Citation: Liu, X.; Liang, H.; Ding, Z.
Analyzing the Seasonal Deformation
of the Sichuan–Yunnan Region Using
GNSS, GRACE, and Precipitation
Data. Appl. Sci. 2022, 12, 5675.
https://doi.org/10.3390/
app12115675
Academic Editors: Kamil Krasuski
and Damian Wierzbicki
Received: 21 April 2022
Accepted: 31 May 2022
Published: 2 June 2022
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Article
Analyzing the Seasonal Deformation of the Sichuan–Yunnan
Region Using GNSS, GRACE, and Precipitation Data
Xikang Liu
1,2
, Hongbao Liang
1,
* and Zhifeng Ding
2
1
The First Monitoring and Application Center, China Earthquake Administration, Tianjin 300180, China;
xikangliu@126.com
2
Institute of Geophysics, China Earthquake Administration, Beijing 100081, China; zhfding@vip.sina.com
* Correspondence: lhb131421@126.com
Abstract:
The Global Navigation Satellite System (GNSS) time series non-constructive deformation
shows significant seasonal variations, and the study of its periodic term components and possible
physical mechanisms has important theoretical significance and application value for the accurate use
of the data and more in-depth analysis. In this paper, wavelet transform (WT) is used to extract the
seasonal terms of 24 GNSS continuous station time series, Gravity Recovery and Climate Experiment
(GRACE) displacement time series and precipitation data in the Sichuan–Yunnan area, and the three
data sets are compared and analyzed in terms of amplitude, phase and cross-correlation coefficient
(CC), and the results show that the seasonal deformation in the area is strongly related to the
precipitation variation. GNSS and GRACE have good consistency in the vertical component, and
the seasonal variation is mainly related to the hydrological load; the difference in the horizontal
component is obvious, and the amplitude of the seasonal term of GNSS is larger than that of GRACE,
indicating that the resolution of GRACE in the horizontal component is lower than that of the vertical
component, and the overall estimation accuracy is lower than that of GNSS. There are significant
seasonal terms of annual and semi-annual cycles for the three GNSS components, and the vertical
component mainly shows the seasonal deformation of the annual cycle with the strongest seasonality;
the horizontal component mainly shows the deformation of the semi-annual cycle, and the seasonality
of the N component is stronger than that of the E component, and they are negatively correlated with
a coefficient of −0.90.
Keywords:
Global Navigation Satellite System; Gravity Recovery and Climate Experiment;
seasonal deformation
1. Introduction
Changes in surface mass (e.g., atmospheric pressure, non-tidal oceans, and hydro-
logical loading) can change the gravitational field and three-dimensional displacement of
the elastic crust [
1
–
3
]. Many studies have found that seasonal variations in hydrological
loading, which is majorly affected by abundant precipitation, are the main cause of seasonal
crustal deformation [4–6].
GNSS, which accurately responds to tectonic and non-tectonic movements, is a highly
precise multi-dimensional method that can be applied on large scales to observe crustal
deformation. It is not only subject to large-scale regional tectonic movements, but is also
particularly sensitive to changes in local observation environments; thus, it contains more
complex motion information. Related research results show that the Chinese GNSS time
series are mainly dominated by linear motion in the horizontal direction with periodic
variations [
7
,
8
], while the vertical direction shows complex periodic oscillations and non-
linear motion. Moreover, the periodic fluctuations differ among different stations. Gravity
Recovery and Climate Experiment (GRACE) satellite (include GRACE and GRACE-FO)
observations comprehensively respond to terrestrial gravity field anomalies. Global time-
varying gravity data provided by GRACE have been widely used to study terrestrial water
Appl. Sci. 2022, 12, 5675. https://doi.org/10.3390/app12115675 https://www.mdpi.com/journal/applsci
