OPR-T381-RA-22 Mariana Islands Western Pacific Ocean NOAA Ship Rainier (S221) H13582 12 Agrihan Island Northern Mariana Islands United States 10000 2022 Hector L. Casanova, CAPT/NOAA Navigable Area 2022-01-07 2022-06-20 2022-08-06 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter meters UTC Pacific 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 (MA11) UTM 55N, 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 This survey is referred to as H13582, "Agrihan Island" (sheet 12) within the Project Instructions. The assigned survey area encompassed an estimated 1,072 square nautical miles located approximately 300 nautical miles north of Guam in the Western Pacific Ocean. 19.009913 145.54995399999999 18.667699000000002 145.759137 H13582 assigned survey area. SupportFiles\H13582_Assigned_Survey_Area.jpg The originally assigned survey limits extended into areas with depths greater than RAINIER could efficiently acquire quality multibeam data. Therefore we requested, and the Operations Branch approved, that we survey to the 1,500 meter depth contour and not beyond. See Supplemental Records for more information. This project's requirement to coordinate hydrographic operations with reef diving priorities imposed significant limitations on the amount of MBES data we could acquire for this survey. The amount of bathymetric data we did acquire for H13582 totaled 85 square nautical miles. Acquired H13582 MBES coverage, note pink colored surface indicates 1,500-meter depths or greater. SupportFiles\H13582_Acquired_Coverage.jpg The ecosystem surrounding the Commonwealth of the Northern Mariana Islands (CNMI) is experiencing stress imposed by climate change and other environmental factors. This survey is part of extensive hydrographic project intended to map the bathymetry and habitat around the CNMI in support of nautical charting and habitat mapping. With the collaboration and partnership of the National Centers for Coastal and Ocean Science (NCCOS), the NOAA Coral Reef Conservation Program (CRCP), and the National Marine Fisheries Service (NMFS), this survey will also study the health of coral reef systems, ocean chemistry, and fisheries habitat. This team has developed a strategy to map the waters from nearshore to depths greater than 1000 meters. Within these waters, the ship's crew and visiting scientists will map bathymetry and backscatter and characterize habitat, while concurrently performing coral reef assessment dives and collecting other oceanographic observations. Data collected during this mission are pivotal to long-term biological and oceanographic monitoring of coral reef ecosystems around the CNMI. Data from this survey will add to information collected during prior monitoring and mapping projects. Oceanographic and ecological time series data will allow scientists to evaluate potential changes in environmental conditions and coral reef health in the Mariana Archipelago. This will enable federal and state resource managers to more effectively conserve the coral reef ecosystems of the CNMI, and to manage ecosystems services. Data collected during this survey also support monitoring components of the CRCP Coral Reef Ecosystem Integrated Observing System. The entire survey is adequate to supersede previous data. We used Pydro QC Tools (v.3.7.0) Grid QA to analyze H13582 multibeam echosounder (MBES) data density. The submitted H13582 variable-resolution surfaces met HSSD density requirements as shown in the histogram below. Grid QA results determined that a lower than expected percentage of H13582 nodes met full coverage resolution requirements as explained below. For project OPR-T381-RA-22 Resolution Requirements graphs produced by Pydro’s Grid QA tool have been showing relatively low percentages of grid nodes meeting full coverage resolution requirements. The likely cause of this issue is RAINIER’s use of 64m grids in depths greater than 1000m to maintain a reasonable data density. Since the Grid QA tool was written to match the HSRR specifications with a maximum 32m grid in all waters greater than 640m, RAINIER grids created using the 64m increase in resolution will always fail the resolution requirements check in areas exceeding 1000m. This will of course decrease the percentage of grid nodes meeting coverage resolution requirements. For surveys with a large percentage of area greater than 1000m in depth, this