Evaluation of simulated surface fluxes, temperatures and boundary layer evolution at the building greyzone in London

伦敦建筑灰区模拟表面通量、温度和边界层演化的评估

• 批准号: 1934830
• 金额: --
• 依托单位: University of Reading
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1934830
• 关键词: Evaluation; simulated; surface; fluxes; temperatures

The next generation of weather and climate models may have higher spatial resolution than the current 1.5 km used routinely by the Met Office (the so-called UKV version of the Unified Model (UM)). Versions now under development are at 500, 330, 100 and 50 m resolution. This will mean that conditions across cities can be resolved with important implications for forecasts and decision-making, particularly under hazardous situations. The proposed research will assess these new modelling capabilities, specifically using a network of observations in London, in a robust manner, to identify deficiencies/strengths and to work to improve their performance. In the context of cities, enhanced spatial resolution of the UKV means that the 3-dimensional nature of the urban environment has to be addressed in more detail. To do this the urban land surface model used within the UKV is being updated to include MORUSES (Met Office Reading Urban Surface Exchange Scheme, Porson et al. 2010, QJRMS) (via JULES - Joint UK Land Environment Simulator). MORUSES calculates the surface energy balance as a function of the spatially varying street canyon geometry. Therefore it allows the variability of the sensible heat fluxes over urban areas to be simulated responding to complex varying building morphology, common in many cities. MORUSES uses grid scale building geometry to calculate effective roughness lengths for heat via a resistance network taking into account 3 different flow regimes in street canyons. This allows the variability of sensible heat over urban areas (well documented observationally) to be captured with complex varying building morphology, common in cities. MORUSES simulates fluxes of heat and momentum in the inertial sublayer at resolutions of O(1km). However, higher resolutions approach the 'building grey zone', where large buildings/streets start to become resolved. The building greyzone problem, and larger inhomogeneity at O(100m) scales, raise questions as to whether the 'effective roughness length' concept for heat and momentum can parametrise these exchanges, or if a vertically distributed approach to parametrise these exchanges is needed.The research proposed here aims to test MORUSES (and higher resolution models) in London using a wide range of point and spatially representative meteorological observations. This makes new use of infrastructure located in London, installed as part of NERC ClearfLO and other research programmes (www.met.reading.ac.uk/micromet). Using these observations across a range of scales, model performance will be evaluated for a wide range of meteorological conditions. The London observational network also provides a unique opportunity to undertake 3-d model evaluation at multiple, nested scales.Data to be used include turbulent sensible heat fluxes determined by eddy covariance (EC) and scintillometry techniques;boundary layer height and cloud cover using ceilometry; and surface temperatures from fast response infra-read cameras.Specifically the student will* develop O(100m) input dataset for MORUSES and compare against UKV* develop scale-appropriate products for model evaluation* compare performance of MORUSES at different resolutions against observations* test the MORUSES approach for high-rise buildings* test evolution of the boundary layer simulated by the model against lidar derived BL heightThe project will make significant contributions to urban observational work, theory & modelling.The PhD student will gain skills in state of the art observations and their analysis; insights into urban land-surface schemesand real-time assessment. This research will improve state of the art modelling in urban environments.

下一代天气和气候模型的空间分辨率可能比英国气象局目前常规使用的1.5公里（所谓的统一模型（UM）的UKV版本）更高。目前正在开发的版本有500、330、100和50米分辨率。这意味着可以解决城市之间的情况，对预测和决策产生重要影响，特别是在危险情况下。拟议的研究将评估这些新的建模能力，特别是使用伦敦的观测网络，以强有力的方式，以确定不足/优势，并努力提高其性能。在城市的背景下，增强空间分辨率的UKV意味着城市环境的三维性质必须得到更详细的解决。为此，正在更新UKV中使用的城市地表模型，以包括MORUSES（英国气象局阅读城市地表交换计划，Porson等人，2010年，QJRMS）（通过JULES -联合英国陆地环境模拟器）。MORUSES计算表面能量平衡作为空间变化的街道峡谷几何形状的函数。因此，它允许在城市地区的显热通量的变化进行模拟响应复杂的变化，在许多城市中常见的建筑形态。MORUSES使用网格尺度的建筑几何形状，通过考虑街道峡谷中3种不同流动状态的阻力网络计算热量的有效粗糙长度。这使得城市地区感热的变化（观测记录良好）可以通过城市中常见的复杂变化的建筑形态来捕获。MORUSES以O（1 km）的分辨率模拟惯性子层中的热量和动量通量。然而，更高的分辨率接近“建筑物灰色区域”，其中大型建筑物/街道开始变得清晰。建筑物的灰色地带问题，以及O（100米）尺度上更大的不均匀性，提出了关于热量和动量的“有效粗糙长度”概念是否可以参数化这些交换的问题，或者是否需要垂直分布的方法来参数化这些交换。这里提出的研究旨在测试MORUSES（和更高分辨率的模式）在伦敦使用广泛的点和空间代表性的气象观测。这使得位于伦敦的基础设施得到新的利用，这些基础设施是作为NERC ClearfLO和其他研究方案的一部分安装的（www.met.reading.ac.uk/micromet）。利用这些观测数据，将对各种气象条件下的模式性能进行评估。伦敦观测网还提供了一个独特的机会，在多个嵌套的尺度上进行三维模式评估，使用的数据包括用涡度相关（EC）和测风技术确定的湍流感热通量，用测风技术确定的边界层高度和云量，和表面温度从快速响应红外相机。具体来说，学生将 * 开发O（100米）MORUSES的输入数据集并与UKV进行比较 * 为模型评估开发适合规模的产品 * 将MORUSES在不同分辨率下的性能与观测值进行比较 * 测试MORUSES高层建筑的方法 * 模式模拟的边界层演变与激光雷达导出的边界层高度的对比试验该项目将对城市观测工作作出重大贡献，理论与建模。博士生将获得最先进的观察和分析技能;洞察城市地表方案和实时评估。这项研究将提高城市环境中最先进的建模水平。