Hourly extreme precipitation changes under the influences of regional and urbanization effects in Beijing

Abstract

Short duration extreme precipitation has devastating impacts on city area. Local urbanization effects, superimposed upon regional climate change, complicate examination of long‐term changes in short duration precipitation extremes in urban areas. Based on high‐quality rain gauge observations of summer time hourly precipitation in Beijing Region over 1977–2013, this study reveals that despite the general drying tendency for North China, the urban area of Beijing has experienced more hourly precipitation extremes (HPE) than the suburban area since 2004, coinciding with the surge in the growth of urban built‐up areas. These hourly urban precipitation extremes are increasingly inclined to occurring during night‐time, especially during 1800 LST to 0200 LST (UCT+8). On the one hand, the amplified urban heat inland effect, which was more significant at night‐time, seems to have facilitated formation of more intense small scale thermal‐low and resultant ascending branch; on the other hand, it has favoured to establishing unstable stratification in the lower level. This possible mechanism explains the preference of HPE in urban areas during night‐time and climate change diversity under the influence of megacity superposition.

Influence of urbanization on hourly extreme precipitation over China

“…The effect is carried over to diurnal variability in that the enhancement impact of urban areas on extreme precipitation can be found mostly at the peak time. These results conform to the diurnal cycles in prior research (Ploshay andLau 2010, Liu et al 2021) and related studies on the urbanization effect on regional precipitation (Yuan et al 2020). Urban areas tend to affect peak precipitation by increasing the intensity or frequency of extreme precipitation in most areas, leading to an increase in the proportion of extreme precipitation.…”

Divergent Urban Signatures in Rainfall Anomalies Explained by Pre‐Storm Environment Contrast

“…The rainfall anomalies over this quadrant are statistically different from the other three quadrants (based on the Student's t test, P = 0.05, Figure S5a in Supporting Information ). The positive rainfall anomalies over the city (79.2% above the domain‐average, Figure S5a in Supporting Information ) might be partially associated with the enhanced convection driven by the elevated surface temperature within the urban canopy (e.g., Harnack & Landsberg, 1975; Shepherd, 2006; Simón‐Moral et al., 2021; Yuan et al., 2020). The second cluster of positive rainfall anomalies is associated with the mechanic perturbations of urban canopy through enhanced surface roughness (i.e., buildings) that leads to decelerated flows.…”

Vertical divergence profiles as detected by two wind‐profiler mesonets over East China: Implications for nowcasting convective storms

“…Distribution of the hourly rainfall rates (color‐dotted, mm·hr −1 ) from automated surface stations in Beijing from 0200 to 0500 Local Standard Time (LST), July 16, 2018. White to black shadings indicate terrain elevations (unit: m), the black lines denote the Beijing metropolitan region, and the magenta lines represent the urban built‐up area in 2010 based on the satellite image data from the US Defense Meteorological Satellite Program (DMSP)/Operational Linescan System (OLS) (Yuan et al ., 2020) [Colour figure can be viewed at wileyonlinelibrary.com]…”