reduction can be significant. The OCS QC tools team has been made aware of this issue and are working on a solution for this deviation from the specifications. See the Supplemental Records for more information. Pydro derived plot showing HSSD density compliance of H13582 finalized variable-resolution MBES data. SupportFiles\H13582_MB_VR_MLLW_Final.QAv6.density.png Pydro derived plot showing Grid QA results of H13582 full coverage resolution requirements. SupportFiles\H13582_MB_VR_MLLW_Final.QAv6.pct_res.full_cov.png All waters Complete Coverage (Refer to HSSD Section 5.2.2.3) As stated above, survey operations were significantly impacted by reef diving priorities. We did acquire 118 nautical miles of ship (deep-water) MBES data for this survey, unfortunately time constraints prevented us from investigating H13582 nearshore areas. Acquired H13582 MBES coverage. SupportFiles\H13582_Coverage.jpg S221 0.0 118.6 0.0 0.0 0.0 0.0 0.0 2.2 0.0 0.0 118.6 0.0 0.0 0.0 0.0 0.0 2.2 0.0 1.9 0 0 0 0 84.9 2022-06-20 2022-08-06 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. S221 70.4 4.7 NOAA Ship RAINIER (S221). SupportFiles\NOAA_Ship_RAINIER_2022.jpg We acquired all data for H13582 with NOAA Ship RAINIER. The vessel acquired depth soundings, backscatter imagery and sound speed profiles. Positioning and Attitude System Applanix POS MV 320 v5 MBES Kongsberg Maritime EM 710 Sound Speed System ODIM Brooke Ocean MVP200 Sound Speed System Teledyne RESON SVP 70 NOAA Ship RAINIER (S221) acquired a single 2.2 nautical mile (1.9% of mainscheme) MBES crossline across limited depth ranges, water masses and boat days due to time constraints, however we believe it has value for evaluating the internal consistency of H13582 sonar data. We performed crossline analysis using the Compare Grids function within Pydro Explorer on Caris variable-resolution surfaces of H13582 mainscheme only and crossline only data. Results showed 99.5% of grid nodes met allowable uncertainties as shown in the Pydro generated plots below. H13582 crossline surface overlaid on mainscheme tracklines. SupportFiles\H13582_XL.jpg Pydro derived plot showing node percentage pass value of H13582 mainscheme to crossline data. SupportFiles\H13582_VR_MS_Only-H13582_VR_XL_Only_fracAllowErr_Freq.png Pydro derived plot showing absolute difference statistics of H13582 mainscheme to crossline data. SupportFiles\H13582_VR_MS_Only-H13582_VR_XL_Only_depth_delta.png ERS via VDATUM 0.0 0.11 S221 1 0.05 Total Propagated Uncertainty (TPU) values for survey H13582 were derived from a combination of fixed values for equipment and vessel characteristics, as well as from field assigned values for sound speed uncertainties. Tidal uncertainty was provided in metadata for the NOAA vertical datum transformation model used for this survey. In addition to the usual a priori estimates of uncertainty, real-time and post-processed uncertainty sources were also incorporated into the depth estimates of this survey. Real-time uncertainties for position, navigation and vessel motion data from Applanix POS MV were applied during acquisition and initially in post-processing. POSPac SBET and RMS files were subsequently applied in Caris HIPS to supersede POS MV uncertainties associated with GPS height and position. Uncertainty values of the submitted finalized grids were calculated in Caris using "Greater of the Two" of uncertainty and standard deviation (scaled to 95%). Grid QA v6 within Pydro QC Tools was used to analyze H13582 TVU compliance. H13582 met HSSD requirements in 99% percent of grid nodes as shown in the histogram plot below. Pydro derived plot showing TVU compliance of H13582 finalized multi-resolution MBES data. SupportFiles\H13582_MB_VR_MLLW_Final.QAv6.tvu_qc.