EPR ISS Community Memo Sept Page of To EPR

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					EPR ISS Community Memo – Sept. 21, 2007

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To: EPR ISS PIs and R2K Community From: Dan Fornari, Suzanne Carbotte, and Vicki Ferrini Date: Sept 21, 2007 Subject: Status of EPR ISS Infrastructure Components – Transponder Navigation, Benchmarks, detailed SM2000 near-bottom multibeam bathymetry maps, and Data Management Office activities Greetings: In advance of upcoming Fall 2007 Alvin diving programs to the EPR ISS we wanted to inform the PIs of 2007 field programs and the R2K community about several ongoing efforts at the site. The topics covered in this memo are: 1) status of various data sets collected earlier this year at the EPR ISS, 2) LBL transponder navigation data analysis and final ‘positions’ for transponders and hiT vents, 3) results of deploying benchmarks at several locations along the EPR axis between 9° 48’-51’N, 4) ongoing Data Management Office efforts and continued request for data from upcoming programs This information will also be posted on the Ridge2000 website and the link highlighted in the next R2K weekly news email blast. If you have any questions on these topics please do not hesitate to contact us or the R2K Office. Best Regards, Dan, Suzanne and Vicki EPR ISS Community Memo Sept. 21, 2007 1. EPR ISS data sets collected on AT15-17 cruise Three days of Jason2 ROV time were funded by the NSF and R2K to conduct a variety of surveying and recovery tasks associated with the EPR ISS in the 9° 50’N area, specifically related to the 2005-2006 eruptions (i.e., recovering OBSs stuck in the new flows), as well as establishing seafloor benchmarks to aid in future studies at the vent sites, and repeat mapping and sampling. All vehicle data from Jason dive J2-268 have been submitted to the DMO and are available to the community for advanced processing. The detailed summary of the ROV dive operations is posted on the R2K website at: http://www.ridge2000.org/science/iss/epr/index.php and is also available through the DMO at: http://www.marine-geo.org/link/entry.php?id=AT15-17. High-resolution near-bottom SM2000 multibeam data were collected throughout the duration of dive J2-268. These data were collected to generate 1-meter bathymetric maps that will soon be made available to community for use as base-maps for experiments. These data also provide a baseline of well-constrained seafloor topographic data that can be used to assess future changes at the site. Examples of the bathymetry data are presented in the J2-268 dive summary (see URLs above). Processed 1-m grids are being compiled and will be provided to PIs of upcoming field programs as well as to the community for use in presenting their posteruption data. The grids and related data will be posted on the DMO site with links from the R2K site and notification when the data are posted via the R2K weekly email report. We expect this will be done within the next month.

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2) LBL transponder navigation data analysis James Kinsey, a post-doc at WHOI, has been working on analysis of a variety of navigation data sets related to the J2-268 dive. James, Vicki and others are preparing a G3ed data brief in order to get the various navigation and high-resolution bathymetry data sets into the literature formally. The navigation analysis includes comprehensive re-calculation of the acoustic travel times for the three primary transponders in the 9° 49’-51’N area when benchmarks were deployed and surveyed-in. The analysis also includes correlative data sets pertaining to overall precision and accuracy of GPS data and how they translate into bottommoored LBL transponder positions, vehicle position, and ultimately the positions of features on the seafloor. These data will be valuable for both operational and science users in understanding LBL navigation limitations (at all R2K ISSs) and how to best address navigation needs for science applications. 3) Benchmarks along the EPR axis between 9° 48’-51’N Four benchmarks were deployed along the EPR axis, adjacent to several well-studied high-T and diffuse vent areas in the region between 9° 48’-51’N. Photographs of each benchmark and the areas where they were deployed are detailed in the J2-268 report. They include: BioVent (Benchmark 1), Tica (Benchmark 2), Bio-9 and P-vents (Benchmark 3), and Ty/Io vents (Benchmark 4). The LBL navigation analysis by Kinsey has produced final, surveyed positions for each benchmark and the adjacent hiT vents, listed in in Tables 1 and 2, below. These positions should be factored into Alvin dive plans and navigation protocols. As discussed in previous memos, it would be very beneficial if Alvin dives in areas where benchmarks were deployed would visit the benchmark and collect 5-10 minutes of LBL navigation data, as time permits. The times of these surveys should be called-out in the cruise data package for the DMO. Also, if specific surveys are planned in these areas, one could position Alvin, pointing north, in front of the benchmark and input the x/y position of the benchmark into DVLNAV and ‘reset’ the navigation. This would provide an additional navigational reference point that should improve navigation during dive operations. 4) Recovery of Tide Gauge at EPR ISS near 9° 50.5’N and Other Deployed Instrumentation A self-recording SeaBird SBE26 tide gauge was originally deployed in April 2006 from R/V Knorr near Tica vent. Details of this deployment and the resulting data are provided at the DMO site. The tide gauge was redeployed on Alvin Dive 4318 (AT15-15 cruise), at 18:40Z at the following position in the axial trough: 9° 50.105’N, 104° 17.087’W x= 4763 y=77108 Depth = 2505 m The tide gauge will need to be recovered on one of the upcoming cruises. Dan Fornari will contact the Chief Scientists of the upcoming Alvin cruises and the Expedition Leader to coordinate this instrument recovery and downloading of the data. Figure 1 is a site map of the EPR ISS showing the locations and IDs of the instrumentation that is currently deployed at the ISS. In addition to the tide gauge mentioned above, this includes the various LADDER moorings, which will be recovered this fall by Mullineaux and Thurnherr et al., and the Bottom Pressure Recorders (BPRs) of Webb, Cormier, Buck that will remain deployed for the next few years. A listing of the surveyed positions of these instruments is available at the DMO site at: http://www.marine-geo.org/link/station_groups.php?feature_id=EPR&subset=current

