Eintrag weiter verarbeiten
Mechanisms of Low‐Frequency Oxygen Variability in the North Pacific
Gespeichert in:
| Zeitschriftentitel: | Global Biogeochemical Cycles |
|---|---|
| Personen und Körperschaften: | , , , , |
| In: | Global Biogeochemical Cycles, 33, 2019, 2, S. 110-124 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
American Geophysical Union (AGU)
|
| Schlagwörter: |
| Zusammenfassung: | <jats:p>This study investigates the mechanisms of interannual and decadal variability of dissolved oxygen (O<jats:sub>2</jats:sub>) in the North Pacific using historical observations and a hindcast simulation using the Community Earth System Model. The simulated variability of upper ocean (200 m) O<jats:sub>2</jats:sub> is moderately correlated with observations where sampling density is relatively high. The dominant mode of O<jats:sub>2</jats:sub> variability explains 24.8% of the variance and is significantly correlated with the Pacific Decadal Oscillation (PDO) index (<jats:italic>r</jats:italic> = 0.68). Two primary mechanisms are hypothesized by which the PDO controls upper ocean O<jats:sub>2</jats:sub> variability. Vertical movement of isopycnals (“heave”) drives O<jats:sub>2</jats:sub> variations in the deep tropics; isopycnal surfaces are depressed in the eastern tropics under the positive (El Niño‐like) phase of PDO, leading to O<jats:sub>2</jats:sub> increases in the upper water column. In contrast to the tropics, changes in subduction are the primary control on extratropical O<jats:sub>2</jats:sub> variability. These hypotheses are tested by contrasting O<jats:sub>2</jats:sub> anomalies with the heave‐induced component of variability calculated from potential density anomalies. Isopycnal heave is the leading control on O<jats:sub>2</jats:sub> variability in the tropics, but heave alone cannot fully explain the amplitude of tropical O<jats:sub>2</jats:sub> variability, likely indicating reinforcing changes from the biological O<jats:sub>2</jats:sub> consumption. Midlatitude O<jats:sub>2</jats:sub> variability indeed reflects ocean ventilation downstream of the subduction region where O<jats:sub>2</jats:sub> anomalies are correlated with the depth of winter mixed layer. These mechanisms, synchronized with the PDO, yield a basin‐scale pattern of O<jats:sub>2</jats:sub> variability that are comparable in magnitude to the projected rates of ocean deoxygenation in this century under “unchecked” emission scenario.</jats:p> |
|---|---|
| Umfang: | 110-124 |
| ISSN: |
0886-6236
1944-9224 |
| DOI: | 10.1029/2018gb005987 |