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. None Exist There were no other factors that affected corrections to soundings. We acquired six sound speed profiles ("casts") for this survey at discrete locations within the assigned area at least once every four hours, when significant changes to surface sound speed were observed, or when shifting operations to a new area. All sound speed profiles were concatenated into a master file and applied to H13582 MBES data using the "Nearest distance within Time" (4 hours) profile selection method. H13582 sound speed cast locations. SupportFiles\H13582_SVP.jpg 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 were acquired as .all files logged during MBES operations and subsequently processed by RAINIER personnel. The .GSF files created during processing, and backscatter mosaic data has been delivered with this report. Backscatter processing procedures are described in the DAPR. Overview of H13582 multibeam acoustic backscatter. SupportFiles\H13582_MBAB.jpg N/A N/A N/A N/A N/A N/A NOAA Profile 2022v2 H13582_MB_VR_MLLW CARIS VR Surface (CUBE) Variable Resolution 55.7 3038.8 NOAA_VR Complete MBES H13582_MB_VR_MLLW_Final CARIS VR Surface (CUBE) Variable Resolution 55.7 3038.8 NOAA_VR Complete MBES We generated the submitted H13582 surfaces using NOAA recommended parameters for depth-based (Ranges) Caris variable-resolution bathymetric grids. Following correspondence with the Project Manager, we generated the submitted surfaces with an updated Range/Resolution file, NOAA_DepthRanges_CompleteCoverage_2022_RA, that includes 64-meter grids for depths exceeding 1,000 meters. See Supplemental Records for more information. We used Pydro flier finder tool with default settings as a quality control check of H13582 MBES grid data. We examined each of the potential fliers identified by the program, rejected errant soundings, then re-ran the process until we were satisfied that all remaining fliers identified were false-positives and represent actual seafloor topography. Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying DAPR. Mean Lower Low Water ERS via VDATUM OPR_T381-RA-22_GuamCNMI_EC_ERTDM2021_NAD83(MA11)-MLLW OPR_T381-RA-22_GuamCNMI_EC_ERTDM2021_NAD83(MA11)-MHW All submitted H13582 MBES data were vertically referenced to the ellipsoid. VDATUM models included with the Project Instructions were used for referencing H13582 data to MLLW and MHW. North American Datum 1983 (MA11) Projected UTM 55 Precise Positioning-Real time Extended (PP-RTX) processing methods were used in Applanix POSPac MMS (v8.5) software for post-processing horizontal correction of submitted H13582 MBES data. The Wide Area Augmentation System (WAAS) was used for real-time horizontal control during data acquisition. US5SP08M 45602 9 2020-09-30 2020-09-30 US2SP01M 931650 19 2021-09-07 2021-09-07 We investigated a charted 86-fathom depth reported in 1964, located approximately 11.5 nautical miles north of Agrihan Island. A single line of MBES coverage showed the actual depths to be approximately 1,600 fathoms (see image below). Unfortunately, time constraints imposed by prioritizing reef diving operations, resulted in no additional MBES coverage on shoal areas located elsewhere within the assigned H13582 area. H13582 soundings (in red) overlaid on Chart 81004. Chart and survey units in fathoms. SupportFiles\86_fathom_Rep_1964.jpg Due to time constraints, we were unable to investigate a charted 365-fathom depth reported in 1964, located in the northeast part of the assigned survey area. No uncharted features with navigational significance were identified for this survey. The charted anchorage area on the southwest side of Agrihan Island was inshore of our survey operations and not addressed. No Aids to navigation (ATONs) are located within the assigned H13582 survey area. No Maritime Boundary Points were assigned for this survey. No bottom samples were required for this survey. No overhead features exist for this survey. No submarine features are located within the H13582 survey area. No platforms exist for this survey. No ferry routes or terminals exist for this survey. We identified a prominent seafloor feature in the H13582 MBES data that was strikingly hull-shaped, however its height 55-100 meters effectively rules it out as a vessel. Subset view of hull-shaped H13582 seafloor feature. SupportFiles\UnknownObject.jpg Surface plan-view showing location of H13582 hull-shaped seafloor feature. SupportFiles\Unknown_Object_Chart.jpg No present or planned construction or dredging exist within the survey limits. We recommend that the entire assigned H13582 survey area be completed when practical. No new ENC scales 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 Specifications and 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. Hector L. Casanova, CAPT/NOAA Chief of Party 2022-09-27 Collin H. Walker, LT/NOAA Field Operations Officer 2022-09-27 James B. Jacobson Chief Survey Technician 2022-09-27 Caroline M. Jahn, ENS/NOAA Sheet Manager 2022-09-27