Complex Principal Component Analysis of Antarctic Ice Sheet Mass Balance

Jingang Zhan,Hongling Shi,Yixin Yao,Yong Wang

doi:10.3390/rs13030480

Abstract

Ice sheet changes of the Antarctic are the result of interactions among the ocean, atmosphere, and ice sheet. Studying the ice sheet mass variations helps us to understand the possible reasons for these changes. We used 164 months of Gravity Recovery and Climate Experiment (GRACE) satellite time-varying solutions to study the principal components (PCs) of the Antarctic ice sheet mass change and their time-frequency variation. This assessment was based on complex principal component analysis (CPCA) and the wavelet amplitude-period spectrum (WAPS) method to study the PCs and their time-frequency information. The CPCA results revealed the PCs that affect the ice sheet balance, and the wavelet analysis exposed the time-frequency variation of the quasi-periodic signal in each component. The results show that the first PC, which has a linear term and low-frequency signals with periods greater than five years, dominates the variation trend of ice sheet in the Antarctic. The ratio of its variance to the total variance shows that the first PC explains 83.73% of the mass change in the ice sheet. Similar low-frequency signals are also found in the meridional wind at 700 hPa in the South Pacific and the sea surface temperature anomaly (SSTA) in the equatorial Pacific, with the correlation between the low-frequency periodic signal of SSTA in the equatorial Pacific and the first PC of the ice sheet mass change in Antarctica found to be 0.73. The phase signals in the mass change of West Antarctica indicate the upstream propagation of mass loss information over time from the ocean–ice interface to the southward upslope, which mainly reflects ocean-driven factors such as enhanced ice–ocean interaction and the intrusion of warm saline water into the cavities under ice shelves associated with ice sheets which sit on retrograde slopes. Meanwhile, the phase signals in the mass change of East Antarctica indicate the downstream propagation of mass increase information from the South Pole toward Dronning Maud Land, which mainly reflects atmospheric factors such as precipitation accumulation.

Highlights

Introduction iationsAntarctica shows an important regulatory role in climate changes
During the period 2003–2017, the ice sheet in Antarctica exhibited a trend of large mass loss in West Antarctica and mass increase in East Antarctica
The first principal components (PCs) and its corresponding spatial mode from Gravity Recovery and Climate Experiment (GRACE) satellite data successfully captured the spatial pattern of the dominant trend in the mass change of the Antarctic ice sheet

Summary

Introduction

Introduction iationsAntarctica shows an important regulatory role in climate changes. The relationship between the ice sheet and climate change over Antarctica has been intensively studied. Studies [1,2,3,4,5,6] indicate there has been an increased warming of the atmosphere over Antarctica during the second half of the 20th century, especially in the western Antarctic Peninsula (WAP) with the rates of 0.4 ◦ C/decade. Analyzed stacked temperature records and noted that the atmospheric temperature has shifted from 0.32 ◦ C/decade to −0.47 ◦ C/decade between 1979–2014. This climate change contributed to the regional mass balance of glaciers. El Niño changes and atmospheric circulation changes in Antarctica have affected the ice sheet balance [7,9,10]

Methods

Results

Discussion

Conclusion