441
1 INTRODUCTION
Theneedtoevaluatethepossibilityofpassagealong
theNorthernSeaRoute(NSR)arosewhenvesselsof
relativelylow ice classappeared on theNSR. Rapid
changes in sea ice cover cause periodic blocking of
individualsections ofthe NSRby driftingice fields.
Thisappliesespeciallytothespaceconstraintsatthe
nodes of the route and especially to the narrow
passages. In these pla
ces there occur specific
phenomenon of ice cover (concentration processes,
pressure of ice, hummocking and drift of sea ice)
whichreducethesafetyofvessels,especiallythoseof
low iceclass. For this reason, hydrometeorological
data,especiallyinformat
ionabouticeconditionsand
specific risksarising ineach section ofthe NSR,are
veryimportanttoshipping.Thereexistvarioustypes
oficedata requiredtoevaluatethepassageofvessels
throughtheiceandtheshipʹssafespeed.The above
datawereinit
iallydescribedandusedover20years
ago in theʺIce Passportʺ for Russian vessels. The
content of theʺIce Passportʺ is now defined by the
IMOandthesamedocumenttooktheofficialnameof
theʺIce Certificateʺ (IMO, 2011). The Ice Certificate
describesseaworthiness ofvessels in ice,ta
king into
account structure of the hull, dimensions,
displacement, propulsion system, characteristics of
thepropeller,theageandactualconditionofthehull.
The Ice Certificate contains a vessel’s speed in
conjunction with sea ice cover thickness,
concentrationoficefloe,icefloesize,icepressureand
hummocking. It facilitates the ma
king of well
founded and documented decisions (IMO 2011).
Calculations of the above mentioned vessel’s safe
speed on ice have been described by Ryvlin and
Chejsin(1980).
These sources of limited content or accessibility
wereusedforrouteplanninginiceformanyyears.In
recent yearsthere haveappeared a large number of
new data sources, mainly in the form of processed
sat
ellite images. However, the quality of the
Functionality of Sea Ice Data Sources on the NSR
T.Pastusiak
GdyniaMaritimeUniversity,Gdynia,Poland
ABSTRACT:ThefunctionalityofavailableofficialsourcesofseaicedatafortheNorthernSeaRoutetodateis
low.Inrecentyearsalargenumberofnewpubliclyavailablesourceshaveappeared.Theirfunctionalityfor
purposes of route planning has yet to be evaluated. This study presents results of qualit
ative and expert
analysesofvarioussources.Itisproposedtousenewindicatorstoenablecomparisonoffunctionalityofdata
sources.Newsourcesprovidethetechnicalprogressthatisinstrumentalinreducingtheamountofeffortand
influenceofthehumanfactorinthedecisionmakingsystem.Thestudyalsopresentssolutionstotheproblem
oflimit
edbandwidthavailableathighlatitudeswithIridiumsatellitesystem.Presentedsolutionscanbeused
onanyvesselbyanycompanyornavigatortoimplementordesignthedecisionsupportsystemrelatedtoroute
planninginiceinaccordancewiththerequirementsoftheISMCodeandconceptofeNavigation.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 10
Number 3
September 2016
DOI:10.12716/1001.10.03.09
442
information available for use in the procedure of
planning and monitoring a voyage from an e
Navigation point of view has not been assessed.
Assumed in this study is that the scheme of route
planningthroughicecoveredareasofthe NSRshall
take into account the safety of the
decision process,
facilitation of downloading more reliable and
complete data in the most useful format and
functionality,whichistominimiseinvolvementofthe
user (IMO, 2008; Patraiko, 2008; Jurdzinski and
Pastusiak,2009).Theuser(navigator)shouldbeable
to control a vessel traffic safety according to
applicable rules and
should not be engaged in
activitieswhicharenotdirectlyrelatedtothevessel’s
movement control. It is possible to minimise
workload during downloading data sources,
digitalisation, processing and evaluation of results.