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5) Data Management Office efforts Cruise metadata, sample positions, and a number of datasets from EPR post-eruption cruises (TCS06NH, AT15-06, AT15-12, AT15-13, AT15-15, AT15-16, AT15-17) are available through the R2K Data Portal. Thanks to all who have submitted data. Processed navigational data with links to seafloor imagery are accessible in GeoMapApp and can be downloaded as Google Earth files at http://www.marine-geo.org/link/entry.php?id=R2K_GoogleEarth Compiling data from multiple dives and cruises into composite products helps establish navigational consistency, which is an important component of time-series observations. Please remember to accurately log the times of all sample acquisition events during dive operations. Accurate logging of sample times facilitates the extraction of sample position from both realtime and ‘renav’ vehicle data and improves our ability to accurately geo-reference dive data and observations. As was done last year, a small, 100GB Firewire hard-drive will be provided to the EPR ISS science parties and shipboard SSSG tech on Atlantis to copy the data from each cruise. The data from last year have also been stored onboard on the EPR ISS data server set up by the WHOI SSSG tech, Dave Sims, this onboard server will once again be operational for the EPR ISS Alvin dive programs. Dan Fornari will coordinate the set-up of the EPR ISS data server with the Atlantis SSSG tech, and delivery and return of the data drive with each Chief Scientist of upcoming EPR ISS cruises. Table 1. EPR ISS Benchmarks Surveyed-in during J2-268 (AT15-17 cruise) April 2007 (Data processed by James Kinsey, WHOI) Positions below are least-squares fits to 3-transponder solutions. (Origin of EPR ISS transponder network is 9° 08’N 104° 20’W) Benchmark 1 (near Biovent) X: 4274 Y: 79221 Lat: 9.849643 Lon: -104.294450 Depth: 2504 m Benchmark 2 (near Tica area) X: 4624 Y: 78172 Lat: 9.840160 Lon: -104.291266 Depth: 2501 m Benchmark 3 (near Bio9 and P vents) X: 4644 Y: 77995 Lat: 9.838563 Lon: -104.291082 Depth: – 2501 m Benchmark 4 (near Ty and Io vents) X: 4732 Y: 77650 Lat: 9.835440 Lon: -104.290279 Depth: 2503 m

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Table 2. Vent Locations from J2-268 (AT15-17 cruise) April 2007 (Data processed by James Kinsey, WHOI) Vent locations below are post-eruption positions computed from least-squares fits to 3transponder solutions during 3-5 minute intervals when Jason2 was sitting in front of each vent during Dive 268 collecting video data. (Origin of EPR ISS transponder network is 9° 08’N 104° 20’W). Positions for all other vents within the EPR site are based on pre-eruption navigation and are available from the DMO site at:

http://www.marine-geo.org/link/targets.php?id=EPR
Bio9 Vent X: 4609 Y: 77993 Lat: 9.838541 Lon: -104.291398 Depth: 2509 m P Vent X: 4629 Y: 77933 Lat: 9.837996 Lon: 104.291219 Depth: 2509 m Ty Vent X: 4690 Y: 77635 Lat: 9.835307 Lon: 104.290665 Depth 2502 m Io vent X: 4682 Y: 77624 Lat: 9.835206 Lon: -104.290735 Depth: 2502 m

Table 3. Surveyed EPR ISS transponder positions used for Jason Dive268 navigation. ID (Freq) X Y Depth (m) Dec. Lat N Dec. Long. W C (11.5) 4113 78369 2343 9.841913 -104.295914 D (10.0) 4972 78283 2344 9.841162 -104.288010 G (10.5) 5369 76952 2354 9.829130 -104.284488

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-104˚20' -104˚10' 10˚00'

-2500
-104˚19' 9˚52' -104˚18' -104˚17' -104˚16' -104˚15'

-2550 9˚50' -2600 -2650 Depth

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(m)

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-2700 9˚40' -2750 -2800

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Hi-T vents (post-eruption) Transponders LADDER moorings Bottom Pressure Recorders
km 0 1 2

9˚47'

9˚30'

9˚46'

Figure 1. Overall map showing positions of LADDER moorings, BPRs and permanent transponder net deployed at the EPR ISS as of Fall 2007 (right), and detailed map (top) that also shows locations of hiT vents. Bathymetry used is EM300 data from White et al. 2007 G3ed paper.

9˚20'

km 0 5 10

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