Journal Article

Upscaling Northern Peatland CO2 Fluxes Using Satellite Remote Sensing Data

Tuittila, Eeva-Stiina, Kelly, Julia, Rinne, Janne, Eklundh, Lars, Weslien, Per, Lohila, Annalea, Klemedtsson, Leif, Junttila, Sofia, Nilsson, Mats, Kljun, Natascha, Aurela, Mika, Vestin, Patrik

2021

Overview

Peatlands play an important role in the global carbon cycle as they contain a large soil carbon stock. However, current climate change could potentially shift peatlands from being carbon sinks to carbon sources. Remote sensing methods provide an opportunity to monitor carbon dioxide (CO2) exchange in peatland ecosystems at large scales under these changing conditions. In this study, we developed empirical models of the CO2 balance (net ecosystem exchange, NEE), gross primary production (GPP), and ecosystem respiration (ER) that could be used for upscaling CO2 fluxes with remotely sensed data. Two to three years of eddy covariance (EC) data from five peatlands in Sweden and Finland were compared to modelled NEE, GPP and ER based on vegetation indices from 10 m resolution Sentinel-2 MSI and land surface temperature from 1 km resolution MODIS data. To ensure a precise match between the EC data and the Sentinel-2 observations, a footprint model was applied to derive footprint-weighted daily means of the vegetation indices. Average model parameters for all sites were acquired with a leave-one-out-cross-validation procedure. Both the GPP and the ER models gave high agreement with the EC-derived fluxes (R2 = 0.70 and 0.56, NRMSE = 14% and 15%, respectively). The performance of the NEE model was weaker (average R2 = 0.36 and NRMSE = 13%). Our findings demonstrate that using optical and thermal satellite sensor data is a feasible method for upscaling the GPP and ER of northern boreal peatlands, although further studies are needed to investigate the sources of the unexplained spatial and temporal variation of the CO2 fluxes.

• Publisher: MDPI AG
• Subject: carbon / carbon dioxide / carbon sinks / climate change / Climate Research / Earth and Related Environmental Sciences / ecosystem respiration / ecosystem respiration (ER) / eddy covariance / Environmental Sciences & Ecology / Finland / Fjärranalysteknik / footprint analysis / Geology / Geovetenskap och relaterad miljövetenskap / global carbon budget / GPP / gross primary production / gross primary production (GPP) / gross primary productivity / Imaging / Klimatforskning / Natural Sciences / Naturgeografi / Naturvetenskap / net ecosystem exchange / net ecosystem exchange (NEE) / peatland / peatlands / Physical Geography / Remote Sensing / satellites / Science & Photographic Technology / Sentinel-2 / soil carbon / surface temperature / Sweden / temporal variation / upscaling / vegetation