Decadal Ocean/Atmosphere Variability
in the North Pacific in CCSM2(Model Years 350-999)
Young-Oh Kwon and Clara Deser
NCAR
9th Annual CCSM Workshop (July 7-9 2004, Santa Fe, NM)
EOF 1 (22 %) Winter SST Anomalies CCSM2
Winter SST Kuroshio Extension Index
Power Spectrum Winter SST Kuroshio Extension Index
~16 yr~40 yr
102580
Qnet and Precipitation in the Kuroshio Extension
SST
Local Qnet
SST
Local Precipitation
Correlation between Winter SST KEIand Indices at Other Depths
Band Pass Filtered : 10 – 25 yrs Band-Pass Filtered : 25 – 80 yrs
Shaded areas are significant at 95 % C.L.Contour interval : 0.1
Correlation between Winter SST KEI and Temperature on the Section along 40 °N
Band Pass Filtered : 10 – 25 yrs
Shaded areas are significant at 95 % C.L.Contour interval : 0.1
Winter Temperature Anomaly at 500 m
Contour interval : 0.2 °C
SST, Qnet and Precipitation along 40 °N
Contour intervals : 0.5 °C, 20 W/m2, 0.5 mm/day
Winter SST KEI and Position of the Kuroshio SST
Kuroshio Position
~30 yr
Winter SST KEI and Kuroshio TransportSST
Kuroshio Transport
~40 yr
Observed Winter SST in Kuroshio Extension (Reynolds SST : 1901-2000)
~20 yr
Observed Winter SST Anomaly along 40 °N
Band Pass Filtered : 7 – 15 yrs Band-Pass Filtered : 15 – 25 yrs
Contour interval : 0.2 °C
Summary
• Robust decadal (~16 years) and interdecadal (~40 years) variability in Kuroshio Extension.
– SST, precipitation, surface heat flux, and subsurface temperature.
• Ocean dynamics likely play an active role.
– Anomaly penetrating down to 1000 m.
– Propagating with the Kuroshio Extension.
– Heat flux and precipitation responding to SST anomaly.
– Anomalous Ekman heat transport acts as a positive feedback response to the SST anomalies.
– Similar spectral peaks in Kuroshio transport and position.
• Weak atmospheric response.
• Some resemblance to Nature.