Land Atmosphere Feedback Analysis (LAFA)

陆地-大气反馈实验(LAFE)在美国大气辐射测量(ARM)计划的南大平原(SGP)站点部署了几个最先进的扫描激光雷达和遥感系统。这些仪器将扩充ARM成套仪器，以便收集一个数据集，用于研究地面和大气之间的反馈过程。遥感系统的新协同作用将用于同时测量陆地-地表通量以及大气对流边界层中水平和垂直的湍流和输送过程。将利用仪器的扫描能力来研究土壤-植被系统的空间不均匀对陆地-大气(LA)反馈的影响。观测的时间段是2017年8月，因为可以观察到不同农田和裸地之间的地表通量存在很大差异。由于传感器协作性的高时间和垂直分辨率，水平风、温度和湿度的平均廓线、它们的梯度、它们的四阶高阶矩的廓线以及感热和潜热通量的廓线可以从靠近地面到CBL顶部的界面层测量到。在这项陆地大气反馈(LAFA)建议中，将利用LAFE数据集，并--在选定的LAFE观测期间--UHOH WRF-NOAHMP模式系统将在从对流允许尺度到大涡模拟(LES)尺度的多湍流参数化集合中运行。基于LAFE观测和模式输出，LAFA有两个目标：1)确定水汽、温度和垂直速度脉动的高阶矩以及潜热通量廓线，并研究卷吸通量和方差的新的相似关系。为此，根据通量、方差和梯度之间的关系来分析LAFE结果。2)验证大涡模拟运行，改进中尺度模式中的湍流参数。模型输出将直接与LAFE数据进行比较，从而验证具有以前未实现的细节的LES。这些结果将有助于理解大涡模拟在多大程度上可用于湍流过程的分析和湍流参数的推导。对于对流允许尺度上的模式输出，提取相应的湍流参数化的参数和变量。WRF物理套件中提供的不同局地和非局地湍流参数将得到验证，它们的性能将得到具体说明，并将得到改进和建议。因此，LAFA将有助于加深对过程的理解，并在下一代天气预报、气候和地球系统模式中更准确地表示LA交换和CBL。

The Land-Atmosphere Feedback Experiment (LAFE) deploys several state-of-the-art scanning lidar and remote sensing systems at the US Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP) site. These instruments will augment the ARM instrument suite in order to collect a dataset for studying feedback processes between the land-surface and the atmosphere. The novel synergy of remote sensing systems will be applied for simultaneous measurements of land-surface fluxes as well as horizontal and vertical turbulent and transport processes in the atmospheric convective boundary layer (CBL). The impact of spatial inhomogeneities of the soil-vegetation system on land-atmosphere (LA) feedback will be studied using the scanning capability of the instrumentation. The time period of the observations is August 2017, as large differences in surface fluxes between different fields and bare soil can be observed. Due to the high temporal and vertical resolution of this sensor synergy, mean profiles of horizontal wind, temperature, and humidity, their gradients, profiles of their higher-order moments up to the forth order as well as profiles of sensible and latent heat fluxes can be measured from close to the surface to the interfacial layer at the CBL top. Within this Land Atmosphere Feedback (LAFA) proposal, the LAFE data set will be exploited and - for selected LAFE observation periods - the UHOH WRF-NOAHMP model system will be operated in a multi-turbulence parameterization ensemble from the convective permitting scale down to the large eddy simulation (LES) scale. Based on the LAFE observations and the model output, LAFA has two objectives: 1) Determine profiles of higher-order moments of water vapor, temperature, and vertical velocity fluctuations as well as latent heat flux profiles and investigate new similarity relationships for entrainment fluxes and variances. For this purpose, the LAFE results are analyzed with respect to relationships between fluxes, variances, and gradients. 2) Verify LES runs and improve turbulence parameterizations in mesoscale models. The model output will directly be compared with the LAFE data permitting a verification of LES with previously unachieved detail. The results will provide an understanding how far LES can be used for the analysis of turbulent processes and for the derivation of turbulence parameterizations. With respect to the model output on the convection permitting scale, the corresponding parameters and variables of the turbulence parameterizations will be extracted. Different local and non-local turbulence parameterizations available in the WRF physics suite will be verified, their performance will be specified, and improvements will be developed and suggested.Therefore, LAFA will contribute to an advanced process understanding and a more accurate representation of LA exchange and the CBL in the next generation of weather forecast, climate, and earth system models.