# Presentation: 509626

## Argo Profilersmissions, sampling rates, accuracy etc

- Howard Freeland
- D.F.O. Science/Pacific Region, Canada
- Tel: (250)-363-6590
- Email: FreelandHj@pac.dfo-mpo.gc.ca

- A

## Argo Profilersmissions, sampling rates, accuracy etc

- Howard Freeland
- D.F.O. Science/Pacific Region, Canada
- Tel: (250)-363-6590
- Email: FreelandHj@pac.dfo-mpo.gc.ca

- A

## Argo Profilersmissions, sampling rates, accuracy etc

- Howard Freeland
- D.F.O. Science/Pacific Region, Canada
- Tel: (250)-363-6590
- Email: FreelandHj@pac.dfo-mpo.gc.ca

- B

- 16th Nov.  2006
- 2658 floats

## The Argo community plans to deploy 3000 floats

## And we very nearly are there!

## How does an Argo float work?

- SOLO Float
- Courtesy of the animation wizards at Woods Hole and Scripps.

- APEX Float

- PROVOR Float

## How many of each float type?

- 20th Nov. 2006

## How are floats being launched? 

**How are floats being launched?**

- Floats are most commonly launched from research vessels

- Dropped from aircraft....

- Or deployed from container vessels

## The Air Launch is so neat, you’ve got to see this... 

**The Air Launch is so neat, you’ve got to see this...**

## Finally, what does a mission look like 

**Finally, what does a mission look like**

- X

## Alternate missions exist.... 

**Alternate missions exist....**

- Ocean surface

- 1000 db

- 2000 db

- 1) Launch

- 2) Dive

- 3) 10-d drift

- 4) Dive
- to 2000

- 5) Profile
-         to 0

- 6) Transmit
-         data

- Etc.

- The standard mission repeats 1) to 6) until batteries expire.

## Alternate missions exist.... 

**Alternate missions exist....**

- Ocean surface

- 1000 db

- 2000 db

- 1) Launch

- 2) Dive

- 3) 10-d drift

- 4) Dive
- to 2000

- 5) Profile
-         to 0

- 6) Transmit
-         data

- Etc.

- This is Park and Profile, PnP = 2
- I use PnP = 2, Riser is using 3 or 4
- a recent addition is DPF = Deep Profile First

- 7) Dive

- 8) 10-d
-     drift

- 9) Profile
-         to 0

## Alternate missions exist.... 

**Alternate missions exist....**

- Ocean surface

- 1000 db

- 2000 db

- 1) Launch

- 2) Dive
- to 2000

- 3) Profile
-         to 0

- 4) Transmit
-         data

- Etc.

- a recent addition is DPF = Deep Profile First
- this enhances quality control if the float was launched from a research vessel & doing CTDs

- 5) Dive

- 6) 10-d
-     drift

- 7) Profile
-         to 0

## New sensors are appearing

- Water intake and platinum resistance thermometer.
- Conductivity cell
- Aanderaa optode sensor, for dissolved oxygen which has gained acceptance because of perceived high value for the data return, and has minimal impact on the primary Argo mission.

## New sensors are appearing

- Wet Labs FLNTU fluorometer & turbidity sensor.

**New sensors are appearing**

## How do we get the critical information?

## Two critical items about float performance1) Accuracy, from manufacturer

- 						Resolution
- Sensor		Accuracy		Reported
- Pressure		2.4 dbar		0.1
- Temperature	0.002		0.001
- Salinity		0.005		0.001

- Analysis of floats recovered with various times at sea shows that these are being met and that sensors usually show little drift.

## Two critical items about float performance2) Float energetics

- Energy stored on an APEX = 2350 kJ (alkaline cells)
- => 220 profiles via Argos

|  | kJ/Profile |
| --- | --- |
| Controller | 0.71 |
| Buoyancy | 4.19 |
| SBE-41 | 1.55 |
| Argos Communications | 2.19 |
| Self discharge | 1.67 |
| Total | 10.31 |

## The messages are broadcast to a satellite 

**The messages are broadcast to a satellite**

## The messages are broadcast to a satellite 

**The messages are broadcast to a satellite**

**02442 25410  65 32 J 3 2006-11-17 06:09:37  44.963  233.944  0.000 401652016**
**      ****2006-11-17 06:03:37  1         72           05           11           A7**
**                                     ****85           E2           1B           51**
**                                     ****12           6B           85           BB**
**                                     ****19           5D           12           B0**
**                                     ****85           87           17           6A**
**                                     ****14           00           85           79**
**                                     ****15           73           14           A2**
**                                     ****85           59           13           81**

- This is message number 5, messages were received in the order:-  7, 8, 7, 9, 10, 11, 1, 10, 2, 5, 7, 9, 10, 8 etc

- 11A7 (hex) = 4519 (decimal) = pressure 451.9

- 85E2 (hex) = 34274 (decimal) = salinity 34.274

- 1B51 (hex) = 6993 (decimal) = temperature 6.993

## The messages are broadcast to a satellite 

**The messages are broadcast to a satellite**

- Floats in the Gulf of Alaska get 24 passes/day and it takes 8 hours to get a profile home.

