SIGRID-3: A New WMO format for Ice Chart Archival and Exchange:

Status and Remaining Issues

IICWG-4, April 7-10St. Petersburg, Russia

The IICWG

Ad Hoc Format Working Group

The IICWG Ad Hoc Format Working Group

From the Arctic and Antarctic Research Institute, Vasily Smolyanitsky, Yuri Scherbakov, and Viktor Porubaev;

From the Canadian Ice Service, Richard Chagnon and John Falkingham;

From the Danish Meteorological Institute, Henrik Steen Andersen and Morten Lind;

From the U.S. National Ice Center, Jonathan Hasse, Doug Lamb, and Paul Seymour; (lead on SIGRID-3 Technical description document)

From the U.S. National Snow and Ice Data Center, Florence Fetterer.

GDSIDB SIGRID-3 Format Progress

• ETSI-1 and GDSIDB - IX, Buenos Aires, 21-25 October 2002: IICWG ad hoc format team presented proposed SIGRID-3 format to Expert Team on Sea Ice

• Need to make final edits (Wednesday 9 AM IICWG-4 Technical Breakout mtg)• V. Smolyanitsky will submit final draft and recommendations for formal approval and

publication by WMO Secretariat, through JCOMM (M. Krasnoperov)

• We anticipate a later revised version, or addendum

• Supplementary material, examples on GDSIDB web site

• DMI, NIC (and CIS?) will begin producing charts for archive in SIGRID-3 as soon as format is finalized

GDSIDB Vision – to preserve ice chart data in archives, and to make digital versions of ice charts available for research use

GDSIDB at AARI: http://www.aari.nw.ru/gdsidb/

GDSIDB at NSIDC: http://nsidc.org/noaa/gdsidb/

Some Characteristics of SIGRID-3• Based on ESRI shapefile format• Each chart will have at least 4 files - .shp (polygon

shapes), .dbf (attributes), .shx (index) and .met (metadata) • File naming convention will include identifiers for issuing

country/organization, geographic region and date• Recommended projection will be polar stereographic true at

60N with central meridian at 180 using the WGS84 spheroid • Ice attributes will follow existing WMO SIGRID codes and

field names • Metadata will follow the FGDC metadata standard, and be in

XML if possible.

References - Chagnon. 2001. CIS/NIC Proposed SIGRID 3 Format. CIS Informal Paper, Canadian Ice Center, Ottawa.Hasse. 2001. National Ice enter Shapefile Format Options. NIC Informal Paper, 24 October, National Ice Center, Washington, DC.

SIGRID-3 Format Information and Tools

Online:http://nsidc.org/noaa/iicwg/ahfwg_discussion.htmlhttp://nsidc.org/noaa/gdsidb/formats.htmlhttp://nsidc.org/noaa/gdsidb/s3development

• SIGRID-3 shapefiles examples• Technical description of shapefiles• Links to info on xml editors….

Here:Arc Explorer (free software for viewing shapefiles [and FGDC metadata?]Sample shapefiles from DMI and NICMetadata Tools SurveySIGRID-3_Draft_9Paper copy of WMO SIGRID format

Remaining Issues Before SIGRID-3 Document is Finalized

• Section 2.3 on Required database fields – need to distinguish between info needed to make dBase fields on one’s own, and info needed by ESRI software user.

• Section 2.4 on “dummy” or “missing” variable – need clarification. SIGRID uses “99” for undetermined or unknown. This does not cover all cases.

(work we have to do today)

Remaining Issues Before SIGRID-3 Document is Finalized

• Any issues brought by J. Falkingham for R. Chagnon?

• Section 2.4 on “dummy” or “missing” variable – need clarification. SIGRID uses “99” for undetermined or unknown. This does not cover all cases.

• Page 3 – [….], Page 7 – [….], Page 9 – [….] • Other issues?

(work we have to do today)

Other Remaining (non-critical) Issues

• Table 2 – Can we create a more informative XML example? Either for document, or for website –HA

• When not an ice polygon (e.g. have L, W, N, or S in poly_type column, are other columns filled with –9?

• Metadata -- Can we create a “master” dtd and stylesheet? Any volunteers?

Other Remaining Issues

• Metadata -- Need lists of acceptable keywords. Perhaps each center proposes their own. Any volunteers?

