Vertical land motion rates for the years 2015 to 2023 - Norton Sound, Alaska

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?
   Shirzaei, Manoocher, Dasho, Oluwaseyi, Tiwari, Ashutosh, and Erikson, Li, 20250926, Vertical land motion rates for the years 2015 to 2023 - Norton Sound, Alaska: data release DOI: 10.5066/P1RTIKBK, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

   Online Links:

   • https://doi.org/10.5066/P1RTIKBK

   This is part of the following larger work.
   Shirzaei, Manoocher, Dasho, Oluwaseyi, Tiwari, Ashutosh, and Erikson, Li, 2025, Vertical land motion rates for the years 2015 to 2023 - Coastal Alaska: data release DOI:10.5066/P1RTIKBK, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

   Online Links:

   • https://doi.org/10.5066/P1RTIKBK

   Other_Citation_Details:

   Suggested Citation: Shirzaei, M., Dasho, O., Tiwari, A., and Erikson, L., 2025, Vertical land motion rates for the years 2015 to 2023 - Coastal Alaska: U.S. Geological Survey data release, https://doi.org/10.5066/P1RTIKBK.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -166.95007
   East_Bounding_Coordinate: -159.69790
   North_Bounding_Coordinate: 65.30995
   South_Bounding_Coordinate: 62.59433
   

3. What does it look like?

   Vertical_Land_Motion_NortonSound.png (JPEG)

   Map showing the area for which vertical land motion (VLM) data are available.

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

   Beginning_Date: 01-Jan-2015

   Ending_Date: 31-Dec-2023

   Currentness_Reference:

   collection years of SAR data used to determine vertical land motion

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

   Geospatial_Data_Presentation_Form: comma-delimited text
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (1013385)
   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 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is International GNSS Service 14.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      
7. How does the data set describe geographic features?

   Vertical_Land_Motion_NortonSound_CoastalAlaska.csv

   vertical land motion rates (Source: Producer defined)

   Longitude

   Longitudinal values for the dataset expressed in degrees (Source: USGS)

   Range of values
   Minimum:	-166.95007
   Maximum:	-159.69790
   Units:	Decimal Degrees
   Resolution:	0.00001

   Latitude

   Latitudinal values for the dataset expressed in degrees (Source: USGS)

   Range of values
   Minimum:	62.59433
   Maximum:	65.30995
   Units:	Decimal Degrees
   Resolution:	0.00001

   VLMrate_cm_per_yr

   Rate of vertical change in land mass, where positive values indicate uplift, negative values indicate subsidenc. (Source: USGS)

   Range of values
   Minimum:	-5.0
   Maximum:	5.0
   Units:	centimeters (cm) per year
   Resolution:	0.1

   VLMerror_cm_per_yr

   1-sigma error of VLM rates (Source: USGS)

   Range of values
   Minimum:	0.1
   Maximum:	0.3
   Units:	cm per year
   Resolution:	0.1

   Entity_and_Attribute_Overview: The first line of the csv file is a header line.
   Entity_and_Attribute_Detail_Citation: U.S. Geological Survey
   

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Manoocher Shirzaei
   • Oluwaseyi Dasho
   • Ashutosh Tiwari
   • Li Erikson
2. Who also contributed to the data set?
3. To whom should users address questions about the data?
   U.S. Geological Survey, Pacific Coastal and Marine Science Center

   Attn: PCMSC Science Data Coordinator

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@usgs.gov

Why was the data set created?

How was the data set created?

1. From what previous works were the data drawn?

   Sentinel-1A/B satellites (source 1 of 1)

   Agency, European Space, 2021, Sentinel-1 SAR: Copernicus, online.

   Online Links:

   • https://search.asf.alaska.edu/

   Type_of_Source_Media: online database
   Source_Contribution: Source was used to build a seamless map of vertical land motion
   

2. How were the data generated, processed, and modified?

   Date: 15-Jan-2022 (process 1 of 2)

