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errors' and eectively model the sound speed component of the TPU of MBES depths (Imahori, 2007).Currently, sound speed sensors are not used in the most eective manner, causing oversampling in someareas and under sampling in others. The present method to resolve the lack of sampling is to acquiresound speed data in a near continual manner (e.g. using a moving vessel proler with a sound speedsensor) when possible. While this method has proved to be adequate in many cases, it will undoubtablyshorten the sensor equipment operational lifetime.To test a new approach, on May 28 and July 8-9, 2008 in Solomons, MD, we used a Hydroid REMUS100 Autonomous Underwater Vehicle (AUV) tted with a SBE 49 FastCAT CTD sensor (Figure 1) toacquire temperature, salinty and pressure data (which would be used to calculate sound speed and thuscreate sound speed proles (SSP)).Figure 1: Image of the REMUS 100 AUV tted with SBE 49 FastCAT CTD sensor being deployed.The purpose of this experiment was to create a proof-of-concept method using the REMUS to completelycharaterize sound speed uncertainty in a hydrographic project area. Moreover, the ship couldcontinue acquiring multibeam data while the REMUS acquired data for calculating sound speed. Eachposition of the AUV dive (and therefore sound speed cast location) taken July 8-9 was determined withthe aid of the Rutgers University's Regional Ocean Modeling System (ROMS) for the Chesapeake Bay.While NOAA's Coast Survey Development Lab (CSDL) has been working with the REMUS AUV andthe ROMS for a few years, this is the rst time that the two have been used in tandem. This paper hopesto lay the ground work for using the ROMS, when it is available, to support NOAA's use of an AUV toacquire SSPs in the most ecient manner. The ROMS model application domain covers the whole of theChesapeake Bay, from the entrance of the Sasquehanna River in the north to the 100m isobath on theshelf in the south and Washington, DC in the west to Ocean City, MD. The model bottom bathymetrywas created from inverse-square interpolation of National Ocean Service (NOS) sounding measurements.In this paper we will discuss the specications of the REMUS and the ROMS, how the ROMS particlepath tracking was utilized to determine sound speed cast locations and the preparation involved withusing both the REMUS and ROMS. Additionally, this paper will describe the two experiments to enhanceour understanding of how to run the AUV in a cast mode senario and to collect sound speed proles to test2
and rene our algorithm which would be then inserted into NOAA's Velocwin software. Finally, we willdiscuss our results of our rened algorithm and how we conducted a temperature and salinity validationexercise. This proof-of-concept experiment will not only be a benet to hydrographers by helping themdetermine where to eectively sample sound speed and access the environmental uncertainty componentof sound speed (Imahori and Hiebert, 2008), but it will also help NOAA validate the ROMS with thesalinity and temperature observational data collected by the REMUS.2 ProjectNOAA's Oce of Coast Survey maintains the Survey Vessel BAY HYDROGRAPHER (Figure 2), whichis homeported in Solomons, MD. The vessel serves as the primary test and evaluation platform for CSDL.Initial plans were to deploy the REMUS with the FastCAT CTD sensor from the Bay Hydrographer todevelop mission planning guidelines in the familiar environment of the Chesapeake prior to conductingoperational testing in the dynamic and harsh environment of Kachemak Bay, Alaska for NOAA'sHydropalooza (http://oceanservice.noaa.gov/hydropalooza).Figure 2: NOAA S/V BAY HYDROGRAPHERDuring the planning of this project and discussions of future work on sound speed with CSDL (Imahoriand Hiebert, 2008), a ROMS application to the Chesapeake Bay (CBOFS2 - Chesapeake Bay OperationalForecast System which is currently under development) was brought to our attention. It was hoped thatthis model set-up would allow us to gain an understanding of the physical oceanography of the Solomonsregion and provide guidance as to where we should acquire CTD (thus SSPs) with the REMUS.Unlike the salinity and temperature data we were planning on using from the BAY HYDROGRA-PHER's past projects to deduce the oceanographic variability, the ROMS via Lagrangian particle pathtracking, would enable us to see the eects the tidal water elevations and currents thus showing the movementsof the water 'parcels' both in the horizontal and the vertical (up and down the water column).This would in turn provide us with added information about the extent of the horizontal and verticalmixing/dispersion associated with the intervals of the tidal cycle for our SSP collection.The REMUS 100 AUV weighs approximately 55 kg and is 180 cm in length. The REMUS can operateat a maximum depth of 100 m and has an endurance of up to 18 hours. The REMUS's maximum speedis 5 knots, but typical survey speed is 3-4 knots. The REMUS can not work eectively in areas wherethe current is greater than 3 knots.3
Page 1: An integrated approach to acquiring
Page 5 and 6: ≤ Δy ≤ 3380m in the two spatia
Page 7 and 8: Figure 4: Image of 3 REMUS AUV CTD
Page 9 and 10: Figure 6: Tides for Solomons, MD Ju
Page 11 and 12: Figure 9: This image is of the vert
Page 13 and 14: Figure 10: This image is of the ver
Page 15 and 16: Figure 12: Vertical path of REMUS o
Page 17 and 18: osets could be due to an initial os
Page 19: Shchepetkin, A. F. and McWilliams,

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