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A cubic relationship between air‐sea CO 2 exchange and wind speed
Author(s) -
Wanninkhof Rik,
McGillis Wade R.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl900363
Subject(s) - wind speed , environmental science , atmospheric sciences , meteorology , term (time) , climatology , physics , geology , quantum mechanics
Using recent laboratory and field results we explore the possibility of a cubic relationship between gas exchange and instantaneous (or short‐term) wind speed, and its impact on global air‐sea fluxes. The theoretical foundation for such a dependency is based on retardation of gas transfer at low to intermediate winds by surfactants, which are ubiquitous in the world's oceans, and bubble‐enhanced transfer at higher winds. The proposed cubic relationship shows a weaker dependence of gas transfer at low wind speed and a significantly stronger dependence at high wind speed than previous relationships. A long‐term relationship derived from such a dependence, combined with the monthly CO 2 climatology of Takahashi [1997], leads to an increase in the global annual oceanic CO 2 uptake from 1.4 Gigaton C yr −1 to 2.2 Gigaton C yr −1 . Although a cubic relationship fits within global bomb‐ 14 C oceanic uptake constraints, additional checks are warranted, particularly at high wind speeds where the enhancement is most pronounced.