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There is increasing evidence that local rainfall extremes can increase with warming at a higher rate than expected from the Clausius‐Clapeyron (CC) relation. The exact mechanisms behind this super‐CC scaling phenomenon are still unsolved. Recent studies highlight invigorated local dynamics as a contributor to enhanced precipitation rates with warming. Here, cold pools play an important role in the process of organization and deepening of convective clouds. Another known effect of cold pools is the amplification of low‐level moisture variability. Yet, how these processes respond to climatic warming and how they relate to enhanced precipitation rates remains largely unanswered. Unlike other studies which use rather simple approaches mimicking climate change, we present a much more comprehensive set of experiments using a high‐resolution large eddy simulation (LES) model. We use an idealized but realistically forced case setup, representative for conditions with extreme summer precipitation in midlatitudes. Based on that, we examine how a warmer atmosphere under the assumption of constant and varying relative humidity, lapse rate changes and enhanced large‐scale dynamics influence precipitation rates, cold pool dynamics, and the low‐level moisture field. Warmer conditions generally lead to larger and more intense events, accompanied by enhanced cold pool dynamics and a concurring moisture accumulation in confined regions. The latter are known as preferred locations for new convective events. Our results show that cold pool dynamics play an increasingly important role in shaping the response of local precipitation extremes to global warming, providing a potential mechanism for super‐CC behavior as subject for future research. Plain Language Summary: Observations and models show that rain extremes are increasing with global warming. Aggregated over large areas and long‐time intervals, this increase will roughly follow the higher water holding capacity of air at a warmer temperature. However, local extreme storms show a much stronger response. This indicates that, in addition to a potentially greater local moisture availability in a warmer climate, rain events consume moisture from a larger area. Investigating this aspect requires expensive high‐resolution models. We do this by simulating a typical summer day with heavy rainfall on an area roughly the size of the Netherlands. By changing the temperature along with other characteristics of the atmosphere, we mimic the impact of climatic change. Our results show that warmer conditions generally lead to larger and more intense storms. Furthermore, we find that moisture transport near the surface through the winds created by storms plays an important role. This can result in an accumulation of moisture at certain locations that stems from greater distances away. Freshly developing storms eventually can harvest this additional moisture. This feedback process intensifies under warmer and moister conditions and provides a potential mechanism for the strong increase of local rainfall extremes in a warmer climate. Key Points: Warmer conditions lead to more intense and larger rain cellsRain cell properties show distinct, well‐defined relations with cold pool propertiesLargest variations at high temperature, with reductions of RH leading to very strong cold pool dynamics and vigorous rain systems [ABSTRACT FROM AUTHOR]

A 50-year hourly data set of global shortwave radiation, cloudiness and visibility over the Netherlands was used to quantify the contribution of aerosols and clouds to the trend in yearly-averaged all-sky radiation (1.81 ± 1.07 W m−2 decade−1). Yearly-averaged clear-sky and cloud-base radiation data show large year-to-year fluctuations caused by yearly changes in the occurrence of clear and cloudy periods and cannot be used for trend analysis. Therefore, proxy clear-sky and cloud-base radiations were computed. In a proxy analysis hourly radiation data falling within a fractional cloudiness value are fitted by monotonic increasing functions of solar zenith angle and summed over all zenith angles occurring in a single year to produce an average. Stable trends can then be computed from the proxy radiation data. A functional expression is derived whereby the trend in proxy all-sky radiation is a linear combination of trends in fractional cloudiness, proxy clear-sky radiation and proxy cloud-base radiation. Trends (per decade) in fractional cloudiness, proxy clear-sky and proxy cloud-base radiation were, respectively, 0.0097 ± 0.0062, 2.78 ± 0.50 and 3.43 ± 1.17 W m−2. To add up to the all-sky radiation the three trends have weight factors, namely the difference between the mean cloud-base and clear-sky radiation, the clear-sky fraction and the fractional cloudiness, respectively. Our analysis clearly demonstrates that all three components contribute significantly to the observed trend in all-sky radiation. Radiative transfer calculations using the aerosol optical thickness derived from visibility observations indicate that aerosol–radiation interaction (ARI) is a strong candidate to explain the upward trend in the clear-sky radiation. Aerosol–cloud interaction (ACI) may have some impact on cloud-base radiation, but it is suggested that decadal changes in cloud thickness and synoptic-scale changes in cloud amount also play an important role. [ABSTRACT FROM AUTHOR]

Results are presented of two large-eddy simulation (LES) runs of the entire year 2012 centered at the Cabauw observational supersite in the Netherlands. The LES is coupled to a regional weather model that provides the large-scale information. The simulations provide three-dimensional continuous time series of LES-generated turbulence and clouds, which can be compared in detail to the extensive observational dataset of Cabauw. The LES dataset is available from the authors on request. This type of LES setup has a number of advantages. First, it can provide a more statistical approach to the study of turbulent atmospheric flow than the more common case studies, since a diverse but representative set of conditions is covered, including numerous transitions. This has advantages in the design and evaluation of parameterizations. Second, the setup can provide valuable information on the quality of the LES model when applied to such a wide range of conditions. Last, it also provides the possibility to emulate observation techniques. This might help detect limitations and potential problems of a variety of measurement techniques. The LES runs are validated through a comparison with observations from the observational supersite and with results from the 'parent' large-scale model. The long time series that are generated, in combination with information on the spatial structure, provide a novel opportunity to study time scales ranging from seconds to seasons. This facilitates a study of the power spectrum of horizontal and vertical wind speed variance to identify the dominant variance-containing time scales. [ABSTRACT FROM AUTHOR]