OPR-F364-FH-22 Onslow Bay, NC Cape Lookout Onslow Bay, NC NOAA Ship Ferdinand Hassler (S250) H13594 1 15 NM SE of Cape Lookout North Carolina United States 40000 2022 Michael Gonsalves, CDR/NOAA Basic Hydrographic Survey 2022-02-08 2022-03-11 2022-03-25 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter meters UTC Atlantic Hydrographic Branch Any revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/. Products created during office processing were generated in NAD83 UTM 18N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit. CC0-1.0 (NOAA Field Units) CC0-1.0 https://creativecommons.org/publicdomain/zero/1.0/ https://creativecommons.org/publicdomain/zero/1.0/legalcode These data were produced by NOAA and are in the public domain within the United States. NOAA waives any potential copyright and related rights in these data worldwide through the Creative Commons Zero 1.0 Universal Public Domain Dedication (CC0). NOAA Survey H13594 (sheet 1) is located 15 nautical miles southeast of Cape Lookout in Onslow Bay, North Carolina and encompasses approximately 52 square nautical miles. 36.829600000000006 75.4774 36.684599999999996 75.22030000000001 Data were acquired within the assigned survey limits as required in the Project Instructions and HSSD unless otherwise noted in this report. Sheet limits for survey H13594 (ENC US3SC10M). SupportFiles\A.1 Survey Limits.png The objective of survey H13594 was to acquire high quality multibeam bathymetric and backscatter data. The existing charted soundings within this area is from 1970 and earlier. The shoaling seabed is exposed to open ocean and has likely changed from numerous storms and hurricanes over the past several decades. This data will provide modern bathymetry for updating National Ocean Service nautical charting products as well as support the Seabed 2030 global mapping initiative. The entire survey is adequate to supersede previous data. Data acquired in H13594 meet multibeam echo sounder (MBES) coverage requirements for complete coverage, as specified by the 2022 HSSD. This includes crosslines (Section B.2.1), NOAA allowable uncertainty (Section B.2.2) and density requirements (Section B.5.2). All waters in survey area Complete Coverage (Refer to HSSD Section 5.2.2.3) All waters in survey area Acquire backscatter data during all multibeam data acquisition (Refer to HSSD Section 6.2) Survey coverage was in accordance with the requirements listed above and in the HSSD. Survey coverage for H13594 (ENC US3SC10M). Dashed black line indicates assigned sheet limits. SupportFiles\A.4 Survey Coverage.PNG S250 0.0 806.68 0.0 0.0 0.0 0.0 0.0 39.55 0.0 0.0 806.68 0.0 0.0 0.0 0.0 0.0 39.55 0.0 4.9 4 0 0 0 55.72 2022-03-11 2022-03-12 2022-03-13 2022-03-14 2022-03-15 2022-03-16 2022-03-22 2022-03-23 2022-03-25 Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, quality control procedures and data processing methods. Additional information to supplement sounding and survey data, and any deviations from the DAPR are discussed in the following sections. S250 37.7 3.85 NOAA Ship Ferdinand R. Hassler (S-250). SupportFiles\B.1.1 Vessels - S250.PNG MBES Kongsberg Maritime EM 2040 MBES Backscatter Kongsberg Maritime EM 2040 Positioning and Attitude System Applanix POS MV 320 v5 Conductivity, Temperature, and Depth Sensor Teledyne RESON SBE 19plus V2 Sound Speed System Teledyne RESON SVP 70 Multibeam echo sounder crosslines acquired for this survey totaled 4.90% of mainscheme acquisition. Ferdinand R. Hassler (S-250) acquired 39.55 nautical miles of multibeam crosslines. H13594 crossline data is adequate for verifying and evaluating the internal consistency of the survey data. The Compare Grids function in Pydro Explorer analyzed finalized VR surfaces of H13594 crossline-only data and mainscheme-only data. In the difference surface, 99.5% of nodes met IHO allowable Total Vertical Uncertainty (TVU) standards. Refer to Figures 4-6 for additional crossline results. H13594 crossline surface overlaid on mainscheme tracklines. Color scale coded as green = meets IHO standard and red = fails IHO standard (ENC US4NC16M). SupportFiles\B.2.1a Crossline Difference Surface.PNG Pydro derived plot showing percentage-pass value of nodes in