WETCHIMP-WSL: intercomparison of wetland methane emissions models over West Siberia-猫眼课题宝

DOI：

10.5194/bg-12-3321-2015

发表时间：

2015-01

期刊：

Biogeosciences

影响因子：

4.9

通讯作者：

中科院分区：

地球科学2区

文献类型：

作者：

T. Bohn;J. Melton;A. Ito;T. Kleinen;R. Spahni;B. Stocker;Bowen Zhang;Xudong Zhu;R. Schroeder;M. Glagolev;S. Maksyutov;V. Brovkin;Guangsheng Chen;S. Denisov;A. Eliseev;A. Gallego-Sala;K. McDonald;M. Rawlins;W. Riley;Z. Subin;H. Tian;Q. Zhuang;J. Kaplan

抽象的。湿地是世界上最大的甲烷天然来源，甲烷是一种强大的温室气体。甲烷排放对土壤温度和湿度等环境因素的高度敏感性引发了人们对气候变化潜在正反馈的担忧。这种风险在高纬度地区尤其重要，这些地区经历了明显的变暖，并且永久冻土的融化可能在未来 100 年内释放大量的不稳定碳。然而，由于湿地面积和单位面积排放量的不确定性以及实地观测的缺乏，全球模型对于排放量的大小和空间分布存在分歧。最近在西西伯利亚低地 (WSL) 进行的密集实地活动使这里成为评估高纬度环境中基于过程的大规模湿地模型性能的理想地区。在此，我们介绍湿地和湿地 CH4 模型比较项目 (WETCHIMP) 的后续结果，重点关注西西伯利亚低地 (WETCHIMP-WSL)。我们根据 CH4 排放总量、模拟湿地面积和每单位湿地面积的 CH4 通量评估了该领域的 21 个模型和 5 个反演，并将这些结果与密集的原位 CH4 通量数据集、几张湿地地图和两个卫星地表水产品进行了比较。我们发现（a）尽管个体估计值存在很大分散性，但根据正演模型（5.34±0.54 Tg CH4 yr−1）、反演（6.06±1.22 Tg CH4 yr−1）和现场观测（3.91±1.29 Tg CH4 yr−1）对WSL年度总排放量的12年平均估计值基本一致； (b) 仅使用地表水产品的正向模型来估计遭受 CH4 排放严重偏差的湿地面积； (c) 与反演模型和更复杂的正演模型不同，缺乏适合高纬度地区的土壤热物理学或不饱和泥炭地实际排放的模型年际时间序列往往由单一环境驱动因素（洪水或气温）主导； (d) 不同模型的生物地球化学方案的差异对性能的影响相对较小； (e) 多年或数十年的观测记录对于评估模型对长期气候变化的响应至关重要。

Abstract. Wetlands are the world's largest natural source of methane, a powerful greenhouse gas. The strong sensitivity of methane emissions to environmental factors such as soil temperature and moisture has led to concerns about potential positive feedbacks to climate change. This risk is particularly relevant at high latitudes, which have experienced pronounced warming and where thawing permafrost could potentially liberate large amounts of labile carbon over the next 100 years. However, global models disagree as to the magnitude and spatial distribution of emissions, due to uncertainties in wetland area and emissions per unit area and a scarcity of in situ observations. Recent intensive field campaigns across the West Siberian Lowland (WSL) make this an ideal region over which to assess the performance of large-scale process-based wetland models in a high-latitude environment. Here we present the results of a follow-up to the Wetland and Wetland CH4 Intercomparison of Models Project (WETCHIMP), focused on the West Siberian Lowland (WETCHIMP-WSL). We assessed 21 models and 5 inversions over this domain in terms of total CH4 emissions, simulated wetland areas, and CH4 fluxes per unit wetland area and compared these results to an intensive in situ CH4 flux data set, several wetland maps, and two satellite surface water products. We found that (a) despite the large scatter of individual estimates, 12-year mean estimates of annual total emissions over the WSL from forward models (5.34 ± 0.54 Tg CH4 yr−1), inversions (6.06 ± 1.22 Tg CH4 yr−1), and in situ observations (3.91 ± 1.29 Tg CH4 yr−1) largely agreed; (b) forward models using surface water products alone to estimate wetland areas suffered from severe biases in CH4 emissions; (c) the interannual time series of models that lacked either soil thermal physics appropriate to the high latitudes or realistic emissions from unsaturated peatlands tended to be dominated by a single environmental driver (inundation or air temperature), unlike those of inversions and more sophisticated forward models; (d) differences in biogeochemical schemes across models had relatively smaller influence over performance; and (e) multiyear or multidecade observational records are crucial for evaluating models' responses to long-term climate change.

WETCHIMP-WSL: intercomparison of wetland methane emissions models over West Siberia

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