Tower- and chamber-based greenhouse gas flux measurements from Howland Forest, Maine (2012-2018)

Carbon dioxide (CO2), methane (CH4),
and nitrous oxide (N2O) are the greenhouse gases largely responsible
for anthropogenic climate change. Natural plant and microbial metabolic
processes play a major role in the global atmospheric budget of each. We have
been studying ecosystem-atmosphere trace gas exchange at a sub-boreal forest in
the northeastern United States for over two decades. Historically our emphasis was
on turbulent fluxes of CO2 and water vapor. In 2012 we embarked on
an expanded campaign to also measure CH4 and N2O. Here we
present continuous tower-based measurements of the ecosystem-atmosphere
exchange of CO2 and CH4, recorded over the period
2012-2018 and reported at a 30-minute time step. Additionally, we describe a five-year
(2012-2016) dataset of chamber-based measurements of soil fluxes of CO2,
CH4, and N2O (2013-2016 only), conducted each year from
May to November. These data can be used for process studies, for biogeochemical
and land surface model validation and benchmarking, and for regional-to-global
upscaling and budgeting analyses.

二氧化碳（CO2）、甲烷（CH4）以及氧化亚氮（N2O）是导致人为气候变化的主要温室气体。自然植物和微生物的代谢过程在全球大气预算中扮演着至关重要的角色。自二十多年前起，我们便在北美东北部的亚寒带森林中研究生态系统与大气之间的微量气体交换。历史上，我们的研究重点在于二氧化碳和水蒸气的湍流通量。2012年，我们启动了一项扩展计划，旨在同时测量甲烷和氧化亚氮。在此，我们展示了2012年至2018年期间，以连续塔为基础的生态系统与大气之间CO2和CH4交换的连续测量数据，并按30分钟的时间步长进行报告。此外，我们还描述了一个为期五年的（2012-2016）数据集，该数据集记录了从2013年至2016年每年5月至11月进行的基于气室土壤通量测量数据，包括CO2、CH4和N2O。这些数据可用于过程研究、生物地球化学和地表模型验证及基准测试，以及区域至全球的扩展和预算分析。