H13594 mainscheme and crossline data. SupportFiles\B.2.1b Crossline Percentage Pass.png Pydro derived plot showing absolute difference statistics of H13594 mainscheme and crossline data. SupportFiles\B.2.1c Crossline Absolute Difference.png ERS via VDATUM 0.0 0.097 S250 4.0 N/A N/A 0.5 Total Propagated Uncertainty (TPU) values for survey H13594 were derived from a combination of fixed values for equipment and vessel characteristics, as well as from field assigned values for sound speed uncertainties. Additionally, real-time and post-processed uncertainty sources associated with position were applied using SBET and RMS files generated using POSPac MMS software. The bathymetric surface is compliant with 2022 HSSD uncertainty standards; over 99.5% of all nodes pass. Pydro derived plot showing Total Vertical Uncertainty (TVU) compliance of H13594's finalized VR surface. SupportFiles\B.2.2 TVU.png H13594 junctions with surveys H13595 and H13597. Both surveys are within the same project area (OPR-F364-FH-22). The junction analyses for these surveys can be found in their respective Descriptive Reports. Overview of H13594 junctions with H13595 and H13597 (ENC US3SC10M). SupportFiles\B.2.3 Junction Overview.png Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. None Exist There were no conditions or deficiencies that affected equipment operational effectiveness. Variable Sound Speed The large shoaling area in the southwest corner of H13594 showed a large variation in sound speed between it and surrounding areas. In some cases, the north and south sides of the survey display a surface sound speed difference up to 7 meters per second. The ship's Moving Vessel Profiler was not available during acquisition on H13594, so manual CTD casts were taken at a reduced frequency of every 4 hours. This reduced frequency of sampling caused sound speed artifacts across the surface but most significantly over the shoal area. Any data exceeding the allowable vertical uncertainty for those depths were rejected. See Figure 9 for example of this data rejection. Comparison between the uncleaned (left) and cleaned (right) 2-meter surfaces at 10x exaggeration. SupportFiles\B.2.6 SV Comparison New.PNG Sound speed casts were acquired approximately every four hours. A total of 27 sound speed casts were acquired on H13594. Additional casts were taken when significant changes to surface sound speed were observed. Sound speed profiles were acquired using a Sea-Bird Scientific SBE 19plus profiler. All casts were concatenated into a master file and applied to the MBES data using the "Nearest in distance within time" (4 hours) profile selection method. H13594 sound speed profile locations. SupportFiles\B.2.7 Sound Speed Cast Locations.PNG All equipment and survey methods were used as detailed in the DAPR. All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR. Raw backscatter data was acquired as .all files logged during MBES acquisition and processed by the field unit per 2022 HSSD. The .GSF files and backscatter mosaic has been delivered with this report. Overview of H13594 backscatter mosaics (US3SC10M). SupportFiles\B.4 Backscatter Overview.PNG CARIS HIPS/SIPS 11.3.14 CARIS BASE Editor 5.5.8 Fledermaus FMGT 7.9.5 NOAA Profile Version 2021 H13594_MB_VR_MLLW CARIS VR Surface (CUBE) Variable Resolution 24.2 46.7 NOAA_VR Complete MBES H13594_MB_VR_MLLW_Final CARIS VR Surface (CUBE) Variable Resolution 24.2 46.7 NOAA_VR Complete MBES H13594_MBAB_2m_S250_300kHz_1of1 MB Backscatter Mosaic 2 N/A Complete MBES Submitted surfaces were generated using the NOAA recommended parameters for depth-based (Ranges) CARIS variable-resolution bathymetric grids as specified in the 2022 HSSD. QC Tools' Flier Finder, available in NOAA's Pydro XL-19 suite, detected edge fliers that were rejected during surface cleaning. After multiple rounds of cleaning, Flier Finder detected zero fliers. Pydro QC Tools Grid QA was used to analyze H13594 multibeam echosounder (MBES) data density. The submitted H13594 variable-resolution (VR) surface met HSSD density requirements as shown in the histogram below. Pydro derived plot showing HSSD density compliance of H13594 finalized variable-resolution surface. SupportFiles\B.5.2 