Determining air‐sea CO₂ fluxes using pCO₂ disequilibrium requires knowing the gas transfer velocity and air‐sea pCO₂ difference. Most pCO₂ measurements are made from ships, whose uncontaminated seawater intakes are located at >5‐m depth to prevent ingestion of air. However, there could be bias in determinations of CO₂ fluxes if there is disagreement between pCO₂ measurements at the surface and 5 m. Seawater measurements made at the near surface and 5 m in the eastern Equatorial Pacific Ocean show that precipitation can dilute surface seawater salinity and lower the pCO₂ and dissolved inorganic carbon and raise pH of the same water, and that these changes in ocean chemistry are largely missed by measurements at 5 m. This finding implies that estimates of ocean CO₂ uptake might be underestimated, since rain will lower surface ocean pCO₂ in both source and sink regions and, hence, increase uptake in sink regions and decrease outgassing in source regions.

中文翻译：

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降水导致的表层海洋pCO2减少：来自东部热带太平洋的观测

使用pCO ₂不平衡确定海气中的CO ₂通量需要知道气体传输速度和海气中pCO _2的差异。大多数pCO _2的测量是从船舶上进行的，这些船舶的未污染海水入口位于> 5 m深度，以防止空气摄入。但是，如果在表面和5 m处的pCO ₂测量值不一致，则在确定CO ₂通量时可能会有偏差。在赤道东太平洋近地表和5 m处进行的海水测量表明，降水可以稀释表层海水的盐度并降低pCO _2。和溶解的无机碳并提高同一水的pH值，并且在5 m处的测量结果很大程度上忽略了海洋化学的这些变化。这一发现暗示着对海洋CO ₂吸收的估计可能被低估了，因为降雨将降低源区和汇区的表层海洋pCO ₂，从而增加汇区的吸收并减少源区的脱气。