20230421 12282900 1.0 TRUE jonathan.edwards-opp National Ice Center (NIC) (301) 817-3911 (301) 817-3990 4521 Suitland Road Washington DC 20395 US liaison@natice.noaa.gov 20060317 ArcGIS Metadata 1.0 National Ice Center (NIC) GL230420_lam The SIGRID-3 vector archive format is one of the World Meteorological Organization (WMO) standards for archiving digital ice charts in the Global Digital Sea Ice Data Bank (GDSIDB). The WMO ice chart archiving formats are the Sea Ice Grid (SIGRID) format developed in 1981 and formalized in 1989 and its successor SIGRID-2. The National Ice Center digital Ice Analysis charts (Hemispheric, Regional and Daily are encoded in SIGRID-3 and have two main components: the shapefile containing the Ice Analysis ice information (ice polygons and related attributes) and the metadata describing the Ice Analysis data under the SIGRID-3 format. The National Ice Center legacy ice data set contains hemispheric spatial data files from 1972 through 2004 inclusive. Regional Spatial data files of the traditional "seas"(ex Beaufort Sea) have been available since 1997. Legacy data are available in various formats from the National Snow and Ice Data Center in Boulder, Colorado ( http://nsidc.org/ ). Legacy Great Lakes charts are available from the Great Lakes Environmental Research Laboratory in Ann Arbor, Michigan ( http://www.glerl.noaa.gov/ ). Currently (October, 2006), spatial data files are available for each hemisphere, and for each sub-regional area, of which there are approximately 62. The ice analyses for each sea or sub-sea are also available in a jpeg format. They represent the ice conditions for the week in which they are published. Data for the analyses can go back 96 hours from when they are completed. They are dated with the week they are published. They are based on an analysis and integration of all available data on ice conditions, including weather and oceanographic information, visual observations from shore, ship and aircraft, airborne radar, satellite imagery and climatological information. The Regional Ice Analyses describe areas of differing ice conditions using the WMO ice observing standards, and indicate where significant changes in the amount, stage of development and form of the predominant ice types have occurred. The Regional Ice Analyses for all of the Northern and Southern Hemisphere Seas are produced every other week. The analyses for the Bering, Chukchi, Beaufort, Arctic Basin (High Arctic), Northern East Greenland, Barents, Kara and White Seas and the Cook Inlet are produced at least weekly. The Ross Sea is produced weekly during Austral Summer navigation season. The Chesapeake and Delaware Bay areas are produced weekly when there is ice. The analyses for the Great Lakes (when there is ice and in collaboration with the Canadian Ice Service), the Bering Sea, the Cook Inlet and the Chukchi and Beaufort Seas are produced twice per week when there is an ice edge present. The National Ice Center also produced daily ice edges in text format for both the Northern and Southern Hemispheres. The SIGRID-3 Regional Ice Analysis products are mainly used for climate analysis, climate change studies and as input to the Global Digital Sea Ice Data Bank (GDSIDB). They can also provide ice information to marine community to enhance the safety and the efficiency of marine operations in ice-encumbered waters. Great Lakes East sea ice ice type ice age ice concentration form of ice floe size none at the present time sea ice ice type ice age ice concentration form of ice floe size Great Lakes East With accreditation from the National Ice Center same as Publication Date The first step consists on manually creating a Regional Ice Analysis coverage and incorporating data from the various source information. Automated validity checks are performed during attribute (WMO Egg code, in accordance with the World Meteorological Organization standards for reporting ice conditions) and line entry. A topological polygon build is done to clean the coverage, corrections are made (if required) and a chart is produced for manual quality control. Once completed the Regional Ice Analysis coverage is automatically converted to a shapefile, the metadata is generated and they are packaged as a SIGRID-3 product (.tar) for distribution. The ice interpretation (boundaries, concentrations, ice types and floe sizes) of Satellite and Airborne imagery is done visually with the help of climatological data, ground truthing and meteorological data. The reliability and accuracy of the data set is directly related to the availability, resolution and the affects of atmospheric (cloud, daylight, etc.) and ground (snow, rain, sea state, etc.) conditions on the source information. The source information is incorporated in the Regional Ice Analysis if the source information publication or acquisition date is plus or minus 3 days of the Regional Ice Analysis publication date. The only exception is the Regional Ice Analysis source information where we use the previous publication date. Note that the time period information for all source information represent the time period during which it was available and may or may not have been incorporated in the Regional Ice Analysis product. Since 1968, Regional Ice Analyses have been compiled from numerous data sources generally acquired plus or minus three days of its publication date. Over the years, data sources have included a wide variety of satellite imagery, aerial reconnaissance and ship borne reports. Each data source and its availability over the years is described in their respective source information. The Regional Ice Analyses are presently being generated using in house software (ISIS system: ERDAS and ARC/Info). RADARSAT Imagery - % of total