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Home Instrumentation Ionogram Data SAO Explorer Drift Data

Drift Explorer

GIROprovidesaccuratespecification of

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electrondensity intheEarth'sionosphe

re at >60locationsin theworld

37 GIROlocationsprovidereal-timeionospheric datato the

centralserver inLowell,Massachusettswithinseveralminutes

GIROsites areequipped

byDigisondeinstruments thatuse highfrequency remotesoundingtechnique to

probebottomsideionosphere from80 km upto thepeak of

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ionosphericplasmadensity

Real-time

andretrospective datafromGIROlocationsareingestedin LowellDigitalIonogram

DataBase(DIDBase)

GIROdata areopenedfor publicaccessviaDIDBase

WebPortalandcustomsoftwaretools fordigisondedataanalysis,SAOExplorer

and DriftExplorer Please

makesure toreadRules of

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the Road

Contac

t:

Prof.

Bodo W.

Reinisch, LDI

Prof.

Ivan A.

Galkin,

UMLCA

R

Digisonde is an ionospheric radar,

ionosonde, that uses high frequency (HF)radio waves for the vertical-incidenceremote sounding of the ionosphere, atechnology incepted by Sir EdwardAppleton in the late 1920s

Digisonde is an acronym for DigitalIonospheric Goniometric Ionosonde

The first Digisonde wasdeployed at Eglin AFB inFlorida in 1969

123 digisondes have been builtby UMLCAR engineers as ofMarch 2010

Full station list by instrument is

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Digisonde belongs to a class of advancedionosondes that evaluate angle of arrival,polarization, and Doppler frequency shiftof skywave signals reflected from theionosphere, in addition to their travel time

that is conventionally used to determinerange to the reflection point

here

Digisondeionogrampresentssignalsreflectedfrom theionospherein the

frequency vstravel timeframe, withsignalstrengthmapped tothe imageintensity,and colorused torepresent

signal status(polarization,angle ofarrival,Dopplershift)

Individualreflectedsignals(echoes)observed on

eachsoundingfrequencyform tracesin theionogramimage

Red color

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shades areused forverticallypropagatingordinary

polarizationechoes

The leadingedge ofvertical O-trace (blackline) has tobe extractedin order tocalculatevertical

ElectronDensityProfile (EDP)up to thepeak density

TopsideEDP sectionabove thepeak density(dashed line)is obtained

inassumptionof the -Chapmanshape of theprofile

Extractionandinterpretationof the signaltraces in

recordedionogramimages is anintelligent,machine-hardproblem offeature

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recognition ARTIST

software isreponsiblefor automatic

ionograminterpretationandcalculation ofthe EDP

DigisondeSpread-FDirectogramdisplays timehistory of

echoespropagatingoff-verticallyafterreflectingfromirregularplasmastructures

Y-axis istime, and X-

axis ishorizonaldistance intheionosphereto thereflectionpoint, with 0corresponding to thesounder

location Vertical

echoes arenot shown;blankdirectogrammeans quiet(horizontally

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stratified)ionosphere

Signatures inthedirectograms

indicatedevelopmentof Spread Fconditions

Doppler signof echoes isanalysed tolabel plasmastructuresapproachingon one side

anddeparting tothe otherside with thesame color

In theexampledirectogram,developmentandeastward

drift of 8plasmabubbles isdetected byCachimbodigisonde inBrazil

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SAO Explorer is the flagshipsoftware tool for working withGIRO ionograms

SAO-X has capability ofaccessing ionograms and

ionogram-derived data from60+ locations in the LowellDIDBase (via TCP/IP port3060)

DIDBase is Digital IonogramDataBase

9+ million ionogram images 12+ million ionogram-derived

records Web Portal access for image

browsing

Common SAO Explorer Data Visualizations and Tools

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Interactive ionogram scaling

environment Mouse-driven leading edge

highlighter ARTIST-5 autoscaling

algorithm to reduce overallmanual effort

Profile inversion algorithmNHPC

Visualization controls,including content selectors,data labels, and detail-on-

demand context window

Time series of commonionospheric characteristics

IRI-2001 model valuesavailable for comparisons

Plain text export for externaldata analysis

Time history of the verticalprofile of electron density

X axis is time, Y axis isaltitude, and color is mappedto plasma density

Example from Millstone HIllobservatory illustrates

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ionospheric response to astrong interplanetary shockevent

Doppler

Skymap: Skymap

presentsionosphericechoes in 2Dskycoordinatesystem thatmaps theechoes

("sources")onto a 2Dfundamentalskymap planeusing theirazimuth andzenith arrivalangles, thusdiscarding therangeinformation

The skymapplanepresents thezenith angleas radius andazimuth angleas polarangle of the

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polarcoordinatesystem

Color ismapped to

the Dopplerfrequencyshift, with redshadescorresponding to recedingplasma, blueshades - toapproachingplasma, andgreen shades

- to slowlymovingplasma

ObservedDopplerfrequencyshift isconverted tothe light-of-sight (LOS)velocity that

is further splitinto horizontaland verticalcomponents

Drift DataAnalysis(DDA)techniquetreats thewhole area ofionosphere

illuminated byDigisondesignal as asingle entitymoving at thesame bulkdrift velocity

DDA uses the

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least squaresfit method toobtain best fitof all sourcesvisible on the

skymap withtheirindividualDoppervelocities tocompute theLOS bulkvelocityvector

Calculatedhorizontal

and verticaldrift velocitycomponentsare shown inthe skymapusing thearrowsymbols

Skymaps arealso used todetermine the

center ofreflectionsthatcorrespondsto the large-scale tilt oftheionosphericplasmadistribution inthe reflecting

area

The examplefromTrivandrumdigisonde inIndia shows aclassicnighttime

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zonal drift ofionizationbubblesacross thestation from

West to East

Timeseries ofthe DDAbulk driftvelocity:

Driftvelocityvector ispresented by onechart oftheverticalvelocitycomponent Vz

and twocharts ofthehorizontalvelocitycomponents thatcan useeitherCartesian (EastandNorthcomponents ) orcylindrical(asimuth

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andradialcomponents)represen

tations Error bar

indicatehow wellthe bulkvelocityvectorrepresentsunderlying

skymapsources Larger

errorbarscorrespond togreaterdeviation ofobserve

dplasmamotionsin theskymapfrom thecollective bulkmotionassumed by

DDAalgorithm

Localsunriseandsunsettimes

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arelabeledappropriately inthe

centralpanel ofthe plot

Thisexamplevelocityplot fromTrivandrumdigisonde shows

classicsignatures of theequatorialplasmadrift: (1)westwarddaytimezonal

drift at~270azimuth,(2)eastwardmighttime drift at~90azimuth,and (3)

verticaluplift oftheplasmainresponse to thepre-

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reversalenhancement oftheelectric

fieldduringeveninghours

Drift Explorer is the mainsoftware tool for working withGIRO ionospheric drift datausing DDA technique

Drift-X has capability ofaccessing drift data records,

including raw receive channeldata and derived data(skymaps, ionospheric tilt,velocity time series) from 39locations in the Lowell DriftBase(via TCP/IP port 3060)

4+ million raw drift datameasurements

3+ million Doppler skymaps 3+ million drift velocity records

Common Drift Explorer Data Visualizations and Tools

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Interactive skymap browser Skymap Survey

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Separate panels for drift in Eand F regions of the ionosphere

Detail-on-demand window forextended data display at thecrosshair pointer position

Display of frequency and heightintervals where the raw driftdata were acquired for velocitycalculations

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