Time-series measurements of oceanographic and water quality data collected in the Herring River, Wellfleet, Massachusetts, USA, November 2018 to November 2019

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Suttles, Steven E, De, Olivia A Meo, Ganju, Neil K, Bales, Robert D, and Marsjanik, Eric D, 20230421, Time-series measurements of oceanographic and water quality data collected in the Herring River, Wellfleet, Massachusetts, USA, November 2018 to November 2019: data release DOI:10.5066/P95AE74D, U.S. Geological Survey, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

   Online Links:

   • https://doi.org/10.5066/P95AE74D
   • https://cmgds.marine.usgs.gov/data-releases/datarelease/10.5066-P95AE74D

   Other_Citation_Details:

   Suggested citation: Suttles, S.E., De Meo, O.A., Ganju, N.K., Bales, R.D., and Marsjanik, E.D., 2023, Time-series measurements of oceanographic and water quality data collected in the Herring River, Wellfleet, Massachusetts, USA, November 2018 to November 2019: U.S. Geological Survey data release, https://doi.org/10.5066/P95AE74D.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -70.07230
   East_Bounding_Coordinate: -70.05390
   North_Bounding_Coordinate: 41.93660
   South_Bounding_Coordinate: 41.91810
   

3. What does it look like?

   https://cmgds.marine.usgs.gov/data-releases/media/2023/10.5066-P95AE74D/ef9dc65d3ad8471fb55c1cc242275ece/mudflat_spyder_wellfleet_tsdata.jpg (JPEG)

   Photo of spyder frame with deployed instruments and GNSS receiver getting vertical positions during low tide on a mudflat in Herring River, Wellfleet, Massachusetts.

4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 13-Nov-2018

   Ending_Date: 19-Nov-2019

   Currentness_Reference:

   ground condition at time data were collected

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: netCDF files
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      

      Indirect_Spatial_Reference:

      Data were collected continuously at each sensor. Refer to self-describing netCDF files for more location information.

      This is a Raster data set.
   2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1983 (National Spatial Reference System 2011).
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.
      

      Vertical_Coordinate_System_Definition:

      Altitude_System_Definition:

      Altitude_Datum_Name: North American Vertical Datum of 1988 using Geoid 12B
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:

      Explicit elevation coordinate included with horizontal coordinates

      Depth_System_Definition:

      Depth_Datum_Name: Mean sea level
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates
      

7. How does the data set describe geographic features?

   Entity_and_Attribute_Overview:

   NetCDF files are self-describing and attribute information may be found in the header of the file itself.

   Entity_and_Attribute_Detail_Citation:

   The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Steven E Suttles
   • Olivia A De Meo
   • Neil K Ganju
   • Robert D Bales
   • Eric D Marsjanik
2. Who also contributed to the data set?
   Jonathan Borden (USGS retired) significantly contributed to the data collection efforts for this dataset. Marinna Martini (formerly USGS) participated in data collection activities and did preliminary processing of the RBR Dwave pressure logger data using the stglib processing code.
3. To whom should users address questions about the data?
   Steven E Suttles

   U.S. Geological Survey, Northeast Region

   Mechanical Engineer

   384 Woods Hole Road

   Woods Hole, MA
   

   US

   508-458-8700 (voice)

   whsc_data_contact@usgs.gov

   Contact_Instructions:

   The contact email address is a generic address in the event the person is no longer with USGS.

Why was the data set created?

How was the data set created?

1. From what previous works were the data drawn?
2. How were the data generated, processed, and modified?

   Date: 19-Nov-2019 (process 1 of 20)

