The Vertical Structure of Eddy Heat Transport Simulated by an Eddy-Resolving OGCM

Bo Young et al.

Outline

• Introduction• Model description • Result– Distribution of EKE and D-EHT– Distribution of He, Hd and HK

– Seasonal variation of He, Hd and HK

– Vertical profiles of the zonally averaged T, EKE EHT– Effect of a seasonal thermocline on the structure of

mesoscale eddy• Conclusion

Introduction

• Heat transport by mesoscale eddy or eddy heat transport(EHT) constitutes an important part in meridional heat transport in the ocean (Wunsch 1999,and Roemmich and Gilson 2001)

• Since the information below the sea surface is not available from Satellite, an assumption is introduced for the vertical, structure depth integrated value of EHT(D-EHT)(Stammer 1998).

• Qiu and Chen assumed that the effective depth of EHT (He:=D-EHT/EHTsurface) is constant.

• To resolve the mesoscale eddy and estimation of D-EHT require the resolution of 1/10 degree(Meijers et al. 2007)

• The clarification of the vertical structure of EHT provides essential information for the parameterization of lateral mixing in coarse-resolution OGCMs (Killworth 1998)

Model

• Research Institute for Applied Mechanics Ocean Model• Pacific ocean model covers 50S-65N, 95E-70W, 70

vertical level, 1/12 degree.• Advection momentum: the generalized Arakawa

scheme (ishizaki and Motoi 1999).• Vertical mixings : Noh scheme• Input data: WOA94 climatological mean temperature

and salinity.• Model integrated : 25 years

ResultDistribution of EKE and D-EHT

𝐸𝐾𝐸=12

(𝑢′𝑢′+𝑣′ 𝑣 ′ )

𝐷−𝐸𝐻𝑇=𝜌𝑐𝑝∫𝑇 ′𝑣 ′ 𝑑𝑧

Zonally Integrated D-EHT

𝑣 ′𝑇 ′=−𝐴h𝜕𝑇 /𝜕 𝑦

Distribution of He, Hd and HK

𝐻𝑒=∫𝑣 ′𝑇 ′ (𝑧 )/𝑣 ′𝑇 ′ (0)𝐻𝑑=𝑃𝑒𝑛𝑒𝑡𝑟𝑎𝑡𝑖𝑜𝑛 h𝑑𝑒𝑝𝑡 𝑜𝑓 𝐸𝐾𝐸 𝐻𝑘

𝐻𝑘= h𝑑𝑒𝑝𝑡 𝑎𝑡 𝐸𝐾𝐸 𝑑𝑒𝑐𝑟𝑒𝑎𝑠𝑒𝑠𝑡𝑜5×10− 3𝑚2𝑠− 2

Seasonal variation of He, Hd and HK

Comparison of the mirdional disrtribution

Vertical profiles of the zonal average

Effect of a seasonal thermocline on the structure of mesoscale eddy