Using the BFAST Algorithm and Multitemporal AIRS Data to Investigate Variation of Atmospheric Methane Concentration over Zoige Wetland of China

Yuanyuan Yang,Yong Wang

doi:10.3390/rs12193199

Abstract

The monitoring of wetland methane (CH4) emission is essential in the context of global CH4 emission and climate change. The remotely sensed multitemporal Atmospheric Infrared Sounder (AIRS) CH4 data and the Breaks for Additive Season and Trend (BFAST) algorithm were used to detect atmospheric CH4 dynamics in the Zoige wetland, China between 2002 and 2018. The overall atmospheric CH4 concentration increased steadily with a rate of 5.7 ± 0.3 ppb/year. After decomposing the time-series of CH4 data using the BFAST algorithm, we found no anomalies in the seasonal and error components. The trend component increased with time, and a total of seven breaks were detected within four cells. Six were well-explained by the air temperature anomalies primarily, but one break was not. The effect of parameter h on decomposition outcomes was studied because it could influence the number of breaks in the trend component. As h increased, the number of breaks decreased. The interplays of the observations of interest, break numbers, and statistical significance should determine the h value.

Highlights

Among all natural and anthropogenic sources, wetlands are the single largest methane (CH4) source and contribute 20%~40% of the total global CH4 emission [1]
Our aims are (i) to capture the CH4 dynamic in the Zoige wetland using the Breaks for Additive Season and Trend (BFAST) algorithm coupled with remote-sensing observations of a time-series and (ii) to investigate the role of air temperature in altering a CH4 time-series
Increase of Atmospheric CH4 Concentration Derived From Atmospheric Infrared Sounder (AIRS) Data

Summary

Introduction

Among all natural and anthropogenic sources, wetlands are the single largest methane (CH4) source and contribute 20%~40% of the total global CH4 emission [1]. Wetland CH4 emissions result from interactions between several biological, chemical, and physical processes that primarily include CH4 production, transportation, and oxidation. Methanogenic bacteria carry out the production by decomposing a limited number of relatively simple substrates under strictly anaerobic conditions. The production rate is limited by the availability of substrate and regulated by climatic and edaphic factors such as temperature, water table position, and pH [2,3,4,5,6]. CH4 can be transported to the atmospheric through various pathways: molecular diffusion, ebullition, and via vascular plant stems [7]. The difference between the production and oxidation rates determines the rate of CH4 emission into the atmosphere

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