OPR-D304-FH-15Approaches to Chesapeake BayApproaches to Chesapeake BayNOAA Ship FERDINAND R. HASSLERH12843513 Miles East of Sheep House HillNorth CarolinaUnited States400002015LCDR Briana J. Welton, NOAANavigable Area2015-07-242015-08-052015-10-18Multibeam Echo SounderMultibeam Echo Sounder BackscattermetersUniversal Transverse Mercator (UTM)UTCAtlantic Hydrographic BranchNOAASurvey H12843 was conducted in the Chesapeake Bay, with a sublocality of 13 Miles East of Sheep House Hill as shown in Figure 1.36.595026555675.695523055636.424003805675.5935755556H12843 survey limitsSupportFiles\H12843_Area_Surveyed.jpgSurvey Limits were extended to the East to include the portion of H12842. Survey H12842 was opened, but only a small amount of acquisition was conducted on the sheet and was then merged into H12843 for processing efficiency.The purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. In addition, this project will improve the chart for traffic navigating the Atlantic Ocean Channel and will support the Bureau of Ocean Energy Management (BOEM) research in the area.The entire survey is adequate to supersede previous data.All waters in survey areaComplete Multibeam with BackscatterSurvey coverage was in accordance with the requirements listed above and in the HSSD.Survey layout for OPR-D304-FH-15 over raster chart 12200.SupportFiles\H12843_Coverage_Overview.jpgS25001026.30000057.0001026.30000057.005.5800051.02015-08-052015-08-062015-08-132015-08-142015-08-182015-08-202015-08-212015-08-222015-08-272015-08-282015-09-032015-09-092015-10-18Mainscheme survey lines were run with a dual-head multibeam echosounder. Linear nautical miles were calculated using statistics from the port head.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.S25037.73.77NOAA Ship FERDINAND R. HASSLERSupportFiles\Hassler_stern_bow_clean.pngNOAA Ship FERDINAND R. HASSLER (S250), shown in Figure 3, acquired all surveyed soundings during operation for H12843Reson7125MBESApplanixPOS M/V 320 V5Positioning and Attitude SystemHemisphereMBX-4Sound Speed SystemAMLMicroCTDSound Speed SystemBrooke OceanMVP-200Sound Speed SystemRESONSVP-70Sound Speed SystemSea BirdSBE 19+Sound Speed SystemA geographic plot of crosslines is shown in Figure 4. It should be noted that crossline coverage did not reach the eastern extent of the survey area, leaving the six easternmost mainscheme lines without a crossline. Crosslines were filtered to remove soundings greater than 45 degrees from nadir. To evaluate crossline agreement, two 2-meter surfaces were created: one from crossline depths, the other from mainscheme depths. These two surfaces were differenced using CARIS HIPS/SIPS. The 2.6 million nodes have a difference value range from -0.45 meters and 0.80 meters. The statistical analysis of the differences between the mainscheme and crossline surfaces is sown in Figure 5. The average difference between the surfaces is -0.04 meters with a standard deviation of 0.08 meters; Ninety-five percent of nodes agree within +/- 0.16 meters of the mean.Location of crosslines for H12843.SupportFiles\H12843_XL_MS_Diff.pngH12843 crossline difference statistics: mainscheme minus crossline. SupportFiles\H12843_MS-XL.png0.010.102VDATUMS2501.01.00.5Two tidal models were available for water level corrections associated with survey H12843. A discrete tide zone file, produced by CO-OPS for project OPR-B304-FH-15, was provided to the field unit. Additionally, a vertical datum transformation (VDatum) model was delivered to the field unit in the project instructions. All data for survey H12843 were reduced to MLLW via VDatum. This model functioned as a gridded separation model for GPS tide computations with a 0.102 meter uncertainty. Final TPU calculations are derived from the following sources: VDatum separation model, sound velocity (MVP and surface sound velocimeter), HVF uncertainties, and SBET post processed uncertainty. Error data sources applied through CARIS processing software are listed in Figure 6.Sources of error data applied during CARIS processing.SupportFiles\H12839_uncertainty_source.pngTwo prior surveys to the north junctions with H12843. See Figure 7 for further information.H12843 Junction