Determining regional-scale carbon losses from tropical peatlands using ISBAS-InSAR.

印度尼西亚和马来西亚80%的泥炭地(占地球土壤碳的15%)现在被排干，用于生产纸浆和棕榈油。泥炭分解的相关增加和大规模森林火灾现在是全球温室气体排放的重要贡献者。然而，由于茂密的热带泥炭地森林具有挑战性的规模和无法进入，这些过程造成的碳损失和整个东南亚泥炭地排水的影响仍然没有得到很好的量化。因此，基于现场的下沉测量是评估热带泥炭地碳损失的一种空间有限的方法。天基平台为定期和高效的泛区域监测提供了机会。卫星干涉合成孔径雷达(InSAR)是一种测量地表运动的技术，它的发展有可能解决这一问题。诺丁汉大学开发的一种新的“间歇性小基线子集”(ISBAS)建模技术，无论地面覆盖情况如何，都能很好地覆盖几乎所有的地表。这使得能够长期测量整个流域、地区和国家的泥炭地表面运动。重要的是，ISBAS技术能够使用C波段InSAR数据确定热带森林树冠下的地表变形，从而能够在空间尺度90x90米的范围内连续监测0.1-40厘米/年的地表运动。因此，空间干涉合成孔径雷达的运动应该与热带泥炭地的碳损失直接相关，从而能够对原本无法到达的热带泥炭地的碳损失进行泛区域评估。这是一种新的方法，因为InSAR尚未用于确定热带泥炭地的沉降。该项目旨在确定InSAR测量的泥炭表面下沉速度是否可以替代东南亚热带泥炭地的碳损失速度。将利用统计回归建模技术，将InSAR和实地测量的沉降量与泥炭碳储量数据结合起来，以验证将沉降量作为碳损失的替代指标。

80% of peatland in Indonesia and Malaysia (15% of Earth's soil carbon) is now drained for production of pulpwood and palm oil. Associated increases in peat decomposition and large-scale forest fires are now significant contributors to global greenhouse gas emissions. However, carbon losses from these processes and the impact of peatland drainage remain poorly quantified across SE Asia because of the challenging scale and inaccessibility of dense tropical peatland forests. Field-based subsidence measurements are therefore a spatially limited approach for assessing carbon losses from tropical peatlands. Space-based platforms offer the opportunity for regular and efficient pan-regional monitoring. A development in satellite interferometric synthetic aperture radar (InSAR), a technique that measures surface motion, has the potential to solve this problem. A new 'intermittent small baseline subset' (ISBAS) modelling technique, developed at the University of Nottingham, provides excellent coverage across almost all land surfaces irrespective of ground cover. This enables long term measurement of peatland surface motion across whole catchments, regions and countries. Importantly, the ISBAS technique is able to determine surface deformation under tropical forest canopy using C-band InSAR data, enabling continuous monitoring of surface motion ranging from 0.1 - 40 cm/yr at spatial scales 90x90m. Thus, space-based InSAR-derived motions should directly relate to tropical peatland carbon loss, allowing pan-regional assessment of carbon loss from otherwise inaccessible tropical peatlands. This is a novel approach as InSAR is yet to have been used to determine subsidence of tropical peatland sites. This project aims to determine whether rate of subsidence of the peat surface measured by InSAR is a proxy for rate of carbon loss in tropical peatlands in SE Asia. InSAR and field measurements of subsidence will be combined with peat carbon stock data using statistical regression modelling techniques to validate the use of subsidence as a proxy for carbon loss.