Analysis of urban rainfall from hourly to seasonal scales using high‐resolution radar observations in the Netherlands

Abstract

In this article an analysis of urban rainfall from hourly to seasonal scales is conducted for the Netherlands, with a focus on its capital, Amsterdam. In addition, the potential of synoptic weather types and local wind directions to categorize extreme rainfall in Amsterdam is assessed. An analysis of gauge‐adjusted daily radar rainfall retrievals with 1 km spatial resolution for 10 years shows that rainfall is enhanced over Dutch cities compared to their rural surroundings, with a maximum of a 14.2% increase over the largest cities in winter. The annual cumulative rainfall in Amsterdam appears to be significantly higher compared to its surroundings. This is due both to the higher frequency of occurrence of urban rainfall and to the higher hourly mean intensities. Extreme hourly rainfall rates appear to be affected by urban areas only in summer. Diurnal and weekly rainfall cycles do not reveal any significant urban influence. A wind direction analysis reveals that extreme rainfall events can primarily be attributed to westerly and next to southerly air masses. An analysis of the Jenkinson and Collinson (JC) and the German Weather Service (Deutscher Wetterdienst, DWD) weather types with rainfall and extreme rainfall events reveals that the JC weather types are more indicative of situations associated with rainfall extremes, whereas the DWD weather types are more indicative of situations resulting in higher accumulated rainfall amounts.

The `urban meteorology island': a multi-model ensemble analysis

“…The summer afternoon and evening sub-grid scale precipitation enhancement in cities is also documented by Manola et al (2020), who analysed observed precipitation features in Amsterdam and its surroundings. Differences occur in summer morning, when they found an increase of the same magnitude as in afternoon.…”

“…Theeuwes et al (2019) describe the observed cloud cover enhancement over Paris and London during summer as a consequence of increased convection caused by UHI. Manola et al (2020) show increased summer precipitation intensities and also overall precipitation increase in the city of Amsterdam in comparison to rural surroundings, also as a result of enhanced convection over the urban area. Enhanced convection, turbulence and mixing can cause, under special weather conditions, even wind speed increase over cities (Droste et al, 2018).…”

Urban-climate interactions during summer over eastern North America

“…This result is partly consistent with previous modeling studies (e.g., Li et al 2016;Zhang et al 2019), which reported that urban surfaces lead to reduced near-surface moisture and precipitation. However, it should be noted that some other studies (e.g., Karlický et al 2020;Manola et al 2020) have reported increases in precipitation due to more frequent thermal convection associated with atmospheric instability from the heated urban surfaces.…”

Atmospheric dreams and perspectives

“…So besides of greenhouse gases in the atmosphere, here the regional climate is also influenced by land use effects. It also turns out that Dutch cities do enhance precipitation and this can amount by around 11% for the 5 largest cities [20].…”