Seawater total alkalinity (TA) is one important determinant used to monitor the ocean carbon cycle, whose spatial distributions have previously been characterized along the United States East Coast via discrete bottle samples. Using these data, several regional models for TA retrievals based on practical salinity (S) have been developed. Broad-scale seasonal or interannual variations, however, are not well resolved in these models and existing data are highly seasonally biased. This study reports findings from the first long duration deployment of a new, commercially available TA titrator aboard a research vessel and the continuous underway surface TA measurements produced. The instrument, operated on seven East Coast USA cruises during six months in 2017 and for two months in 2018 on the summertime East Coast Ocean Acidification survey (ECOA-2), collected a total of nearly 11,000 surface TA measurements. Data from these efforts, along with a newly synthesized set of more than 11,000 regional surface TA observations, are analyzed to re-examine distributions of TA and S along the United States East Coast. Overall, regional distributions of S and TA generally agreed with prior findings, but linear TA:S regressions varied markedly over time and deviated from previously developed models. This variability is likely due to a combination of biological, seasonal, and episodic influences and indicates that substantial errors of ±10–20 μmol kg⁻¹ in TA estimation from S can be expected due to these factors. This finding has likely implications for numerical ecosystem modeling and inorganic carbon system calculations. New results presented in this paper provide refined surface TA:S relationships, present more data in space and time, and improve TA modeling uncertainty.

海水总碱度（TA）是用于监测海洋碳循环的重要决定因素，其空间分布先前已通过不连续的瓶子样品在美国东海岸进行了表征。利用这些数据，已经开发了几种基于实际盐度（S）的TA检索区域模型。但是，在这些模型中不能很好地解决大规模的季节性或年际变化，并且现有数据存在很大的季节性偏差。这项研究报告了在研究船上首次长时间部署新的市售TA滴定​​仪并进行连续进行中的表面TA测量的发现。该仪器在2017年的六个月内和在2018年的两个月的美国东海岸巡洋舰上进行了夏季东海岸海洋酸化调查（ECOA-2），总共收集了近11,000个表面TA测量值。分析了这些工作的数据以及一组新合成的11,000多个区域地面TA观测值，以重新检查美国东海岸的TA和S分布。总体而言，S和TA的区域分布总体上与先前的发现一致，但是线性的TA：S回归随时间变化显着，并且与先前开发的模型有所不同。这种可变性可能是由于生物学，季节和情节因素的综合影响，并表明±10–20μmolkg的显着误差 总体而言，S和TA的区域分布总体上与先前的发现一致，但是线性的TA：S回归随时间变化显着，并且与先前开发的模型有所不同。这种可变性可能是由于生物学，季节和情节因素的综合影响，并表明±10–20μmolkg的显着误差 总体而言，S和TA的区域分布总体上与先前的发现一致，但是线性的TA：S回归随时间变化显着，并且与先前开发的模型有所不同。这种可变性可能是由于生物学，季节和情节因素的综合影响，并表明±10–20μmolkg的显着误差由于这些因素，可以预期从S得出的TA估计为^-1。这一发现可能对生态系统数值模拟和无机碳系统的计算产生影响。本文提出的新结果提供了精细的表面TA：S关系，提供了更多的时空数据，并改善了TA建模的不确定性。