   Beginning on November 12, 2018, instruments to measure time-series data of water quality, water level, currents, waves, and changes to the seabed elevations were deployed at four locations in the Herring River estuary in Wellfleet, Massachusetts. Bottom landing fiberglass platforms were deployed in the main channel on either side of a flow restriction at the Chequessett Neck bridge that limits the reach of saltier Cape Cod Bay water inland of the bridge. The platform upstream (landward) of the bridge had a multi-parameter water quality sonde (YSI EXO2) that measured pressure, salinity, water temperature, turbidity, oxygen, fluorescent dissolved organic matter (fDom), Chlorophyll and blue green algae fluorescence. The platform seaward (downstream) of the restriction also had a multi-parameter sonde measuring the same water quality parameters as the upstream sonde, and also included an acoustic doppler current profiler (Nortek Aquadopp) to make current profile measurements and a fast-sampling pressure logger (RBR Dwave) to measure tides and non-directional waves. On a tidal mudflat between the bridge and the seaward bottom platform, two stainless steel altimeter frames (custom built called "spyder" frames) were deployed, each with a profiling seabed altimeter (EchoLogger EA400), a turbidity sensor (WET Labs ECO-NTU), and an RBR Dwave. At approximately 3-month intervals instruments were retrieved to download data and refresh batteries, and then redeployed for the next segments. During these turnarounds the bottom landing platforms were turned around the same day by swapping instruments at time of recovery with instruments of the same type with minimal loss of data (a couple of sample intervals typically), while with the instruments on the mudflat spyder frames swapping was not an option and there was typically 2 or 3 days without data collection at those sites between deployment segments. The spyder frames were removed in January 2019 due to concerns of ice formation and were re-established in late March 2019 when the threat of ice in the area had passed. Most instruments measured and recorded parameters at 15-minute intervals during the deployments, except for the RBR Dwaves which burst sampled pressure data at a 4 Hz sampling rate for 1024 seconds, every 30 minutes. Specifics are given in the metadata of the self-describing netCDF files. Data collection ceased on October 14, 2019 for the EXO2 sonde on the landward (upstream) bottom platform due to battery depletion. The seaward bottom lander was recovered on October 23, 2019, and the 2 spyder frames on November 19, 2019, which marked the end of data collection of this dataset. More information on each of the deployment and recovery segments and data processing is given in additional process steps. Steve Suttles is the contact for this process step and subsequent process steps until otherwise noted. Person who carried out this activity:
   

   Steven E Suttles

   U.S. Geological Survey, Northeast Region

   Mechanical Engineer

   384 Woods Hole Road

   Woods Hole, MA
   

   US

   508-458-8700 (voice)

   whsc_data_contact@usgs.gov

   Contact_Instructions:

   The contact email address is a generic address in the event the person is no longer with USGS.

   Date: 15-Nov-2018 (process 2 of 20)

   Deployment A: A Nortek Aquadopp, YSI EXO2, and RBR Dwave were deployed at mooring 1121 (the seaward channel location) on a bottom lander platform on November 12, 2018. RBR Dwaves, EchoLogger EA400s, and ECO NTUs were deployed on a spyder frame at moorings 1122 (shallow flank location) and 1123 (flank deep location) on November 14, 2018. A YSI EXO2 was deployed at mooring 1120 (the landward channel location) on a bottom lander platform on November 15, 2018. On November 15, 2018, SP80 RTK receiver was used to get horizontal and vertical positions for bottom lander at mooring 1120, and altimeter spyder frames at moorings 1122 and 1123.

   Date: 16-Jan-2019 (process 3 of 20)

   Recovery A part 1: The sensors and spyder frames were recovered at moorings 1122 and 1123 on January 16, 2019, due to anticipated ice in the area. Moorings 1122 and 1123 were on mudflats and the water level drops below the sensor on most low tides (twice daily).

   Date: 15-Feb-2019 (process 4 of 20)

   Recovery A part 2: The sensors were recovered at mooring 1120 on February 13, 2019, and at mooring 1121 on February 15, 2019.

   Date: 15-Feb-2019 (process 5 of 20)

   Deployment B part 1: A YSI EXO2 was deployed at mooring 1120 (the landward channel location) on a bottom lander platform on February 13, 2019. A Nortek Aquadopp, YSI EXO2, and RBR Dwave were deployed at mooring 1121 (the seaward channel location) on a bottom lander platform on February 15, 2019.

   Date: 27-Mar-2019 (process 6 of 20)

   Deployment B part 2: Spyder frames and RBR Dwaves, EchoLogger EA400s, and ECO NTUs were deployed (re-established) at moorings 1122 (shallow flank location) and 1123 (deep flank location) on March 27, 2019.

   Date: 08-Apr-2019 (process 7 of 20)

   SP80 RTK receiver was used to get horizontal and vertical positions of altimeter spyder frames at moorings 1122 (shallow flank location) and 1123 (deep flank location) on April 8, 2019.

   Date: 16-May-2019 (process 8 of 20)

   Recovery B part 1: The EXO2 sonde was recovered at mooring 1120 on May 13, 2019, and sensors at mooring 1121 on May 16, 2019. The recovered sensors were brought back to the lab and data were downloaded and archived on a WHCMSC file server.

