Synthetic aperture radar (SAR) data applications for tropical peatlands monitoring activities: An overview

The availability of synthetic aperture radar (SAR) data for remote sensing (RS) applications brings a new prospect that enables continuous and cloud-free tropical peatlands monitoring activities. This paper comprises an overview of studies implementing SAR data for tropical peatlands monitoring activities that summarize the typically discussed topics, commonly utilized SAR data types, and frequently applied methods based on articles published from 2010 to the first semester of 2022. Overall, the focus of the studies frequently discussed the following topics: peat mapping, above-ground biomass (AGB) estimation on peatlands, and peat subsidence monitoring. The most commonly utilized frequency band of SAR data for the analysis is the L-band, and if the study applied a multi-frequency analysis, the C- and L-band combination is typically selected. Moreover, in terms of polarization, a multi-polarization analysis is more employed than a single-polarization analysis, where the dual-polarization SAR data are mainly utilized. Furthermore, the typically applied methods included: classification schemes (unsupervised, supervised, and machine learning), regression analysis, and interferometric SAR (InSAR) analysis. Finally, SAR data applications, combined with field data, act as a viable solution to be used along with the current techniques for supporting the RS-based tropical peatlands monitoring activities toward the sustainable management of tropical peatlands.