The decisionmaking process should affect not only
content of the data sources but also their accuracy,
resolution,availability
and informationon reliability
and overall quality. Determined in this study are
criteria for assessing the operational sources of
information related to navigation in sea ice covered
areasontheNSRandqualityassessmentprocedures
ofdesignateddatasources.Thesecriteriacontainthe
information content of data sources, accuracy,
resolution,
reliability,generalqualityofdatasources,
workloadandweightofthecontent.
2 RESEARCHMETHODS
In orderto assess theavailability and the quality of
information about current hydrometeorological
conditions, information from the services GMDSS
(Safety NETforecasting areas of METAREA XX and
XXI and also NAVTEX data) was systematically
collectedforaoneyearperiodoftime,followedbyan
evaluation of their content. There was found a high
levelofgeneralisationoficedataprovidedbyvarious
means from the official sources. This indicates that
they cannot be used as a sole basis for passage
planningonthe
NSR,especiallyinnarrowpassages.
Therefore, other available data sources on the Web
wereanalysed, whichcontainmorepreciselydefined
parametersoftheseaicecover recognisedintheIce
Certificate or classified as hazards that occur on the
NSR. In total, 80 groups of data sources were
analysed. Data sources
were evaluated using
qualitonomicanalysis(HolodnikJanczurak,2007)by
newly developed indicators. Values of adopted
quality scale are in the range from 0 (worst) to 1
(best).Theweightsassignedforeachdatasourcesets
are according to their ascending or descending
importance for their intended purpose, which is to
evaluatethepossibilityofpassingapartoftheNSR.
The cumulative level of quality reached by various
datasourcesisdefinedbytheformulafortheaverage
value of quality indicators (HolodnikJanczurak,
2007). Firstly is taken into account the safety and
effectiveness of the decisionmaking process of the
route planning, helping to obtain information more
reliableandmorecomplete inamoreuseful format,
next functionality and automatic operation with
minimalinvolvementofuser(eNavigationcriterion).
Secondly it is assumed that the information and
commands for direct implementation on a vessel’s
bridgebynavigatorsʺshouldbegiven
inaclearand
simplemannerʺ(ISMcriterion).
The author created a mathematical model of
assessmentbasedonexpertresearch.Thisarosefrom
the experience of the author, interviews with
practitioners and experts as well as a qualitative
analysis of problem and conclusions. Appropriate
softwarewasusedfortypeoffile
ormethodofdata
storage during study. In first place was the use of
Windows software as the most widespread and the
software supported by it or freeware software
supportedbyWindowsora licensedsoftwareoflow
priceofpurchaseandthereforeeasilyaccessibletoa
navigatoronthe
shiportoshipowner.Datasources
arerelatedtothetimeperiod20112012.
3 CHARACTERISTICSOFSEAICEDATA
SOURCES
The evaluation of functionality of analysed sea ice
datasourcesforvoyageplanningpurposestakesinto
accountseveralcharacteristics.Themostimportantof
theseareoutlinedbelow.
3.1 Weight
ofthecontent
Weight of the content (Table 1) was determined on
the basis of its usefulness for voyage planning. The
highestweightwasgiventotheparametersdescribed
intheIceCertificateandparametersconsideredtobe
the most serious threat to navigation on the NSR.
Theydirectlyinclude
strengthofthevesselʹshulland
ability to overcome ice with a safe speed under
definediceconditions. Theweight ofthe icedrift in
Table1isequal0.5.Thisvaluewasadoptedforopen
sea conditions. In case of narrow straits the
importance of ice drift data increases
due to the
existenceoflocalphenomenaofclosinga leadandthe
icejeteffect.Increasedvaluesoftheweightcoefficient
upto1.0shouldbeconsideredintheseregions.
