Multi-beam bathymetry

paleoceanic circulation, paleoproductivity, sea-ice distribution and ice sheet dynamics on the surrounding continents in the Pleistocene in a relatively high UHVROXWLRQ )XUWKHUPRUH WKH PDSSLQJ RI NH\ OLWKRORJLFDO OD\HUV PD\ DOORZ WKH correlation paleoenvironmental events across the Arctic Ocean.

,Q WKLV IUDPHZRUN WKH JHRORJLFDO SURJUDPPH LQFOXGHG VSHFL¿F SURMHFWV HJ PDSSLQJ VHD ÀRRU VWUXFWXUHV DORQJ WKH VKLSV WUDFN E\ VZDWK EDWK\PHWU\ DQG sediment echosounder, re-sampling stations visited during VIII/3 and ARK-IX/4 in 1991 and 1993, respectively, to possibly identify the impact of recent climate change on benthic foraminifer faunas, and collecting surface sediments for calibration of paleoceanographic proxies such as biomarkers, benthic foraminifer faunas, and stable oxygen and carbon isotope composition of planktic and benthic IRUDPLQLIHUV)LQDOO\LQRUJDQLFJHRFKHPLVWU\VWXGLHVLQLWLDWHGGXULQJ$5.;;,,, in 2008 to unravel the origin of manganese-rich layers in the Arctic Ocean, were continued to supplement the records from the East Siberia continental margin with data sets from the various basins visited during the expedition. In the following, we will describe the methods related to work during the expedition.

The geological station work was conducted along the oceanographic transects outside the Russian EEZ. Sites on submarine highs were selected for coring by XVLQJLQIRUPDWLRQRQVHDÀRRUDQGVXEERWWRPVWUXFWXUHIURPVZDWKEDWK\PHWU\

and sediment echosounding (Hydrosweep and Parasound) to obtain hemipelagic sedimentary records not overprinted by sediment redeposition. Surface and sub-surface sediments were taken by gravity corer, giant box corer, and multicorer.

8.1 Multi-beam bathymetry

Patricia Slabon Alfred-Wegener-Institut Objectives

The main task of the bathymetric work was to conduct multibeam (MB) surveys in support of the geological and oceanographical programs using the new Hydrosweep '6V\VWHP$WODV+\GURJUDSKLFDQGPRQLWRUWKHGDWDDFTXLVLWLRQWRHQVXUHKLJK resolution spatial depth information throughout the expedition. Due to the reduced number of MB-staff, no data processing was carried out. The recorded MB-data is a valuable contribution to datasets of IBCAO (International Bathymetric Chart of the

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Another interest was to create a progress report about the new operation software RI+\GURVZHHS'6DQGWKHDFTXLVLWLRQV\VWHP+<3$&.ZKLFKZHUHLQVWDOOHGLQ 2FWREHU6HYHUDORSHQTXHVWLRQVUHPDLQHGDIWHUWKHDFFHSWDQFHWHVWDQGVHD trials, which were reviewed during this cruise in detail. All problems concerning data collection and visualization were reported to the corresponding companies. Jointly with the system manufacturer and HYPACK it was tried to solve these problems.

Work at sea

The multibeam survey was started on August 6, 2011 at 9:00am UTC for testing SXUSRVHV$IWHUVROYLQJVHYHUDOWHFKQLFDOSUREOHPVGDWDDFTXLVLWLRQZDVVWDUWHGLQ

and was continued until September 22 at 7.30pm UTC, before entering the Russian ((=1RGDWDDFTXLVLWLRQZDVFDUULHGRXWZLWKLQWKH5XVVLDQ((=

At the beginning of the cruise, Hydrosweep (Hydromap Control) caused several system errors that generally were solved by total system shut down and restart.

The HYPACK software caused also problems that forced repeatedly a restart of the system. Apart from all technical problems, HYPACK and Hydrosweep operated UHODWLYHO\VWDEOH5XQWLPHHUURUVRFFXUULQJUDQGRPO\GLGQRWUHTXLUHDQ\UHSDLURU a complete reboot of the system.

When leaving the Russian EEZ on September 29 at 3:29pm UTC into international ZDWHUV DQG HQWHULQJ WKH 1RUZHJLDQ ((= GDWD DFTXLVLWLRQ ZDV FRQWLQXHG XQWLO October 3, 2011 at 9:31am UTC. During the transit to Bremerhaven, heavy sea off the Norwegian coast caused systematic errors and thus poor depth measurements, obviously due to unsatisfactory measurements of ships attitude. These effects were mainly observed in shallow water regions.

