The urban heat island is a representative urban climate characteristic, which can affect heat-stress conditions and extreme precipitation that are closely connected with human life. Better understanding of urban-climate interactions, therefore, is crucial to ultimately support better planning and adaptation in various application fields. This study assesses urban-climate interactions during summer for eastern North America using regional climate model simulations at 0.22° resolution. Two regional climate model experiments, with and without realistic representation of urban regions, are performed for the 1981–2010 period. Comparison of the two experiments shows higher mean temperatures and reduced mean precipitation in the simulation with realistic urban representation, which can be attributed primarily to reduced albedo and soil moisture for the urban regions in this simulation. Furthermore, the mean temperature and precipitation in the simulation with improved urban representation is also closer to that observed. Analysis of short-duration precipitation extremes for climatologically different sub-regions, however, suggests that, for higher temperatures, the magnitudes of precipitation extremes are generally higher in the simulation with realistic urban representation, particularly for coastal urban regions, and are collocated with higher values of convective available potential energy and cloud fraction. Enhanced sea and lake breezes associated with lower sea level pressure found around these regions, contribute additional water vapor and further enhance dynamic convective development, leading to higher precipitation intensities. Analysis of temperature extremes clearly demonstrates that urban regions experience aggravated heat-stress conditions due to relatively higher temperatures despite reduced relative humidity. Double the number of extreme heat spells lasting six or more days are noted for the coastal urban regions in the study domain. This study, in addition to demonstrating the differences in urban-climate interactions for climatologically different regions, also demonstrates the need for better representation of urban regions in climate models to generate realistic climate information.

城市热岛是具有代表性的城市气候特征，可以影响与人类生活密切相关的热应激条件和极端降水。因此，更好地理解城市-气候相互作用对于最终支持在各种应用领域进行更好的规划和适应至关重要。本研究使用分辨率为 0.22° 的区域气候模型模拟来评估北美东部夏季的城市-气候相互作用。在 1981-2010 年期间进行了两个区域气候模型实验，有和没有城市区域的真实表现。两个实验的比较表明，在具有真实城市表征的模拟中，平均温度更高，平均降水量减少，这主要归因于本模拟中城市地区的反照率和土壤湿度降低。此外，具有改进城市代表性的模拟中的平均温度和降水量也更接近于观察到的值。然而，对气候不同子区域的短时降水极端事件的分析表明，对于较高的温度，在具有现实城市代表性的模拟中，特别是沿海城市地区，降水极端事件的强度通常更高，并且与较高的温度并置。对流可用势能和云分数的值。在这些地区周围发现与较低海平面压力相关的增强的海风和湖风，增加了水蒸气，并进一步增强了动态对流发展，导致更高的降水强度。对极端温度的分析清楚地表明，尽管相对湿度降低，但由于温度相对较高，城市地区经历了加剧的热应激条件。研究领域中沿海城市地区的持续六天或更长时间的极端高温天气数量翻了一番。这项研究除了证明气候不同地区的城市-气候相互作用的差异外，还表明需要在气候模型中更好地代表城市地区，以生成现实的气候信息。研究领域中沿海城市地区的持续六天或更长时间的极端高温天气数量翻了一番。这项研究除了证明气候不同地区的城市-气候相互作用的差异外，还表明需要在气候模型中更好地代表城市地区，以生成现实的气候信息。研究领域中沿海城市地区的持续六天或更长时间的极端高温天气数量翻了一番。这项研究除了证明气候不同地区的城市-气候相互作用的差异外，还表明需要在气候模型中更好地代表城市地区，以生成现实的气候信息。