4:45 PM - 5:00 PM
[ACG37-18] Mooring measurement near a marine-terminating glacier in Bowdoin Fjord in northwestern Greenland
Keywords:Greenland, Fjord, Marine-terminating glacier
Two moorings were deployed in Bowdoin Fjord, one at 17 km from the glacier front (BF17) and another at approximately 1 km from the glacier front (BF01), respectively. The ocean depth was 540 m at BF17 and 186 m at BF01. The moorings were equipped with a pressure sensor (DEFI2-D50HG, JFE Advantech), thermistors (NWT-SN, Nichiyu Giken and SBE56, Seabird), current meters (INFINITY-EM, JFE Advantech) and conductivity-temperature sensors (SBE-37SM, Seabird). At BF17, a current meter and a conductivity-temperature sensor were at the depths 527 m and 530 m, respectively. A pressure sensor and seven thermistors were at 220 m and 222, 246, 268, 318, 368, 418, and 468 m, respectively. At BF01, a current meter and a conductivity-temperature sensor were at the depths of 167 m and 170 m, respectively. The instruments were operated from August 2016 to July 2018 at BF17 and from July 2017 to July 2018 at BF01.
At BF17, temperature near the bottom was lower during northward current (towards the glacier). Temperature variations corresponded well with that of salinity throughout the year, i.e. temperature increased when salinity decreased. From August to October, we observed fortnightly temperature variations suggesting the influence of tide on water exchange in the fjord. In early August, water near the bottom at BF01 flowed towards the glacier and temperature near the bottom rapidly decreased. This event occurred when the daily mean air temperature measured at Qaanaaq Airport exceeded 0 °C, indicating the initiation of subglacial discharge. Temperature variations near the bottom at BF01 correlated with salinity, i.e. temperature and salinity increased at similar timings. Both at BF17 and BF01, temperature variations were small in winter and spring, which we attribute to sea ice cover usually observed in Bowdoin Fjord from November to June. Our data suggested that tide plays a key role in water exchange in the fjord, whereas water property near the glacier front was strongly influenced by meltwater discharge. In the presentation, water property variations and fjord circulation are discussed with weather conditions, and the data obtained at BF17 are compared with those at BF01.
This research was funded by the Arctic research project Arctic Challenge for Sustainability (ArCS).
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