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Simulating Water Residence Time in the Coastal Ocean: A Global Perspective
Author(s) -
Liu Xiao,
Dunne John P.,
Stock Charles A.,
Harrison Matthew J.,
Adcroft Alistair,
Resplandy Laure
Publication year - 2019
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 - 10.1029/2019gl085097
Subject(s) - environmental science , oceanography , biogeochemical cycle , residence time (fluid dynamics) , range (aeronautics) , boundary current , grid , ocean current , climatology , geology , meteorology , geography , geodesy , chemistry , materials science , geotechnical engineering , environmental chemistry , composite material
Exchanges between coastal and oceanic waters shape both coastal ecosystem processes and signatures that they impart on global biogeochemical cycles. The timescales of these exchanges, however, are poorly represented in current‐generation, coarse‐grid climate models. Here we provide a novel global perspective on coastal residence time (CRT) and its spatio‐temporal variability using a new age tracer implemented in global ocean models. Simulated CRTs range widely from several days in narrow boundary currents to multiple years on broader shelves and in semi‐enclosed seas, in agreement with available observations. Overall, CRT is better characterized in high‐resolution models (1/8° and 1/4°) than in the coarser (1° and 1/2°) versions. This is in large part because coastal and open ocean grid cells are more directly connected in coarse models, prone to erroneous coastal flushing and an underestimated CRT. Additionally, we find that geometric enclosure of a coastal system places an important constraint on CRT.