JULES EMulator of ecosystem services (JEM)

生态系统提供许多服务，如木材、食物和水。它们是抵御洪水、储存碳的天然屏障，也是文化遗产和娱乐场所。为了可持续和盈利，未来的景观决策需要考虑生态系统提供的各种服务以及它们对气候变化的反应。英国承诺减少排放（到2050年至少比1990年的水平低80%），这意味着土地的碳储存和温室气体排放是未来土地利用和管理的核心。目前正在讨论更加雄心勃勃的减排目标及其影响，这增加了在理解水和生物地球化学综合循环的基础上制定土地利用决策的必要性。基于过程的陆地表面模型是预测陆地与大气之间碳、水和地表热交换的极好工具。英国的社区陆地表面模型JULES被用于气象局统一模型（UM）框架，应用范围从气候变化到天气预报。JULES预测植被的生产力、植被和土壤中的碳积累、土壤含水量、径流以及植被和土壤的温室气体排放——这意味着它可以用于评估土地利用变化和气候变化对几种生态系统服务的影响。在UM内，JULES以公里尺度分辨率运行，用于天气预报。JULES还用于评估全球碳循环：例如，在全球碳项目中，每年使用JULES计算由于土地利用变化导致的碳净土地汇和排放。然而，在这些模拟中，空间分辨率（50公里）不足以解决景观尺度的问题。在千米尺度分辨率下运行JULES的计算成本非常高。在1.2公里的分辨率下，有近8万个网格单元。在144个核心上运行，一个10年的模拟需要70个小时。关于土地利用变化的决定应包括更长的时间尺度变化和不确定性量化。一个生态系统模拟器可以对碳储量和水循环的变化及其不确定性进行更可靠的统计计算，并为更好地校准生态系统开辟道路。在这个短期项目中，我们将设计和构建JULES模拟器，为与碳和水循环相关的生态系统服务的未来评估提供信息。

Ecosystems provide many services, such as timber, food, and water. They are a natural protection against floods, store carbon, and are locations of cultural heritage and recreation. To be sustainable and profitable, future landscape decisions need to consider the various services provided by ecosystems as well as their responses to climate change. The UK's commitment to reducing emissions (to at least 80% below 1990 levels by 2050) means that carbon storage and greenhouse gas emissions from land are central to future land use and management. More ambitious emission reduction targets and their implications are currently being discussed, increasing the need to build land use decisions upon an understanding of the integrated water and biogeochemical cycles. Process-based land surface models are excellent tools for predicting carbon, water, and surface heat exchanges between the land and atmosphere. The UK's community land surface model, JULES, is used in the Met Office Unified Model (UM) framework for applications ranging from climate change to weather forecasting. JULES predicts productivity of vegetation, carbon accumulation in vegetation and soils, soil water content, runoff, and emissions of greenhouse gases from vegetation and soils - meaning it can be used for evaluating the impacts of land use change and climate change on several ecosystem services. Within the UM, JULES is run at a km-scale resolution for weather forecasting. JULES is also used for evaluating the global carbon cycle: for example, each year JULES is used to calculate the net land sink of carbon and emissions due to land use change in the Global Carbon Project. However, in these simulations the spatial resolution (>50km) is inadequate for addressing landscape-scale issues. The computational cost of running JULES at km-scale resolution is very high. At a 1.2km resolution, there were nearly 80,000 grid cells. Running on 144 cores, a 10-year simulation took 70 hours. Decisions on land use changes should incorporate longer timescale changes and uncertainty quantification. An emulator of JULES would allow for more robust statistical calculation of changes in carbon stocks and the water cycle and their uncertainty and open the way for better calibration of JULES. During this short project we will design and build emulators of JULES to inform future evaluation of ecosystem services related to the carbon and water cycles.