OPR-R344-FA-23 Pribilof Islands, AK Pribilof Islands NOAA Ship Fairweather (S220) H13796 1 English Bay Alaska United States 20000 2023 CDR Meghan McGovern Navigable Area 2023-05-10 2023-06-13 2023-08-13 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 UTM 02N, 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 The survey area is located in English Bay, Alaska 57.214708 170.55962000000002 57.030726 170.226718 H13796 Sheet Limits (in black) overlaid onto Charts US4AK3SB and US4AK3SC file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Coverage_Overview.png Data were not acquired to the survey limits in accordance with the requirements in the Project Instructions and the 2022 NOS Hydrographic Surveys Specifications and Deliverables (HSSD). Coverage acquired in H13796 is shown in the figure below. In all areas coverage extended to the sheet limits or the 3.5 meter contour NALL, except the north east portion. This area was not acquired due to weather constraints. The area without coverage is shown below. Area of H13796 sheet limits not acquired due to weather constraints. file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Area_of_NALL_Unreached_Due_to_Weather.png The Pribilof Islands, a group of four volcanic islands in the Bering Sea, are located 400-km north of the Aleutian Chain. They provide habitat to large colonies of seabirds and marine mammals. The principal islands are Saint Paul and Saint George; they host resident Aleut communities and receive the bulk of shipped supplies and freight. The primary commerce of the Pribilof Islands began in the 1800s with fur seal harvesting, but was halted in the 1980s and has since transitioned to a fishery-based economy (1). Today’s halibut and crab industries employ residents, and provide economic and social benefits for constituents of western Alaska. The income generated from local vessel landing ranged between approximately $1 million to $5.5 million between 2003 and 2015 (2). During crab season, the St. Paul harbor serves over 230 transient vessels (3) The southwestern shore of St. George is frequently used by commercial fishing vessels for shelter in the Bering Sea during storms. Additionally, cruise ships transport birders that make up 70% of the tourism industry on Pribilof Islands; other attractions include wildlife sightings (e.g., fur seals, Steller sea lions, walruses, whales) (2). Accurate navigational charts are integral to safe transit and continual delivery of goods and services for the Pribilof Islands. Additionally, the islands are one of the few areas to provide a potential lee for vessels transiting in the Bering Sea in inclement weather. The majority of the area was last surveyed in the 1950s; this project will provide modern bathymetric data for updating NOS charting products, improving maritime safety, as well as support the Seabed 2030 global mapping initiative. 1 https://www.apiai.org/tribes/st-paul/ 2 https://media.rainpos.com/141/st_paul_island_ceds_7_13_17_20170908132525.pdf 3 www.amiq.org/aleuts.html The entire survey is adequate to supersede previous data. Data acquired in H13796 meet multibeam echo sounder (MBES) coverage requirements for complete coverage, as required by the HSSD. This includes crosslines (see Section B.2.1), NOAA allowable uncertainty (see Section B.2.10), and density requirements (see Section B.2.11). All waters in survey area Complete Coverage The entirety of H13796 was acquired with (Complete Coverage), meeting the requirements listed above and in the HSSD. H13796 survey coverage overlaid onto Charts US4AK3SB and US4AK3SC file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Coverage_Overview.png 2805 0.0 126.08 0.0 0.0 0.0 0.0 0.0 3.03 0.0 2806 0.0 101.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2807 0.0 75.87 0.0 0.0 0.0 0.0 0.0 4.07 0.0 2808 0.0 40.77 0.0 0.0 0.0 0.0 0.0 0.0 0.0 S220 0.0 290.97 0.0 0.0 0.0 0.0 0.0 22.99 0.0 0.0 665.52 0.0 0.0 0.0 0.0 0.0 30.09 0.0 4.52 1 0 0 0 34.87 2023-06-13 2023-06-14 2023-06-15 2023-06-16 2023-07-18 2023-07-19 2023-07-20 2023-08-13 Refer to the OPR-R344-FA-23 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. 2805 8.6 1.1 2806 8.6 1.1 2807 8.6 1.1 2808 8.6 1.1 S220 70.4 4.8 MBES Kongsberg Maritime EM 2040 MBES Kongsberg Maritime EM 712 Conductivity, Temperature, and Depth Sensor Sea-Bird Scientific SBE 19plus V2 Conductivity, Temperature, and Depth Sensor AML Oceanographic MVP200 Positioning and Attitude System Applanix POS MV 320 v5 Sound Speed System Teledyne RESON SVP 70 Sound Speed System Teledyne RESON SVP 71 The equipment was installed on the survey platform as follows: S220 utilizes the Kongsberg EM 712MBES, a POS M/V v5 system for position and attitude, SVP 70 surface sound speed sensors, and AML Oceanographic MVP 200 for conductivity, temperature, and depth (CTD) casts. All launches utilize the Kongsberg EM 2040 MBES, a POS M/V v5 system for position and attitude, SVP 71 surface sound speed sensors, and Sea-Bird SBE 19plus v2 CTDs for conductivity, temperature, and depth casts. Crosslines were collected, processed and compared in accordance with Section 5.2.4.2 of the HSSD. For adequate comparison, 4.52% of crossline to MBES data was acquired. To evaluate crosslines, a surface generated via data strictly from mainscheme lines and a surface generated via data strictly from crosslines were created. From these two surfaces, a difference surface (mainscheme - crosslines = difference surface) was generated (see figure below). Statistics