Global average of air-sea CO 2 transfer velocity from QuikSCAT scatterometer wind speeds

• Published in: Journal of Geophysical Research
• Main Authors: Boutin, Jacqueline, Quilfen, Yves, Merlivat, Liliane, Piolle, Jean-François
• Other Authors: Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Spatiale (LOS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]; Southern Ocean
• Online Access: https://hal.science/hal-00760019; https://hal.science/hal-00760019/document; https://hal.science/hal-00760019/file/2007JC004168.pdf; https://doi.org/10.1029/2007JC004168

International audience The absolute calibration of the relationship between air-sea CO 2 transfer velocity, k, and wind speed, U, has been a topic of debate for some time, because k global average, $\langle$k$\rangle$, as deduced from Geochemical Ocean Sections Study oceanic 14 C inventory has differed from that deduced from experimental k-U relationships. Recently, new oceanic 14 C inventories and inversions have lead to a lower $\langle$k$\rangle$. In addition, new measurements performed at sea in high-wind speed conditions have led to new k-U relationship. Meanwhile, quality and sampling of satellite wind speeds has greatly improved. The QuikSCAT scatterometer has provided high-quality wind speeds for more than 7 years. This allows us to estimate the global distributions of k computed using k-U relationships and temperature-dependent Schmidt numbers from 1999 to 2006. Given the difficulty of measuring in situ wind speed very accurately, we performed a sensitivity study of the $\langle$k$\rangle$ uncertainty which results from QuikSCAT U uncertainties. New QuikSCAT-buoy U comparisons in the northern Atlantic Ocean and in the Southern Ocean confirm the excellent precision of QuikSCAT U (RMS difference of about 1 m s -1 ), but it is possible that QuikSCAT overestimates wind speeds by 5%, leading to a possible overestimation of k derived with quadratic relationships by 10%. The $\langle$k$\rangle$ values obtained with two recent experimental k-U relationships are very close, between 15.9 and 17.9 cm h -1 , and within the error bar of k average deduced from the new oceanic 14 C inventory.