Collaborative Research: Surface pCO2 and the effects of Winter Time Overturning in the Drake Passage

拟议中的项目将扩大观测套件，并延长现有的时间序列，测量R/VIB L.M.古尔德横跨德雷克海峡的断面的表面溶解二氧化碳（pCO2）。额外的观测包括氧气、营养物质和总CO2 （TCO2）浓度，以及TCO2的13C与12C比值。持续和扩大的时间序列将有助于实现两个主要的科学目标：在德雷克海峡的四个主要水块状态中，对地表二氧化碳种类的时空变异性和趋势进行量化，以及了解导致地表二氧化碳分压变异性和由此产生的德雷克海峡二氧化碳海气通量的主要过程和这些过程中的变化。扩大后的计划还将包括对TCO2的14C/12C的分析，以及对一次短期冬季巡航的观测结果的具体研究，目的是验证德雷克海峡表层水中溶解的二氧化碳是由冬季混合程度决定的假设。鉴于现在和将来可能影响南大洋深水通风的两种情况，这一点具有特别重要的意义：由于观测到较高的纬向风，水柱分层减少，或者由于降水增加和气候变化导致的变暖，分层增加。如果冬季混合决定了德雷克海峡的年平均pCO2，那么大气pCO2的增加趋势对海面pCO2的影响应该很小。

The proposed project will expand the suite of observations and lengthen the existing time series of underway surface dissolved carbon dioxide (pCO2) measurements transects across the Drake Passage on the R/VIB L.M. Gould. The additional observations include oxygen, nutrients and total CO2 (TCO2) concentrations, and the 13C to 12C ratio of TCO2. The continued and expanded time series will contribute towards two main scientific goals: the quantification of the spatial and temporal variability and the trends of surface carbon dioxide species in four major water mass regimes in the Drake Passage, and the understanding of the dominant processes and changes in those processes that contribute to the variability in surface pCO2 and the resulting air-sea flux of CO2 in the Drake Passage. The expanded program will also include the analysis of the 14C/12C of TCO2 and the specific study of the observations on one short wintertime cruise, with the objective of testing the hypothesis that the dissolved carbon dioxide in surface waters of the Drake Passage is determined by the degree of winter mixing. This is of special significance in light of two scenarios that may be affecting the ventilation of Southern Ocean deep water now and in the future: a decrease in water column stratification with the observations of higher zonal winds, or an increase in stratification due to higher precipitation and warming from climate change. If winter mixing determines the mean annual pCO2 in the Drake Passage, the increasing trend in atmospheric pCO2 should have little effect on sea surface pCO2.