show the mean difference between the depths derived from mainscheme data and crossline data was 0.03 meters and 95% of nodes falling within 0.24 meters. For the respective depths, the difference surface was compared to the allowable NOAA uncertainty standards. In total, 99.5+% of the depth differences between H13796 mainscheme and crossline data were within allowable NOAA uncertainties. Overview of H13796 crosslines overlaid on sheet limits with charts US4AK3SB and US4AK3SC file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_XL_Comparison_Overview.png H13796 crossline and mainscheme difference statistics file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_MB_VR_MLLW_Mainscheme_Final-H13796_MB_VR_MLLW_XL_Final_depth_delta.png ERS via ERTDM 0.0 0.1 S220 N/A 1 N/A 0.5 280x (all launches) 2 N/A N/A 0.5 In addition to the usual a priori estimates of uncertainty via device models for vessel motion and ERTDM/VDATUM/TCARI, real-time and post-processed uncertainty sources were also incorporated into the depth estimates of survey H13796. Real-time uncertainties were provided via EM 2040/EM712 MBES data and Applanix Delayed Heave RMS. Following post-processing of the real-time vessel motion, recomputed uncertainties of vessel roll, pitch, gyro and navigation were applied in CARIS HIPS and SIPS via a Smoothed Best Estimate of Trajectory (SBET) RMS file generated in Applanix POSPac. No junctions exist for this survey 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. Casts were conducted at a minimum of one every four hours during launch acquisition. Casts were conducted more frequently in areas where the influx of freshwater had an effect on the speed of sound in the water column and when there was a change in surface sound speed greater than two meters per second. MVP casts on S220 were conducted at an average interval of 4 hours guided by observation of the surface sound speed and targeted to deeper areas. All sound speed methods were used as detailed in the DAPR. H13796 SVP locations plotted over survey coverage with charts US4AK3SB and US4AK3SC file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_SVP_Locations.png All equipment and survey methods were used as detailed in the DAPR. Holidays H13796 data were reviewed in CARIS HIPS and SIPS for holidays in accordance with Section 5.2.2.3 of the HSSD. Sixteen holidays which meet the definition described in the HSSD for complete coverage were identified via HydrOffice QC Tools Holiday Finder tool. This tool automatically scans the surface for holidays as defined in the HSSD and was run in conjunction with a visual inspection of the surface by the hydrographer. Nine holidays are due to a gaps in coverage where not enough overlap was achieved. Reasonable attempts were made to acquire these gaps but time was limited due to weather. Six holidays are due to acoustic shadowing in steep, rocky areas as seen in the figure below. These shadows are formed due to lack of coverage on the “back” side of a feature. All areas with acoustic shadows were investigated in CARIS subset editor to verify that least depths were found. One holiday was due to the least depth on a feature of which is a DTON. Reasonable attempts were made to cover all gaps in coverage that resulted from lack of coverage over the tops of features and underwater rocks when it was safe and prudent to do so. For areas where it was unsafe to do so the features were added or updated accordingly in the Final Feature File accompanying this submission. An example of such a feature is shown in the figure below. H13786 Holidays plotted over survey coverage with charts US4AK3SB and US4AK3SC file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Holidays.png NOAA Allowable Uncertainty The surface was analyzed using the HydrOffice QC Tools Grid QA feature to determine compliance with specifications. Overall, 99.5+% of nodes within the surface meet NOAA Allowable Uncertainty specifications for H13796 (see figure below). H13796 allowable uncertainty statistics file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_MB_VR_MLLW_final.GQv6.tvu_qc.png Density The surface was analyzed using the HydrOffice QC Tools Grid QA feature to determine compliance with specifications. Density requirements for H13796 were achieved with at least 99.5+% of surface nodes containing five or more soundings as required by HSSD Section 5.2.2.3 (see figure below). H13796 data density statistics file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_MB_VR_MLLW_final.GQv6.density.png 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 stored in the .kmall and .all file for Kongsberg systems. All backscatter were processed to GSF files and a floating point mosaic was created by the field unit via Fledermaus FMGT 7.10.2. See Figure below for a greyscale representation of the complete mosaic. Five separate backscatter mosaics were created for each vessel at 2 meter and 6 meter resolution based on the specifications for 300kHz and 70-100kHz systems. All equipment and survey methods were used as detailed in the DAPR. A relative backscatter calibration was performed by the field unit via a backscatter calibration site in order to bring the survey systems on each of the launches into alignment. H13796 Backscatter comprised of mosaics from S220, 2805, 2806, 2807, and 2808 file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Backscatter.png CARIS HIPS and SIPS 11.4.26 QPS Fledermaus 7.10.2 NOAA Profile Version 2023 