지구온난화에 의한 북서태평양에서의 상세 해수면 상승 예측(I) - 해수팽창을 고려한 지역해양순환모형의 규모축소 모의 실험 - 서울대학교 세미나 지구온난화에 의한 북서태평양에서의 상세 해수면 상승 예측(I) - 해수팽창을 고려한 지역해양순환모형의 규모축소 모의 실험 - 김 동 훈 연세대학교 2012/11/13

The impact of global warming? Basic Knowledge The impact of global warming? rising ocean temp. < rising land temp. → large changing in seasonal monsoon rising temp. in the Arctic (decreasing Albedo in the Arctic area) → increasing the heat capacity of the Arctic Ocean → reducing the temperature gradient by latitude → changing major ocean currents

To project regional sea level rise due to global warming Coupled Model (Atmosphere - Ocean - Land Surface - Sea Ice) Regional simulations in high resolution Parallel optimazation for long-term simulations Compressible or Mass conservation Ocean Models : thermal expansion, melting land ice, runoff, … Global Warming water forcing source free surface rigid-lid steric dynamics Dynamic Height :

∆SST ∆SSH A Previous Study CO2 Doubling (after 70 years) in the Northwestern Pacific Ocean SST : 1.5℃ ↑ SSH : 10cm ↑ (steric effect) ∆SST ∆SSH Kim, D.-H., 1999: Sea Level Change due to Global Warming in the Northwestern Pacific Ocean Dynamic Height :

CM2.1 vs. ReMOM Model Configuration (ReMOM, Regional MOM4.1) Regional MOM4.1 : B-grid hydrostatic nonBoussinesq ocean model with pressure vertical coordinate Northwestern Pacific (115°E~150°E, 20°N~52°N) : 0.2° x 0.2° x 34layers I.C. & B.C. : IPCC(CM2.1,MIROC3.2H,HADCM3) SRES A1B & B1 (100yr simulation) Sea Surface : Wind Stress, SST, SSS (1day restoring) Lateral B.C. : T, S, U, V (sponge boundary = 1day~30day) Sponge B.C. 1day ~ 30 day CM2.1 vs. ReMOM Coarse Resolution Depth in CM2.1(IPCC) (Grid Spacing: 1°) Fine Resolution Depth in ReMOM (Grid Spacing: 0.2°)

Total Calculations : 900 years Model Projection (ReMOM, Regional MOM4.1) CM2.1 I.C. & B.C. SRES A1B SRES B1 2001 2100 Control Run using mean states of 1991 ~ 2000 100 yrs Scenario Runs (100 yrs) MIROC3.2H I.C. & B.C. SRES A1B SRES B1 2001 2100 Control Run using mean states of 1991 ~ 2000 100 yrs Scenario Runs (100 yrs) Average Difference (= 2090s – 1990s) HADCM3 I.C. & B.C. SRES A1B SRES B1 2001 2100 Control Run using mean states of 1991 ~ 2000 100 yrs Scenario Runs (100 yrs) Total Calculations : 900 years

SRES A1B SRES B1 3℃ SST 2℃ SST 35cm SSH 25cm SSH SST & SSH in the Northwestern Pacific Ocean (NWPO) SRES A1B SRES B1 3℃ SST 2℃ SST MIROC3.2H HADCM3 CM2.1 35cm SSH MIROC3.2H 25cm SSH HADCM3 CM2.1

Compare with CM2.1 : SST & SSH in the NWPO (SRES A1B) CM2.1 vs. ReMOMw/ CM2.1 3℃ CM2.1: SST 3℃ ReMOM: SST 12cm CM2.1: SSH 30cm ReMOM: SSH

CM2.1 vs. ReMOMw/ CM2.1 ∆SST ∆SST ∆UV ∆UV Compare with CM2.1 : ∆SST & ∆SurfaceCurrents (SRES A1B) CM2.1 vs. ReMOMw/ CM2.1 ∆SST ∆SST ∆UV ∆UV

