We report the
interannual variations of winter CO2
partial pressure in surface waters (pCO2sea)
and overlying air (pCO2air)
and air-sea CO2 flux in the
extensive area (3-34°N) from subtropical to equatorial along 137°E during the period of 1983-2003. The pCO2sea varied largely in
the equatorial region of 3-6°N, depending on the variations of the
oceanographic conditions related to the El Niño-Southern Oscillation (ENSO) events. The pCO2sea variations in the subtropical gyre north of 23°N were small due to highly
counteracting effects between anti-correlated sea surface temperature (SST)
and dissolved inorganic carbon (DIC) anomalies through the entrainment
process, irrespective of large variations of SST. By contrast, it was
found that there occurred a low negative correlation between SST and DIC in the
region restricted around 15-18°N in the North Equatorial Current, which resulted
in a large amplitude of variations of pCO2sea
and hence CO2 influx. The interannual
variations of CO2 flux depended predominantly on those of the
difference between pCO2sea
and pCO2air (ΔpCO2) south
of 18°N but on those of wind speed in the northern region.
Author: T. Midorikawa, M. Ishii, K. Nemoto, H. Kamiya, et al (midorika at mri-jma dot go dot jp)
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