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

下一代天气和气候模式的空间分辨率可能会高于英国气象局目前常规使用的1.5公里(所谓的UKV版本的统一模式(UM))。目前正在开发的版本有500米、330米、100米和50米分辨率。这将意味着，可以解决各城市的情况，对预测和决策产生重要影响，特别是在危险情况下。拟议的研究将以强有力的方式评估这些新的建模能力，特别是使用伦敦的观测网络，以找出不足/优势并努力改进其表现。在城市方面，UKV空间分辨率的提高意味着必须更详细地处理城市环境的三维性质。为此，UKV内使用的城市地面模型正在更新，以包括MORUSES(英国气象局阅读城市地面交换计划，Porson等人。2010年，QJRMS)(通过Jules-联合英国陆地环境模拟器)。MORUSES计算作为空间变化的街道峡谷几何形状的函数的表面能量平衡。因此，它可以模拟城市地区感热通量的变化，以响应复杂的变化的建筑形态，这在许多城市很常见。MORUSES使用网格尺度的建筑几何形状来计算通过阻力网络的热量的有效粗糙度长度，同时考虑了街道峡谷中的三种不同的流动状态。这使得城市地区上空的显热的可变性(有很好的观测记录)可以用城市中常见的复杂的变化的建筑形态来捕捉。MORUSES模拟了O(1公里)分辨率下惯性层中的热通量和动量通量。然而，更高的分辨率接近了“建筑灰色地带”，在那里，大型建筑/街道开始变得清晰。建筑灰色地带问题，以及在O(100米)尺度上更大的不均匀，引发了这样的问题：热和动量的有效粗糙度概念是否可以参数增加这些交换，或者是否需要垂直分布的方法来参数增加这些交换。本文提出的研究旨在利用广泛的点和空间代表性的气象观测来检验伦敦的MORUSES(和更高分辨率的模式)。这使得位于伦敦的基础设施得到了新的利用，这些基础设施是作为NERC ClearfLO和其他研究计划的一部分安装的(www.met.reading.ac.uk/micromet)。利用这些在各种尺度上的观测，将在广泛的气象条件下评估模型的性能。伦敦观测网还提供了在多个嵌套尺度上进行三维模式评估的独特机会。将使用的数据包括由涡旋协方差(EC)和闪烁技术确定的湍流感热通量；使用天顶测量确定的边界层高度和云量；具体来说，学生将*为MORUSES开发O(100m)输入数据集，并与UKV进行比较*开发适合比例的产品进行模型评估*比较MORUSES在不同分辨率下的性能与观测值*测试高层建筑的MORUSES方法*测试由模型模拟的边界层的演变与激光雷达得出的BL高度。该项目将对城市观测工作、理论和建模做出重大贡献。博士生将获得最先进的观测和分析技能；对城市地表模式的洞察和实时评估。这项研究将改善城市环境中最先进的建模技术。

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.