Compare with CM2.1 : Steric Sea Level Changes (SRES A1B) CM2.1 vs. ReMOMw/ CM2.1

SRES A1B SRES B1 ∆SST ∆SST ∆UVsurface ∆UVsurface Spatial Distribution of ∆SST & ∆SurfaceCurrents SRES A1B SRES B1 ∆SST ∆SST Northward expansion of the Kuroshio separation area Transport increase of the Tsushima warm current ∆UVsurface ∆UVsurface

SRES A1B SRES B1 ∆SSH ∆SSH steric ∆SSH ∆SSH nonsteric Sea Level Changes(Rise) SRES A1B SRES B1 ∆SSH steric ∆SSH steric ∆SSH nonsteric ∆SSH nonsteric

=> Pressure Gradients : (non-)Boussinesq Ocean Climate Model In ocean climate modelling, it has been traditional to exploit the large degree to which the ocean fluid is incompressible, in which case the volume of fluid parcels is taken as constant. These fluids are said to satisfy Boussinesq kinematics. Boussinesq Approximation : ignore variations in density => Pressure Gradients : => Continuity Eq. : Primitive Eq. : Mass Conservation Eq.(M) → Volume Conservation Eq.(V) Boussinesq fluids Boussinesq fluids : heating → decreasing the density By volume conservation, decreasing the density reduces the mass and bottom pressure while the sea level remains unchanged. non-Boussinesq fluids : heating → decreasing the density By mass conservation, decreasing the density increases the volume and sea level, while the bottom pressure remains unchanged.

Non-Boussinesq Ocean Climate Model Primitive Eq. : Mass Conservation Eq.(M) → Volume Conservation Eq.(V) Boussinesq fluids source water forcing dynamics steric Pressure based vertical coordinates : It can be diagnosed in a straightforward manner. Depth based vertical coordinates :

∆SSH ∆SSH Steric & nonSteric Sea Level Changes(Rise) (SRES A1B) 35cm Ref. Sea Level Changes in CM2.1 ∆SSH steric ∆SSH nonsteric <--- Sea Level Change after 100 year ----> 35cm East Sea & Pacific : governed by steric effect Yellow Sea : governed by non-steric effect

쿠로시오수의 대륙붕 유입과 대만해류 대마난류(TWC)의 두개의 기원 - 쿠로시오의 대륙붕 유입(OIK) - 대만해류(TSC, 쿠로시오수와 무관) 대륙붕 유입(OIK) : PK + PT - 해수면 차이에 의해 유입 - PK는 관측으로 입증되었으나 PT는 뚜렷히 입증된 바 없음 대마난류(TWC)의 수송량은 - TSC와 OIK가 서로 경쟁적으로 기여

Transport changes due to Global Warming ReMOMw/ CM2.1

대마난류 대만난류 쿠로시오 해류 w/ CM2.1 w/ HadCM3 w/ MIROC3.2h Transport changes due to Global Warming 대마난류 대만난류 쿠로시오 해류 w/ CM2.1 w/ HadCM3 w/ MIROC3.2h 증가 감소

Transport changes due to Global Warming

Summary We simulated regional sea level as a prognostic variable using non-Boussinesq Ocean Model For the SRES A1B and B1, ReMOM predicts that the ensemble averaged sea levels rise 35 cm and 25 cm, respectively, in the Northwestern Pacific Ocean. Large-scale warmings are found in the middle of East Sea and Kuroshio separation area. The sea level rise in East Sea is mainly governed by steric effect, while the nonsteric effect mainly contribute on sea level rise in Yellow Sea. Transport of Kuroshio/Tsushima Current has decreased/increased, respectively.

Thank you… Kim, Dong-Hoon (http://www.dhkim.info, mailto:dohnkim@gmail.com)

Spatial Distribution of Surface Currents and its Difference CM2.1 vs. ReMOMw/ CM2.1 Surface Currents Surface Currents Northward expansion of the Kuroshio separation area Transport increase of the Tsushima warm current ∆UV ∆UV

∆SSS ∆UV Compare to CM2.1 : non-steric .vs. steric (SRES A1B) ∆SSH Runoff change after 100 years SSS change after 100 years ∆SSS ∆UV ∆SSH ∆runoff