Representation of disturbance in the Joint UK Land Environment Simulator Vn4.8 (JULES)
Representation of disturbance in the Joint UK Land Environment Simulator Vn4.8 (JULES)
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DOI：
10.5194/gmd-2018-149
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发表时间：
2018-07
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通讯作者：
Chantelle Burton;R. Betts;M. Cardoso;T. Feldpausch;A. Harper;C. Jones;D. Kelley;E. Robertson;A. Wiltshire
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作者：
Chantelle Burton;R. Betts;M. Cardoso;T. Feldpausch;A. Harper;C. Jones;D. Kelley;E. Robertson;A. Wiltshire
抽象。扰动的表示是陆面建模中的一个关键因素，但在碳循环模型中通常约束不足。特别是，土地使用的变化和火灾可以被视为大规模的扰动，而没有充分说明其潜在的复杂性和相互作用。在这里，我们描述的陆面模型JULES（英国联合陆地环境模拟器）的发展，代表土地利用变化和火灾作为单独的干扰。我们使用海德（全球环境历史数据库）的土地覆盖数据集来分析土地利用变化对全球植被的影响，并耦合火灾模型INFERNO（自然环境相互作用火灾和排放算法），以动态植被在JULES评估如何干扰的代表性影响模拟当今植被。我们测试模型的性能，评估包括土地使用和火灾干扰对标准基准。使用曼哈顿度量，整体干扰提高了植被覆盖的模拟相比，观测高达53%。草显示出高达52%的改善，范围偏差从-66%降至13%。总的木本覆盖率提高了121%，从减少森林范围在热带地区，虽然模拟的树木覆盖现在太稀疏，在一些地区。干扰通常会减少树木和灌木的覆盖，增加草。结果表明，干扰提供了重要的贡献，在全球范围内的植被的现实建模，虽然在某些地区火灾和土地利用一起导致过度干扰。这项工作提供了一个代表土地利用变化和火灾之间的全部复杂性和相互作用，可用于地球系统模型的重大贡献。
Abstract. The representation of disturbance is a critical factor in land-surface modelling, but is generally poorly constrained in carbon cycle models. In particular, land-use change and fire can be treated as large-scale disturbances without full representation of their underlying complexities and interactions. Here we describe developments to the land surface model JULES (Joint UK Land Environment Simulator) to represent land-use change and fire as separate disturbances. We use the HYDE (History Database of the Global Environment) land cover dataset to analyse the impact of land-use change on global vegetation, and couple the fire model INFERNO (INteractive Fire and Emission algoRithm for Natural envirOnments) to dynamic vegetation within JULES to assess how the representation of disturbance affects the simulation of present day vegetation. We test model performance, evaluating the inclusion of land use and fire disturbance against standard benchmarks. Using the Manhattan Metric, overall disturbance improves the simulation of vegetation cover compared to observations by up to 53 %. Grasses show an improvement of up to 52 %, with biases in extent reduced from −66 % to 13 %. Total woody cover improves by up to 121 % from a reduction in forest extent in the tropics, although simulated tree cover is now too sparse in some areas. Disturbance generally decreases tree and shrub cover and increases grasses. The results show that the disturbances provide important contributions to the realistic modelling of vegetation on a global scale, although in some areas fire and land-use together result in over-disturbance. This work provides a substantial contribution towards representing the full complexity and interactions between land-use change and fire that could be used in Earth System Models.