Table1.Weightcoefficientofcontent
_______________________________________________
WeightWeight
_______________________________________________
Iceunderpressure 1.0 Openingsinice1.0
Hummockedice 1.0Formationofsnowandice
“cushion”atvessel’shull 1.0
Iceforms1.0Stageoficemelting1.0
Thicknessofice 1.0Icedrift0.5
Thicknessofsnow 1.0Fog0.25
Concentration1.0Icingofvessel
0.25
Floesizes
1.0
_______________________________________________
3.2 Resolution‐characteristicsofpositionprecisionon
maps
Datasourceshavevariousformsandmethodsofdata
recordinganddatapresentation.Mostsourcesdonot
containinformationonthescaleofthemap.Therefore
anewconceptfortheresolutionhasbeenintroduced‐
the minimum identifiable distance. Resolution was
adopted
asacriterionforcomparingtheprecisionof
position of various kinds of data sources. Three
443
methodsto determine theresolution of data sources
weredevelopedfor:
vector files (SIGRID3, KML, KMZ), raster image
graphics and their vector transformations (BMP,
JPGPNG,GIF,TIF,EPS,PDF) theshortestlength
of a straight line, which approximates to isoline
curveofthesmallestobservedradius,
griddedfiles(GRIB, NetCDF,HDF)thelengthof
thesidesofasinglegrid,
raster files (BMP, JPG, PNG, GIF, TIF) with an
averagedgridofdatathatdoesnotcoincidewith
themeridiansandparallels‐thelengthoftheside
of a single grid that is
specified by the
manufacturer.
3.3 Volumeofdatastoragesourcesanddatatransfer
indicators
Inordertocompareabilitytodownloaddatasources
were developed indicators (measures) of volume of
the internet file transfer
V
f
and the volume of
internet file transfer with the necessary elements of
the website
V
w
. File data transfer rate indicator
Q
f
(Formula 1) is the quantity of files able to be
downloaded during visibility of one satellite of the
Iridiumsatellitesystemabovethehorizon.
1
3600
f
f
B
Q
V
(1)
where:
Q
f
file data transfer rate indicator,
V
f

volume of the internet file transfer [kB],
B
data
transfer rate of Iridium satellite system [kB/s].
Bandwidth adopted for calculations is equal to 7.2
kb/s, equal to 0.95 kB/s,
τ
I
the average time of
availabilityofoneIridiumsatelliteabovethehorizon
[hours]. According to information from the Iridium
company
τ
I
is a pproximately equal to 10 minutes.
Forthe purpose of calculations the value
τ
I
= 0.1667
hourshasbeenadopted.
Replacing
V
f
intheformula(1)to
V
w
allowsthe
obtainmentofformulaforrateindicator
Q
w
ofthefile
datatransferwithnecessaryelementsofthewebsite.
Data transfer rate indicators
Q
f
and
Q
w
characterise
ability to download a file. In practice it has been
observed that visibility of the next Iridium satellite
does not guarantee the continuity of a download.
Usually a download is aborted. Data transfer rate
indicators
Q
f
and
Q
w
take into account factors
attributable to satellite communication system
(download time and time of visibility of single
satellitebythereceiverofsatellitesystem).
Bothindicators
Q
f
and
Q
w
expresshowmanytimes
aparticularfileorafilewiththeaccompanyingweb
site during visibility of a single satellite by the
receiver for satellite systems can be downloaded. A
comparisonof indicators
Q
f
and
Q
w
candetermine
the cause of reduced data transfer and at the same
time the opportunities to improve it. Under real
conditions the limiting criterion of ability to
downloadafileisvalueofindicator
Q
w
equalto1.
Figure1.Schemeofdownloadingprocedure
Figure2.Schemeofdigitisingprocedure
3.4 Workload
Various data sources were examined and finally
universal procedures for their acquisition and
digitising have been developed. They are shown in
Figures1and 2with anindication ofa samplepath
for a HDF file and NetCDF file. The sequence of
actions in the procedure of downloading and
digitising data sources represents the sequence of
444
necessarysteps(Figure1)requiredtodownloadand
save information XYZ (latitude, longitude and
parameteroficenavigation)onacomputerinaform
acceptable for further mathematical calculations
(Figure2).
