Moving along with daily life, urban residents and commuters create characteristic spatiotemporal patterns which vary extensively with the time of day. These patterns are formed via traffic flows: accordingly, understanding the impact of transportation system is essential for urban planners to evaluate expected urban activities. To explore them, we examine specifically population distributions in Seoul City by analyzing hourly population data based on mobile phone location records in combination with a couple of indicators of the Seoul Subway system. Through clustering and principal component analyses, we first demonstrate that the spatial distribution of the population is categorized according to the time of day, i.e., night, daytime, and evening, variations across which reflect the morphology of land use. We then examine the influence of the subway system on the population, employing ridership and accessibility as indicators. Our linear regression analysis shows that both are associated with the daytime and the evening populations, which implies that only commercial activities are substantially coupled to the subway system. Further, we find that the distinctive difference of night population is encoded in the probability distributions; this is elucidated by means of a multiplicative growth model for the morphological evolution of Seoul, revealing decentralization of residential areas and centralization of commercial areas. This study sheds light on the interplay of a public transportation system and land use, which is of relevance to planners and policymakers wishing to develop neighborhoods in support of sustainable modes.

随着日常生活的移动，城市居民和通勤者创造了随着一天中的时间而广泛变化的特征时空模式。这些模式是通过交通流量形成的：因此，了解交通系统的影响对于城市规划者评估预期的城市活动至关重要。为了探索它们，我们通过分析基于手机位置记录的每小时人口数据并结合首尔地铁系统的几个指标来具体研究首尔市的人口分布。通过聚类和主成分分析，我们首先证明了人口的空间分布是根据一天中的时间进行分类的，即夜间、白天和晚上，这些变化反映了土地利用的形态。然后，我们以客流量和可达性为指标，研究地铁系统对人口的影响。我们的线性回归分析表明，两者都与白天和晚上的人口相关，这意味着只有商业活动与地铁系统密切相关。此外，我们发现夜间人口的显着差异被编码在概率分布中；这通过首尔形态演变的乘法增长模型得到阐明，揭示了住宅区的分散化和商业区的集中化。本研究阐明了公共交通系统和土地利用之间的相互作用，这对于希望开发社区以支持可持续模式的规划者和决策者具有重要意义。