TidalTidal workwork atat thethe NorwegianNorwegian HydrographicHydrographic ServiceService 1st meeting in IHO-TWLWG Rio de Janeiro 2009 Tor Tørresen Norwegian Mapping Authority Hydrograpic Service HowHow wewe areare organisedorganised The Norwegian Hydrographic Service (NHS) is a division in the Norwegian Mapping Authority. Other divisions are the Geodetic Institute and the Land Mapping Service. TidalTidal workwork inin thethe NHSNHS Run a network of 23 tide gauges Quality control of the data Drifting a tidal database Analyse the data Calculate tidal predictions and produce tide tables Distribute tidal data and tidal information TheThe NorwegianNorwegian tidetide gaugegauge networknetwork DifferencesDifferences inin tidaltidal rangerange Tromsø 3 Honningsvåg ] Vardø 2 Hammerfest 1 Tromsø 0 Andenes 51015202630 Harstad Vardø Kabelvåg Narvik 3 2 Rørvik Bodø 3 1 2 ] 0 1 51015202630 Rørvik 0 51015202630 Heimsjø Kristiansund Trondheim Ålesund Måløy 3 Bergen Bergen 2 Oslo 1 Oscarsborg 3 Stavanger Oslo 0 Helgeroa Viker 2 51015202630 3 Tregde 1 2 Stavanger 0 51015202630 1 0 51015202630 DataData flowflow Filtering and Sutron quality control Optical encoder Database 8210 Counterweight Float Level switch Web Electronic Chart Display and Copper cone Information System (ECDIS) Bronze plug TideTide gaugegauge atat TregdeTregde StillingStilling wellwell andand datadata loggerlogger Digital encoder Chain Sutron 8210 Contact point Modem Air pressure sensor RadarRadar TideTide GaugeGauge OldOld andand newnew systemsystem ProjectsProjects Automatic quality control of water level data Mean Sea Surface at the Norwegian Coast. Tidal model for the North Sea, the Norwegian Sea and the Barents Sea. Improving the web-pages http://vannstand.statkart.no Mareano AutomaticAutomatic QualityQuality controlcontrol Is required if the data will be used in near real time. The program must be able to find constant values, gaps, spikes and jumps. False values must be removed and gaps interpolated (if possible). Changes made to the data must be “flagged”. Bad data must not be published. CloseClose upup ofof partpart ofof thethe seriesseries Stavanger,Norway 27.May.2005 (3 hours), 1-minute values 0.78 0.76 0.74 Original 1-minute 0.72 values 0.7 0.68 0.66 Filtered Water Level [m] values 0.64 0.62 0.6 21:00 22:00 23:00 00:00 Time WaterWater levellevel observationsobservations withwith 1010 minuteminute intervalsintervals The sensor is sampled every second for three minutes and the average is calculated. We see a lot of noise, but is it noise?. WaterWater levellevel observationsobservations withwith 11 andand 1010 minuteminute intervalsintervals The 1 minute data are an average of 1 second samples for 60 seconds. We see that the ”noise” is nice oscillations with a period of approximately 20 minutes. The oscillations are probably only found in the harbour where the tide gauge is located. WaterWater levellevel observationsobservations fromfrom BergenBergen Red line is 1-minute observations, blue line is 10-minutes observations. A big ship is leaving the harbour. It creates oscillations at about 10 minutes and the 10-minute values shows to low water level. MeanMean SeaSea LevelLevel atat thethe NorwegianNorwegian CoastCoast We want find a LAT surface relative to the ellipsoid inshore From our primary and secondary harbours we know “a lot” about LAT relative to the MSL We need the MSL relative to the ellipsoid, and this is our first and most difficult problem Our plan is to use cheap pressure gauges in the vicinity of the primary stations and “transfer” MSL to the measuring sites We must also measure with a GPS at each site TidalTidal zoneszones NARVIK KABELVÅG 0,98 0,97 0 0,96 0 Blå tall: 0 1,02 Høydekorreksjonsfaktor 0,97 1,01 0 0 relativt nærmeste primærhavn 1,00 0 0,98 0 1,02 Grønne tall: 0 0 Tidskorreksjon relativt 0,97 0 nærmeste primærhavn 1,03 10 1,01 1,04 10 1,03 5 5 1,00 1,01 5 5 BODØ TheThe modelmodel areaarea MAREANOMAREANO BackgroundBackground The Barents Sea is getting more important (because of oil, gas and politics) A mapping project has started where the Norwegian Hydrographic Service does the hydrographic work and other institutions examine the geology and life on the bottom. The ellipsoide is used as the reference level and the GPS is used to find the water level. .