SIO RAS activities in 2010-2012

O. Kopelevich,Lab. Of Ocean Optics SIO RAS, Moscow

Two directions of SIO RAS activities in the Black Sea

• Field studies;

• Working with satellite ocean color data – processing, analysis, development of the regional algorithms.

Field studies in the eastern part of the Black Sea

The area of our studies

The floating spectroradiometer measures the spectral values of the surface irradiance and the upwelling radiance just below the sea surface to avoid sun glints. The spectral range is 390-700 nm; spectral resolution - 2.5 nm; an accuracy is about 5%.

Vertical profiles of the beam attenuation coefficient and spectral underwater irradiance were also measured.

Along with optical characteristics, concentrations of chlorophyll, suspended matter , and coccolitophoride were measured.

The new CD-ROM continues the long-term series of data on bio-optical characteristics of the seas, surrounding Russia, derived from satellite ocean color data. In comparison with the previous issue of 2009, the data of 2009-2010 are included. As before, the new issue includes color maps with the meanmonthly distributions of the bio-optical characteristics in the Barents, White, Black, and Caspian seas since 1998; diagrams demonstrating variability of the monthly means in different sub-regions and in the whole basins; tables with parameters of the inter-annual changeability of different characteristics.

The bio-optical characteristics included: chlorophyll and total suspended matter (TSM) concentrations, the particle backscattering and yellow substance absorption coefficients.For the first time the sea surface temperature (SST) is included to provide an opportunity for analysis of connection between changes of bio-optical characteristics and SST.All of the bio-optical characteristics from 1998 to 2008 were re-calculated after SeaWiFS and MODIS-Aqua Reprocessing 2009 and for 2009-2010 after Reprocessing 2010. Joining the SeaWiFS and MODIS-Aqua data together - from January 1998 to June 2002 the SeaWiFS monthly averages were converted to the MODIS-like monthly averages.

A new issue of the atlas “Bio-optical characteristics of the Barents, White, Black, and Caspian seas from data of satellite ocean color scanners”

Flow-through Fluorometer (FtF)FtF measures the seawater fluorescence  at two spectral intervals, near 480 and 685 nm. First of them is consistentwith the spectral maximum of the DOM fluorescence,the second corresponds to the maximum of Chl fluorescence. The device also measures seawater temperature by the water intake. FtF provide us with data about spatial changeability of CDOM and phytoplankton between the stations. The ship position, its speed and direction is recorded simultaneously with GPS GlobalSat MR-350. When taking water samples characteristics at the stations, vertical profiles of the DOM and Chl fluorescence can be measured in the ship laboratory.

Main technical characteristics• Excitation of the fluorescence is produced by two super flux light emitting diodes (LED) with maximum of the intensity at 373 nm for DOM and 522.5 nm for Chl (the half-width 10 nm); • the spectral transmittance of the filter is maximal at 480 nm at the DOM channel, and at 685 nm at the Ch channel.

• Stability of the measurement of fluorescence intensity during 12 hours 10%

• Range of measuring the seawater temperature (-4 - +35)0C

•Continuous operation time 120 hours

•Weight (without the flow-through system) 7 kg

•Size 200160360mm.

Measurements by FtF in the BIO-OPT cruises

The cruises:1. «Mare Nigrum»- 30/06/11, 20:30 - 05/07/11,16:00; Romanian waters; total time of measurements - 115.5 h.

2. “Akademik” - 08.07.11, 20:00 – 12/07/11, 13:00; Bulgarian waters; total time of measurements - 89 h.

3. “Akademik” – 12.07.11, 23:00 – 22/07/11, 15:00; Bulgarian and Turkish waters; total time - 226 h.

The total time of instantaneous fluorimetry - 430.5 h.

The water samples for measuring vertical profiles of DOM and Chl fluorescence were taken at 52 stations,totally 241 samples.

1. «Mare Nigrum» - 16 stations, 68 samples;2. “Akademik” - 11 stations, 42 samples;

3. “Akademik” - 25 stations, 131 samples.

The water-intake system

a b

The water-intake unit is adapted to the ship where it is installed. At R/V «Mare Nigrum» a metal pipe 70 mm and a length of 7.5m was used (left photo); the suction hose was put in the pipe. Its end with a check valve was placedin the water and attached to the ship board.

During the “Akademik” cruises, the suction hose with a check valve was deepened under the sea surface by means of halyard with a 9 kg weight.

To provide the sea water circulation through the fluorometer, a self-priming centrifugal pump JP 5 Grundfos was mounted just on board (right photo). For separation of the bubbles formed in the system under seawater taking and its circulation, a special bubble chamber was used.

The flow-through system had provided the seawater pumping from a depth of 1.5 m under the Mare Nigrum speed of 10 knots and the Akademik speed of 7.5 knots.

The Mare Nigrum cruise

The ship track of the Mare Nigrum cruise (left ) and a changeability of seawater temperature (black curve),DOM fluorescence (green), and Chl fluorescenceduring the cruise.

The Mare Nigrum cruise – near the Danube delta

The right Figure shows a changeability of seawatertemperature (black curve), DOM fluorescence, and Chl fluorescence when crossing the Danube estuary zone from south to north and from west to east (see the map). The time period: 01/07/11, 02:30 – 02/07/11, 07:00(local time ).

The changeability during the night mooring in the Danube discharge area

The change of seawater temperature (black curve), DOM fluorescence (green), and Chl fluorescence (red)as a function of the local time during the night anchorage of 1-2 July 2011 near the Danube delta.

The Akademik cruise, 8-12 July 2011

Changeability of DOM (green curve) and Chl fluorescence (red) along the Akademik route from 09 to 12 July 2011.(the direction of the ship movement is shown at the map (right)by black arrows).

The Akademik cruise, 13/07 – 22/07/2011

St. K05-S31

Vertical distributions of DOM (green) and Chl (red)fluorescence at St. K05-S31 down to 600 m/

K06-S18

K06-S25

K06-S36

Vertical distributions of DOM and Chl fluorescenceat different stations of the second cruise of Akademik

Table 1: Bio-optical quantities that was determined during the bio-optical oceanographic cruises (from “OCTOBER Progress Report – 2011”)

+ satellite ocean color data from MODIS-Aqua, MERIS+ phytoplankton (coccolithophoride) ?

Use of joint measurements of DOM fluorescence and salinity(an example from results of the Kara Sea cruise in September 2011)

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Comparison between satellite and ship data on chlorophyll concentration

The black line on MODIS image (left) shows the ship track where chlorophyll concentration was measured by a ship flow-through fluorometer. The right figure shows comparison between the changes of chlorophyll concentration derived from from the ship measurements (line 1) and from MODIS-Aqua satellite data (line 2).

SIO RAS suggestions for 2012

• Joint analysis of the data from BIO-OPT cruises 2011 and data from satellite ocean color sensors (MODIS-Aqua, MERIS);

• We wanted to participate in the cruise 2012 with the advanced FtF;

• The planned improvements: • to include a conductivity meter;• to include measurements of fluorescense spectra at the spectral range of 380-850 nm “on-the-fly” by the operator choice.

Thank you for your attention