Canadian Space Agency (CSA) source information acquisition date 1996-03-13 NOAA Imagery - % of total National Oceanic and Atmosphric Administration (NOAA) source information acquisition date 1970-12-11 Advanced Very High Resolution Radiometer - % of total National Oceanic and Atmosphric Administration (NOAA) source information acquisition date 1998-05-15 OLS Imagery - % of total US Airforce (DMSP) source information acquisition date 1999-05-21 QuikScat Imagery - % of total National Aeronautics and Space Administration (NASA) source information acquisition date 2001-11-01 ERS Imagery - % of total European Space Agency (ESA) source information acquisition date 1992-12-18 2003-06-05 ENVISAT Imagery - % of total European Space Agency (ESA) source information acquisition date 2003-10-09 MODIS - % of total National Aeronautics and Space Administration (NASA) source information acquisition date 2004-12-01 SAR Imagery - % of total SIP Challenger source information acquisition date 1990-01-01 1995-03-31 SLAR Imagery - % of total Canadian Ice Service (CIS) source information acquisition date 1978-02-13 Observed Charts - % of total Canadian Ice Service (CIS) source information publication date 1957-06-14 Image Analysis Charts - % of total Canadian Ice Service (CIS) source information publication date 1990-01-18 Daily Ice Analysis Charts - % of total Canadian Ice Service (CIS) source information publication date 1959-02-16 Regional Ice Analysis Charts - % of total Canadian Ice Service (CIS) source information publication date 1968-06-25 Estimate - % of total National Ice Center (NIC) source information publication date Regional Ice Analyses in SIGRID-3 format The SIGRID-3 vector archive format is one of the World Meteorological Organization (WMO) standards for archiving digital ice charts in the Global Digital Sea Ice Data Bank (GDSIDB). The WMO ice chart archiving formats are the Sea Ice Grid (SIGRID) format developed in 1981 and formalized in 1989 and its successor SIGRID-2. A Regional Ice Analysis encoded in SIGRID-3 has two main components: the shapefile containing the Regional Ice Analysis ice information (ice polygons and related attributes) and the metadata describing the Regional Ice Analyses data under the SIGRID-3 format. A shapefile consists of three core files (but may include several optional files). Each file in the set shares the shapefile name with a different extension. The main file (*.shp) stores shape geometry and must always have an index file (*.shx). A database file (*.dbf) stores all the attributes of the shapes in the main file. SIGRID-3 uses the widely accepted, public domain eXtensible Markup Language (XML) for metadata (information on the Regional Ice Analysis and how it was generated). A file in XML stores the metadata that pertains to each Regional Ice Analysis. Metadata includes projection, location, keywords, and contact information. A file in XML can be read using a web browser, and it is easy to make it available for searches via the Internet. To archive a Regional Ice Analysis in SIGRID-3 (.tar), four files are required: three for the Regional Ice Analysis in shapefile format (.shp,.shx,.dbf) and one for the metadata (xml). The database file consists of a set of mandatory and optional fields which are described in the Entity Type Definition Source and are listed below. As per SIGRID standards: undetermined or unknown applicable fields are reported as "99", empty applicable fields are reported as "-9" and empty or unknown non applicable fields are reported as null. Two new attributes (COVSHP_ , COVSHP_ID) are added to the list of SIGRID-3 attributes during the automatic conversion of the Regional Ice Analysis from coverage to shapefile. They are both sequential unique whole numbers that are automatically generated by the ESRI conversion tool (as is the FID Label). For more information, please refer to the SIGRID-3: A Vector Archive Format for Sea Ice Charts Developed by the International Ice Charting Working Groups Ad Hoc Format Team for the WMO "Global Digital Sea Ice Data Bank" project (WMO/TD-No. 1214, 2004) Feature Class 0 FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. FID OID 4 0 0 Shape Feature geometry. ESRI Coordinates defining the features. Shape Geometry 0 0 0 ICECODE ICECODE String 45 0 0 CT Total concentration of all ice in the area WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI CT String 2 0 0 CA Partial concentration of thickest ice WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI CA String 2 0 0 SA Stage of development of thickest ice WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI SA String 2 0 0 FA Form of ice corresponding to SA WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI FA String 2 0 0 CB Partial concentration of second thickest ice WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI CB String 2 0 0 SB Stage of development of second thickest ice WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI SB String 2 0 0 FB Form of ice corresponding to SB WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI FB String 2 0 0 SO SO String 2 0 0 SD SD String 2 0 0 CC Partial concentration of third thickest ice WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI CC String 2 0 0 SC Stage of development of third thickest ice WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI SC String 2 0 0 FC Form of ice corresponding to SC WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI FC String 2 0 0 FP FP String 2 0 0 FS FS String 2 0 0 POLY_TYPE Surface Type WMO JCOMM ETSI SIGRID-3 WMO JCOMM ETSI POLY_TYPE String 2 0 0 Shape_Leng Shape_Leng Double 19 0 0 Shape_Area Shape_Area Double 19 0 0 Area of feature in internal units squared. Esri Positive real numbers that are automatically generated.