It has been observed that data sources come
together in three groups with similar downloading
and digitising patterns. These
are: (1) vector files
KMZ,SIGRID3andShapefile,(2)rasterandvector
mapswithgridcoordinatesBMP,JPG,TIF,GIF,PDF,
EPSandrastergeoreferencedmapsGEOTIFFand(3)
griddedfilesGRIB1,GRIB2,NetCDFandHDF.
Workloadisthenumberof operationsperformed
in
diagrams(Figure 1and Figure2), which involves
anoperatordownloadingafilefromtheInternetand
digitisingthedata.Workloadindicator
Q
e
istheratio
of workload of downloading and digitalisation of
examined file
e
i
to the highest workload occurring
amongtheexaminedfiles
e
max
.Ithasbeendescribed
byformula2.
max
i
e
e
Q
e
 (2)
3.5 Accuracy
Thefilesareavailabletotheuserforacertainperiod
of time after the moment from which they were
issued. In the considerations was adopted the
indicator
Q
a
(Formula 3) referring to the number of
hours of delay
t
a
and the number of hours of
operational planning cycle
t
o
, which was assumed
equal to 168 hours. Time shift is always negative
when consideringʺanalysisʺ. Time shift, as a rule,
must be positive when consideringʺforecastsʺ. This
indicator prefers forecast over analysis (the future
statemorethanthehistoricalone).
2
oa
a
o
tt
Q
t
 (3)
Based on different scales of the operational
planning for the navigation in ice (Khvochtchinski
andBatskikh, 1998; Timco et al., 2005), the assumed
averagedurationoftheoperationalplanningcycleis
equalto7days(168hours).
3.6 Qualitycharacteristicsofadatasource
Theabilitytoexportor
writethedataina formatthat
isfitforreadingandprocessingsoftware.
Table2.Exportofdataindicator
Q
1
_______________________________________________
Indicator
Q
1
_______________________________________________
Unabletoexportdata0.00
Cannotexportnorsavefilesinsimpletextformats 0.25
Textfiles(TXT,ASCII)possibleforusebyspecialised0.50
software(suchasMATLAB)
Textfiles(TXT,PRN,CSV,XLSX)withacomplex 0.75
structureofdatastorage(storedinseparatetabsof
MSExcel)
Text
files(TXT,CSV,XLSX)withasimpleCSV 1.00
structuresuitableforeasyuseinMSExcel
_______________________________________________
The simplicity of transferring data and their
application in reading and processing software was
adopted as a quality criterion of the data source
(Table2). Simplicity and clarity received the highest
position in evaluation scales due to requirements of
theISMCodeandtheeNavigationconceptcriteria.
3.6.1 Explanation
ofthescaleoftherelevantinformation
(legend)
It is assumed that the navigator on board the
vessel uses what he found on board. A equipment
deficiency would cause difficulties for the navigator
tocarryouthisorhertasksandimpairthequalityof
work done. Availability of scale
of presented
information
Q
2
(Table 3) helps determine a proper
value in relation to limits and increases precision of
the assessment. In the same way it helps to avoid
improperreading.Scaleclarityindicator
Q
3
allowsto
assignthepropervalueofthisparameter(Table4)to
establishedstandardscalesofjudgment.
