Filtering and gap-filling strategies in eddy covariance CO2 flux series of mountainous forests: Comparison based on measurements from Qingyuan-Ker Towers
文献类型：期刊论文
| 作者 | Li, Tongtong1,2,3; Gao, Tian1,3,4,5; Teng, Dexiong1,3,4,5; Chen, Zhi6; Yang, Bai7; Wang, Xingchang4,8; Zhao, Changming9; Zhang, Jinsong10,11; Huang, Hui10,11; Guan, Chao9 |
| 刊名 | SCIENCE CHINA-EARTH SCIENCES
 |
| 出版日期 | 2025-12-17 |
| 卷号 | N/A |
| 关键词 | Complex terrain Forest ecosystem Eddy covariance Friction velocity threshold Gap-filling |
| ISSN号 | 1674-7313 |
| DOI | 10.1007/s11430-024-1723-y |
| 产权排序 | 6 |
| 文献子类 | Article ; Early Access |
| 英文摘要 | Although the eddy covariance (EC) technique has been widely adopted to measure the CO2 and water vapor exchanges between ecosystems and the atmosphere, challenges remain for its applications in mountainous regions. Ideally, the EC technique requires homogeneous canopies and flat underlying surfaces. Over complex terrain, heterogeneity of source/sink areas across wind directions complicates data analysis, particularly quality control (filtering) and gap-filling of nocturnal CO2 flux data. In this study, we evaluated the performance of nocturnal CO2 flux filtering in mountainous forests (comparing cases with or without wind direction sector partitioning) and assessed different gap-filling methods for the analyzed data that were measured from the Qingyuan-Ker Towers in Northeast China from January 2020 to December 2022. Results showed that surface roughness varied across wind direction sectors, leading to reduced accuracy in nocturnal CO2 fluxes filtering if the conventional friction velocity (u*) threshold method (a single threshold for all wind sectors) was applied. Alternative to the conventional method, identifying the u* threshold (uc*) based on wind sectors could significantly improve the accuracy of nighttime CO2 flux filtering. The gaps in the CO2 flux series of forest ecosystems over complex terrain are filled using four methods: mean diurnal course (MDC), look-up table (LUT), marginal distribution sampling (MDS), and random forest (RF). Biases in the filled nocturnal net ecosystem carbon exchange (NEE) were substantially reduced by 16%, in comparison to the adopted conventional method, following a treatment of data filtering based on wind-sector-specific uc* values. In general, the accuracy of all four gap-filling methods decreased with increasing gap length; however, the RF method consistently outperforms the others, yielding more robust and reliable estimates of annual NEE. Through extensive analyses in this study, we recommend identifying uc* values for canopies in different directions surrounding a flux tower, with a moving window and a careful selection of gap-filling methods when processing EC data from a mountainous forest. These findings advance methodologies in handling flux data from forest ecosystems over complex terrains. |
| URL标识 | 查看原文 |
| WOS关键词 | NET ECOSYSTEM EXCHANGE ; CARBON-DIOXIDE ; ENERGY-BALANCE ; UNCERTAINTY ; ALGORITHMS ; RESPIRATION ; ADVECTION ; EQUATION ; QUALITY ; REGIMES |
| WOS研究方向 | Geology |
| 语种 | 英语 |
| WOS记录号 | WOS:001641976200001 |
| 出版者 | SCIENCE PRESS |
| 源URL | [http://ir.igsnrr.ac.cn/handle/311030/219371]  |
| 专题 | 生态系统网络观测与模拟院重点实验室_外文论文 |
| 通讯作者 | Gao, Tian |
| 作者单位 | 1.Chinese Acad Sci, CAS Key Lab Forest Ecol & Silviculture, Inst Appl Ecol, Shenyang 110016, Peoples R China; 2.Shandong Normal Univ, Coll Geog & Environm, Jinan 250358, Peoples R China; 3.Natl Observat & Res Stn, Qingyuan Forest CERN, Shenyang 110016, Liaoning, Peoples R China; 4.Chinese Acad Sci, Inst Appl Ecol, CAS CSI Joint Lab Res & Dev Monitoring Forest Fl, Shenyang 110016, Peoples R China; 5.Key Lab Terr Ecosyst Carbon Neutral, Shenyang 110016, Liaoning, Peoples R China; 6.Chinese Acad Sci, Key Lab Ecosyst Network Observat & Modeling, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China; 7.Campbell Sci Inc, Logan, UT 84321 USA; 8.Northeast Forestry Univ, Sch Ecol, Harbin 150040, Peoples R China; 9.Lanzhou Univ, Coll Ecol, State Key Lab Herbage Improvement & Grassland Agro, Lanzhou 730000, Peoples R China; 10.Chinese Acad Forestry, Res Inst Forestry, Beijing 100091, Peoples R China; |
| 推荐引用方式 GB/T 7714 | Li, Tongtong,Gao, Tian,Teng, Dexiong,et al. Filtering and gap-filling strategies in eddy covariance CO2 flux series of mountainous forests: Comparison based on measurements from Qingyuan-Ker Towers[J]. SCIENCE CHINA-EARTH SCIENCES,2025,N/A. |
| APA | Li, Tongtong.,Gao, Tian.,Teng, Dexiong.,Chen, Zhi.,Yang, Bai.,...&Zhu, Jiaojun.(2025).Filtering and gap-filling strategies in eddy covariance CO2 flux series of mountainous forests: Comparison based on measurements from Qingyuan-Ker Towers.SCIENCE CHINA-EARTH SCIENCES,N/A. |
| MLA | Li, Tongtong,et al."Filtering and gap-filling strategies in eddy covariance CO2 flux series of mountainous forests: Comparison based on measurements from Qingyuan-Ker Towers".SCIENCE CHINA-EARTH SCIENCES N/A(2025). |
入库方式： OAI收割
来源：地理科学与资源研究所
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