   To generate high-resolution maps of surface deformation over the study area, we applied Wavelet-based InSAR (WabInSAR) algorithm (Lee and Shirzaei, 2023; Shirzaei, 2013; Shirzaei and Bürgmann, 2012; Shirzaei and others, 2019), a cutting-edge multitemporal interferometric synthetic aperture radar (InSAR) processing framework to SAR images acquired in ascending orbit of Sentinel-1 A/B satellites between 2015 and 2023. We first generated a large set of high-quality Interferograms using GAMMA software (Werner and others, 2000). We applied a multi-looking factor of 30 by 5 in the range and azimuth direction to improve the signal-to-noise ratio and obtain an average ground resolution of about 60 m by about 60 m. We discarded distributed scatterers with coherence of less than 0.65 and permanent scatterers with amplitude dispersion of more than 0.3, following the approach detailed in (Lee and Shirzaei, 2023). Next, we employed a minimum cost flow phase unwrapping algorithm (Costantini, 1998) modified to be applied to a sparse set of less noisy pixels (Costantini and Rosen, 1999) to estimate absolute phase changes in each interferogram. We corrected all unwrapped interferograms for the effect of orbital error (Shirzaei and Walter, 2011) and reduced the effects of topographically correlated atmospheric phase delay and spatially uncorrelated digital elevation model (DEM) error (Shirzaei, 2013; Shirzaei and Bürgmann, 2012). We used a reweighted least-squares optimization to estimate each pixel's line-of-sight (LOS) time series and velocity (Shirzaei, 2013). Assuming that the principal deformation is vertical, we used the satellite unit vectors (Hanssen 2001) and projected the LOS in the vertical direction. To transform the InSAR-based vertical land motion (VLM) to the IGS14 global reference frame, we utilized the global VLM model generated by Hammond and others (2021), which mainly includes long-wavelength deformation signals due to glacial isostatic adjustment, tectonics, and total water storage changes in a global reference frame and applied an affine transformation (Blackwell and others, 2020; Ohenhen and Shirzaei, 2022). Values exceeding +/- the mean plus 2 times the standard deviation of the VLM rates are deemed outliers and were removed. Person who carried out this activity:
   

   Manoocher Shirzaei

   Virginia Tech

   Geophysicist

   925 Prices Fork Road

   Blacksburg, VA
   

   510-333-9305 (voice)

   shirzaei@vt.edu

   Data sources used in this process:

   • Sentinel-1A/B satellites

   Date: 12-Dec-2025 (process 2 of 2)

   The metadata was edited to remove a space in the network resource link. No data were changed. (mau@usgs.gov)

3. What similar or related data should the user be aware of?
   Blackwell, E., Shirzaei, M., Ojha, C., and Werth, S., 2020, Tracking California’s sinking coast from space: Implications for relative sea-level rise.

   Other_Citation_Details:

   Blackwell, E., Shirzaei, M., Ojha, C., and Werth, S., 2020, Tracking California’s sinking coast from space: Implications for relative sea-level rise: Science Advances, vol. 6, p. eaba4551, https://doi.org/10.1126/sciadv.aba4551.

   Costantini, M., 1998, A novel phase unwrapping method based on network programming.

   Other_Citation_Details:

   Costantini, M., 1998, A novel phase unwrapping method based on network programming: Geoscience and Remote Sensing, IEEE Transactions on, vol. 36, p. 813-821

   Costantini, M., and Rosen, P.A., 1999, A generalized phase unwrapping approach for sparse data.

   Other_Citation_Details:

   Costantini, M., and Rosen, P.A.,1999, A generalized phase unwrapping approach for sparse data: IEEE 1999 International Geoscience and Remote Sensing Symposium. IGARSS'99 (Cat. No.99CH36293), Hamburg, Germany, 1999, vol.1, p. 267-269

   Hanssen, R.F., 2001, Radar interferometry, data interpretation and error analysis.

   Other_Citation_Details:

   Hanssen, R.F., 2001, Radar interferometry, data interpretation and error analysis. Kluwer Academic Publishers, ISBN: 978-0-7923-6945-5

   Hammond, W.C., Blewitt, G., C. Kreemer, and Nerem, R.S., 2021, GPS Imaging of Global Vertical Land Motion for Studies of Sea Level Rise.

   Other_Citation_Details:

   Hammond, W.C., Blewitt, G., Kreemer, C., & Nerem, R.S., 2021, GPS Imaging of Global Vertical Land Motion for Studies of Sea Level Rise: Journal of Geophysical Research: Solid Earth, vol. 126, e2021JB022355, https://doi.org/10.1029/2021JB022355

   Lee, J.-C., and Shirzaei, M., 2023, Novel algorithms for pair and pixel selection and atmospheric error correction in multitemporal InSAR.

   Other_Citation_Details:

   Lee, J.-C., and Shirzaei, M., 2023, Novel algorithms for pair and pixel selection and atmospheric error correction in multitemporal InSAR: Remote Sensing of Environment, vol. 286, 113447

   Ohenhen, L.O., Shirzaei, M., Ojha, C., Sherpa, S.F., and Nicholls, R.J., 2024, Disappearing cities on US coasts.

