Platform Repeat Argo and Underway Moorings Tide gauges Animal Glider/AUV Satellite Airborne Ice stations Ice Shelf hydrography other samplimg sensors Stations & drifters* Traverses (surface) Parameter Temperature XBT, XCTD Yes <- suspended moorings CTDs, and distributed temperature sensing (DTS) Salinity XBT, XCTD Yes <- suspended moorings CTDs Velocity In surface Yes Surface <- moorings layer (ADCPs) Tracers Nutrients Developing Oxygen Yes Microstructure

Sea ice Wind, accumulation If ice-free Automatic Automatic weather weather stations on stations on ice shelves ice shelves and fast ice and fast ice Sea surface height If ice-free (SLR) Seabed pressure

Ice SHELF topography InSAR, Radar Radar (RES) GPS (spot and Laser and Laser values or altimetry altimetry traverse) Ice SHELF thickness buoyancy Radio Echo seismic, estimates Sounding RES from surface (RES), topography buoyancy estimates from surface topography Ice SHELF flow speed InSAR, GPS feature tracking, Glacier topography InSAR, Radar Radar (RES) GPS and Laser and Laser altimetry altimetry Glacier flow speed InSAR, GPS, feature boreholes tracking, to measure depth profiles of velocity. SST If ice-free SSS If ice-free Bottom topography gravimetry seismic below ice SHELF

Bottom topography gravimetry seismic (seafloor Bathymetry under floating ice ?)

Bottom topography RES, RES, (Bedrock under gravimetry Seismic grounded ice)

Ice SHELF basal upward Phase melt/freeze rates looking Coherent altimeter RES (instrument at surface) Ice SHELF englacial Embedded Embedded temperatures (for temperatur temperatur ocean ice heat e sensors e sensors: transfer fluxes) (boreholes) thermistor chains or DTS (boreholes) * Good as complement to other methods, but there is a problem with the drifters moving out of the measurement region too fast.

DTS - Distributed Temperature Sensing - e.g. optic fibre systems RES - Radar echo Sounding - i.e. Radar that penetrates ice sheets