Document Type

Data Set

Publication Date

2021

Keywords

New Hampshire Continental Shelf, Seafloor, Sediment, Photographs, Western Gulf of Maine

Department

Center for Coastal and Ocean Mapping

Disciplines

Earth Sciences | Geology | Geomorphology | Oceanography | Sedimentology

Description or Abstract

An approximately 4.5 km transect running from lower Portsmouth Harbor seaward onto the inner continental shelf was established to serve as the field site for the Newcastle Backscatter Experiment (NEWBEX). Acoustic backscatter measurements were made along the transect to examine relationships between backscatter and seafloor properties. This transect takes advantage of the diversity and heterogeneity of bottom types in lower Portsmouth Harbor and approach. In support of NEWBEX, a field campaign was undertaken to describe the sedimentologic characteristics of the seafloor along the transect. A total of five cruises were carried out approximately seasonally on November 26, 2012 and June 20, July 3, October 21, and December 17, 2013. Based on multibeam echosounder bathymetry (MBES), acoustic backscatter (from the NEWBEX acoustic work), sediment analysis, and video, the seafloor along the NEWBEX transect was subdivided into five major divisions representing different depositional environments including: Lower Portsmouth Harbor Channel Lag Deposits; Lower Portsmouth Harbor Sand Wave Field; Mouth Channel Lag Deposits; Inner Shelf Rippled Sands; and Heavily Vegetated Rocky Inner Shelf. Two transitional areas were also identified, one with a variable seafloor composition and one with bimodal sediments.The "New Hampshire Continental Shelf Geophysical Database: 2012-2013 NEWBEX Field Campaign – Seafloor Photographs and Sediment Data” presented here was developed by the University of New Hampshire (UNH) Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM/JHC) as part of a series of databases for the continental shelf off New Hampshire. This database includes 770 seafloor photographs representing major seafloor types along and surrounding the transect, and grain size statistics and characterizations of 94 bottom sediment samples.

DOI

https://dx.doi.org/10.34051/d/2021.7

Grant/Award Number and Agency

NOAA Joint Hydrographic Center Grant No. NA10NOS4000073

Access

Public (open access)

Download

Share

COinS