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Short Citation:
National Centers for Coastal Ocean Science, 2023: Massachusetts Bay - Internal wave packets digitized from SAR imagery,

Item Identification

Title: Massachusetts Bay - Internal wave packets digitized from SAR imagery
Short Name: internal_wave_packets
Status: Completed
Publication Date: 2006

This feature class contains internal wave packets digitized from SAR imagery at 1:350,000 scale in Massachusetts Bay. Internal waves are nonsinusoidal waves that occur at the interface between two layers of ocean water of differing densities (Brown et al., 1989 p.9). They occur when seasonally stratified water is forced by diurnal tides over abrupt topographic features, such as banks or ledges. These processes often produce several internal waves at once and as a result, internal waves usually propagate horizontally in groups or packets. As these packets approach shallow water (typically 25 to 40 m in depth), they gradually disappear due to increasing bottom attenuation, disrupting the pycnocline and vertically mixing water of differing densities (Jackson and Apel, 2004 p.198).


Created to support the biogeographic assessment of Stellwagen Bank National Marine Sanctuary.



Supplemental Information:

Jackson, C.R. and J.R. Apel. 2004. Synthetic Aperture Radar Marine User's Manual. NOAA NESDIS: Washington, D.C. pp. 464. Available from:


Theme Keywords

Thesaurus Keyword
ISO 19115 Topic Category
ISO 19115 Topic Category
NOS Data Explorer Topic Category Environmental Monitoring
None Internal Waves
None SAR
None Synthetic Aperture Radar

Temporal Keywords

Thesaurus Keyword
None 1998-2003

Spatial Keywords

Thesaurus Keyword
None Massachusetts Bay
None Stellwagen Bank National Marine Sanctuary

Physical Location

Organization: National Centers for Coastal Ocean Science
City: Silver Spring
State/Province: MD

Data Set Information

Data Set Scope Code: Data Set
Maintenance Frequency: None Planned
Data Presentation Form: vector digital data
Distribution Liability:

These data were prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Although all data have been used by NOAA, no warranty, expressed or implied, is made by NOAA as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by NOAA in the use of these data or related materials.NOAA makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA can not assume liability for and damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.

Data Set Credit: National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Program:

Support Roles

Data Steward

CC ID: 466494
Date Effective From: 2006
Date Effective To:
Contact (Position): NCCOS Scientific Data Coordinator
Email Address:


CC ID: 466496
Date Effective From: 2006
Date Effective To:
Contact (Position): NCCOS Scientific Data Coordinator
Email Address:

Metadata Contact

CC ID: 466497
Date Effective From: 2006
Date Effective To:
Contact (Position): NCCOS Scientific Data Coordinator
Email Address:

Point of Contact

CC ID: 466495
Date Effective From: 2006
Date Effective To:
Contact (Position): NCCOS Scientific Data Coordinator
Email Address:

Principal Investigator

CC ID: 466498
Date Effective From: 2006
Date Effective To:
Contact (Person): Costa, Bryan
Email Address:


Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 466501
W° Bound: -70.783468
E° Bound: -69.587833
N° Bound: 42.762758
S° Bound: 41.530974

Extent Group 1 / Time Frame 1

CC ID: 466500
Time Frame Type: Range
Start: 1998-05-14
End: 2003-09-29

Spatial Information

Spatial Representation

Representations Used

Vector: Yes

Vector Representation 1

CC ID: 584446
Complex Object Present?: Yes
Complex Object Count: 254

Access Information

Security Class: Unclassified
Data Access Procedure:

Please contact the Stellwagen Banks NMS Research Coordinator for additional information on data access (;

Data Access Constraints:


Data Use Constraints:

None. Acknowledgement of the National Oceanic and Atmospheric Administration, Center for Coastal Monitoring and Assessment, Biogeography Program would be appreciated in products derived from these data.



CC ID: 466492
URL Type:
Online Resource

Activity Log

Activity Log 1

CC ID: 466512
Activity Date/Time: 2015-06-18

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 466511
Activity Date/Time: 2017-04-05

Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using '' script. Contact Tyler Christensen (NOS) for details.

Activity Log 3

CC ID: 584444
Activity Date/Time: 2017-09-13

Partial upload of Spatial Info section only.

Technical Environment


Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog

Data Quality

Completeness Report:


Conceptual Consistency:



Process Steps

Process Step 1

CC ID: 466490

BACKGROUND:Synthetic Aperture Radar (SAR) can detect internal waves by emitting pulses of X-band (3cm), C-band (6cm) and L-band (24 cm) microwave energy, producing a two-dimensional radar backscatter map of the roughness of the ocean surface (Jackson and Apel, 2004 p.21, 41). In SAR imagery, internal waves appear as packets or groups of waves characterized by: 1) Alternating bands of bright and dark bands. The bright band is associated with the convergence zone, as determined by the orbital particle motion within the internal wave. 2) Curvilinear wave crests bent by refraction 3) Decreasing wave crest lengths from front to back of each packet 4) Decreasing wavelengths from front to back of each packet, indicating propagation direction and that nonlinear wave dispersion is in effect. 5) Decreasing wave amplitudes from front to back of each packet 6) Propagation parallel to significant isobaths Less often, internal waves may also be seen composed of only dark bands with no associated bright bands. This varying appearance is due to sensitivity to wind speed and wind direction, as well as to the orientation of the wave groups to the radar platform (Jackson and Apel, 2004 p.47). METHODS: In this study, the following methodology was used to identify and delineate internal wave packets in ESRI ArcGIS (ArcView) 9.1. First of all, a search extent was defined in order to narrow the geographic area in which to look for the internal waves. This area roughly covered from 42 deg 44 min 19 sec N to 41 deg 30 min 2 sec N and from 71 deg 8 min 3 sec W to 69 deg 36 min 30 sec W. Each of the 66 SAR images (which were taken between May 14, 1997 and August 29, 2003) were examined for internal waves, using the internal wave packet characteristics listed above as an identification guide. A ESRI polygon shapefile was created with columns recording the SAR image tile name, its year, date and time, as well as the internal wave packet area, packet propagation direction and moon phase during which it occurred. All internal wave packets were digitized at a 1:350,000 scale and saved in this shapefile, along with the necessary attribute information. The internal wave packet data were analyzed using a non-parametric Kruskal-Wallis test for significant differences in the median with a Dunn's post hoc test.

Process Date/Time: 2006-01-01 00:00:00

Child Items

Rubric scores updated every 15m

Rubric Score Type Title
Entity Internal_Wave_Packets

Catalog Details

Catalog Item ID: 39341
GUID: gov.noaa.nmfs.inport:39341
Metadata Record Created By: Tyler Christensen
Metadata Record Created: 2017-04-05 12:51+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2023-05-30 18:09+0000
Metadata Record Published: 2017-09-13
Owner Org: NCCOS
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2017-09-13
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2018-09-13