGIN OVER CYPRUS

Hei

gh

t, k

mH

eig

ht,

km

Nicosia Feb. 26 – Mar 19, 2009

Nicosia Feb. 26 – Mar 19, 2010

MODELING OF INTERMEDIATE DESCENDING LAYERS

THE CYPRUS DIGITAL IONOSONDE CONTRIBUTES TO GLOBAL MODELING

TOPSIDE INVESTIGATION OVER CYPRUS

The ionosonde can only probe up to the F2peak. Therefore to investigate the

topside ionosphere over Cyprus we used satellite data.

Occulting LEO

Occulting GPS

Calibrating GPS

Ground receiver

1-sec data (LINK 4)

20 msec data (LIN

K 2)

1-s

ec d

ata

(LIN

K 3

)

20 msecdata

Ionosphere

Neutral atmosphere

Earth

(LINK 1)

GPS Sat.

GPS Sat.

GPS Sat.10 sec data

10 sec

dat

a

10 sec d

ata

GPS sounding of the Ionosphere onboard CHAMP

GPS Satellite

CHAMP

CHAMP Orbit

Radio Signal

Occulting LEO

Occulting GPS

Calibrating GPS

Ground receiver

1-sec data (LINK 4)

20 msec data (LIN

K 2)

1-se

c dat

a (L

INK 3

)

20 msecdata

Ionosphere

Neutral atmosphere

Earth

(LINK 1)

GPS Sat.

GPS Sat.

GPS Sat.10 sec data

10 sec d

ata

10 s

ec d

ata

Occulting LEO

Occulting GPS

Calibrating GPS

Ground receiver

1-sec data (LINK 4)

20 msec data (LIN

K 2)

1-s

ec d

ata

(LIN

K 3

)

20 msecdata

Ionosphere

Neutral atmosphere

Earth

(LINK 1)

GPS Sat.

GPS Sat.

GPS Sat.10 sec data

10 sec

dat

a

10 sec d

ata

COSMIC vs ionosonde peak characteristics over Cyprus

0

4

8

12

0 4 8 12

Nicosia foF2 (MHz)

CO

SM

IC f

oF

2 (

MH

z)

R=0.96

160

220

280

340

160 220 280 340

Nicosia hmF2 (km)

CO

SM

IC h

mF

2 (

km

)

R=0.87

Area considered with positions of one week of RO electron density

measurements and location of Cyprus ionosonde station.

RADIO OCCULTATION MEASUREMENTS

COSMIC VS IONOSONDE PEAK IONOSPHERIC

CHARACTERISTICS OVER CYPRUS

COSMIC VS IONOSONDE TOPSIDE PROFILE COMPARISON OVER CYPRUS

ELECTRON DENSITY PROFILE MODELS OVER CYPRUS

GPS system

• The GPS constellation is constituted by a

network of 24 satellites orbiting at 20,200

km from the Earth surface. They are evenly

distributed within 6 orbitals planes inclined

55 with respect to the Earth’s equator and

equally spaced at 60. Each satellite has a

period of 12 hours.

• GPS satellites transmit two simultaneous

PRN signals whose carrier frequencies are

1575.42 MHz and 1227.60 MHz,

respectively. GPS receivers record these

signals as Pseudo Range and Relative

Phase.

Civilian GPS Applications Potentially Impacted

MEASUREMENT OF TEC BY SPECIAL GPS RECEIVERS

Dual-frequency GPS data recorded by GPS receivers enable an estimation of

ionospheric variability because of the frequency dependent delay imposed on the

signal due to the ionosphere. By processing code and phase measurements on two

frequencies in the L-band ( L1=1575.42 MHz, L2=1227.60 MHz) it is possible to

extract an estimate of the Total Electron Content (TEC) measured in total electron

content units.