- Floats in the Gulf of Guinea get 12 passes/day and it takes 16 hours to get a profile home, also costs kJ and total profiles.

## The consequence is:- 

**The consequence is:-**

- An easy exercise, count the floats in the Gulf of Mexico!

## A tightly integrated system 

**A tightly integrated system**

- A typical Canadian float uses the same parameters that Steve Riser uses, he has advised many nations.
- Average latitude = 50°N – 8 hours at sea surface
- We use PnP = 2 (i.e. drift at 1000 dbars, profile from 2000     every second profile)
- Transmit data from 72 levels
- Accuracy as specified by the manufacturer
- We have floats running with >170 profiles completed we think 200 profiles/float is likely.
- What can we improve or change?  Very little it seems....

## How can we escape these constraints? 

**How can we escape these constraints?**

|  | Argos
kJ/profile | Iridium
kJ/profile |
| --- | --- | --- |
| Controller | 0.71 | 0.38 |
| Buoyancy | 4.19 | 4.14 |
| SBE-41 | 1.55 | 4.21 |
| Communications | 2.19 | 0.40 |
| Self discharge | 1.67 | 1.61 |
| Total | 10.31 | 10.75 |

- Energy stored on an APEX = 2350 kJ (alkaline cells)
- 220 Argos profiles or 208 Iridium profiles
-                                             – this may change too!

## From Webb Research, and I assume Martec/Metocean will follow - 

**From Webb Research, and I assume Martec/Metocean will follow -**

- Energy stored on an APEX = 2350 kJ (alkaline cells)
- 220 Argos profiles or 208 Iridium profiles
- WRC is experimenting with a carbon-fibre hull for their floats.
- Lighter material means more batteries can be carried.
- Slightly compressible hull implies less energy needed to move from 2000 dbars to the surface.
- We can use lithium batteries, but that poses serious operational issues.
- In Canada we are not rushing to adopt Iridium communications or lithium batteries, for a variety of reasons, including shipping inflexibility.

## How can we escape these constraints? 

**How can we escape these constraints?**

- Switching to Iridium has immediate benefits:-
- Only 3 minutes at the sea surface, so grounding risk is greatly reduced and fouling risk is greatly reduced.
- Much larger files are transferred easily.
- The fraction of profiles passing DMQC will increase.
- But, switching to Iridium is not without costs:-
- Iridium does not supply positions, so increased capital cost.
- With only 3 min at the surface we lose surface trajectories.
- Adding Iridium to a standard float does cost energy and, therefore, profiles.

## An Iridium antenna needs care 

**Standard patch configuration**

**Mai-tai configuration**
**this IS sub-optimal for communications, but....**

## An Iridium antenna needs care 

**Standard patch configuration in tow tank dye test**

**Mai-tai configuration in tow tank dye test**

## What of the future? 

**What of the future?**

- One obstacle for the objective of global coverage is the difficulty of operating in ice-infested waters.
- Three approaches have been designed......
- JAMSTEC/Metocean
- Germany – ice detection algorithms – store profiles for future transmission
- US (WHOI – Breck Owens) approach of probing for openings in the ice.

## JAMSTEC Under-Ice sampling....

## Arctic Argo started this year

## German Under-Ice sampling system....

## German Under-Ice sampling....

- Each float has a built-in ice-detection algorithm.  If a float detects close approach to the freezing point of sea-water then the ascent is aborted and the profile saved for future transmission.
- When ice clears the float delivers a set of profiles.  This sometimes happens during the ice-covered season if a float is lucky to find a hole in the ice.
- Profiles are of no value without positions, so each float carries a Rafos receiver that allows it to determine its position underwater.

## WHOI Under-Ice sampling system....

- Use Iridium communications to detect the presence of ice, algorithm is simple:-
- Have I stopped rising, if yes, can I hear Iridium satellites?
- If “yes” then the float is in water, if “no” it is under ice.
- 2) If the float is not under ice, transmit 1 or more profiles.
- 3) If the float is under ice, descend 50 metres, wait 1 hour and try again, then again, then again.
- 4) After 50 probes descend to drift depth and wait 10 days.
- This system is still experimental but shows great promise.  It will work best in marginal ice zones.

## Argo is a global ocean sampling program available to anyone anywhere.  It is yours, to use as you see fit, but please, please we have written a data manual, read it...

- Howard Freeland
- D.F.O. Science/Pacific Region, Canada
- Tel: (250)-363-6590
- Email: FreelandHj@pac.dfo-mpo.gc.ca

- A