Density.png Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying 2022 DAPR. Mean Lower Low Water ERS via VDATUM OPR_F364_FH_22_VDatum_xyNAD83-MLLW_geoid12b.csar North American Datum 1983 Projected UTM 18 RTX Post Processed Real-Time Extended (PP-RTX) processing methods were used in Applanix POSPac MMS 8.7 software to produce SBETs for horizontal and vertical corrections. The Wide Area Augmentation System (WAAS) was used for real-time horizontal control during data acquisition. Survey soundings from H13594 were generated from a finalized variable resolution CUBE surface in CARIS HIPS and SIPS and compared with the soundings from the largest scale Electronic Navigational Chart (US4NC16M) using CA Tools SS vs Chart comparison tool (Figure 13). Contours from H13594 were also generated and visually compared with the charted contours from the largest scale Electronic Navigational Charts. The 36.5 meter (120 foot) contour generally agrees between the survey and the chart, with some outstanding deeper areas inshore of the charted 36.5 contour (Figure 14). Overview of CA Tools' Soundings vs. Chart comparison of survey H13594 and ENC US4NC16M: grey line = coverage border, red soundings = H13594 soundings; black soundings = ENC soundings; grey targets = "DtoN" soundings flagged by CA Tools. file:///Q:/FerdinandHassler_SheetManager/2022/OPR-F364-FH-22/Surveys/H13594/2_Proc%20Drive/2022/OPR-F364-FH-22/H13594/Processed/Reports/Survey/Descriptive_Report/Report/Images/D.1%20Chart%20Comparison%201%20-%20CA%20Tools%20Overview.PNG Comparison of 36.5 meter contour: grey line = coverage border; blue line = H13594's 36.5 meter contour; black line = ENC 36.5 meter contour (US4NC16M). SupportFiles\D.1b Chart Comparison 3 - Contours.PNG US4NC16M 80000 23 2021-09-07 2021-11-23 US3SC10M 432720 35 2021-12-10 2022-04-18 CA Tools flagged 25 soundings as potential Dangers to Navigation, and, although none of these soundings fall within the HSSD requirements for sounding designation/DtoN designation, the hydrographer recommends the addition of these shoaler soundings to the ENC (Figure 15). These shoal soundings still fall within their charted depth contour. CA Tools flagged 25 soundings as potential Dangers to Navigation. While none of these soundings fall within NOAA's definition of a DTON (HSSD Section 1.6.1) and are are deep enough to not represent a hazard to surface navigation, the hydrographer recommends the addition of these shoaler soundings to the ENC (figure 15). H13594 soundings vs. charted soundings over southern shoal area: grey line = coverage border, red soundings = H13594 soundings; black soundings = ENC soundings; grey targets = soundings flagged by CA Tools. SupportFiles\D.1c Chart Comparison 2 - Shoal Area.PNG No charted features exist for this survey. No uncharted features exist for this survey. No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channel and range lines within the survey limits. No Aids to navigation (ATONs) exist for this survey. No Maritime Boundary Points were assigned for this survey. Four bottom samples were assigned and investigated. Refer to the Final Feature File for location and sample attribution. No overhead features exist for this survey. No submarine features exist for this survey. No platforms exist for this survey. No ferry routes or terminals exist for this survey. No abnormal seafloor and/or environmental conditions exist for this survey. No present or planned construction or dredging exist within the survey limits. No new surveys or further investigations are recommended for this area. No new insets are recommended for this area. As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports. All field sheets, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch. The survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys and Specifications Deliverables, Field Procedures Manual, Letter Instructions, and all HSD Technical Directives. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies noted in the Descriptive Report. Michael Gonsalves, CDR/NOAA Chief of Party 2022-05-20 Daniel Helmricks, LT/NOAA Operations Officer 2022-05-20 Amanda M. Finn, Physical Scientist Sheet Manager 2022-05-20 Data Acquisition and Processing Report 2022-05-20