PRODUCT USER MANUAL For Regional High ... - MyOcean

PRODUCT USER MANUALFor Regional High Resolution Sea Ice Charts SvalbardRegionSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002WP leader: SIW TAC, Lars-Anders Breivik Issue: 2.0Contributors: Frode DinessenMyOcean version scope : Version 2.0Approval Date : 28 October 2011Project N°: FP7-SPACE-2007-1Work programme topic: SPA.2007.1.1.01 - development of upgraded capabilities for existing GMES fast-trackservices and related (pre)operational services. Duration: 39 Months

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1CHANGE RECORDIssue Date § Description of Change Author Validated By1.016.09.2011AllCreation of thedocumentFrode DinessenLars-Anders Breivik2.028.10.2011layoutAdaptation to newtemplate2.1 17-11-2011 Update Nomenclatureof fileL. Crosnier WP17© My Ocean – Public Page 2/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1TABLE OF CONTENTSI INTRODUCTION ......................................................................................................................................... 5II HOW TO DOWNLOAD A PRODUCT ......................................................................................................... 6II.1 Download a product through the MyOcean Web Portal Subsetter Service ......................................... 6II.2 Download a product through the MyOcean Web Portal Directgetfile Service .................................... 6III DESCRIPTION OF THE PRODUCT SPECIFICATION ...................................................................... 7III.1 General Description ................................................................................................................................. 7III.2 General Information ................................................................................................................................ 7III.3 Details of datasets ..................................................................................................................................... 8IV NOMENCLATURE OF FILES .................................................................................................................. 10IV.1 Nomenclature of files when downloaded through the MyOcean Web Portal Subsetter Service ..... 10IV.2 Nomenclature of files when downloaded through the MyOcean Web Portal Directgetfile Service 10IV.3 Grid type and Geographical Projection ............................................................................................... 10IV.4 Domain coverage (includes image of domain + projection used if any)............................................. 11IV.5 Update Time ........................................................................................................................................... 12IV.6 Temporal extend of analysis and forecast stored on delivery mechanism ........................................ 12IV.7 Other information: mean centre of Products, land mask value, missing value ................................ 12V FILE FORMAT ........................................................................................................................................... 13V.1 Netcdf ........................................................................................................................................................ 13V.2 Structure and semantic of NetCDF maps files ...................................................................................... 13V.3 Reading software...................................................................................................................................... 16© My Ocean – Public Page 3/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1GLOSSARY AND ABBREVIATIONSTACSIWNetCDFCFRMSSDNPCPUftpOpenDAPSubsetterDirectgetfileThematic Assembly CentreSea Ice and WindNetwork Common Data FormClimate Forecast (convention for NetCDF)Root mean squareSeaDataNet (climatology)Production CenterProduction UnitProtocol to download filesOpen-Source Project for a Network Data Access Protocol. Protocol todownload subset of data from a n-dimensional gridded dataset (ie: 4dimensions: lon-lat,depth,time)MyOcean service tool to download a NetCDF file of a selectedgeographical box using values of longitude an latitude, and time rangeMyOcean service tool (FTP like) to download a NetCDF file© My Ocean – Public Page 4/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1IINTRODUCTIONThis guide describes the regional sea ice product SIW-METNO-ARC-SEAICE_HR-OBS- from theMyOcean Sea Ice and Wind Thematic Ensemble Centre, what data services are available to accessthem, and how to use the files and services.This products is produced and disseminated by met.no. It is a high resolution regional sea ice realtimeproduct for the Svalbard and Barents sea region covering the area from east Greenland toNovaya zemlya.The data are freely available under the MyOcean data license.