WDC for Geophysics, Beijing(中国地球物理学科中心)

Author-submitted data information

ID 300
Title Water level and barometric pressure observation data obtained from CENC (China Earthquake Networks Center) and InSAR measurements from modified Sentinel-1 imagery
Creator Yan Zhang
Subject Groundwater observation data (water level and barometric pressure) and InSAR results
Publisher Xiukuan Zhao
Description Groundwater data (water level and barometric pressure) of well Gaocun (Tianjin province) is selected in this study. The well is located at longitude 116.87° and latitude 39.62°. The groundwater observation data comes from the analog and digital observation instruments of the Gaocun groundwater station (Tainjin Province) of the China Earthquake Networks Center. The water-level and barometric data are of high quality, and the selection is based on the catalogs provided by provincial (Tainjin) earthquake administrations. Besides, this selected well is away from the coast to minimize the effects of ocean tides.

InSAR (Interferometric synthetic aperture radar) measurements over well Gaocun processed by GMTSAR software are also used in this study. The phase in the SAR imagery represents the round-trip travelling distance from the sensor to the ground targets. Interferograms reflect the surface deformation relying on the phase differences between repeat passes. The phase differences mainly include the ground deformation spanning the acquisition time, the atmospheric noise, satellite orbital errors. Here we used one ascending track of Sentinel-1 to monitor ground deformation in Gaocun from 2014 to 2019. Compiled with GPS observations, we removed the long-wavelength atmospheric phase screens and orbital errors. Time-series InSAR analysis was used to resolve the cumulative subsidence in the vertical direction at Gaocun well.

1-Water level data:
Data file 1 (1981010100--2019032823) provided by the Tianjin province to the CENC (in the matrix form): the first number indicates the time (year-month-day), and the following data is the water level (unit-m), 24 data per day, hourly data;
Data file 2 (2019032900--2020050923) provided by CENC (in the form of 2 columns): the first column indicates the time (year-month-day-hour), and the second column is the water level data (unit-m), hourly data. During the analysis of the paper, in order to calculate the phase shifts and the amplitude ratios, we resampled the hourly-data into the minute-data.

2-Barometric data:
There are two sequences, the left column is the time (year-month-day-hour-min), and the right column is the barometric pressure (unit-hPa).

3-InSAR data:
There are two sequences, the left column is the decimal year, and each time corresponds to one SAR scene, the Sentinel-1 SAR scenes were collected every 12 days. But the data collection before 2016 is irregular, and thus the time intervals are not uniform during our observing timeframe. The right column indicates the cumulative subsidence (mm) collocated with the well location in Gaocun.
Contributor Yan Zhang, Li-Yun Fu, Xiao-Long Sun, Xie Hu, Xiao Yu, and Qiu-Ye Yang
Date 1-The tidal response analysis: water level data are from January 1st, 1981 to May 9th, 2020, during which two huge earthquakes occurred (the 2008 MW 7.9 Wenchaun earthquake and the 2011 MW 9.1 Tohoku earthquake).

2-The barometric response analysis: both the water level data and the barometric pressure data are from January 1st, 2017 to May 30th, 2019.

3-The INSAR data analysis: ground deformation in Gaocun are monitored from 2014 to 2019 (Only since September 2014, there are InSAR records for well Gaocun).
Type 1-Water level observation: Since the year 1981, the SW40-1 (Chong-Qing) analog observation water-level instrument is used to document the water-level change in this well, which has a resolution of 1 mm, and sampling rate of 1 per hour. Since the year 2001, the LN-3A digital water-level instrument is used, which has an observation accuracy of ≤ 0.2% full scale, resolution of 1 mm, and sampling rate of 1 per minute.
(In order to be uniform, we used the hourly data from January 1st, 1981 to May 9th, 2020, and resampled into the minute-data to do calculations.)

2-Barometric pressure observation: Barometric pressure is documented with a RTP-1 digital instrument with a sampling rate of 1 sample/min.

3-INSAR observation: InSAR measurements are from The Copernicus Sentinel-1 SAR scenes with a sampling rate of 1 sample/ 12 days in this research region.
Format the *.DIG format data (can be read directly using the software of MATLAB, et al.) has been stored in the files.
URL http://www.geophys.ac.cn/ArticleData/20210823ByZhang.zip
DOI 10.12197/2021GA001
Language eng
Rights China Earthquake Networks Center (groundwater data); The Copernicus Sentinel-1 SAR scenes were collected by the European Space Agency (ESA) and are available from the Copernicus Open Access Hub (https://scihub.copernicus.eu/dhus/#/home) and the Alaska Satellite Facility (https://search.asf.alaska.edu/).