   Date: 19-Jun-2019 (process 9 of 20)

   Recovery B part 2: RBR Dwaves, EchoLogger EA400s, and ECO NTUs were recovered at moorings 1122 and 1123 on June 19, 2019. The recovered sensors were brought back to the lab and raw data were downloaded and archived on the WHCMSC file server. SP80 RTK receiver was used to get horizontal and vertical positions of spyder frames at moorings 1122 and 1123 using average values for 15-minute occupations.

   Date: 16-May-2019 (process 10 of 20)

   Deployment C part 1: A YSI EXO2 was deployed at mooring 1120 (landward channel location) on a bottom lander platform on May 13, 2019. A Nortek Aquadopp, YSI EXO2, and RBR Dwave were deployed at mooring 1121 (seaward channel location) on a bottom lander platform on May 16, 2019. SP80 RTK receiver was used to get horizontal and vertical positions of platform at mooring 1120 on May 13, 2019.

   Date: 21-Jun-2019 (process 11 of 20)

   Deployment C part 2: RBR Dwaves, EchoLogger EA400s, and ECO NTUs were deployed on a spyder frame at moorings 1122 (shallow flank location) and 1123 (deep flank location) on June 21, 2019.

   Date: 07-Aug-2019 (process 12 of 20)

   Recovery C part 1: The sensors were recovered at mooring 1120 on July 25, 2019, and at mooring 1121 on August 7, 2019. The recovered sensors were brought back to the lab and raw data were downloaded and archived on the WHCMSC file server.

   Date: 17-Sep-2019 (process 13 of 20)

   Recovery C part 2: The sensors were recovered at moorings 1122 and 1123 on September 17, 2019. The recovered sensors were brought back to the lab and raw data were downloaded and archived on the WHCMSC file server.

   Date: 07-Aug-2019 (process 14 of 20)

   Deployment D part 1: A YSI EXO2 was deployed at mooring 1120 (landward channel location) on a bottom lander platform on July 25, 2019. A Nortek Aquadopp, YSI EXO2, and RBR Dwave were deployed at mooring 1121 (seaward channel location) on a bottom lander platform on August 7, 2019. SP80 RTK receiver was used to get horizontal and vertical positions of platforms at moorings 1120 and 1121 on July 25, 2019, and August 7, 2019, respectively.

   Date: 19-Sep-2019 (process 15 of 20)

   Deployment D part 2: RBR Dwaves, EchoLogger EA400s, and ECO NTUs were deployed on a spyder frame at moorings 1122 (shallow flank location) and 1123 (deep flank location) on September 19, 2019. SP80 RTK receiver was used to get horizontal and vertical positions of platforms at moorings 1122 and 1123 using average values for 15-minute occupations.

   Date: 23-Oct-2019 (process 16 of 20)

   Recovery D part 1: The sensors were recovered at mooring 1120 on October 21, 2019, and at mooring 1121 on October 23, 2019. The recovered sensors were brought back to the lab and raw data were downloaded and archived on the WHCMSC file server.

   Date: 19-Nov-2019 (process 17 of 20)

   Recovery D part 2: The sensors were recovered at moorings 1122 and 1123 on November 19, 2019. The recovered sensors were brought back to the lab and raw data were downloaded and archived on the WHCMSC file server.

   Date: Jan-2023 (process 18 of 20)

   The raw data files from each sensor were processed and converted to netCDF using stglib python libraries, a package of code to process data consistent with procedures of the USGS Coastal/Marine Hazards and Resources Program. In stglib, attributes conforming to Climate and Forecast (CF) Conventions version 1.6 were added. All times are in Coordinated Universal Time (UTC). Corrected pressure data were calculated by finding an offset with local atmospheric pressure readings when the pressure sensor was reading in air just prior to deployment and then applying the time-series of local atmospheric pressure over the course of the deployment to remove the atmospheric contribution to the deployed pressure data, leaving only the pressure due to seawater in the corrected pressure data variable (standard_name "sea_water_pressure_due_to_seawater" in netCDF files). Data quality assurance and quality control (QAQC) was performed by inspecting all variables and replacing spurious values with the fill value. Details of which portions of data were flagged and replaced are available in the metadata in each netCDF file and information about the individual QAQC trimmig functions are available in the stglib documentation (https://stglib.readthedocs.io/en/latest/) in the "Instrument configuration file" section. The netCDF files are named using the convention ####XYZZZ-a.nc where '####' is the mooring number, 'X' is the position on the mooring of the sensor with 1 being closest to the surface and 3 being the most submerged, 'Y' is a letter (A through D) corresponding to the sequential deployment at each mooring location, and 'ZZZ' is an abbreviation for the instrument that was deployed. For example, in the file 11201Aexo-a.nc, '1120' is the mooring number, '1' is the position of the sensor on the mooring, 'A' indicates the first deployment, and 'exo' refers to the YSI EXO2 sensor.

