Deep NINJA update

Taiyo Kobayashi & Toshio Suga (JAMSTEC)

Available from TSK since April 2013

Specification of Deep NINJA

• Max. profile depth: 4000 dbar

– From tropics to high-latitudes with seasonal ice

– About 90% of the ocean’s volume is measurable

• Pressure hull: Aluminum alloy

• Sensor: SBE 41CP

– Enough capacity for additional sensors

• Communication: Iridium SBD, two-way

• Position fixing: GPS

• Est. lifetime: more than 1 year (by Lithium battery)

• Functions: Avoidance of surface sea ice

Avoidance of groundings

210 cm

25 cm

50 kg

210 cm

25 cm

50 kg

14 Deep NINJA floats have been deployed.

2012/ 8: 2 floats in the subarctic NP (for a

deep field test).

2012/12: 4 floats in SO (by R/V Mirai).

2013/ 7: One float in the subtropical NP

(by R/V Mirai, for a field test)

2014/1~3: 7 floats in SO (by R/V Umitaka &

Shirase)

Preliminary results of the Southern Ocean observation

Deep NINJAs deployed in

2012 have worked very

well. Totally, 84 CTD

profiles (including 53 deep

profiles) have been

obtained until now (as of

March 14, 2014).

Measurements under sea ice. Positions are interpolated linearly.

Ice covered (Jun.-Nov.)

Pot. temp. observed by a Deep NINJA (blue) for a year.

Preliminary results of the Southern Ocean observation Deep NINJAs deployed in 2012 have worked very well. Totally, 84 CTD profiles

(including 53 deep profiles) have been obtained until now (as of March 14, 2014). - The floats off the Adelie Coast lost contact in June 2013 due

to the sea ice extension.

- At the end of Nov. 2013, a float resumed data transmission.

=> Success in deep measurements under ice (surviving

through a winter).

=> Success in a throughout the year observations in the

Antarctic deep layer.

Measurements under sea ice. Positions are interpolated linearly.

Ice covered (Jun.-Nov.)

Pot. temp. observed by a Deep NINJA (blue) for a year.

Salinity bias found in float measurements The first profiles of Deep NINJAs were compared with R/V Mirai’s CTD observations conducted at the float deployment sites within 24 hours from the deployment.

In all of the 5 cases, there are biases of float salinity. The bias is “less saline at deeper (colder) layer”, or looks like delta-S = S0 + p * S1 -S0: A constant component. -S1: A component depending on (probably) pressure The component S0, which is yielded by various reason, is correctable in DMQC, while the component S1 is not. A parameter of SBE41/41CP to cancel pressure effects on conductivity/salinity (ε) might be adjusted.

Conductivity = (g + hf2 +if3 + jf4)/(1 + δt + εp) [siemens/meter]