Effect of wind regarding reliability and variability on the flux estimates of the air-sea CO2 exchange in the East China Sea

• Main Authors: Zhi-Yu Luo, 羅智譽
• Other Authors: 曾鈞懋
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/94896553266910480931

碩士 === 國立臺灣大學 === 海洋研究所 === 102 === To accurately investigate air-sea CO2 exchange in the coastal waters, especially for the East China Sea (ECS), is challenging because of the environment complexities and diversity of the shelf seas, easily affected by human activities and climate changes. Reliable assessments of air-sea CO2 exchange fluxes in the ECS are additionally limited by inadequately spatiotemporal coverage and shortage of manpower resources. Here, we explore seasonally representative CO2 uptakes by the whole ECS by combining the remote sensing data and field observations. We firstly evaluated the results of Tseng et al. (2014) and further demonstrated the reliability and representativeness of Tseng’s empirical algorithm for computing pCO2 by using remote sensing data including SST, Chlorophyll a (Chl-a) and wind speed. Secondly, we demonstrated the satellite wind speed data are higher than those collected in land weather station (field wind speed = 0.8 × satellite wind speed), in order to re-evaluate the CO2 fluxes in the ECS. The average annual flux between 2003 and 2010 was constrained to -1.1 mol C m-2 y-1 as a net sink of atmospheric CO2 with the seasonal mean fluxes of -2.1 (Mar.-May), -0.3 (June-Aug.), -0.2 (Sep.-Nov.) and -1.9(Dec.-Jan.), respectively. The flux seasonality showed a strong sink in spring and winter, a sink-to-source transition during late summer – mid-fall period and a source-to-sink transition in late fall. Finally, the annual mean CO2 flux estimated in this study was nearly one half of those reported previously, indicating the importance of wind effect regarding spatial variability and reliability of wind field. Especially in some severe weather events, the more spatial gradients of wind speed would make more significant impact on the air-sea exchange flux of CO2 in continental margins.