   Date: Jan-2023 (process 19 of 20)

   ECO-NTU data at moorings 1122 and 1123 were trimmed for times when the sensor was not fully submerged using the co-located EA400 raw altitude data. When altitude data were not in valid range ECO-NTU data were filled. A custom python script (maskntu2ea400.py) was used for this purpose.

   Date: 24-Aug-2023 (process 20 of 20)

   Additional cross-reference was added to the metadata as well as updating the contacts for process steps. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: VeeAnn A. Cross

   Marine Geologist

   384 Woods Hole Rd.

   Woods Hole, MA
   

   USA

   (508) 548-8700 x2251 (voice)

   (508) 457-2310 (FAX)

   vatnipp@usgs.gov

3. What similar or related data should the user be aware of?
   De, Olivia A Meo, Suttles, Steven E, Ganju, Neil K, and Marsjanik, Eric D, 2022, Suspended-sediment concentrations and loss-on-ignition from water samples collected in the Herring River during 2018-19 in Wellfleet, MA: date release DOI:10.5066/p9zl2ipn, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/p9zl2ipn

   De, Olivia A Meo, Suttles, Steven E, Ganju, Neil K, and Marsjanik, Eric D, 2023, Water quality data from a multiparameter sonde collected in the Herring River during November 2018 to November 2019 in Wellfleet, MA: data release DOI:10.5066/P9K3SCK, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9K3SCK

   De, Olivia A. Meo, Suttles, Steve E., Ganju, Neil K., and Marsjanik, Eric D., 2023, Calibrating Optical Turbidity Measurements with Suspended-Sediment Concentrations from the Herring River in Wellfleet, Massachusetts, from November 2018 to November 2019: Data Report 1180, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.3133/dr1180