© My Ocean – Public Page 5/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1IIHOW TO DOWNLOAD A PRODUCTII.1 Download a product through the MyOcean Web Portal Subsetter ServiceYou first need to register. Please find below the registration steps:http://www.myocean.eu/web/34-products-and-services-faq.php#1Once registered, the MyOcean FAQ http://www.myocean.eu/web/34-products-and-servicesfaq.phpwill guide you on How to download a product through the MyOcean Web Portal SubsetterService.II.2 Download a product through the MyOcean Web Portal Directgetfile ServiceYou first need to register. Please find below the registration steps:http://www.myocean.eu/web/34-products-and-services-faq.php#1Once registered, the MyOcean FAQ http://www.myocean.eu/web/34-products-and-servicesfaq.phpwill guide you on How to download a product through the MyOcean Web PortalDirectgetfile Service.© My Ocean – Public Page 6/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1III DESCRIPTION OF THE PRODUCT SPECIFICATIONIII.1 General DescriptionDetailed description:The operational sea ice service at met.no produces sea ice concentration charts based on a manualinterpretation of satellite data.The satellite data used are Synthetic Aperture Radar data from Radarsat and Envisat and visual andinfrared data from MODIS and NOAA.The Radarsat data are in scansar wide mode dual polarization. Each scene covers an area of 500 x500 km and is resampled to a spatial resolution of 150 meter. The scenes are mainly focused aroundthe Svalbard area.The Envisat data are in wideswath mode with a swath with of 450 km and are resampled to a spatialresolution of 250 meters.The data cover most of met.no ice charting area.The MODIS and NOAA data cover the charting area several times each day and are resampled to1000 x 1000 meter.The operator uses the latest available satellite data and draws the ice chart in an ArcGIS productionsystem.A new gridded sea ice concentration product is available every weekday around 1400 GMT at aspatial resolution of 1000 meter.III.2 General InformationProduct LinesSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Geographical coverage 80 W 80°E ; 60°N 85°NVariablesAnalysisForecastAvailable time seriesTemporal resolutionTarget delivery timeIce concentrationYesNoFrom 1 January 2010 – on goingDaily analysisDaily on working days before 15 UTC© My Ocean – Public Page 7/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1Horizontal resolutionNumber of vertical levelsFormat1.0 degSurface parameterNetcdf CF1.4Table 1: SEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002 Product SpecificationDetailed information on the systems and products are on MyOcean web site: www.myocean.eu .III.3 Details of datasetsThe product follows the WMO Concentration Color code for sea ice, where the concentration classesare defined by concentration intervals:• Fast ice: 10/10• Very Close Drift Ice: 9-10/10• Close Drift Ice: 7-8/10• Open Drift Ice: 4-6/10• Very Open Drift Ice: 1-3/10• Open Water: < 1/10These concentration intervals are converted to fixed concentration values in the gridded productdescribed by the “sea_ice_area_fraction” variable:• Fast ice: 100• Very Close Drift Ice: 95• Close Drift Ice: 75• Open Drift Ice: 50• Very Open Drift Ice: 20• Open Water: 5© My Ocean – Public Page 8/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1To reflect the WMO concentration intervals the “concentration_range” variable is given in theproduct defined by a +- concentration value for each grid point.DATASETSVARIABLES AND UNITor GEOGRAPHICALCOVERAGENAME OF VARIABLES INTHE NETCDF FILEor DOMAIN AREAMETNO-ARC-SEAICE_CONC-L4-NRT-OBS Ice concentration [%]"sea_ice_area_fraction"METNO-ARC-SEAICE_CONC-L4-NRT-OBS Concentration range [%]“concentration_range”Table 2: List of the datasets© My Ocean – Public Page 9/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1IV NOMENCLATURE OF FILESThe nomenclature of the downloaded files differs on the basis of the chosen download mechanismSubsetter or Directgetfile service.IV.1 Nomenclature of files when downloaded through the MyOcean Web PortalSubsetter ServiceFiles nomenclature when downloaded through the MyOcean Web Portal Subsetter is based onproduct dataset name and a numerical reference related to the request date on the MIS.The scheme is: datasetname-nnnnnnnnnnnnn.ncwhere :.datasetname is a character string within one of the following :· METNO-ARC-SEAICE_CONC-L4-NRT-OBS. nnnnnnnnnnnnn: 13 digit integer corresponding to the current time (download time) inmillisecondssince January 1, 1970 midnight UTC..nc: standard NetCDF filename extension.Example:METNO-ARC-SEAICE_CONC-L4-NRT-OBS_1303461772348.ncIV.2 Nomenclature of files when downloaded through the MyOcean Web PortalDirectgetfile ServiceFiles nomenclature when downloaded through the MyOcean Web Portal Directgetfile is based ason aZIP file: (for example)47558af621d7b4f2ca2cc7e037c67d0e_ice_conc_svalbard_7439f45570aa2e13df4e58ee9ec126b4containing the Netcdf filesice_conc_svalbard_201111151500.ncIV.3 Grid type and Geographical ProjectionThe product is gridded in a regular grid of 1000x1000 meter covering the area showed in the figurebelow. The projection used are polar stereographic with the following projection parameters:Polarstereographic (proj=stere lat_0=90.0 lat_ts=90.0 lon_0=0.0 R=6371000)© My Ocean – Public Page 10/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1IV.4 Domain coverage (includes image of domain + projection used if any)© My Ocean – Public Page 11/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1Figure 2: Spatial coverage of the SIW-METNO-ARC-SEAICE_HR-OBS productIV.5 Update TimeThe products are updated every weekday at 4 pmIV.6 Temporal extend of analysis and forecast stored on delivery mechanismThe product is stored since 1. January 2010IV.7 Other information: mean centre of Products, land mask value, missingvalueLand mask values are defined as value -99.