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The Global Methane Budget

全球甲烷预算

基本信息

批准号：
NE/N015932/1
负责人：
Andrew Watson
金额：
$ 32.87万
依托单位：
UNIVERSITY OF EXETER
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FN015932%2F1
关键词：
Global Methane Budget

项目摘要

Methane is the second most important greenhouse gas contributing to human-induced global warming. Atmospheric methane concentrations have increased sharply since 2007, and dramatically in 2014, for reasons that are not understood. The overall increase since 2007 is comparable to the largest growth events over the past 1000 years. The recent rises have occurred worldwide, but after an Arctic pulse in 2007, the growth has been primarily in the tropics and southern hemisphere. Strong growth continues in 2015. Carbon isotopic evidence suggests that the increase is due to sources that are predominantly biogenic in origin, with changes in the anthropogenic sources from fossil carbon and burning (e.g., natural gas leakage, coal mining and so on) playing a subordinate role. This, taken with the tropical locus on growth, suggests that the increase has primarily been driven by meteorological change (e.g., temperature, rainfall). Moreover, the global methane budget is currently not well understood. "Bottom-up" estimates, made by aggregating inventories of emissions (e.g. from gas leaks, fires, landfills, cows, etc) or from process models (e.g., wetlands) balanced with known loss processes, are significantly different from '"top-down" budgets assessed by direct measurement of methane in the atmosphere. Why this discrepancy occurs is not known.The project has four components:1. Better Observations are needed to derive estimates of emissions. The project will support a UK observation network for methane and its isotopes. Continuous stations will be at Kjolnes (Norway), Weybourne, Jersey, NERC ship RRS JC Ross, Cape Verde, Ascension, Falklands, Halley Bay, Hong Kong, with partner stations in Canada, Spitsbergen, Bolivia, S. Africa, India, Rwanda and Malaysia. Flask or bag sampling (for methane, 13C and D/H isotopes) will also be undertaken at these stations and at a number of continental stations in S. America, Africa and S, SE and E Asia, with offline analysis in the UK. A D/H measurement facility will be set up. The UK FAAM aircraft will carry out flights across the Atlantic tropics, from Azores to Cape Verde to Ascension.2. Process Studies will address the largest information gaps in the global budget. Tropical emission fluxes and isotopic signatures are not well constrained. Field campaigns will be undertaken in tropical wetlands in Amazonia, Africa, India and SE Asia, and C4 savanna biomass burn regions. Poorly understood anthropogenic sources will be studied in Kuwait and S, SE and E Asia. Characteristic isotopic signatures of regional emissions will be determined, to support global and regional modelling. Land surface modelling and satellite studies will study emissions and responses to change in temperature and precipitation. Major sink processes will be investigated in the tropical atmosphere, with vertically and latitudinally resolved OH and Cl budget studies by the FAAM aircraft, and quantification of tropical uptake by soils.3. Atmospheric modelling will be used to derive regional and global fluxes, apportioned by source type and geography using integrated in situ and remote sensing observing systems. We will carry out regional trajectory studies using models like NAME to assess regional emissions. Global modelling using 3D models will test synthetic estimates of the methane mole fraction and isotopic record. Global inverse modelling for mole fraction, 13C and D/H will be used to estimate fluxes by geographic source and source type, including a comprehensive assessment of the uncertainties that remain once all available observations have been used.4. Integrative studies will use the results from the project to test top-down and bottom-up emission estimates, and evaluate the responses of the global methane budget to projections of climate change.The project will deliver a state of the art greenhouse gas monitoring network and much better knowledge of the global methane budget.

甲烷是导致人类活动引起的全球变暖的第二大温室气体。自2007年以来，大气甲烷浓度急剧增加，2014年急剧增加，原因尚不清楚。自2007年以来的总体增长与过去1000年来最大的增长事件相当。最近的上升发生在世界各地，但在2007年北极脉冲之后，增长主要发生在热带和南半球。2015年继续保持强劲增长。碳同位素证据表明，增加是由于来源主要是生物来源，与化石碳和燃烧的人为来源的变化（例如，天然气泄漏、煤炭开采等）起从属作用。这一点与热带地区的增长轨迹一起表明，增长主要是由气象变化驱动的（例如，温度、降雨量）。此外，全球甲烷预算目前还没有得到很好的理解。“自下而上”的估计，通过汇总排放清单（例如，来自气体泄漏、火灾、垃圾填埋场、奶牛等）或来自过程模型（例如，湿地）与已知的损失过程相平衡，与通过直接测量大气中的甲烷评估的“自上而下”的预算有很大不同。为什么会出现这种差异尚不清楚。该项目有四个组成部分：1.需要更好的观测来估算排放量。该项目将支持英国的甲烷及其同位素观测网络。连续观测站将设在挪威的Kjolnes、泽西岛的Weybourne、NERC船舶RRS JC Ross、佛得角、阿森松岛Ascension、福克兰群岛、哈雷湾、香港，并在加拿大的Spitsbergen、玻利维亚、南太平洋的S.非洲、印度、卢旺达和马来西亚。还将在这些台站和南太平洋的一些大陆台站进行烧瓶或袋取样（对甲烷、13 C和D/H同位素）。美洲、非洲和南亚、东南亚和东亚，在英国进行离线分析。将建立D/H测量设施。英国FAAM飞机将执行横跨大西洋热带地区的航班，从亚速尔群岛到佛得角再到阿森松岛。过程研究将解决全球预算中最大的信息差距。热带排放通量和同位素特征没有得到很好的约束。将在亚马逊、非洲、印度和东南亚的热带湿地以及C4稀树草原生物质燃烧区域开展实地活动。将在科威特以及南亚、东南亚和东亚研究人们对人为来源了解不多的情况。将确定区域排放的同位素特征，以支持全球和区域建模。陆地表面建模和卫星研究将研究排放以及对温度和降水变化的反应。将研究热带大气中的主要汇过程，由FAAM飞机进行垂直和纬度分辨的OH和Cl收支研究，并量化热带土壤的吸收。将使用大气模型，利用综合的现场和遥感观测系统，按源类型和地理分布，得出区域和全球通量。我们将使用NAME等模型进行区域轨迹研究，以评估区域排放。使用三维模型的全球建模将测试甲烷摩尔分数和同位素记录的综合估计。将使用摩尔分数、13 C和D/H的全球逆模型来估计按地理来源和来源类型划分的通量，包括全面评估一旦使用了所有现有观测数据后仍然存在的不确定性。综合研究将利用该项目的结果来测试自上而下和自下而上的排放估计，并评估全球甲烷预算对气候变化预测的反应。该项目将提供最先进的温室气体监测网络，并更好地了解全球甲烷预算。