Table3.Legendavailabilityindicator
Q
2
_______________________________________________
Indicator
Q
2
_______________________________________________
Legendofinformationisnotavailableinsourcefile 0.0
Legendofinformationisnotavailableinsourcefile.0.5
Itishoweveravailableinthedigitalpartofinformation
onawebpageorinapublicationonsourcefile
Legendofinformationisavailableinsourcefile 1.0
_______________________________________________
Table4.Legendclarityindicator
Q
3
_______________________________________________
Indicator
Q
3
_______________________________________________
Thescaleisnotclearlyunderstoodorthereis 0.000
noreference
Simplifiedscaleinrelationtopreciselydefined 0.333
establishedstandard
Scaleofparameterisdescribedincommonly 0.667
knownunits
Scaleofinformationisinaccordancewith 1.000
establishedstandard
_______________________________________________
3.6.2 Typeoffile
File type indicator
Q
4
(Table 5) reflects usability
and simplicity to direct use in the evaluating
possibilities of the NSR passage and also to data
processingwhenusingcomputation.Thescaleoffile
type indicator
Q
4
measures workload for the
application of data sources in the automatic
evaluationofpossibilitytonavigatetheNSR.
Table5.Filetypeindicator
Q
4
_______________________________________________
Indicator
Q
4
_______________________________________________
Rastergraphicfileorotherwithoutgridof 0.000
coordinatesorwithoutgeoreferencedpositions
Textfileofgeographicalpositionsorpositions 0.143
relatedtoareadescribedinanotherdocument
(plaintext)
Rastergraphicfilewithgridofcoordinates0.286
Vectorgraphicfilewithgridofcoordinates  0.429
Rastergeoreferencedgraphic0.572
Vectororgriddedgeoreferencedfile0.715
Textalphanumericfilewithrecordedgeographical0.858
positionsasunordered(complex)dataseries
Textalphanumerictiedpositionsinthisorin 1.000
anotherfileasanordered(simple)dataseries
_______________________________________________
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3.6.3 Reliabilityofdatadescribed
Toassessthereliabilityofinformationonnautical
charts the concept of Zones of Confidence has been
introduced.Onthis basis, onecandetermine quality
of data on nautical charts for safe navigation. The
concept of confidence level was also developed for
thecoverageof
unsurveyedregionsbynauticalcharts
and publications such as those for research vessel
equipmentsupportfornavigationinpoorlysurveyed
regions (Pastusiak, 2011). Sourcesof hydro
meteorologicalandicedatashouldalsobeevaluated
bytheindividualreliabilityindicator.Asameasureof
reliabilityofaparticularparameter ofice
navigation
wasadoptedtheconceptofthepossibilitytomakea
routingdecisiontakingintoaccountthereliabilityof
theparametervaluesreceivedfromprovidersandnot
only the value of a single parameter. Information
obtained from satellite imagery transformations
should be provided with information on quality for
each message (file)
taking into account spatial
distribution.Inthiscase,itispossibletoincludethis
information into data processing and evaluation of
route calculated. Two indicators were adopted in
ordertoassessthereliability(quality)ofthedescribed
parameter: indicator on availability of reliability of
data described as
Q
5
(Table 6) and indicator on
availabilityofqualityscaleofthisparameter
Q
6
(Table
7). Assuming that information about the parameter
qualityallowsitsevaluation,avaluecanbeplacedon
ascaleofquality“theworst‐thebest.ʺ
Table6. Indicator on availability of reliability of data
described
Q
5
_______________________________________________
Indicator
Q
5
_______________________________________________
Noinformationaboutqualityofparameter0.0
Nodataonqualityparameterinthefilebutitis 0.5
availableinaseparatesourceofinformation
Informationaboutthequalityofparameteris 1.0
availableinfile
_______________________________________________
Table7. Indicator on availability of reliability scale of
parameter
Q
6
_______________________________________________
Indicator
Q
6
_______________________________________________
Nodatainfileonscaleofquality0.0
Noqualityscaleinfilecontainingdatabutscaleis 0.5
availableinaseparatesourceofinformation
Informationonqualityscaleisavailableinfile 1.0
containingdataonquality
_______________________________________________
3.6.4 Digitalisation
Theconceptofdigitalisationsetsouthowtomove
data from a source file (usually visualised using
software) to data processing software. For each
separatefile indicators of accessibility were
considered (as described in Table