© My Ocean – Public Page 12/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1VFILE FORMATV.1 NetcdfThe products are stored using the NetCDF format.NetCDF (network Common Data Form) is an interface for array-oriented data access and a librarythat provides an implementation of the interface. The netCDF library also defines a machineindependentformat for representing scientific data. Together, the interface, library, and formatsupport the creation, access, and sharing of scientific data. The netCDF software was developed atthe Unidata Program Center in Boulder, Colorado. The netCDF libraries define a machineindependentformat for representing scientific data.Please see Unidata netCDF pages for more information, and to retrieve netCDF software package.NetCDF data is:* Self-Describing. A netCDF file includes information about the data it contains.* Architecture-independent. A netCDF file is represented in a form that can be accessed bycomputers with different ways of storing integers, characters, and floating-point numbers.* Direct-access. A small subset of a large dataset may be accessed efficiently, without first readingthrough all the preceding data.* Appendable. Data can be appended to a netCDF dataset along one dimension without copyingthe dataset or redefining its structure. The structure of a netCDF dataset can be changed, though thissometimes causes the dataset to be copied.* Sharable. One writer and multiple readers may simultaneously access the same netCDF file.V.2 Structure and semantic of NetCDF maps filesdimensions:time = 1 ;xc = 3812 ;yc = 2980 ;variables:int time(time) ;time:long_name = "reference time of sea ice file" ;time:units = "seconds since 1981-01-01 00:00:00" ;float yc(yc) ;© My Ocean – Public Page 13/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1float xc(xc) ;yc:axis = "Y" ;yc:long_name = "y-coordinate in Cartesian system" ;yc:units = "m" ;xc:axis = "X" ;xc:long_name = "x-coordinate in Cartesian system" ;xc:units = "m" ;float lat(yc, xc) ;lat:long_name = "latitude" ;lat:units = "degrees_north" ;float lon(yc, xc) ;char crs ;lon:long_name = "longitude" ;lon:units = "degrees_east" ;crs:grid_mapping_name = "polar_stereographic" ;crs:straight_vertical_longitude_from_pole = 0.f ;crs:latitude_of_projection_origin = 90.f ;crs:standard_parallel = 90.f ;crs:false_easting = 0.f ;crs:false_northing = 0.f ;crs:proj4_string = "+proj=stere lon_0=0.0 lat_ts=90.0 lat_0=90.0 a=6371000.0b=6371000.0" ;short ice_concentration(time, yc, xc) ;ice_concentration:long_name = "sea ice concentration" ;ice_concentration:standard_name = "sea_ice_area_fraction" ;ice_concentration:units = "%" ;ice_concentration:coordinates = "lon lat" ;ice_concentration:grid_mapping = "crs" ;ice_concentration:source = "met.no" ;ice_concentration:_FillValue = -99s ;ice_concentration:scale_factor = 1.f ;ice_concentration:add_offset = 0.f ;© My Ocean – Public Page 14/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1short concentration_range(time, yc, xc) ;concentration_range:long_name = "concentration range" ;concentration_range:units = "%" ;concentration_range:coordinates = "lon lat" ;concentration_range:grid_mapping = "crs" ;concentration_range:_FillValue = -99s ;concentration_range:comments = "Range of the analyized ice consentration value" ;// global attributes::title = "Total Sea Ice Concentration from national ice services." ;:Conventions = "CF-1.4" ;:netcdf_version_id = "3.6.2-beta6" ;:creation_date = "2011-03-09T14:11:19Z" ;:produced_date = "2011-03-09T14:00:00Z" ;:valid_date = "2011-03-09T14:00:00Z" ;:product_version = "1.0" ;:software_version = "1.0" ;:comment = "The ice concentration is based on a manual interpretation of differentsatellite data. For more information about the the product contact the national ice service" ;:satellite = "Radarsat" ;:sensor = "ASAR" ;:spatial_resolution_latitude = 1000.f ;:spatial_resolution_longitude = 1000.f ;:southernmost_latitude = 54.36565f ;:northernmost_latitude = 88.10237f ;:westernmost_longitude = -80.36474f ;:easternmost_longitude = 85.30225f ;:field_type = "daily" ;:institution = "met.no" ;:institution_references = "http://www.retro.met.no" ;:contact = "iceservice@met.no" ;:operational_status = "operational" ;© My Ocean – Public Page 15/ 16

PUM for SIW TAC regional Arctic sea ice productSEAICE_ARC_SEAICE_L4_NRT_OBSERVATIONS_011_002Ref:SIW-TAC-PUM-011-002Date : 27. October 2011Issue : 2.1}V.3 Reading softwareNetCDF data can be browsed and used through a number of software, like: ncBrowse: http://www.epic.noaa.gov/java/ncBrowse/, NetCDF Operator (NCO): http://nco.sourceforge.net/ IDL, Matlab, GMT…© My Ocean – Public Page 16/ 16