,QWKHGHHSVHD+\GURVZHHSZDVRSHUDWHGLQ(TXDO)RRWSULQW%HDP6SDFLQJPRGH XVLQJDGH¿QHGQXPEHURIEHDPVSHUSLQJ7KHXVHGIUHTXHQF\LVN+]

7KHDSHUWXUHDQJOHRIWKHVRQDUIDQFDQEHVHOHFWHGEHWZHHQVHYHUDOSUHGH¿QHG VHDÀRRUFRYHUDJHV'XULQJWKLVFUXLVHDQRSHQLQJDQJOHRIVWDUERDUG portside, depending on the water depth was used. A larger angle of 200%/200%

FUHDWHGORZUHVROXWLRQDQGSRRUGDWDTXDOLW\2QO\LQVKDOORZZDWHUVEHWZHHQ m and 350 m the wider swath of 200%/200% was chosen. In waters less than 100 m, resulting depths show systematic errors in particular in the outer beams.

In areas with water depths of less than 100 m an angle of 150%/150% was used.

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*.HSX and *.RAW (e.g.: ARK26-3_2011__2291239_0.HSX). In areas exceeding 84°N the universal polar stereographic projection (UPS) was used for visualization, otherwise the UTM projection. As data processing was not carried out, only selected

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FRPSDULQJ WKH 0%GDWD WR WKH '6+,3 1DYLJDWLRQ ¿OHV )XUWKHUPRUH VRPH ¿OHV ZHUH YLVXDOL]HG DQG FKHFNHG XVLQJ &$5,6 +,36 )RU WKH JHQHUDWLRQ RI ZRUNLQJ PDSVRQERDUGIHZGDWDZHUHH[SRUWHGDV$6&,,¿OHVORQJLWXGHODWLWXGHGHSWK During Hydrosweep operation, the actual swath is displayed on the screen. This LQIRUPDWLRQLVXVHGWR¿QGVXLWDEOHORFDWLRQVHVSHFLDOO\IRUWKHPDULQHJHRORJLFDO work in real time. Due to technical problems regarding the import of the SVP 6RXQG 9HORFLW\ 3UR¿OH LQWR +\GURPDS &RQWURO FRUUHFW PXOWLEHDP GHSWKV ZHUH not available.

Echo sounders derive the water depth from the travel time of the acoustic signal UXQQLQJIURPWKHWUDQVGXFHUWRWKHVHDÀRRUDQGEDFNWRWKHUHFHLYHU7KHH[DFW sound velocity in the water column, which depends on pressure, temperature and salinity, is needed. The depth precision can vary strongly due to regional and local variations of the physical parameters in the water column that affect the VRXQGYHORFLW\$ZHOOHVWDEOLVKHGWHFKQLTXHWRGHULYHWKHZDWHUVRXQGYHORFLW\LV to perform CTD (Conductivity, Temperature and Depth) casts.

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8.1 Multi-beam bathymetry

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&7'3UR¿OHVZHUHSURFHVVHGDQGXVHGIRUWKHZDWHUVRXQGYHORFLW\FRUUHFWLRQ 'XULQJ WUDQVLWV QR VRXQG YHORFLW\ SUR¿OHV ZHUH DYDLODEOH +HQFH WKH UHFRUGHG measurements must be processed using external sound velocity data as available for example from ODV (ocean data view), before using them for mapping purposes.

Preliminary results

During the expedition a nearly continuous recording of data was achieved, except for few gaps caused by unexpected system errors and shutdowns. During 36 days RIZRUNLQWKHPDLQVHDUFKDUHDDSUR¿OHOHQJWKRIDERXWQPNP was surveyed, generating 7.2 m. pings and 102 bn. beams (before editing). The DPRXQW RI UDZ GDWD VWRUDJH YROXPH LV *% FUHDWHG E\ VHSDUDWH ¿OHV GLYLGHGLQWR+6;DQG5$:¿OHV7KHREVHUYHGGHSWKVYDU\EHWZHHQOHVVWKDQ PHWHUVLQWKHFRDVWDOUHJLRQVRI1RUZD\DQG*UHHQODQGDQGXSWRPHWHUV LQDFHQWUDOYDOOH\RIWKH*DNNHO5LGJH

Despite the almost permanent ice coverage and the mentioned problems the system ZRUNHGRYHUSHULRGVUHOLDEOHDQGSURYLGHGKLJKTXDOLW\GDWD6RPHGLVWXUEDQFHVLQ the data could not be avoided during ice breaking.

7KH*(%&2B*ULG*HQHUDO%DWK\PHWULF&KDUWRIWKH2FHDQVJLYHVDQRYHUYLHZ on the morphology of the region. These data can be used for general planning. The recorded data differ at several places, due to the low resolution (2 km x 2 km) of the JOREDO*(%&2GDWDVHWZKLFKLVSDUWO\EDVHGRQGHULYHGVDWHOOLWHJUDYLW\GDWDDQG sparse bathymetric echo sounder data collected by submarines and icebreakers.

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Fig. 8.1: Example of differences between bathymetry at the Karasik Seamount from IBCAO (contour lines) and unedited multibeam bathymetry of this cruise (color coded

and shaded).