SurveySupportFiles\H12843_Junction_Location.pngH12306400002011NOAA Ship THOMAS JEFFERSONNSurvey H12843 junctions with survey H12306 with nodes overlapping approximately 20 to 150 meters to the north (See Figure 8). The minimum and maximum depth difference between the two surveys is -2.09 meters and 1.59 meters respectively. Of the greater than one hundred and eighteen thousand overlapping nodes, the average difference is -0.03 meters with a standard deviation of 0.35 meters; Ninety-five percent of the differenced surface nodes are within +/- 0.72 meters of the mean, as shown in Figure 9.Area of overlap between H12843 and H12306.SupportFiles\H12843-H12306_Diff.pngDifference surface statistics for H12843 and H12306.SupportFiles\H12843-H12306_Difference.pngH12341200002011NOAA Ship THOMAS JEFFERSONNSurvey H12843 junctions with survey H12341 with nodes overlapping approximately 30 to 230 meters to the north. The junction was made using the provided survey outlines from the Project Instructions. There are two gaps in data between the two junction surveys that are not covered by side scan data, as shown in the red boxes in Figure 10. The minimum and maximum depth difference between the two surveys is -1.58 meters and 1.57 meters respectively. Of the greater than one hundred and eighteen thousand (118,000) overlapping nodes, the average difference is -0.02 meters with a standard deviation of 0.32 meters; Ninety-five percent of the differenced surface nodes are within +/- 0.64 meters of the mean, as shown in Figure 11.Area of overlap between H12843 and H12341.SupportFiles\H12843-H12341_Diff.pngDifference surface statistics for H12843 and H12341.SupportFiles\H12843-H12341_Difference.pngSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.None ExistThere were no conditions or deficiencies that affected equipment operational effectiveness.Sound Speed ErrorsRefraction issues due to environmental conditions exist in survey H12843. As shown in Figure 12, the likely culprit was the very steep below-layer gradient which moved up and down in the water by about 10 meters per second which were very present on data collected between DN217-226 (See Figure 13). Sound speed casts were taken at a very frequent rate, yet refraction still was an issue, because it was believed that the sound speed variability in nature, specifically, the survey lines may have crossed a significant below-layer sound speed gradient. A number of methods were used to mitigate the refraction. Initially the sonars were being operated using its entire 140 degree swath. After an in port in Norfolk, VA, the hydrographer instituted two changes: the use of Cast-Time to model these refraction issues and the decrease in swath width. This change most likely is the reason why data from DN226 and 227 do not exhibit the extreme refraction issues seen on the earlier days. To mitigate the impacts of refraction on data that was already collected, the hydrographer utilized Subset Editor in CARIS HIPS/SIPS to further eliminate poor data. This did not eliminate all instances of refraction in H12843. The surfaces do meet the Total Vertical Uncertainty requirements (See Section B.5.4 Total Vertical Uncertainty Analysis in this report for more information).Sound speed measurements related to H12843.SupportFiles\H12843_AllSVP.tifSound speed measurements on from DN217-226.SupportFiles\H12843_217-226SVP.tifA total of 484 sound speed measurements were taken within the boundaries of H12843 (See Figure 14). These sound speed measurements were collected using the MVP-200 approximately every 30 minutes. Comparisons were made by the survey watch to assess sound speed variation in the water column. Sound speed corrections were applied in CARIS HIPS/SIPS using Nearest in Distance Within Time (NIDWT) of every 1 hour (for DN 230, 232, 233, and 234), 2 hours (DN 246, 252, and 291), and 4 hours (DN 217, 218, 225, 226, 239, and 240).H12843 sound speed profile locations.SupportFiles\H12843_SV_cast_locations.pngAll 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.Backscatter was logged in RESON datagram 7008 snippets record in the raw .s7k files. The .s7k file also holds the navigation record and bottom