Bouguer gravity anomaly data grid for the conterminous US

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: Robert P. Kucks
Publication_Date: 1999
Title: Bouguer gravity anomaly data grid for the conterminous US
Online_Linkage: Larger_Work_Citation:
Citation_Information:
Originator: Phillips, Jeffrey D.
Originator: Duval, Joseph S.
Originator: Ambroziak, Russell A.
Title:
National geophysical data grids; gamma-ray, gravity, magnetic and topographic data for the conterminous United States
Publication_Date: 1993
Series_Information:
Series_Name: U.S. Geological Survey Digital Data Series
Issue_Identification: DDS-9
Online_Linkage: http://pubs.er.usgs.gov/publication/ds9
Description:
Abstract:
The grid of gravity anomaly data for the conterminous United States and adjacent marine areas was constructed from National Information Mapping Agency (NIMA) gravity data files. It was reprojected to the specifications for the Spatial Data Delivery (SDD) project.
Supplemental_Information:
Digital Data Series DDS-9 (CD-ROM) contains gridded geophysical data (gravity anomaly data only defined here) images generated from the data, software for displaying and analyzing the images, software for processing potential-field geophysical data, and documentation files that describe the data and software.
Purpose:
Gravity anomalies are produced by density variations within the rocks of the Earth's crust and upper mantle. Mapping of these density variations is the primary use of gravity anomalies.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 1998
Ending_Date: 1999
Currentness_Reference: reprocessing for SDD website
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -125
East_Bounding_Coordinate: -65
North_Bounding_Coordinate: 49
South_Bounding_Coordinate: 25
Access_Constraints: None
Use_Constraints: None
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Robert P. Kucks
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing address
Address:
Box 25046, MS 964
Denver Federal Center
City: Denver
State_or_Province: CO
Postal_Code: 80225-0046
Country: USA
Contact_Voice_Telephone: (303) 236-1405
Contact_Electronic_Mail_Address: rkucks@usgs.gov
Data_Set_Credit:
The compilation of onshore data consisted of nearly one million Bouguer gravity anomaly values computed by using a reduction density of 2.67 grams per cubic centimeter. The offshore data consisted of approximately 800,000 free-air gravity anomaly values.