   Other_Citation_Details:

   Ohenhen, L.O., Shirzaei, M., Ojha, C., Sherpa, S.F., and Nicholls, R.J., 2024, Disappearing cities on US coasts: Nature, vol. 627, p.108-115

   Ojha, C., Shirzaei, M., Werth, S., Argus, D.F., and Farr, T.G., 2018, Sustained groundwater loss in California’s Central Valley exacerbated by intense drought periods.

   Other_Citation_Details:

   Ojha, C., Shirzaei, M., Werth, S., Argus, D.F., and Farr, T.G., 2018, Sustained groundwater loss in California's Central Valley exacerbated by intense drought periods: Water resources research, vol. 54, p. 4449-4460, https://doi.org/10.1029/2017WR022250.

   Shirzaei, M., and Walter, T.R., 2011, Estimating the Effect of Satellite Orbital Error Using Wavelet-Based Robust Regression Applied to InSAR Deformation Data.

   Other_Citation_Details:

   Shirzaei, M., and Walter, T.R.,2011, Estimating the Effect of Satellite Orbital Error Using Wavelet-Based Robust Regression Applied to InSAR Deformation Data: IEEE Transactions on Geoscience and Remote Sensing, vol. 49, p. 4600-4605

   Shirzaei, M., and Bürgmann, R., 2012, Topography correlated atmospheric delay correction in radar interferometry using wavelet transforms.

   Other_Citation_Details:

   Shirzaei M., and Bürgmann, R., 2012, Topography correlated atmospheric delay correction in radar interferometry using wavelet transforms: Geophysical Research Letters, vol. 39, https://doi.org/10.1029/2011GL049971.

   Shirzaei, M., 2013, A wavelet-based multitemporal DInSAR algorithm for monitoring ground surface motion.

   Other_Citation_Details:

   Shirzaei, M., 2013, A wavelet-based multitemporal DInSAR algorithm for monitoring ground surface motion, (in English): IEEE Geoscience and Remote Sensing Letters, vol. 10, p. 456-460, https://doi.org/10.1109/Lgrs.2012.2208935.

   Shirzaei, M., Manga, M., and Zhai, G., 2019, Hydraulic properties of injection formations constrained by surface deformation.

   Other_Citation_Details:

   Shirzaei, M., Manga, M., and Zhai, G., 2019, Hydraulic properties of injection formations constrained by surface deformation: Earth and Planetary Science Letters, vol. 515, p. 125-134

   Werner, C., U. Wegmüller, T. Strozzi, and A. Wiesmann, 2000, Gamma SAR and interferometric processing software.

   Other_Citation_Details:

   Werner, C., Wegmüller, U., Strozzi, T., and Wiesmann, A., 2000: Gamma SAR and interferometric processing software. Proceedings of the ERS—ENVISAT Symposium, Gothenburg, Sweden, 16-20 October, https://www.gamma-rs.ch/uploads/media/2000-1_GAMMA_Software.pdf

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

1. How well have the observations been checked?
   A formal accuracy assessment using an independent set of Global Navigation Satellite System (GNSS) vertical was conducted. Results are within the expected range of 1 millimeter per year (mm/yr) standard deviation. Values exceeding +/- the mean plus 2 times the standard deviation of the VLM rates are deemed outliers and were removed.
2. How accurate are the geographic locations?
   A formal accuracy assessment of the horizontal positional information in the data set has not been conducted.
3. How accurate are the heights or depths?
   Data accuracy is assumed to be close to 1 mm/yr.
4. Where are the gaps in the data? What is missing?
   Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
5. How consistent are the relationships among the observations, including topology?
   Data fall within expected/reasonable ranges.

How can someone get a copy of the data set?

1. Who distributes the data set? (Distributor 1 of 1)
   
   U.S. Geological Survey - CMGDS

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@usgs.gov
2. What's the catalog number I need to order this data set? These data are available in csv format accompanied by CSDGM FGDC-compliant metadata.
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. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
4. How can I download or order the data?
   • Availability in digital form:

     Data format:	Zip file (Vertical_Land_Motion_NortonSound_CoastalAlaska.zip) containing csv with VLM data in format comma-delimited text Size: 5.7
     Network links:	https://doi.org/10.5066/P1RTIKBK

   • Cost to order the data: None.

5. What hardware or software do I need in order to use the data set?
   The csv data can be viewed with any text reading software.

Who wrote the metadata?

Dates:

Last modified: 12-Dec-2025

Metadata author:

U.S. Geological Survey, Pacific Coastal and Marine Science Center

Attn: PCMSC Science Data Coordinator

2885 Mission Street

Santa Cruz, CA

831-427-4747 (voice)

pcmsc_data@usgs.gov

Metadata standard:

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