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?
   The EchoLogger EA400 altimeter has a water column resolution up to 7.5 mm, a temperature accuracy of ±0.5 degrees C, and tilt sensor inclination accuracy of ±0.1 degrees. The RBR Dwave, tide and wave instrument, has a pressure accuracy of ±0.05% full scale. The WET Labs ECO NTU turbidity sensor has a sensitivity of 0.12 NTU for 0-1000 NTU range. The Nortek Aquadopp acoustic doppler current profiler (ADCP) has a water velocity accuracy of ±1% of measured value ±0.5 cm/s, a heading and tilt accuracy of ±2 degrees and resolution of 0.1 degree, and a pressure accuracy of ±0.5% of full scale with resolution of 0.005% of full scale. The YSI EXO2 multiparameter sonde has the following accuracies: temperature = ± 0.01 degrees C from -5 to 35 degrees C and ± 0.05 degrees C between 35-50 degrees C, conductivity = greater of ±1% of reading or 0.002 mS/cm, barometric pressure = ±1.5 mmHg from 0-50 degrees C, depth = ± 0.004 m from 0-10 m and ±0.04 m from 0-100 m, salinity = ±1.0% of reading, turbidity = ±2% of reading from 0-999 FNU and ±5% of reading from 1000-4000 FNU, pH = ±0.2 pH units for entire temperature range, fDOM = r-squared > 0.999 for serial dilution of 300 ppb quinine sulfate solution, dissolved oxygen % air saturation = ±1% of reading from 0-200% and ±5% of reading from 200-500%, dissolved oxygen in mg/L = ±0.1 mg/L from 0-20 mg/L and ±5% of reading from 20-50 mg/L, chlorophyll = r-squared > 0.999 for serial dilution of Rhodamine WT solution from 0-400 ug/L Chl a equivalents, and blue-green algae phycoerythrin (BGA-PE) = r-squared > 0.999 for serial dilution of Rhodamine WT solution from 0-280 ug/mL BGA-PE equivalents.
2. How accurate are the geographic locations?
   A combination of a Garmin handheld GPSMAP 78sc Global Positioning System (GPS) and a Spectra SP80 Global Navigation Satellite System (GNSS) receiver using MACORS network for real-time corrections were used to collect horizontal location data. The GPSMAP 78sc has an expected accuracy of +/- 3 m at best whereas the SP80 receiver using MACORS has a theoretical horizontal accuracy of 0.01 m on any single point but repeat occupations of the same spot suggest slightly higher uncertainties up to 0.05 m including user error. For reported horizontal position, the North American Datum of 1983 (2011 realization) reference frame was used.
3. How accurate are the heights or depths?
   In the field a SP80 GNSS receiver was used to collect vertical position data of the fiberglass bottom landing frames at moorings 1120A-D and 1121D, and the two altimeter frames (spyder) on the mudflats at moorings 1122A-D and 1123A-D. On the two spyder frames, 15-minute occupations were collected and averaged to obtain the positions of the top of the EA400 altimeters. Tape down measurements were then made to the seabed. Orthometric elevations relative to the NAVD88 vertical datum were computed using offsets from the National Geodetic Survey Geoid12B model. A U.S Army Corps of Engineers benchmark in Wellfleet Harbor parking lot (WLFLT) was occupied each day the SP80 GNSS was used to collect position data on the deployed platforms to confirm data quality. These data have a theoretical vertical accuracy of 0.02 m on any single point but repeat occupations of the same spot suggest slightly higher uncertainties up to 0.04 m including user error. At locations where vertical elevations using the SP80 receiver were not collected, orthometric elevations (NAVD88) were estimated using the Vdatum tool (https://vdatum.noaa.gov/vdatumweb/) with estimates of local mean sea-level from the corrected pressure data from the deployment; for these cases the uncertainties for vertical position are higher, typically ~ 0.10 m.
4. Where are the gaps in the data? What is missing?
   One of the RBR Dwave instruments (serial_number 055108), used on 2 deployments (1123A and 1121C), had multiple time resets during those deployments which caused incomplete bursts and shifts in the time stamp that made it impossible to realign the time properly and confidently for each data point. The data from this instrument for those 2 deployments were determined to not be suitable for release and are not contained in this dataset. Otherwise, the dataset is considered complete for the information presented herein.
5. How consistent are the relationships among the observations, including topology?
   All turbidity, conductivity, oxygen, chlorophyll, blue green algae, and pH sensors were calibrated and checked in a known standard prior to deployment and checked again after being recovered and brought back to the laboratory to assess any drift or fouling that may have occurred during the deployment. Pressure sensors were compared to local atmospheric pressure data before deployment and an offset was determined. This offset along with the time-series of local atmospheric data were used to find corrected pressure data (variable name "P_1ac" and standard_name "sea_water_pressure_due_to_sea_water" in the netCDF files). These data were processed and converted into a netCDF file with processing code from stglib, a package of code to process data consistent with procedures of the USGS Coastal/Marine Hazards and Resources Program. More information about the stglib package can be found here: https://stglib.readthedocs.io/en/latest/.

How can someone get a copy of the data set?

1. Who distributes the data set? (Distributor 1 of 1)
   
   Olivia A De Meo

   U.S. Geological Survey, Northeast Region

   Technical Information Specialist

   384 Woods Hole Road

   Woods Hole, MA
   

   US

   508-548-8700 (voice)

   whsc_data_contact@usgs.gov

   Contact_Instructions:

   The contact email address is a generic address in the event the person is no longer with USGS.

2. What's the catalog number I need to order this data set? Downloadable data in netCDF format. NetCDF files are named by site location code and deployment sequence at each site. There are 56 processed netCDF files in this dataset.
3. What legal disclaimers am I supposed to read?
   Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
4. How can I download or order the data?
   • Availability in digital form:

     Data format:	Time-series data in netCDF format following Climate and Forecast (CF) Metadata Conventions version 1.6. File download sizes range from 0.16 to 1600 MB. in format NetCDF (version netCDF-4, CF-1.6) Size: 1600
     Network links:	https://cmgds.marine.usgs.gov/data-releases/media/2023/10.5066-P95AE74D/75fda4c4d21b44029fc65aa1f2e8c75c/wellfleet_timeseries_ncfiles.zip https://doi.org/10.5066/P95AE74D

   • Cost to order the data: None.

5. What hardware or software do I need in order to use the data set?
   These data can be viewed with any software capable of reading netCDF files.

Who wrote the metadata?

Dates:

Last modified: 25-Aug-2023

Metadata author:

Steven E Suttles

U.S. Geological Survey, Northeast Region

Mechanical Engineer

384 Woods Hole Road

Woods Hole, MA

US

508-548-8700 (voice)

whsc_data_contact@usgs.gov

Contact_Instructions:

The metadata contact email address is a generic address in the event the person is no longer with USGS.

Metadata standard:

FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)