USGS employees: Godson and Scheibe
Native_Data_Set_Environment:
At the USGS, these data are stored in several binary gridded data formats on UNIX and PC systems. Data have been distributed in GEOSOFT GXF (an ASCII interchange format), Arc/Info export (e00), and ER Mapper binary format.
Keywords:
Theme:
Theme_Keyword_Thesaurus: none
Theme_Keyword: gravity, Bouguer
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificInformation
Place:
Place_Keyword_Thesaurus: none
Place_Keyword: United States
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
Gravity measurements made on the surface of the Earth must be corrected in various way before they can be made into an anomaly map. The free-air correction reduces the measurement to sea level by assuming there is no intervening mass as a uniform slab of constant density, and the complete Bouguer correction includes the effects of constant density topography within 166.7 km of the measurement location. A gravity reference field is subtracted from the corrected measurements to produce the free-air, simple Bouguer, or complete Bouguer anomaly. The data set constitutes many years of individual collection of gravity stations and therefore is difficult to access the precise accuracy.
Quantitative_Attribute_Accuracy_Assessment:
Attribute_Accuracy_Value: overall station accuracy of less than 2 milligals
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Earlier collection of stations was by surveying methods. Positions were also acquired from locations on topographic maps. Recently the station latitudes, longitudes and elevations were acquired by Geopositioning Satellite (GPS) systems.
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 100
Horizontal_Positional_Accuracy_Explanation:
surveying methods - 1.0 meter topographic maps - 3.0 meter GPS systems - 100.0 meter/1.0 meter differential
Vertical_Positional_Accuracy:
Quantitative_Vertical_Positional_Accuracy_Assessment:
Vertical_Positional_Accuracy_Value: 100
Vertical_Positional_Accuracy_Explanation:
surveying methods - 1.0 meter topographic maps - 1.0-20.0 meter GPS systems - 100 meter/1.0 meter differential
Lineage:
Process_Step:
Process_Description:
gravity anomaly grid was extracted from DDS-9 and reprojected using USGS in-house developed software. In-house software was also used to convert from USGS grid format to Arc-Info grid format.
Source_Used_Citation_Abbreviation:
The "state-of-the-art" for gravity data collection changed significantly throughout the data collection period for this data set. Journals such as GEOPHYSICS have periodic articles describing the current state of standard procedures.
Process_Date: 1999
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Robert P. Kucks
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address:
Box 25046, MS 964
Denver Federal Center
City: Denver
State_or_Province: CO
Postal_Code: 80225-0046
Country: USA
Address_Type: mailing address
Contact_Electronic_Mail_Address: rkucks@usgs.gov
Contact_Voice_Telephone: (303)236-1405
Logical_Consistency_Report:
The accuracy of the data set that generated the grid is totally dependant on the individual who collected each gravity station. In the case of a national set they would number in the hundreds. Variations would include latitude, longitude, elevation, raw gravity reading and base station control.
Completeness_Report:
There will always be upgrades and additions to the data set that generated the grid due to regional interests.
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Grid cell
Row_Count: 776
Column_Count: 1321
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Albers_Conical_Equal_Area:
Standard_Parallel: 29.5
Standard_Parallel: 45.5
Longitude_of_Central_Meridian: -96.0
Latitude_of_Projection_Origin: 37.5
False_Easting: 0.
False_Northing: 0.
Map_Projection_Name: Albers Conical Equal Area
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: row and column
Coordinate_Representation:
Abscissa_Resolution: 4.0
Ordinate_Resolution: 4.0
Planar_Distance_Units: kilometer
Geodetic_Model:
Horizontal_Datum_Name: Noth American Datum of 1927
Ellipsoid_Name: CLARKE1866
Semi-major_Axis: 6378.20640
Denominator_of_Flattening_Ratio: 0.99661
Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: grid cell
Entity_Type_Definition: Area of Earth's surface for which gravity anomaly is summarized
Attribute:
Attribute_Label: cell value
Attribute_Definition:
Value, in milligals, of the gravity anomaly of Earth's gravitational field.
Attribute_Definition_Source:
Paterson, N.R., and Reeves, C.V., 1985, Applications of gravity and magnetic surveys: The state-of-the-art in 1985: Geophysics, v. 50, p. 2558-2594.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -340
Range_Domain_Maximum: 95
Attribute_Units_of_Measure: milligal
Attribute_Measurement_Resolution: 0.1
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: -0.3402823E+39
Enumerated_Domain_Value_Definition: areas for which no data are available in the grid
Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Robert P. Kucks
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing address
Address:
Box 25046, MS 964
Denver Federal Center
City: Denver
State_or_Province: CO
Postal_Code: 80225
Country: USA
Contact_Voice_Telephone: (303)236-1405
Contact_Electronic_Mail_Address: rkucks@usgs.gov
Resource_Description: USGS Digital Data Series DDS-9
Distribution_Liability:
The USGS has made every effort to verify the veracity of this information, but is not liable for any inaccuracies.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: ArcInfo export
Format_Version_Number: 7.x
Format_Specification: Arc-Info grid format
Format_Information_Content: Gridded gravity anomaly data
File_Decompression_Technique: gunzip
Transfer_Size: 3.5
Digital_Transfer_Option:
Online_Option:
Digital_Form:
Digital_Transfer_Information:
Format_Name: GeoTIFF
Format_Version_Number: 6
Format_Information_Content: Gridded gravity anomaly data
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Digital_Form:
Digital_Transfer_Information:
Format_Name: OGC WMS
Format_Version_Number: 1.3.0
Format_Information_Content: Bouguer gravity anomaly
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Fees: none
Metadata_Reference_Information:
Metadata_Date: 20180307
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Peter N Schweitzer
Contact_Organization: USGS Eastern Mineral and Environmental Resources Science Center
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing address
Address: 12201 Sunrise Valley Drive
City: Reston
State_or_Province: VA
Postal_Code: 20192-0002
Country: USA
Contact_Voice_Telephone: 703-648-6533
Contact_Facsimile_Telephone: 703-648-6252
Contact_Electronic_Mail_Address: pschweitzer@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

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