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Questions and Answers

Questions and Answers have been archived here from the Ask an Expert web board.

Why don't they launch the Deep ARGO floats in the box like the regular Argos?  

Hi Megan, good question. The Deep Argo is made of glass but has a protective layer of plastic on the outside. They are also easier to put in the ocean as they stay upright rather than tipping over because they are a round shape unlike the long, thin cylinder shaped regular Argo Floats. Sometimes regular Argo Floats are also deployed without a box. Both these types of floats are expensive, have fragile antenna and need to be deployed carefully. You can watch how they are deployed in the videos; http://www.learnz.org.nz/argofloats142/videos.
From Shelley the LEARNZ field trip teacher.

What if the ARGO float data is right and the CTD data is wrong?

Hi Georgia, good question. I think this is less likely as the CTD has been thoroughly tested before taking samples at the same sites as the Argo Floats. If the CTD doesn't work properly during the first test run then it is fixed or the spare CTD is used instead.
From Shelley the LEARNZ field trip teacher.

Do the gliders go from place to place taking samples? Does it have a motor, and why don't they only use gliders instead of ARGO floats?

Hi Angus, gliders don't have a motor but they do have a pump that can change a glider's buoyancy. The gliders are used for quite different things and as they move around more they don't last more than six months. The gliders also are used in shallower water to measure things that change more quickly like in coastal waters. So, Argo floats are good for long term measurements at greater depth, whereas gliders are good for measuring things that change quickly over a short period of time.
From Shelley, the LEARNZ field trip Teacher.

Could they make an argo float that goes deeper than 5000 meters? would there be any point?

Hi Murphy, the Deep Argo floats can go to 6,000m and at the moment there is no need for information from the really deep areas which are often canyons or trenches which are too confined for floats anyway.
From Shelley the LEARNZ field trip Teacher.

Could Solar panels be attached to Argo Floats, so that the battery could be recharged a little when the Argo is on the surface and therefore made to last longer?

Hi Nic, this sounds like a good idea but it's hard to get enough solar energy when the float is down underwater for 10 days and only on the surface for about 20 minutes. Also the weight of the panel would mean that the float would use more energy rising to the surface so this could use up more energy than the panel can generate. Some surface buoys do have solar panels though.
From Shelley, the LEARNZ field trip Teacher.

What did the boats use to measure salinity and temperature? Was it the same as what the Argo Float does?

Hi Georgia, the boats back in the old days would have lowered a bucket on a rope to take water samples to measure temperature using thermometers rather than modern sensors. They would have measured the chemical properties of the water e.g. chloride content to find out salinity (by titration, which finds the proportion of certain chemicals), they would not have measured salinity. Nowadays boats can have sensors that measure the water coming into the ship to find out salinity and temperature. These sensors would be similar to those used on Argo Floats.
From Shelley, the LEARNZ field trip Teacher.

Which is colder the Arctic or Antarctica (water and air temperature)?

Hi Jake, the Antarctic water is often colder as it is deeper and has more salt in it (higher salinity), so can get to lower temperatures. Also the lowest air temperatures have been recorded in inland Antarctica because this is a large landmass rather than just sea ice so the air temperature is not warmed by the ocean so can get to lower levels.
From Shelley the LEARNZ field trip Teacher.

If you put the regular Argo float, down very deep in the ocean, when is the pressure too strong, how long will it survive before it can’t stand all of the pressure, and what would happen to it?

Hi Laura-rose, regular Argo floats are destroyed at around 2,600m deep, where they implode (collapse in on themselves) and are basically squashed. That's why the deep water floats are designed differently and are a sphere rather than a cylinder so can withstand greater pressure.
From Shelley the LEARNZ field trip teacher.