A. Aitsam

Estonian Academy of Sciences

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Jüri Elken

Tallinn University of Technology

Mati Kahru

Scripps Institution of Oceanography

Jaan Laanemets

Tallinn University of Technology

L. Talpsepp

Tallinn University of Technology

J. Pavelson

Tallinn University of Technology

M-J. Lilover

Estonian Academy of Sciences

Volker Fiekas

L. Talsepp

Hans Peter Hansen

Aarhus University

W. Krauss

Karlsruhe Institute of Technology

Cooperative Institutions

Institute of Thermophysics

Estonian Academy of Sciences

Kiel University

Tallinn University of Technology

GEOMAR Helmholtz Centre for Ocean Research Kiel

Stockholm Environment Institute

Institute of Oceanology. PP Shirshov Russian Academy of Sciences

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Scripps Institution of Oceanography

University of California, San Diego

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Coarse-Scale Spatial Structure of Phytoplankton Standing Crop in Relation to Hydrography in the Open Baltic Sea

Marine Ecology Progress Series (1981)

Mati Kahru A. Aitsam Jüri Elken

During a n interdisciplinary study of the BOSEX site in the Gotland Basin, central Baltic Sea, a number of mappings of the chlorophyll and hydrographic fields were made by vertical profilings on a regular grid of 20 X 25 nautical miles with a 5-mile station spacing.Spatial variability of the chlorophyll and density fields was partitioned into the fine-scale [-100 m) and coarse-scale [-10 km) components.The chlorophyll coarse-scale variance dominates over the fine-scale variance by an order of magnitude in the upper layer.The coarse-scale pattern of the phytoplankton standing crop, measured by the vertically integrated chlorophyll a concentration, shows 2.4-fold variations and coupling to the pattern of the intermediate layer thickness.The intermediate layer separates the upper layer, suitable for plant growth, and the deep layer, the source of nutrients.It is suggested that above a thin intermediate layer, by increased vertical current shear and breaking internal waves, the upward flux of nutrients is intensified causing a n enhanced phytoplankton growth and the increased standing crop.

Standing crop

Baltic sea

Open sea

10.3354/meps005311

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Citations (15)

Topographically Induced Variability in the Baltic Sea

Springer eBooks (1983)

A. Aitsam Jüri Elken L. Talsepp Jaan Laanemets

Baltic sea

10.1007/978-1-4615-6648-9_14

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Citations (2)

On the scales of variability and the structure of waters of the Baltic Sea

Ocean Management (1981)

A. Aitsam

Baltic sea

10.1016/0302-184x(81)90037-8

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Citations (0)

Synoptic Scale Variability of Hydrophysical Fields in the Baltic Proper on the Basis of CTD Measurements

Elsevier oceanography series (1982)

A. Aitsam Jüri Elken

CTD

10.1016/s0422-9894(08)71254-6

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Citations (16)

Synoptic Scale Variability in Shallow Seas with an Example from the Baltic Sea

Springer eBooks (1983)

A. Aitsam Jüri Elken

Mooring

Baltic sea

Synoptic scale meteorology

10.1007/978-3-642-68838-6_25

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Citations (1)

Finestructure of the Open Part of the Baltic Sea

Elsevier oceanography series (1982)

A. Aitsam Jaan Laanemets M-J. Lilover

Baltic sea

Temperature salinity diagrams

Open sea

10.1016/s0422-9894(08)71253-4

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A view of the Canary Basin thermocline circulation in winter

Journal of Geophysical Research Atmospheres (1992)

Volker Fiekas Jüri Elken Thomas J Müller A. Aitsam Walter Zenk

During January and February 1989 the recirculation of the subtropical gyre in the eastern North Atlantic was surveyed with a three‐ship experiment. The analysis of hydrographic measurements and velocity data from a shipboard acoustic Doppler current profiler reveals the synoptic‐scale circulation patterns and water mass distributions in the Canary Basin. The geostrophic transport stream function estimated with a horizontally varying reference level of no motion highlights the major currents in three layers representing the vertical structure of the horizontal circulation. The classical circulation scheme is shown by the stream function in the upper 200 m: the Azores, Canary, and North Equatorial currents. Unlike the deep‐penetrating Azores Current, the Canary Current and the North Equatorial Current are restricted to the upper 200 m. Both carry North Atlantic Central Water along the water mass boundary with South Atlantic Central Water. South Atlantic Central Water flows through the passage between the Cape Verde archipelago and Africa via narrow currents into the area north of 14.5°N. At the southern edge of the subtropical gyre we identify an eastward flow of Antarctic Intermediate Water between 700 and 1200 m.

Gulf Stream

Boundary current

Geostrophic current

Antarctic Intermediate Water

10.1029/92jc01095

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Citations (39)

Chlorophyll variability in the Baltic Sea: a pitfall for monitoring

ICES Journal of Marine Science (1985)

Mati Kahru A. Aitsam

Within the time and space scales of quasi-synoptic areal surveys (∼1 day, ∼50 km) thefluorescence, measured by an in situ profiler, is shown to be a reliable measure of the chlorophyll a concentration, although significant areal and temporal differences in the fluorescence yield were observed. Analysis of variance is used to partition the total chlorophyll variance into effects due to differences between large-scale areas in different basins, to time differences between surveys, and to synoptic-scale (∼10 km) and fine-scale (∼100 m) spatial variability. It is shown that the large-scale areal differences in chlorophyll concentration are inevitably missed, being over-shadowed by the other components of variance. The dominant sources of variance are due to the time and to the synoptic-scale space variability. With respect to the variance structure, the total water column chlorophyll is preferable for monitoring purposes. The results point up weaknesses in the conventional practice of monitoring a highly variable parameter via a sparse gridafew times a year.

Baltic sea

10.1093/icesjms/42.2.111

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Citations (4)

Physical and chemical variability of the Baltic Sea: a joint experiment in the Gotland Basin

Continental Shelf Research (1984)

A. Aitsam Hans Peter Hansen Jüri Elken Mati Kahru Jaan Laanemets

Halocline

Eddy

Anticyclone

CTD

Current meter