• Extension of format for points and lines. Yuri? • Proposal by V. Porubayev for alternative coding

of Stage of Development. (part of Proposals for a new WMO Sea Ice Nomenclature – terms, symbols and code tables?)

• Other non-critical issues?

Action Items• ???

BACKGROUND

Current FormatsGDSIDB formats

• SIGRID (Proposed 1981, Thompson)

• SIGRID-1 (Adopted by WMO, 1989)

• SIGRID-2 (Adopted by WMO, 1994)

• SIGRID-3 (Proposed vector format)

• Contour

• e00 (proprietary GIS system export format)

• EASE-Grid

• shapefile

http://nsidc.org/noaa/gdsidb/formats.html for more info

Some other digital ice chart formats

Why a new format?

• SIGRID (Sea Ice Grid) first proposed in 1981 as GDSIDB archive format. SIGRID data archives are kept at AARI and at NSIDC

• Combination of grid (with min. spacing of 15’) and text encoding of ice chart information

• Most ice services no longer regularly submitting data to GDSIDB in SIGRID. (JMA’s continuing SIGRID submissions are noted with gratitude)

• Loss of accuracy and resolution from original charts

• Research community must reformat before using SIGRID files

• Many ice services use GIS for chart production. Therefore, we recommend a GIS vector file output format for "SIGRID-3".

• GIS output files: easy for ice centers to produce; archive data in vector format.• Vector files can be re-projected or re-scaled without loss of information. If desired,

conversion to raster can take place at the archive center.)

For accuracy, and to make charts easier to create

Some SIGRID-1,2 Characteristics

SIGRID: CT46CA309399CB209199CC018799CF1999CN95CD81

Fully Utilized Egg Code: 4-6/3200/7./4.1.7/1/~9 CC/CaCbCc/So/SaSbSc/Sd/

FpFp

SIGRID-3 Objective

• Facilitate the regular submission of ice charts in digital form to the GDSIDB by defining a new SIGRID-3 archive format based on ESRI shapefile format.

• Archive charts in a format that captures all the information in the original charts. A vector format is required.

History• June 2000 -- NIC and NSIDC proof of concept project to convert ESRI ArcInfo

export format E00 files to gridded format completed• July 2000 -- ESRI "Shapefiles" export format suggested as an alternative output

format. (E00 is an ESRI proprietary format, shapefiles are an open format.) ArcView shapefiles are a simple, non-topological format for storing the geometric location and attribute information of geographic features.

• October 2000 -- at IICWG 2, an ad hoc format working group presented a proposal for shapefiles. Ice services endorsed the proposal, pending evaluation.

• March 2001 -- DMI year 2000 Greenland ice charts sent in shapefile format to NSIDC.

• April 2001 -- CIS and NIC created sample charts as shapefiles

• June 2001 -- At JCOMM meeting, GDSIDB experts endorse shapefiles as an ice chart archive format, make recommendations on its implementation

• August 2001 -- Sample DMI charts and background information posted to IICWG web site, comments on the DMI shapefile format solicited.

History• October 2001 -- CIS/NIC shapefile based format proposed for SIGRID-3. Format was

developed at the September U.S./Canada Joint Ice Working Group meeting.

• November 2001 - CIS/NIC shapefile format and DMI shapefile format discussed by Ad Hoc Format Working group at Tromsø IICWG 3 meeting. Representatives of Sweden, Finland and the Baltic states do not use Arc software at present but endorsed the recommendation that shapefiles with FGDC format metadata be adopted as the archive format for ice service charts. They anticipate moving in the direction of GIS tools and shapefile production. NIC (D. Lamb) takes lead on coordinating development of format with CIS and other services for proposal to JCOMM

• May - Sept 2002 - Document for proposed SIGRID-3 in development, led by NICs J. Hasse

• August 23 2002 - telecon to finalize details of proposed format, AARI, CIS, DMI, NIC, NSIDC

• October, 2002 - presentation to ETSI, Buenos Aires meeting.

Advantages of SIGRID-3• Vector files can be re-projected or re-scaled

without loss of information

• Vector files are easier for most ice centers to produce

• Conversion to raster (at grid size of choice) can take place at GDSIDB archive center

• Non-proprietary format means even those centers that do not use commercial GIS packages can produce Shapefiles

NIC charts -- one example

DMI charts -- one example

Sea ice concentration from DMI shapefiles

Sea ice concentration from satellite passive microwave data