The Indian Ocean dynamics is governed by the seasonal reversal of monsoon winds and the associated ocean currents. The relatively deep thermocline along the equator due to a lack of steady easterlies, low-latitude connection to the neighbouring Pacific, and a lack of northward heat export due to the position of the Asian continent are important factors in regulating the ocean state. These features make it a unique ecosystem among the world's tropical oceans and determine key features of potential air-sea interaction at different time scales. The pCO₂ shows a large seasonal variation linked with monsoon circulation. The Indian Ocean’s northwestern part acts as an atmospheric CO₂ source, whereas the northeastern part acts as a net atmospheric CO₂ sink. The region between the latitudes of 15°S-50°S in the Indian Ocean is a major subduction zone because of positive wind stress curl. The subducted water masses are transported to the northern Indian Ocean by the cross-equatorial cell (a shallow meridional overturning circulation). Based on the regional studies carried out on the carbonate system in the Indian Ocean, the area north of 15°S is a source of atmospheric CO_2, while the area between 15°S and 50°S is a sink. A recent synthesis of models (observational climatology) over different spatial scales provides an estimate of the mean value of CO₂ in the north of 37.5°S of the Indian Ocean as − 0.19 ± 0.1 PgC/yr (−0.07 ± 0.14 PgC/yr) during 1985–2018. The estimated decrease in pH (acidification) using model outputs in the Indian Ocean basin is 0.0675 units during 1961–2010, in which the contribution of dissolved inorganic carbon and surface temperature is 69.3 % and 13.8 %, respectively. The range of the Indian Ocean’s annual primary production based on satellite estimates over the last two decades (1998–2018) is 7.72–8.70 Gt C/yr^, whereas the climatological mean is 8.24 ± 0.30 Gt C/yr. This paper consolidates the current state of understanding of the Indian Ocean carbon fluxes, acidification, and productivity using available field and satellite-based measurements, model simulations, and re-constructed datasets. It provides an overview of the functioning of the Indian Ocean’s air-to-sea CO₂ exchange and highlights its influence on global climate. Finally, it aims to highlight the grey areas of the Indian Ocean carbon cycle that need to be understood.

印度洋的动态受季风和相关洋流的季节性逆转控制。由于缺乏稳定的东风而导致赤道沿线相对较深的温跃层、与邻近太平洋的低纬度联系以及由于亚洲大陆的位置而缺乏向北的热量输出是调节海洋状态的重要因素。这些特征使其成为世界热带海洋中独特的生态系统，并决定了不同时间尺度上潜在的海气相互作用的关键特征。 pCO ₂显示出与季风环流相关的较大季节性变化。印度洋的西北部是大气CO ₂源，而东北部是大气CO ₂净汇。印度洋南纬15°-50°之间的区域由于正风应力旋度而成为主要俯冲带。俯冲水团通过跨赤道环流（浅层经向翻转环流）输送到北印度洋。根据对印度洋碳酸盐体系的区域研究，南纬15°以北地区是大气CO _{2 的源区，}南纬15°至50°之间的地区是大气CO 2 的汇区。最近对不同空间尺度的模型（观测气候学）的综合提供了印度洋 37.5°S 以北CO ₂平均值的估计值，为 − 0.19 ± 0.1 PgC/yr (−0.07 ± 0.14 PgC/yr) ）在 1985 年至 2018 年期间。使用模型输出估计 1961 年至 2010 年期间印度洋盆地 pH（酸化）下降了 0.0675 个单位，其中溶解无机碳和表面温度的贡献分别为 69.3% 和 13.8%。根据过去二十年（1998-2018）卫星估计，印度洋的年度初级生产力范围为 7.72-8.70 Gt C/yr ^，而气候平均值为 8.24 ± 0.30 Gt C/yr。本文利用现有的现场和基于卫星的测量、模型模拟和重建的数据集，巩固了对印度洋碳通量、酸化和生产力的当前了解。它概述了印度洋空海CO ₂交换的功能，并强调了其对全球气候的影响。最后，它旨在强调印度洋碳循环中需要理解的灰色地带。