H13796_MB_VR_MLLW_final CARIS VR Surface (CUBE) Variable Resolution 0.8 61.2 NOAA_VR Complete MBES H13796_MB_VR_MLLW CARIS VR Surface (CUBE) Variable Resolution 0.8 61.2 NOAA_VR Complete MBES The NOAA CUBE parameters defined in the HSSD were used for the creation of all CUBE surfaces for H13796. The surfaces have been reviewed where noisy data, or "fliers" are incorporated into the gridded solutions causing the surface to be shoaler or deeper than the true sea floor. Where these spurious soundings cause the gridded surface to vary from the reliably measured seabed by greater than the maximum allowable Total Vertical Uncertainty at that depth, the noisy data have been rejected by the hydrographer and the surface recomputed. Flier Finder, part of the QC Tools package within HydrOffice, was used to assist the search for spurious soundings following gross cleaning. Flier Finder was run iteratively until all remaining flagged fliers were deemed to be valid aspects of the surface. Remaining 707 areas flagged as fliers deemed as valid aspects of the surface file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Flier_Finder_Overview.png Designated Soundings H13796 contains 1 designated sounding in accordance with HSSD Section 5.2.1.2.3. One designated sounding represents a DTON (see Section D.1.6). The figures below show an overview of the survey area and the location of the designated sounding. Location of Designated Sounding in H13796 file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Designated_Sounding_Location.png The designated sounding is on the ridge of the DTON that was unable to be fully developed using multibeam coverage. file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Designated_Sounding.png Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR. Mean Lower Low Water ERS via ERTDM OPR-R344-FA-23_AK_ERTDM_2023_NAD83-MLLW ERS methods were used as the final means of reducing H13796 to MLLW for submission. North American Datum 1983 (2011) Projected UTM 2 RTX Vessel kinematic data were post-processed using Applanix POSPac processing software and RTX positioning methods described in the DAPR. Smoothed Best Estimate of Trajectory (SBET) and associated error (RMS) data were applied to all MBES data in CARIS HIPS and SIPS. The Wide Area Augmentation System (WAAS) was used for real-time horizontal control during data acquisition. During real-time acquisition, all platforms received correctors from the Wide Area Augmentation System (WAAS) for increased accuracies similar to USCG DGPS stations. WAAS and SBETs were the sole methods of positioning for H13796, as no DGPS stations were available for real-time horizontal control. Chart comparison between ENC and soundings from collected data. The soundings from H13796 are generally in agreement with charted soundings of ENC US4AK3SC and ENC US4AK3SB Survey outline with soundings (in red) overlaid with coverage onto ENC US4AK3SC and ENC US4AK3SB file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Soundings_Overview.png Survey outline with soundings (in red) overlaid with coverage onto ENC US4AK3SC and ENC US4AK3SB file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Soundings_Northern_Section.png Survey outline with soundings (in red) overlaid with coverage onto ENC US4AK3SC and ENC US4AK3SB file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Soundings_Mid_Section.png Survey outline with soundings (in red) overlaid with coverage onto ENC US4AK3SC and ENC US4AK3SB file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Soundings_Southern_Section.png US4AK3SC 40000 1 2023-08-22 2021-03-23 US4AK3SB 40000 2 2020-06-30 2021-03-23 Previously charted shoal area was found to be least depth of roughly 14 meters surrounded by 35-40 meter soundings. Updating the contour and depths of this shoal area is recommended. No charted features exist for this survey. Survey H13796 has one new feature that is addressed in the H13796 Final Feature File. Of these features, there is one new Underwater Rock which is submitted as a DTON. No channels exist within the survey limits. No Aids to navigation (ATONs) exist for this survey. Maritime Boundary Points were assigned for this survey, but were not addressed. One bottom sample was acquired in accordance with the Project Instructions for survey H13796. This bottom sample was entered in the H13796 Final Feature File. See Figure below for a graphical overview of sample locations. H13796 Bottom sample location file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Bottom_Sample.jpg 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. A shoal was investigated in H13796 and the charted contour should be updated. Location of a shoal in H13796 file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Shoal_Overview.png H13796 shoaling compared to ENC US4AK3SC and ENC US4AK3SB file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Shoal_Chart_Comparison.png H13796 Shoal in Subset file:///M:/OPRR344FA23/Surveys/H13796/01_HDR/Reports/Descriptive_Report/Images/H13796_Shoal_in_Subset.png No present or planned construction or dredging exist within the survey limits. Recommend completing survey work off the Western side of St. Paul Island. Survey operations in this area were hindered by derelict fishing gear and inclement weather. 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. CDR Meghan McGovern Chief of Party 2023-11-01 LT Michael Card Operations Officer 2023-11-01 HST Michael Lauzon Sheet Manager 2023-11-01