To investigate the boundary layer dynamics of the coastal megacity Shanghai, China, backscatter data measured by a Vaisala CL51 ceilometer are analyzed with a modified ideal curve fitting algorithm. The boundary layer height zi retrieved by this method and from radiosondes compare reasonably overall. Analyses of mobile and stationary ceilometer data provide spatial and temporal characteristics of Shanghai’s boundary layer height. The consistency between when the ceilometer is moving and stationary highlights the potential of mobile observations of transects across cities. An analysis of 16 months of zi measured at the Fengxian site in Shanghai reveals that the diurnal variation of zi in the four seasons follows the expected pattern; for all seasons zi starts to increase at sunrise, reflecting the influence of solar radiation. However, the boundary layer height is generally higher in autumn and winter than in summer and spring (mean hourly averaged zi for days with low cloud fraction at 1100–1200 local time are 900, 654, 934, and 768 m for spring, summer, autumn, and winter, respectively). This is attributed to seasonal differences in the dominant meteorological conditions, including the effects of a sea breeze at the near-coastal Fengxian site. Given the success of the retrieval method, other ceilometers installed across Shanghai are now being analyzed to understand more about the spatial dynamics of zi and to investigate in more detail the effects of prevailing mesoscale circulations and their seasonal dynamics.

Three super city clusters in eastern China, that is, Beijing‐Tianjin‐Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD), have been developed in recent decades. The spatial and diurnal variations of summer hourly rainfall over these city clusters and their possible link to the urbanization are investigated in this study, with the Climate Prediction Center Morphing technique (CMORPH) satellite precipitation estimates at high spatial‐temporal resolutions for 2004‐2009. Although the summer rainfall in eastern China is mainly characterized by large‐scale pattern, significant regional rainfall features over the three city clusters can be clearly observed, which are related to the clustered urbanization. Large hourly rainfall intensity is found over the city clusters or downwind from them. Those regions with large hourly rainfall intensity are named as the city cluster impacted regions (CCIRs), contrast to the surrounding mountainous regions where high frequency and large amount but low hourly intensity of rainfall occur. Location and geometry of each CCIR are unique because of the distinctive geography and structures among city clusters. The CCIR situates right over YRD, but it is shifted to the downwind region with an elongated shape for BTH and a circular shape for PRD. More heavy rain but less light rain occurs over the CCIRs than the surrounding regions. Diurnal variations of light rain amount and frequency can be influenced by both mountain and urbanization, and a diurnal cycle amplitude increase related to the urbanization is detected only over the CCIR of YRD where the terrains are mostly low and flat.

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