TECcf

tion 2

3.40

2

1).(

h

hdhhNTEC

CYPRUS DGPS STATION

GPS+ IGS: Global Iono. scanner

GPS+ IGS

Worldwide scanner of the Ionosphere which allow to generate global VTEC maps from ~30 GPS dual-freq.

transmitters and 300+ global GPS permanent receivers

(50,000+ STECs each 30 seconds).

GUIDANCE APPLICATIONS

IONOSPHERIC IMPACT ON NAVIGATION AND POSITIONINGComplex temporal and spatial changes within the Earth's ionosphere can limit and degrade

the performance of earth to satellite systems. Communication systems involving trans-

ionospheric propagation may be disrupted; global positioning networks compromised and

surveillance (both optical and radar based) systems affected.

NEQUICK ASSESSMENT OVER CYPRUS

NEQUICK ASSESSMENT OVER CYPRUS

• To compare NeQuick with of vTEC (vertical TEC) over Cyprus through a high (2001) andlow (2008) solar activity periods we present a representative month of Fall (September).GPS TEC was derived for each hour and subsequently the median, the lower and upperdeciles were computed to reveal the variability. It is evident that NeQuickunderestimates vTEC during high solar activity especially around midday andoverestimates at low solar activity.

September 2008

0

5

10

15

20

0 6 12 18 24

UT

vT

EC

(TE

CU

)September 2001

0

10

20

30

40

50

60

70

80

0 6 12 18 24

UT

vT

EC

(TE

CU

)

January 2001

0

10

20

30

40

50

0 6 12 18 24

UT

vT

EC

(TE

CU

)

Lower decile

Median

Upper decile

NeQuick

SATELLITE-BASED AUGMENTATION SYSTEM (SBAS)

SATELLITE-BASED AUGMENTATION SYSTEM (SBAS)

EGNOS (THE EUROPEAN GEOSTATIONARY NAVIGATION OVERLAY SERVICE) TYPICAL

PERFORMANCE

Diffractive and refractive

processes from irregular

electron density structure

Causes phase jitter and

amplitude fading – called

scintillation

What is scintillation and why is it important?

Scintillation is important

because it disrupts

satellite-ground

communications and

navigation systems

Particular of interest to

GPS users with safety-

critical applications

IONOSPHERIC INSTABILITIES PRODUCE SCINTILLATIONS

Ionospheric impact on navigation and

positioning

• Ionospheric perturbations will also impact GALILEO

Ionospheric gradients Ionospheric scintillations

GPS/GALILEO

TECVIonospheric

irregularities

Reference

station

User

User

Phase errors

Misleading

Corrections

DGPS Single point user

Signal strength fluctuations

availability and safety reduced

Motion of gradients

v

Dual frequency measurements

enable estimating the

Total Electron Content (TEC)

dsnTEC es

ne

1st order

ionospheric

range error

Is ~ TEC

SCINTILATION IMPACT ON NAVIGATION AND POSITIONING

TEMPORAL AND SPATIAL CHARACERISTICS OF SCINTILLATIONS

CYPRUS SCINTILLATION MONITOR

The scintillation receiver takes 50 GPS measurements per second, and performs statistical analysis on

these measurements. These statistics are shown below. The S4 index is a measure of amplitude

scintillation, that is rapid variation in the apparent signal strength. Sigma phi is a measure of phase

scintillation, that is (roughly speaking) rapid oscillation in the delay between the signal leaving the

satellite and arriving at the receiver.

IONOSPHERIC SCINTILLATIONS OVER CYPRUS

IONOSPHERIC SCINTILLATIONS OVER CYPRUS

IONOSPHERIC SCINTILLATIONS OVER CYPRUS

VLF TRANSMITTERS

US Navy VLF transmitter, at Lualualei, Hawaii. This transmitter has

radiated power of ~500 kW operating at frequency of 21.4 kHz. The towers

in the background are ~460 meters high each.

CYPRUS VLF (AWESOME) STATION

A VLF station has been in operation in the last four years to initiate VLF studies in Cyprus.

