Large scale evaluation of methane budget over frozen boreal forest by synthesis of field observation, process modeling and satellite remote sensing

甲烷（CH4）是一种强烈的温室气体，湿润生态系统是CH4的来源。然而，在湿地和寒带森林的CH4收支和机制仍然是未知的，在CH4汇和源分布不均匀。我们在阿拉斯加的北方森林观测了甲烷通量。通过应用涡度相关、梯度、REA和气室等多种测量方法，获得了准确的CH4通量结果。分析了环境因子与CH4通量之间的关系，并以此为基础改进了过程基础模型VISIT的参数。应用支持向量回归（SVR）方法，利用卫星遥感数据和阿拉斯加23个测站的实测CO2通量数据，对区域尺度CO2通量进行了估算，得到了与以往模型比较可靠的结果。

Methane (CH4) is a strong greenhouse gas and wet ecosystem is CH4 source. However, CH4 budget and the mechanism underlying are still unknown at wetlands and boreal forests on permafrost, where CH4 sink and source distributed heterogeneously. We observed CH4 flux at boreal forest in Alaska. We obtained accurate CH4 flux results by applying multiple measurement methods such as eddy covariance, gradient, REA and chambers. Those approved the sink CH4 flux under dry vegetation conditions while an obvious source under wet conditions after rain, and the seasonal variations at the site were clearly determined.Relationships among environmental factors and CH4 flux were analyzed which were used to improve parameters of a process base model "VISIT". Support vector regression (SVR) was applied to estimate regional scale CO2 flux using satellite remote sensing and measured CO2 flux at 23 tower sites over Alaska, and the reliable results comparing to previous models were obtained.