In the face of rapid urbanization and global warming, it is important to acquire a better understanding of urban climate and land-atmosphere interactions operating therein. The Weather Research and Forecasting (WRF) model is a limited area model that has been used to study urban microclimate in many cities across the globe. However, such a study is lacking for the Canada's capital city: Ottawa. In this article, the WRF model is set-up at 1 km spatial resolution over the Ottawa region and its sensitivity towards the use of different urban parametrization schemes and land-cover datasets is investigated from 01 June to 31 August 2018 which includes an extreme heat weather event spanning from June 30 to July 6. WRF-simulations are performed using the Noah land surface model with two urban parametrization schemes of different complexity, i.e., a simple bulk urban parametrization and a more advanced multilayer urban canopy model (UCM). Both WRF-simulations used the default land use-land cover data from the Moderate Resolution Imaging Spectroradiometer (MODIS) available in WRF. Between these two WRF-simulations, the simulation with the multilayer UCM is found to be more accurate than the bulk scheme simulation in terms of modeled near-surface wind-speed, relative humidity, and total precipitation compared to observations recorded at one urban weather gauging station located within the city limits. Finally, a third WRF-simulation is performed with the multilayer UCM but using a higher resolution 30 m land use-land cover data product for the urban domain. This third WRF-experiment improved further the near-surface wind speed, relative humidity, and total precipitation correspondence to observations within the city. It is worthy to mention that modeled total precipitation is found to be sensitive to both urban parametrization schemes and urban land use-land cover data sets.

面对迅速的城市化进程和全球变暖，重要的是要更好地了解城市气候和其中发生的土地-大气相互作用。天气研究和预报（WRF）模型是一个有限区域模型，已用于研究全球许多城市的城市小气候。但是，加拿大的首都渥太华缺乏这样的研究。在本文中，WRF模型是在渥太华地区以1 km的空间分辨率设置的，其对使用不同城市参数化方案和土地覆盖数据集的敏感性于2018年6月1日至8月31日进行了研究，其中包括极端高温天气事件的时间跨度为6月30日至7月6日。WRF模拟是使用Noah地表模型进行的，该模型具有两种复杂程度不同的城市参数化方案，即 简单的批量城市参数化和更高级的多层城市雨棚模型（UCM）。两种WRF模拟都使用了WRF中可用的中等分辨率成像光谱仪（MODIS）的默认土地利用-土地覆盖数据。在这两个WRF模拟之间，与在一次城市天气测量中记录的观测结果相比，多层UCM模拟在模拟近地表风速，相对湿度和总降水量方面比整体方案模拟更为准确。车站位于城市范围内。最后，使用多层UCM进行了第三次WRF模拟，但使用的是城市领域的高分辨率30 m土地使用-土地覆盖数据产品。第三次WRF实验进一步改善了近地表风速，相对湿度，总降水量与城市内的观测值相对应。值得一提的是，已发现模拟总降水量对城市参数化方案和城市土地利用-土地覆盖数据集均敏感。