It is based on the Atmospheric Weather Electromagnetic System for Observation, Modeling,

and Education (AWESOME), a research-quality monitor developed by Stanford University.

It facilitates the study of several space weather related phenomena like solar flares

VLF MONITORING OVER CYPRUS

STORM MONITORING USING VLF

IONOSPHERIC TOMOGRAPHY OVER CYPRUS

IONOSPHERIC TOMOGRAPHY OVER CYPRUS

MORE RECEIVERS =HIGHER TOMOGRAPHIC RESOLUTION

TOHOKU EARTHQUAKE AND TSUNAMI IN IONOSPHERE

Data and methodology - Seismic events Seismic events

No of Earthq Mw Date time (UT) R (km) Lat (°) Lon (°) Depth

(Km)

Region

E1 7.2 11/12/1999 16:57 1247 40.78 31.21 10 western Turkey

E2 6.9 02/14/2008 10:09 927 36.50 21.67 29 southern Greece

E3 6.5 02/14/2008 12:08 624 36.35 21.86 28 southern Greece

E4 6.4 06/08/2008 12:25 565 37.96 21.53 16 southern Greece

E5 6.3 04/06/2009 1:32 512 42.33 13.33 8.8 central Italy

E6 6.2 06/15/2013 16:11 463 34.45 25.04 10 Crete, Greece

E7 6.2 01/06/2008 5:14 463 37.22 22.69 75 southern Greece

E8 6.0 04/01/2011 13:29 380 35.66 26.56 59.9 Crete, Greece

E9 6.5 11/17/2015 07:10 624 38.6 20.6 11 Lefkada, Greece

E10 6.9 05/24/2014 9:25 927 40.29 25.39 6.43 N. Aegean Sea, Greece

E11 6.1 16-04-2015 18:07 420 34.99 26.98 6.33 Crete Istand

E12 5.6 15-04-2015 08:25 256 34.82 08:25 27.62 Cyprus

EUROPE

CyprusGreeceItalyTurkey

The preparation area is the area where the ionosphere above it is affected by earthquake precursors and is defined as a circle with radius ρ=100.43Μ

km

Data and methodology - Seismic events Seismic events

Strong earthquakes (M>7.5)in 2015

Nepal M7.8 Chile M8.3

Peru M7.6Afghanistan M7.5

Chile M8.3 earthquake

on 16 September 2015

Data and methodology - Seismic events 1. Statistical envelope method

Diurnal TEC variations (red solid line), corresponding upper (blue dotted line) and lower bounds (green dotted line) fixed at μ±1.34σ and mean TEC variationsμ (black solid line) are depicted for 4 GPS stations for 13 days before, during and 1 day after the Chile seismic event at 16th September 2015. Blue shadedareas show the geomagnetically disturbed periods and blue vertical line shows the earthquake main shock. Plots for each GPS station are ordered by theirdistance from the epicenter. The first three stations are located inside and the last outside the earthquake preparation zone. Diurnal variations of Dstgeomagnetic index is also shown (upper panel).

2. Spectral analysis

Fluctuations of differential TEC (T=40m period ) obtained from measurements of 6 satellites (PRN) passing over the area of interest during 15-18 UT at the day of earthquake (16th Sep. 2015). The power spectrographs of the amplitude are also shown. Map shows the number and position of satellites IPP (blue asterisks), the position of the GPS receiver station SANT (pink triangle) and the earthquake epicenter (green asterisk)

Inspection of all spectrograms revealed persistent enhanced amplitude TEC fluctuations on 7, 11, 14, 15September and the day of earthquake 16 September, starting at around 13UT and lasting for approximately 8hours (up to 21 UT), deriving from SANT and CORD receivers measurements which are located near theepicenter. These TEC oscillations are mainly periodic with a period around 20 min. Their time of appearancedemonstrates regularity centered at approximately 1300-2100 UT.

Thank you for your attention!!!