detections for all lines of survey H12843. The files were paired with the CARIS HDCS data, imported, and processed using Fledermaus Geocoder Toolbox (FMGT). The FMGT projects and backscatter mosaic imagery is included in the field submission. The processed mosaic is formated as a geo-referenced tiff image per specifications. The following information is provided as metadata for the processing branch: Backscatter data processing and mosaicing performed in Fledermaus FMGT version 7.4.4b using Reson De-TVG plug-ins where appropriate. Backscatter data has a histogram range of 10 to -70dB Backscatter data is provided in separate layers broken down by survey vessel hull number and sonar operating frequency. H12843_S250_Port_400kHz | 4m resolution mosaic | Absorption Coefficient = 100dB/km H12843_S250_Stbd_400kHz | 4m resolution mosaic | Absorption Coefficient = 100dB/kmNOAA Profile V_5_3H12843_MB_1m_MLLWCUBE114.0830.20NOAA_1mComplete MBESH12843_MB_1m_MLLW_FinalCUBE114.0820.00NOAA_1mComplete MBESH12843_MB_2m_MLLWCUBE213.9328.21NOAA_2mComplete MBESH12843_MB_2m_MLLW_FinalCUBE218.0028.21NOAA_2mComplete MBESGaps in data coverage (holidays) do exist in the 1-meter finalized surface (See Figures 15-16). These gaps in coverage are due to poor overlap in the outerbeams. The holidays occur in flat areas and the hydrographer believes that they do not pose a risk to surface navigation.Example of holiday in the 1-meter finalized surface. SupportFiles\H12843_1m_Holiday_2.pngExample of holiday in the 1-meter finalized surfaceSupportFiles\H12843_1m_Holiday_3.pngData DensityA density analysis was run to calculate the number of soundings per surface node. The results determined that 99.9% of all nodes contained five or more soundings which meets the data density specifications (See Figures 17 and 18).Data density for the 1-meter finalized surface.SupportFiles\H12843_MB_1m_MLLW_Final_Density.pngData density for the 2-meter finalized surface.SupportFiles\H12843_MB_2m_MLLW_Final_Density.pngTotal Vertical Uncertainty AnalysisPydro's Finalized CSAR QA tool was used to calculate the percentage of nodes which meet total vertical uncertainty (TVU) specifications. The resulting statistical analysis yielded only one node failed to meet TVU specifications (See Figures 19 and 20). In addition, a custom layer was created for the finalized surfaces submitted in correlation with H12843. The layer was derived from the difference between the calculated uncertainties of individual nodes and the allowable uncertainty at the coupled node.Total vertical uncertainty analysis for 1-meter finalized surface.SupportFiles\H12843_MB_1m_MLLW_Final_TVU_QC.pngTotal vertical uncertainty analysis for 2-meter finalized surface.SupportFiles\H12843_MB_2m_MLLW_Final_TVU_QC.pngDesignated SoundingsWithin the limits of H12843, two (2) soundings are flagged as designated.All vertical and horizontal control activities conducted during the course of this survey are fully addressed in the following sections. No separate HVCR is submitted.Mean Lower Low WaterVDatum2015_D304_VDatum_NAD83_MLLWAll soundings submitted for H12843 has been reduced to MLLW using documented VDatum techniques.North American Datum of 1983 (NAD83)UTM Zone 18N.Single BaseDUCK 3, Duck, NCNCDULOYOLA, Virginia Beach, VALS03Single Base processing was the primary method used for for Post Processed Kinematics (PPK) processing of Applanix TrueHeave data for Smooth Best Estimate of Trajectory (SBET) production. SBET files have been loaded for all lines for survey H12843 and are used to reduce acquired soundings to MLLW via HSD Operations Branch provided separation model.Driver, VA (289 kHz)Interpolation of SBETsOn occasion, SBET altitude spikes compromised the data's TVU. In these instances, Pydro's POSPAC Automated QC tool was used to interpolate the SBET (See Figure 21 for an example). The interpolated SBET was exported out of the POSPAC Automated QC tool, opened in POSPAC MMS, and exported again to ensure the SBET was in the correct datum (NAD83). The new SBET contains the prefix "interpolated" for easy identification. The following SBETs were interpolated for H12843: DN218 Starboard lines using interpolated_2015_218_S250S_b.sbet DN225 