статья в журнале

En

Journal of Geophysical Research: Oceans

ISSN:21699275

2022

Ye, Haijun²

Tang, S.²

10.1029/2022JC018477

Diurnal variability of the CO2 partial pressure (pCO2) at the sea surface (pCO2sea) and its impact on air-sea CO2 flux estimations are currently poorly understood. In this work, diurnal variations in pCO2sea were examined in the Bay of Bengal (BoB) based on 3-hourly observations collected at the BoB Ocean Acidification moored buoy between November 2013 and November 2018 by a moored autonomous pCO2 system. Significant mean diurnal pCO2sea cycles and a mean diurnal amplitude of 11 ± 9 μatm were observed based on 1215 complete diurnal cycles. One-dimensional mass budget model calculations suggest that temperature was responsible for these mean diurnal variations in pCO2sea and that these variations were intensified by biological activity. The effects of air-sea gas fluxes and mixing on the mean diurnal pCO2sea variability were very low. A weak annual net source of 12.1 mmol m−2 year−1 was estimated at this site. The sampling frequency greatly impacted the annual air-sea CO2 flux estimations. Compared to the 3-hr sampling frequency, random daily sampling resulted in a bias of ±7.7 mmol m−2 year−1 or 64%, and regular daily sampling resulted in a maximum bias of 400%. Factorial experiments showed that wind speed had the largest impact on the air-sea CO2 flux estimations, followed by pCO2sea and atmospheric pCO2 (pCO2air). These findings indicate the importance of obtaining continuous pCO2 measurements to accurately estimate air-sea CO2 flux; additionally, pCO2 and wind speed measurements should be obtained at frequencies higher than 6 hr. © 2022. American Geophysical Union. All Rights Reserved.

air-sea CO2 flux, bay of bengal, diurnal variation, sampling frequency, sea surface pCO2, seasonal variation

2023-04-17 15:18:54