kmaterna/grace_loading

Evaluate GRACE loads on GNSS Stations

Written by Kathryn Materna, 2017

This program takes GRACE Level 3 gravity grids and estimates elastic loading deformation at specified locations. It takes GRACE grids (in total water equivalent) within a certain distance from a station, and integrates the elastic loading effect on that station from each cell. You can:

• compute elastic loading deformation on a PREM earth structure
• use Green's functions for loading disks of several radii on a PREM earth.
• choose among several GRACE gridded solutions (JPL, GFZ, CSR, Mascons).
• use the GRACE scaling grid or not.

This code has not been tested with GRACE-FO data yet.

Pseudo code:

• Read configfile
• Read in station information for your network: name lon lat T1 T2
• For each station,
  • For each timestep from T1 to T2,
    • load grid ---> temp input file
    • station loc -> temp input file
    • timestamp ---> station output file
    • 3D disp. ---> station output file
  • Write output textfile with east, north, up modeled displacements
  • Produce output timeseries plots

Requirements

This GRACE loading software requires standard libraries Python as well as Numpy, Scipy, and Matplotlib. Additionally, it requires a small library called Tectonic_Utils. Please call pip install Tectonic-Utils to install that library.

To install this GRACE loading software, git clone this repository and add the GRACE_Loading/ directory to your $PATH. Add the directory above this repository to your $PYTHONPATH to facilitate imports.

To run

The major options of the program are controlled by a config file in a plain text format. To run a calculation, call in a terminal the driver of this library with the format grace_loading_driver.py config.txt

A basic config.txt would look like:

####################
[io-config]
network = MIBB
gps_infile = input.txt
output_dir = Outputs
GRACE_data_dir = /Users/kmaterna/Documents/B_Research/GEOPHYS_DATA/GRACE/DATA/
mascon_datafile = Mascons/GRCTellus.JPL.200204_202002.GLO.RL06M.MSCNv02CRI.nc
grace_dates_file = GRACE_GRACE-FO_Months_RL06.csv

#########
[calc-config]
greensfunc = Greens_Functions/Wahr_6.206_whole_earth
gf_radius = 6.206
gracetype = Mascon
datasource = JPL
max_distance = 180
scaling = 0

A more detailed config file is given in the file Example/example_config.txt.

Inputs in input.txt would have the format:

TASH 91.552467 27.332209 2012-03-01 2016-08-01
WAAW 96.666748 17.471861 2011-01-01 2017-07-01

Example Output Plot

Citation

If you use this software in research, please cite the paper for which it was developed:

"GNSS characterization of hydrological loading in South and Southeast Asia", Kathryn Materna, Lujia Feng, Eric O Lindsey, Emma M Hill, Aktarul Ahsan, A K M Khorshed Alam, Kyaw Moe Oo, Oo Than, Thura Aung, Saw Ngwe Khaing, Roland Bürgmann. Geophysical Journal International, Volume 224, Issue 3, March 2021, Pages 1742–1752, https://doi.org/10.1093/gji/ggaa500