Starboard lines using interpolated_2015_225_S250S_b.sbetExample of SBET interpolation for 2015_225_S250S. The anomalous data on the left has been edited in POSPAC AutoQC and the resultant SBET is seen on the right.SupportFiles\H12843_InterpolatedSBET.pngBase Station OutagesThroughout acquisition of H12843 the preferred base station used for single base processing was DUCK. During acquisition there was an outage of the DUCK station, requiring the use of an alternate station. LS03 was used, with ship to station distance ranging from 149km to 183km. Though LS03 was far outside the recommended base station range, the SBET that used LS03 was only applied on data acquired during DN 218. A vertical offset ranging from 0.3-0.5 meters can be seen in the data for line 2209 (Figures 22 and 23) due to an SBET that has periods of poor quality vertical solutions. The oscillations in the vertical solution are within the TVU specifications for the depth of the area.The 2-meter combined surface affected by offset.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12843/Descriptive_Report/SupportFiles/SBET_Offset_Overview.jpgDN 218, line 2209 offset shown in subset editor.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12843/Descriptive_Report/SupportFiles/SBET_Offset.jpgThe hydrographer has compared a sounding plot from the surveyed area to the charted soundings. There are no charted contours to compare.1220754880000242014-072016-03-222016-04-02A comparison was performed with Chart 12207 (1:80,000) using depths derived from a 2-meter combined surface. Most charted soundings agree within 3-4 feet of H12843 surveyed depths, with exception of the areas shown below in Figure 24.Chart 12207 comparison.file:///G:/OPR-D304-FH-15/H12843/Separates/Descriptive_Report/Report/SupportFiles/H12843_ChartComp.pngUS4NC32M80000242014-07-012016-04-02falseENC soundings were extracted from the S-57 file and used to create an interpolated .csar surface. The interpolated surface was then differenced with the 2-meter finalized surface from survey H12843. The depth differences range from -6.22 to 5.91 meters. The high depth differences were determined to be the result of coarse resolution soundings extracted from the ENC. All other depth differences mirrored RNC depth differences, with a mean difference value of 0.16 meters, shown in Figure 25. In general, surveyed depths were deeper than charted. Figure 26 shows a surface created by interpolating the differenced point cloud between the ENC and surveyed depths. Negative values indicate areas where surveyed depths are deeper than charted.ENC US4NC32M comparison.SupportFiles\H12843-US4NC32M.pngDifference surface between ENC US4NC32M and H12842.SupportFiles\H12843-US4NC32M_Diff.pngNo Maritime Boundary Points were assigned for this survey.No charted features exist for this survey. One new wreck was identified with data collected for survey H12843. See the final feature file for further information.No Danger to Navigation Reports were submitted for this survey.No shoals or potentially hazardous 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.Six (6) bottom samples were acquired for this survey though one sample did not result in a return after three attempts therefore was not submitted. A total of five (5) bottom samples have been submitted in the final feature file. See final feature file for more information.Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work.No prior survey comparisons exist for this survey.No Aids to navigation (ATONs) exist for this survey.No overhead features exist for this survey.No submarine features exist for this survey.No ferry routes or terminals exist for this survey.No platforms exist for this survey.No Significant Features 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.Field operations for this hydrographic survey were conducted under the direct supervision of the then Chief of Party, Commander Marc S. Moser, 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 Manual, 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.LCDR Briana Welton, NOAAChief of Party2016-05-27LT Nicholas Morgan, NOAAField Operations Officer2016-05-27PS Tyanne FaulkesSheet Manager2016-05-27