Survey, 2015-06-07, Baltic Sea

Baltic Sea 2015, Arkona to Gdańsk

A four-day transect across the south-western Baltic in June 2015, from the Arkona Basin to Gdańsk Bay, 127,640 returns mapping the brackish sea's high coloured-dissolved-organic load alongside chlorophyll and suspended matter. A characteristic CDOM-dominated, optically complex Case-2 setting.

Published figures

Interpolated fields from the campaign, reproduced as issued. Plate titles carry the LIFL-9 under its original designation, UFL-9.

Interpolated chlorophyll a field mapped along the lidar track, Arkona Basin → Gdańsk Bay, Arkona Basin to Gdansk Bay, 2015 — Fig. 1Chlorophyll a

Interpolated CDOM field mapped along the lidar track, Arkona Basin → Gdańsk Bay, Arkona Basin to Gdansk Bay, 2015 — Fig. 2CDOM

Interpolated total suspended matter field mapped along the lidar track, Arkona Basin → Gdańsk Bay, Arkona Basin to Gdansk Bay, 2015 — Fig. 3TSM

Arkona → GdańskBaltic Sea

● Baltic Sea 2015, 2015-06-07 → 2015-06-11127,640 measurements IDW interpolation, 600 samples

Chl-a0.6010.3µg/L

CDOM0.0033.7a.u.

TSS0.993.04mg/L

Fig. 4 Campaign scan. 127,640 lidar returns along the ship track, switchable across Chl-a, CDOM, TSS. Field view interpolates the channel across the surveyed water from the same measurements (inverse-distance weighting). Shoreline: Natural Earth.

The Baltic is brackish, river-fed and among the most coloured of the seas LIFeLiDAR has worked, with a coloured-dissolved-organic load that confounds the band-ratio chlorophyll algorithms tuned for clear ocean water. In June 2015 a LIF LiDAR ran a four-day transect from the Arkona Basin south-east to Gdańsk Bay, returning 127,640 simultaneous measurements of chlorophyll a, CDOM and total suspended matter.

Across the section median CDOM sits near 6 a.u., several times the chlorophyll-fluorescence signal, exactly the regime where separating the two constituents matters most and where passive ocean colour struggles. Measuring all three channels at the same place and time, continuously along the track, is what lets the contributions be disentangled rather than assumed.