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Estimation of Belowground Biomass and Permafrost Active Layer Properties Using Radar and Lidar Measurements: Progress and Challenges
Richard
Chen, University of Southern California, chenrh@usc.edu
(Presenter)
Alireza
Tabatabaeenejad, University of Southern California, alirezat@usc.edu
Kazem
Bakian Dogaheh, University of Southern California, bakiando@usc.edu
Mahta
Moghaddam, University of Southern California, mahta@usc.edu
This project advances methods of retrieving belowground biomass and permafrost active layer properties by developing accurate radar scattering and inverse scattering models of layered ground that include a combination of organic and mineral soils, overlain by vegetation, and containing vegetation roots. We use radar forward scattering models to develop corresponding methods of simultaneously retrieving root biomass, permafrost active layer thickness (ALT), and soil moisture profiles for both organic and mineral layers using the ABoVE Foundational Airborne Measurements, particularly P-band (70 cm) and L-band (24 cm) measurements from the AirMOSS and UAVSAR instruments, respectively.
Our team had a leading role in planning the flight lines for the L-band UAVSAR and the P-band AirMOSS radar instruments in coordination with the ABoVE Science Team, in particular the radar Working Group and JPL. The Alaska lines used the legacy flights lines from Mahta Moghaddam’s IDS project as a baseline, adding several more lines to accommodate the requirements for the science proposed by other selected radar teams. The P- and L-band campaigns were flown 2 weeks apart in both the spring and summer time frames (due to unavailability of one of the data recorders). Nearly all of the planned lines were flown and radar data were successfully acquired. We will present an overview of the flown lines and the corresponding sensors.
We also carried out a 7-day fieldwork at 4 different sites (Coldfoot forest, Imnavait Creek Watershed near Toolik Lake, Happy Valley near Sagwon, and Prudhoe Bay) along Alaska’s Dalton Highway in August 2017 and measured active and organic layer thicknesses, soil moisture, vegetation parameters, and soil roughness. Preliminary analysis of the collected field data will be presented. Moreover, we will present the latest advances to our radar scattering model, which include two new approaches: (1) considering three layers to represent the organic-to-mineral soil transitions more accurately, and (2) characterizing soil texture and moisture vertical profile heterogeneity with continuous profile functions. We investigate the optimal profile function by minimizing the error between predicted and measured radar backscatter signals as well as between in-situ and fitted profiles.
Finally, based on our findings so far, there is no one reliable organic soil dielectric model that can be used at both P and L bands across the ABoVE sites. Therefore, while at this point, we are inclined to use Mironov model as a starting point to proceed with the planned retrievals in 2018, we have come to conclusion that we need to consider development of our own model based on the soil samples collected during the August 2017 fieldwork and possibly a future fieldwork. We will present an overview of this investigation as well.
Associated Project(s):
Poster Location ID: 19
Session Assigned: Permafrost and Hydrology
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