Xiaopei LinWESTPAC Principal Investigator

12th Intergovernmental Session of the IOC Sub-Commission for the Western PacificManila, the Philippines, 2-5 April 2019

Air-Sea Interaction in the Kuroshio Extension and its Climate Impact

(AIKEC)Progress and outputs (May 2017- April 2019)

Workplan ( May 2019-April 2021)

Project Objectives and Steering Group

• Establishthetheoreticalframeworkofthemultiscaleocean-atmosphereinteractioninthemidlatitudes,especiallyintheKuroshioextensionregion,toprovideatheoreticalbasisforunderstandingandpredictingtheglobalclimatechange.

• DevelopsustainableobservationnetworksintheKuroshioextensionregion.• Revealthekeyphysicalprocessesindeterminingclimatechangeandimprove

theunderstandingofoceanandclimatepredictabilityintheNorthPacific.

Project Objectives

Steering Group

• Lixin Wu,OceanUniversityofChina• Xiaopei Lin,OceanUniversityofChina• PingChang,TexasA&MUniversity• Shang-PingXie,ScrippsOceanographyInstitution• BoQiu,UniversityofHawaii

Progress and generated output1.ConstructionoftheKuroshioExtensionobservationsystembyOceanUniversityofChina

• Duringthelasttwocruisesin2017and2018,wehavesuccessfullycompletedthedeploymentandrecoveryofthefirstsetoflargedeep-seaobservationbuoys(China-KuroshioExtensionObservatory,CKEO)inthemid-latitudeKuroshioExtension.

• Weupdatedtheexisting3subsurfacemoorings(M1,M2 andM3)andaseriesofnewmobileobservationplatforms(suchas4000mdeep-seaself-sustainingprofilebuoy,driftingsea-airinterfacebuoy)weresuccessivelycarriedoutinthisarea.

■ Compare method: DIF freely deployed and drifted near the mooring KEO buoy

■ Observation method: the observation frequency and period is same

■ Data usage: the first day after deployment (2018/05/10-11), and distance within 20km

■ Marine environment：3 m maximum wave height

Comparison area

10/60min2 kind observing period10000 set data till now

Compare with KEO Buoy

Main error : 0.095℃

Main error : 0.271hPa

Main error : 0.763%

Main error: 0.443m/s

Compare with KEO Buoy

Progress and generated output

2.Scientificresearchoutcomes

Diapycnal mixing change for two anticyclonic eddies (AEs) passing over the Izu Ridge is continually tracked by 17 Iridium Argo floats.

AsthetwoAEspasstheRidge,thediapycnal mixingisenhanced—totheorderof10-4m2

s1 orlarger,incomparisonwithanambientof10-5m2 s1.

AE1 AE2

BottomTopography

Xu et al. 2017 GRL (Editors’ Highlight)

Decadal Variability of Eddy Characteristics and Energetics in the Kuroshio Extension: Unstable Versus Stable States

Yang et al. 2018 JGR-Ocean

Unstable cases

Identificationofunstablecases:NormalizedEKEwithin142°E-148°E,32.5°N-36.5°Nkeepslargerthan+1formorethan1month

EKE

Composite eddy shedding process in upstream KE

Energy budget analysis during the shedding

Eddysheddingprocessesaretriggeredbybaroclinicinstability(BF),whilebarotropicinstability(BT)becomesthedominatedenergysourceafterthemeanderisfullydeveloped.

Global distribution of OMEA interaction

An Assessment of Representation of Oceanic Mesoscale Eddy-Atmosphere interaction (OMEA) in the Current Generation of General Circulation Models and Reanalyses

l The overall intensity and spatial distribution of OMEA interaction differ significantly among models.

l Surface wind strength and MABL adjustment are two important factors accounting for the inter-model difference.l Fully coupled simulations are necessary to accurately simulate the energy pathway of mesoscale eddies.

Yang et al. 2018 GRL

• Long-term observations for buoys and subsurface moorings

(Power; Rough weather/sea condition; Annual retrieval cruise;

Fund);

• Shipboard submesoscale to mesoscale processes observations;

• Autonomous underwater/surface vehicles under high sea condition

and strong currents;

Challenges

Workplan (May 2019 – April 2021)

Plan A: Maintaining long-term observations in Kuroshio Extension

China (OUC) have sustained 3 subsurface moorings since 2014, which are located at the south/axis/north of Kuroshio Extension.

A tentative surface buoy (CKEO) was deployed in 2017.10 and recovered in 2018.5, which will be deployed again on October, 2019.

OUC will maintain CKEO in future for long time. It will be a twin-buoy for KEO.

Workplan (May 2019 – April 2021)Plan A: Maintaining long-term observations in Kuroshio Extension

2019-crusie planDate: 2019.10.1-2019.11.20RV: Dongfanghong 3 (5000T)Mission:1) re-deploy the CKEO at

39N,149.25E2) Intensive observation within an

eddy using multi-platforms like drifting air-sea interface buoy, wave glider, deep argo and core-argo (the argo float is designed and manufactured by China)

3) Regular CTD casts along the 147.5E section.

4) Underway observations using VMS met-stations, ship-board ADCP, underway CTD. 147.5E line

Workplan (May 2019 – April 2021)

Plan B: The Drifting Air-Sea Interface Buoy (DrIB) and its potential contribution to global data acquisitions of air-sea parameters

p China will draft a 10-year program for developing a global air-sea observing network that uses the drifting air-sea interface buoys (DrIB), which can serve as a critical complement to global observing system for air-sea interface and help enrich the global drifter program with more approaches.

p The design of latest version of DrIB has been finalized after two-years’ testing and achieved a certain adaptability and stability in operation (TRL=5).

Characteristic:■ Following the current■ Real time data communication■ Bidirectional communication on line■ Small volume (R.max=0.5m,H.surface=3m)■ Light weight (<50KG)■ Easy deployed

Obs.Parameter and Accuracy

Range Accuracy

Wind Speed. 0～40 m/s < 5%RMSWind Direction 0～360° ±10°Air Temperature -20～50℃ ±0.25℃Air Pressure 850～1050hPa ±1 hPaRelative Humidity 0～100RH ±2RHSST -5～40℃ ±0.005℃

Expected outputs and/or outcome

• Set up a long-term observation system to serve the community

• Meet the weather forecast and social-economy needs

• Develop new tech for the ocean observation

Be part of the future global observation system, especially the boundary current operational system

Improve our understanding about the multi-scale ocean and climate variability

Improve climate prediction and projection

Recommendations