In order to elucidate the secular trends of oceanic CO 2 uptake in the Indian sector of the Southern Ocean, pCO 2, the partial pressure of CO 2 in the ocean surface layer, has been measured since 1987 on board the icebreaker Shirase. Meridional distributions of pCO 2 along 110δE in early December clearly show steep changes at such fronts as the subtropical front, subantarctic front, and polar front. Although pCO 2 of each zone shows interannual variation, secular trend is detectable. For example, the estimated rate of increase of pCO 2 in the permanent open ocean zone between the polar front (around 53°S) and the northern edge of winter ice cover (63°S) is about 1.3 μatm/y, which is slightly lower than the rate of increase of the atmospheric CO 2 concentration. From the results obtained by multi-ship observations with 4 research vessels in the Southern Ocean in summer, we found that the values of pCO 2 off the coast of the Antarctic Continent (66°S) varied temporally by 100 μatm for 5 months. We also found that nDIC decreased with time from December 2001 to March 2002 in the upper layer from 100 to 200 m due to biological activity during summer.
|Number of pages||11|
|Issue number||SPEC. ISSUE|
|Publication status||Published - 2010 Dec|