Publication Date:
2024-02-07
Description:
Highlights:
• Unique 30-years data of currents and temperature below 1000 m in the Madeira Basin.
• Inter-decadal and long term changes were examined between 1000 m and the bottom.
• Temperature increase by 0.03 ± 0.01 °C/year (1000 m) and 0.02 ± 0.02 °C/year at 1600 m.
• No significant changes at 3000 m and 5000 m at long-term scale.
• The currents and kinetic energy increased in the entire water column over 30-years.
Abstract:
Data from the deep-sea mooring Kiel 276 (33
N, 22W), 5300 m water depth in the northeast Atlantic, was used to investigate the temporal variability of temperature and currents below the main thermocline (1000 m, 1600 m, 3000 m, 5000 m) in the 30-year period (between 1980 and 2009). Daily averages were the basis to assess the temperature and currents changes, as well as kinetic energy, from annual to decadal and long-term scales. Below the main thermocline, no seasonal signal was identified for both, temperature and currents, during the 30 years. The record-length linear temperature trends at 1000 m and 1600 m are 0.03 ± 0.01 °C year−1 and 0.02 ± 0.02 °C year−1, respectively. The mean currents also intensified within the decades in the entire water column, and as a consequence, the mean kinetic energy increased. The fluctuating kinetic energy increased on a decadal scale only at 1000 m, as a possible consequence of the increase in the strength of Mediterranean Water lenses (MEDDIES) that crossed the mooring site. During the period 2001–2009, six MEDDIES crossed the Kiel 276 site, in addition to the 10 MEDDIES identified earlier during the previous 20 years, between 1980 and 2000 (Siedler et al., 2005). The integral time scales are of the same order in all depths (between 30 to 40 days), indicating that events occur on similar time scales, with mesoscale signals dominating and being present within the entire water column.
Type:
Article
,
PeerReviewed
Format:
text
Permalink
