气候变化领域集成服务门户(CCPortal): Upwelling and isolation in oxygen-depleted anticyclonic modewater eddies and implications for nitrate cycling

CCPortal

DOI	https://doi.org/10.1594/PANGAEA.860781
	Upwelling and isolation in oxygen-depleted anticyclonic modewater eddies and implications for nitrate cycling
	Karstensen; Johannes; Schütte; Florian; Pietri; Alice; Krahmann; Gerd; Fiedler; Björn; Grundle; Damian; Hauss; Helena; Körtzinger; Arne; Löscher; Carolin R; Testor; Pierre; Viera; Nuno; Visbeck; Martin
发布日期	2016-05-25
数据集类型	dataset
英文简介	The physical (temperature, salinity, velocity) and biogeochemical (oxygen, nitrate) structure of an oxygen depleted coherent, baroclinic, anticyclonic mode-water eddy (ACME) is investigated using high-resolution autonomous glider and ship data. A distinct core with a diameter of about 70 km is found in the eddy, extending from about 60 to 200 m depth and. The core is occupied by fresh and cold water with low oxygen and high nitrate concentrations, and bordered by local maxima in buoyancy frequency. Velocity and property gradient sections show vertical layering at the flanks and underneath the eddy characteristic for vertical propagation (to several hundred-meters depth) of near inertial internal waves (NIW) and confirmed by direct current measurements. A narrow region exists at the outer edge of the eddy where NIW can propagate downward. NIW phase speed and mean flow are of similar magnitude and critical layer formation is expected to occur. An asymmetry in the NIW pattern is seen that possible relates to the large-scale Ekman transport interacting with ACME dynamics. NIW/mean flow induced mixing occurs close to the euphotic zone/mixed layer and upward nutrient flux is expected and supported by the observations. Combing high resolution nitrate (NO3-) data with the apparent oxygen utilization (AOU) reveals AOU:NO3- ratios of 16 which are much higher than in the surrounding waters (8.1). A maximum NO3- deficit of 4 to 6 µmol kg-1 is estimated for the low oxygen core. Denitrification would be a possible explanation. This study provides evidence that the recycling of NO3-, extracted from the eddy core and replenished into the core via the particle export, may quantitatively be more important. In this case, the particulate phase is of keys importance in decoupling the nitrogen from the oxygen cycling.
空间范围	Median Latitude: 11.864081 * Median Longitude: -22.618383 * South-bound Latitude: 6.999500 * West-bound Longitude: -26.000333 * North-bound Latitude: 19.299833 * East-bound Longitude: -17.500000
时间范围	2014-03-17T21:17:00 - 2014-04-14T19:14:00
语种	英语
国家	国际
学科大类	气候变化
学科子类	气候变化
文献类型	数据集
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/215402
推荐引用方式 GB/T 7714	Karstensen,Johannes,Schütte,et al. Upwelling and isolation in oxygen-depleted anticyclonic modewater eddies and implications for nitrate cycling.2016-05-25.https://doi.org/10.1594/PANGAEA.860781.