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Remote Sensing:

Remote Sensing:. Observing a BIG COUNTRY. David Griffin & Edward King. CSIRO Marine and Atmospheric Research . It’s a big country, with a lot happening. Forecasting currents is like weather forecasting.

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Remote Sensing:

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  1. Remote Sensing: Observing a BIG COUNTRY David Griffin & Edward King CSIRO Marine and Atmospheric Research

  2. It’s a big country, with a lot happening David Griffin

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  5. Forecasting currents is like weather forecasting People talk about using models to interpolate observations (time and space) and/or extrapolate to other variables That’s true but remember: 1) models only represent a subset (length- and time-scales) of reality -> some details cannot be forecast 2) eddy-resolving models generate eddies spontaneously, i.e., creates spectrum - > a critical number of obs are required before skillful forecasts (and accurate hindcasts) can be made What can satellites provide? David Griffin

  6. Satellites are the principal means of making models track reality Satellites are a cost-effective way of obtaining broad-scale observations of a few key variables, continuously. Especially cost effective for Australia. Remember that. Sea level (-> geostrophic velocity), wave height, sea surface temperature, salinity, gravity (->mass), colour (-> chl-a, bathymetry, etc) But there’s a catch. The ‘oceanography’ needs to be carefully teased from the raw data. Eg: ‘coastal altimetry’. Hence the formation of space agency mission-specific science teams. We are invited to respond to the ESA Sentinel-3 AO (Nov) We are already members of various STs. Typically in ‘spare time’. David Griffin

  7. Altimeters measure lines of sea level anomaly David Griffin

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  10. Sea level anomaly: OI using 3 altimeters David Griffin

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  15. Why measure sea level? Because you can. Because SLA(x,y) = f(T(x,y,z), S(x,y,z)) But there’s a catch: the Earth is lumpy (>100m). GRACE and GOCE measure the geoid down to 100km scales. Sea level = Range – orbit - geoid – path_delays – aliases Sea level = Range – orbit – MSS + MDT – path_delays – aliases 0.20m = 1350km – 1300km – 50m + 1m – 0.2m – 0.2m Spectrum of errors: 1cm to 2m Mostly well controlled. Under-sampling is the main problem. David Griffin

  16. Altimetric sea level = steric height (+ barotropic) David Griffin

  17. We read track data from NOAA/TUDELFT RADS David Griffin

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  19. Sea Surface Temperature Crucial for correcting drift in models Meso-scale information mostly lost during assimilation issues: cloud clearing, atmospheric corrections, geo-location, diurnal variability - > good validation information (when skies are clear) Feature-track currents: a mix of good and bad IMOS processes NOAA AVHRR and MODIS SST to GHRSST standard Recently discovered: geolocation errors in CAPS Microwave radiometers: low res but all-weather Need to prepare for AVHRR replacements David Griffin

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  21. Ocean Colour SeaWiFS, MODIS, MERIS Under-exploited for a decade or more IMOS now processing MODIS (aqua) routinely, from L0 data NASA SeaDAS 6.1 -> 6.4 algorithms. Back-process pre-2011 soon David Griffin

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  23. Summary For modelling, altimetry, SST and Ocean colour are the mainstays Gravity and salinity missions are the new kids on the block Next talk: Synthetic Aperture Radar Immediate future: Australian involvement in the ESA Sentinels. AO announced in a month. Australia – ESA collaboration agreement Australia – India, Aust-China, ….. David Griffin

  24. Thank you David Griffin & Edward King +61 3 6232 5244 David.Griffin@csiro.au oceancurrent.imos.org.au CSIRO Marine and Atmospheric Research

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