Kang Daiwen, Heath Nicholas K, Gilliam Robert C, Spero Tanya L, Pleim Jonathan E
Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
Air Quality and Atmospheric Composition, Atmospheric and Environmental Research, Lexington, MA 02421, USA.
Geosci Model Dev. 2022 Nov 23;15(12):8561-8579. doi: 10.5194/gmd-15-8561-2022.
The lightning assimilation (LTA) technique in the Kain-Fritsch convective parameterization in the Weather Research and Forecasting (WRF) model has been updated and applied to continental and hemispheric simulations using lightning flash data obtained from the National Lightning Detection Network (NLDN) and the World Wide Lightning Location Network (WWLLN), respectively. The LTA technique uses lightning data to trigger the Kain-Fritsch convective parameterization via realistic temperature and moisture perturbations. The impact of different values for cumulus parameters associated with the Kain-Fritsch scheme on simulations with and without LTA were evaluated for both the continental and the hemispheric simulations. Comparisons to gauge-based rainfall products and near-surface meteorological observations indicated that the LTA improved the model's performance for most variables. The simulated precipitation with LTA, using WWLLN lightning flashes in the hemispheric applications, was significantly improved over the simulations without LTA when compared to precipitation from satellite observations in the equatorial regions. The simulations without LTA showed significant sensitivity to the cumulus parameters (i.e., user-toggled switches) for monthly precipitation that was as large as 40 % during convective seasons for monthly mean daily precipitation. With LTA, the differences in simulated precipitation due to the different cumulus parameters were minimized. The horizontal grid spacing of the modeling domain strongly influenced the LTA technique and the predicted total precipitation, especially in the coarser scales used for the hemispheric simulation. The user-definable cumulus parameters and domain resolution manifested the complexity of convective process modeling both with and without LTA. These results revealed sensitivities to domain resolution, geographic heterogeneity, and the source and quality of the lightning dataset.
天气研究和预报（WRF）模型中Kain-Fritsch对流参数化的闪电同化（LTA）技术已经更新，并分别使用从国家闪电探测网络（NLDN）和全球闪电定位网络（WWLLN）获得的闪电数据应用于大陆和半球模拟。LTA技术利用闪电数据，通过实际的温度和湿度扰动来触发Kain-Fritsch对流参数化。针对大陆和半球模拟，评估了与Kain-Fritsch方案相关的积云参数的不同值对有无LTA模拟的影响。与基于雨量计的降雨产品和近地表气象观测的比较表明，LTA改善了模型对大多数变量的性能。在半球应用中，使用WWLLN闪电数据进行LTA模拟的降水，与赤道地区卫星观测的降水相比，比没有LTA的模拟有显著改善。没有LTA的模拟显示，月降水量对积云参数（即用户切换开关）的敏感性很高，在对流季节，月平均日降水量的敏感性高达40%。使用LTA时，由于不同积云参数导致的模拟降水差异最小化。建模域的水平网格间距强烈影响LTA技术和预测的总降水量，特别是在用于半球模拟的较粗尺度上。用户可定义的积云参数和域分辨率表明了有和没有LTA时对流过程建模的复杂性。这些结果揭示了对域分辨率、地理异质性以及闪电数据集的来源和质量的敏感性。
