The seasonal cycle represents one of the largest signals of dissolved inorganic carbon (DIC) in the ocean, yet these seasonal variations are not well established at a global scale. Here, we present the Mapped Observation‐Based Oceanic DIC (MOBO‐DIC) product, a monthly DIC climatology developed based on the DIC measurements from GLODAPv2.2019 and a two‐step neural network method to interpolate and map the measurements. MOBO‐DIC extends from the surface down to 2,000 m and from 65°N to 65°S. We find the largest seasonal amplitudes of surface DIC in the northern high‐latitude Pacific (∼30 to >50 μmol kg⁻¹). Surface DIC maxima occur in hemispheric spring and minima in fall, driven by the input of DIC into the upper ocean by mixing during winter, and net community production (NCP) driven drawdown of DIC over summer. The seasonal pattern seen at the surface extends to a nodal depth of <50 m in the tropics and several hundred meters in the subtropics. Below the nodal depth, the seasonal cycle of DIC has the opposite phase, primarily owing to the seasonal accumulation of DIC stemming from the remineralization of sinking organic matter. The well‐captured seasonal drawdown of DIC in the mid‐latitudes (23° to 65°) allows us to estimate the spring‐to‐fall NCP in this region. We find a spatially relatively uniform spring‐to‐fall NCP of 1.9 ± 1.3 mol C m⁻² yr⁻¹, which sums to 3.9 ± 2.7 Pg C yr⁻¹ over this region. This corresponds to a global spring‐to‐fall NCP of 8.2 ± 5.6 Pg C yr⁻¹.

中文翻译：

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近全球海洋中的季节性碳动力学

季节周期代表海洋中最大的溶解性无机碳（DIC）信号之一，但在全球范围内这些季节变化尚不明确。在这里，我们介绍了基于映射的观测海洋DIC（MOBO-DIC）产品，基于GLODAPv2.2019的DIC测量结果开发的每月DIC气候学以及两步神经网络方法以对测量值进行内插和映射。MOBO-DIC从地面向下延伸到2,000 m，从65°N延伸到65°S。我们发现北高纬太平洋的表面DIC的最大季节性振幅（约30至>  50μmol kg ^-1）。表面DIC的最大值发生在半球的春季，秋天则最小，这是由于DIC在冬季通过混合将其输入上层海洋的驱动，而夏季则是由净群落生产（NCP）驱动的DIC的下降。在地表看到的季节性模式在热带地区延伸至<50 m的节点深度，在亚热带地区延伸至数百米。在节深以下，DIC的季节周期具有相反的相位，这主要是由于DIC的季节性积累源于下沉的有机物的再矿化作用。DIC在中纬度（23°至65°）中捕获良好的季节性下降，使我们能够估算该地区春季至春季的NCP。我们发现空间上相对均匀的弹簧下降NCP为1.9  ±  1.3 mol C m ^-2  yr ^-1，在该区域 总计为3.9  ± 2.7 Pg C yr ^-1。这对应于8.2 ±  5.6 Pg C yr ^-1的全球春季至春季NCP  。