An analysis of the horizontal regime of denitrification in the eastern tropical North Pacific1

A method using isentropic analysis to estimate nitrate removals by denitrification in the oxygen deficient waters of the eastern tropical North Pacific agreed reasonably well with a technique based on vertical distributions. Dynamic computations permitted an estimate of the horizontal advective transport of these nitrate deficits out of the study region; such transport was a large fraction of the total, indicating that horizontal processes are important. The horizontal transports used in combination with estimates for vertical losses and horizontal diffusive losses yielded a denitrification rate of ⋍2 × 10 13 g N yr ‒1 for the portion of the eastern tropical North Pacific east of ⋍112°W. This value was in good agreement with estimates based on the application of respiration rates to the appropriate volumes of oxygen deficient water and with an estimate based on a vertical model.