Correction: Jin et al. Influence of the Nocturnal Effect on the Estimated Global CO₂ Flux. Remote Sens. 2022, 14, 3192

Text Correction

We believe that several sentences in the description of the source (sink) changes of CO₂ are prone to ambiguity and are not particularly well presented. There were errors in the original publication [1].

1. 

The original sentence was located in **Abstract**, **Paragraph 1**, **Penultimate sentence of the abstract**:

**The mean global daily CO₂ flux estimated based on the nocturnal effect and the sub-regional pCO_2w algorithm (cor_F_com) was −6.86 mol m⁻² y⁻¹ (September 2020–August 2021), which was smaller by 0.75 mol m⁻² y⁻¹ than that based solely on the sub-regional pCO_2w algorithm (day_F_com)**.

A correction has been made to **Abstract**, **Paragraph 1**, **Penultimate sentence of the abstract**:

**The mean global daily CO₂ flux estimated based on the nocturnal effect and the sub-regional pCO_2w algorithm (cor_F_com) was −6.86 mol m⁻² y⁻¹ (September 2020–August 2021), which was greater by 0.75 mol m⁻² y⁻¹ than that based solely on the sub-regional pCO_2w algorithm (day_F_com = −7.61 mol m⁻² y⁻¹)**.

2. 

The original sentence was located in **Abstract**, **Paragraph 1**, **Last sentence of the abstract**:

**That is, compared with day_F_com, the global cor_F_com value overestimated the CO₂ sink of the global ocean by 10.89%**.

A correction has been made to **Abstract**, **Paragraph 1**, **Last sentence of the abstract**:

**That is, compared with cor_F_com, the global day_F_com value overestimated the CO₂ sink of the global ocean by 10.89%**.

3. 

The original sentence was located in **Results and Discussion**, **3.5.2. Estimation of the CO₂ Flux Using the Nocturnal Effect**, **Paragraph 3**, **Last three sentences of the paragraph**:

**Specifically, compared with day_F_com, the global cor_F_com value increased by 4.90 × 10⁻⁴ mmol m⁻² d⁻¹, thereby overestimating the oceanic CO₂ sink by 10.21%. The mean monthly increase was 2.50 mmol m⁻² month⁻¹, thus overestimating the mean oceanic CO₂ sink by 10.68%. The mean annual increase was 0.75 mol m⁻² y⁻¹, thereby overestimating the mean oceanic CO₂ sink by 10.89%**.

A correction has been made to **Results and Discussion**, **3.5.2. Estimation of the CO₂ Flux Using the Nocturnal Effect**, **Paragraph 3**, **Last three sentences of the paragraph**:

**Specifically, compared with day_F_com, the global cor_F_com value increased by 0.18 mmol m⁻² d⁻¹, thereby day_F_com overestimating the oceanic CO₂ sink by 10.21%. The mean monthly increase was 2.50 mmol m⁻² month⁻¹, thus day_F_com overestimating the mean oceanic CO₂ sink by 10.68%. The mean annual increase was 0.75 mol m⁻² y⁻¹, thereby day_F_com overestimating the mean oceanic CO₂ sink by 10.89%**.

4. 

The original sentence was located in **Conclusions**, **Paragraph 5**, **Last three sentences of the paragraph**:

**Compared with day_F_com, the global cor_F_com value was greater by 4.90 × 10⁻⁴ mmol m⁻² d⁻¹, thereby overestimating the oceanic CO₂ sink by 10.21%. The mean monthly increase was 2.50 mmol m⁻² month⁻¹, thus overestimating the mean oceanic CO₂ sink by 10.68%. The mean annual increase was 0.75 mol m⁻² y⁻¹, thus overestimating the mean oceanic CO₂ sink by 10.89%**.

A correction has been made to **Conclusions**, **Paragraph 5**, **Last three sentences of the paragraph**:

**Compared with day_F_com, the global cor_F_com value was greater by 0.18 mmol m⁻² d⁻¹, thereby day_F_com overestimated the oceanic CO₂ sink by 10.21%. The mean monthly increase of cor_F_com was 2.50 mmol m⁻² month⁻¹, thus day_F_com overestimated the mean oceanic CO₂ sink by 10.68%. The mean annual increase of cor_F_com was 0.75 mol m⁻² y⁻¹, thus day_F_com overestimated the mean oceanic CO₂ sink by 10.89%**.

5. 

We want to add the following two sentences on CO₂ source and sink to **Introduction**, **Paragraph 2**, after the phrase:

**At present, the sea–air CO₂ flux can be measured directly using the eddy correlation method. Alternatively, the CO₂ flux is often calculated by the block method formula [4], as follows: sea–air CO₂ flux = sea–air gas transfer velocity × solubility of CO₂ in seawater × (pCO₂ in seawater–pCO₂ in air)**.

The added sentence is:

**If the CO₂ flux is positive, it means that CO₂ enters the atmosphere from the ocean, i.e., the ocean is the source of CO₂. If the CO₂ flux is negative, it means that CO₂ enters the ocean from the atmosphere, i.e., the ocean is the sink of CO₂**.

The authors apologize for any inconvenience caused and state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.