Relationship between Surface Temperature and Extreme Rainfalls: A Multi-Time-Scale and Event-Based Analysis*

Abstract

Recent studies have examined the relationship between the intensity of extreme rainfall and temperature. Two main reasons justify this interest. First, the moisture-holding capacity of the atmosphere is governed by the Clausius–Clapeyron (CC) equation. Second, the temperature dependence of extreme-intensity rainfalls should follow a similar relationship assuming relative humidity remains constant and extreme rainfalls are driven by the actual water content of the atmosphere. The relationship between extreme rainfall intensity and air temperature (Pextr–Ta) was assessed by analyzing maximum daily rainfall intensities for durations ranging from 5 min to 12 h for more than 100 meteorological stations across Canada. Different factors that could influence this relationship have been analyzed. It appears that the duration and the climatic region have a strong influence on this relationship. For short durations, the Pextr–Ta relationship is close to the CC scaling for coastal regions while a super-CC scaling followed by an upper limit is observed for inland regions. As the duration increases, the slope of the relationship Pextr–Ta decreases for all regions. The shape of the Pextr–Ta curve is not sensitive to the percentile or season. Complementary analyses have been carried out to understand the departures from the expected Clausius–Clapeyron scaling. The relationship between dewpoint temperature and extreme rainfall intensity shows that the relative humidity is a limiting factor for inland regions, but not for coastal regions. Using hourly rainfall series, an event-based analysis is proposed in order to understand other deviations (super-CC, sub-CC, and monotonic decrease). The analyses suggest that the observed scaling is primarily due to the rainfall event dynamic.

Changes in intensity of high temporal resolution precipitation extremes in Romania: implications for Clausius-Clapeyron scaling

“…Therefore, it can be concluded that the magnitude of the CC scaling in Romania is mainly dependent on storm duration, storm intensity and season, in agreement with other studies (Hardwick-Jones et al 2010, Panthou et al 2014. However, some details in the CC scaling mentioned above are specific to the Romanian area, that could be explained by an additional influence of other regional factors such as an increase in atmospheric instability covering Romania simultaneously with more frequent cyclonic southern circulations crossing this area in spring and more precipitable water in summer (Busuioc et al 2016).…”

“…In some areas, a strong difference between coastal (showing dependence close to CC scaling) and inland regions (showing a super-CC scaling) has been found (Panthou et al 2014). The intensity of sub-daily precipitation extremes is more sensitive to temperature changes compared to the intensity of daily extremes (Westra et al 2014).…”

Relevance of the correlation between precipitation and the 0 °C isothermal altitude for extreme flood estimation

“…Panthou et al (2014) found similar results for Canada and could nuance that ''the longer an event was, the less pronounced was the increase of extreme rainfall intensities with temperature". Similarly, Wasko et al (2015) showed in a study conditioning the scaling on precipitation event duration that, in Australia, moisture availability limitations cannot be found for short events (1 h-2 h).…”

Effects of sample size on estimation of rainfall extremes at high temperatures

“…1. This drop was also observed by Brandsma and Buishand (1997), Klein Tank and Koennen (1993), Panthou et al (2014), and Westra et al (2014). More details about the methods used in each referenced article can be found in Tables 1 and 2.…”