Seasonal and interannual variability of phytoplankton biomass west of the Antarctic Peninsula

Abstract. The regional climate model RACMO2 has been a powerful tool for improving SMB estimates from GCMs or reanalyses. However, new yearly SMB observations for West Antarctica show that the modelled interannual variability in SMB is poorly simulated by RACMO2, in contrast to ERA-Interim, which resolves this variability well. In an attempt to remedy RACMO2 performance, we included additional upper air relaxation (UAR) in RACMO2. With UAR, the correlation to observations is similar for RACMO2 and ERA-Interim. The spatial SMB patterns and ice sheet integrated SMB modelled using UAR remain very similar to the estimates of RACMO2 without UAR. We only observe an upstream smoothing of precipitation in regions with very steep topography like the Antarctic Peninsula. We conclude that UAR is a useful improvement for RCM simulations, although results in regions with steep topography should be treated with care.

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Interannual variability in phytoplankton biomass and species composition in northern Marguerite Bay (West Antarctic Peninsula) is governed by both winter sea ice cover and summer stratification

Limnology and Oceanography ◽

10.1002/lno.10391 ◽

2016 ◽

Vol 62 (1) ◽

pp. 235-252 ◽

Cited By ~ 39

Author(s):

P. D. Rozema ◽

H. J. Venables ◽

W. H. van de Poll ◽

A. Clarke ◽

M. P. Meredith ◽

...

Keyword(s):

Species Composition ◽

Sea Ice ◽

Interannual Variability ◽

Antarctic Peninsula ◽

Phytoplankton Biomass ◽

Ice Cover ◽

West Antarctic ◽

Marguerite Bay ◽

West Antarctic Peninsula

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The water masses of the east coast of Tasmania: Seasonal and interannual variability and the influence on phytoplankton biomass and productivity

Marine and Freshwater Research ◽

10.1071/mf9870569 ◽

1987 ◽

Vol 38 (5) ◽

pp. 569 ◽

Cited By ~ 87

Author(s):

G Harris ◽

C Nilsson ◽

L Clementson ◽

D Thomas

Keyword(s):

Interannual Variability ◽

Primary Productivity ◽

Phytoplankton Biomass ◽

Seasonal Cycle ◽

East Coast ◽

Spring Bloom ◽

Water Masses ◽

Seasonal And Interannual Variability ◽

Summer Temperatures

The seasonal and interannual variability of the water masses, nutrients, phytoplankton biomass and primary productivity of the waters off the eastern coast of Tasmania are described. The seasonal and interannual variability in the water masses on the east coast could be explained by the varying influence of tropical and subantarctic waters and the presence of the northern edge of the subtropical convergence north-east from Maria Island. The physical oceanography was dominated by mesoscale events and the influence of the two parent water masses was highly episodic. Subtropical water rarely extended as far south as Tasman Island in summer and subantarctic water never extended as far north as Flinders Island. Data from satellite Advanced Very High Resolution Radiometer (AVHRR) images confirmed the hydrographic data and were used to interpret the seasonal and interannual variability. Interannual variability in maximum summer temperatures at Maria Island was correlated with the southerly extension of subtropical waters and with El Nino/Southern Oscillation events at least until the mid-1970s. There was evidence of a long-term warming at Maria Island and a cyclic fluctuation of 10-15 years in smoothed maximum summer temperatures. The decline in nitrate, and hence the phytoplankton spring bloom, occurred a month earlier inshore than offshore. Long-term data records from the inshore station at Maria Island showed strong interannual changes in the timing of the nitrate decline. The timing of the spring bloom varied from year to year by as much as 4 months. The seasonal cycle of phytoplankton biomass in 1984 and 1985 showed spring (October) and autumnal (April) blooms, with an early summer bloom in December. Low chlorophyll levels in February and March coincided with the influence of subtropical water. The seasonal cycle of phytoplankton biomass was therefore a complex function of seasonal and episodic events. Primary productivity data from the spring of 1984 showed low productivity on the west coast of Tasmania but high productivity on the east coast around Maria Island and the islands in Bass Strait.

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