scholarly journals Resolving Inconsistencies in Extreme Precipitation‐Temperature Sensitivities

2020 ◽  
Vol 47 (18) ◽  
Author(s):  
J. B. Visser ◽  
C. Wasko ◽  
A. Sharma ◽  
R. Nathan
2021 ◽  
Author(s):  
Maria Aleshina ◽  
Vladimir Semenov ◽  
Alexander Chernokulsky

<p>Precipitation extremes are widely thought to intensify with the global warming due to exponential growth, following the Clausius-Clapeyron (C-C) equation of atmosphere water holding capacity with rising temperatures. However, a number of recent studies based on station and reanalysis data for the contemporary period showed that scaling rates between extreme precipitation and temperature are strongly dependent on temperature range, region and moisture availability. Here, we examine the scaling between daily precipitation extremes and surface air temperature over Russian territory for the last four decades using meteorological stations data and ERA-Interim reanalysis. The precipitation-temperature relation is examined for total precipitation amount and, separately, for convective and large-scale precipitation types. In winter, a general increase of extreme precipitation of all types according to C-C relation is revealed. For the Russian Far East region, the stratiform precipitation extremes scale with surface air temperature following even super C-C rates, about two times as fast as C-C. However, in summer we find a peak-like structure of the precipitation-temperature scaling, especially for the convective precipitation in the southern regions of the country. Being consistent with the C-C relationship, extreme precipitation peaks at the temperature range between 15 °C and 20 °C. For the higher temperatures, the negative scaling prevails. Furthermore, it was shown that relative humidity in general decreases with growing temperature in summer. Notably, there appears to be a temperature threshold in the 15-20 °C range, beyond that relative humidity begins to decline more rapidly. This indicates that moisture availability can be the major factor for the peak-shaped relationship between extreme precipitation and temperature revealed by our analysis.</p>


Author(s):  
Conrad Wasko

As climate change alters flood risk, there is a need to project changes in flooding for water resource management, infrastructure design and planning. The use of observed temperature relationships for informing changes in hydrologic extremes takes many forms, from simple proportional change approaches to conditioning stochastic rainfall generation on observed temperatures. Although generally focused on understanding changes to precipitation, there is an implied transfer of information gained from precipitation-temperature sensitivities to flooding as extreme precipitation is often responsible for flooding. While reviews of precipitation-temperature sensitivities and the non-stationarity of flooding exist, little attention has been given to the intersection of these two topics. Models which use temperature as a covariate to assess the non-stationarity of extreme precipitation outperform both stationary models and those using a temporal trend as a covariate. But care must be taken when projecting changes in flooding on the basis on precipitation-temperature sensitivities, as antecedent conditions modify the runoff response. Although good agreement is found between peak flow-temperature sensitivities and historical trends across Australia, there remains little evaluation of flood projections using temperature sensitivities globally. Significant work needs to be done before the use of temperature as a covariate for flood projection can be adopted with confidence. This article is part of a discussion meeting issue ‘Intensification of short-duration rainfall extremes and implications for flash flood risks’.


2021 ◽  
Author(s):  
Sarosh Alam Ghausi ◽  
Axel Kleidon ◽  
Subimal Ghosh

<p>One direct effect of climate warming on hydrology is the increase in moisture holding capacity of atmosphere at the rate of 7%/°C as suggested by the Clausius Clapeyron equation. Extreme precipitation largely depends on the amount of precipitable water in the atmospheric column and is thus expected to scale with temperature at the same rate. Observations, however, show significant variability in precipitation - temperature scaling rates, with negative scaling dominating in the tropical regions. These scaling relationships assume a one way causality, i.e. temperature is independent of precipitation. However, we show here that temperatures strongly co-vary with precipitation through the effect that clouds have on surface radiation. The presence of clouds associated with precipitation events result in lower solar isolation at the surface, further leading to reduced temperatures. This induces a two-way causality and thus temperature is no longer independent of precipitation. To remove this cooling effect of clouds, we used a surface energy balance model with a thermodynamic constraint to derive clear sky temperatures during precipitation events. We then show using observations from India, that extreme precipitation scaled with clear sky temperatures shows an increase consistent with the CC rate. On contrary, the negative scaling obtained using observed temperatures misrepresent the precipitation response to warming as a result of the co-variation with the cloud radiative effect. Our findings reveal that scaling relationships not only show how precipitation changes with temperature but also how atmospheric conditions associated with precipitation affect temperature. Thus, this covariation needs to be taken into account when using observations to derive scaling relationships that are then used to infer the extreme precipitation response to climate change.</p>


2021 ◽  
pp. 1-42
Author(s):  
Johan B. Visser ◽  
Conrad Wasko ◽  
Ashish Sharma ◽  
Rory Nathan

AbstractObservational studies of extreme daily and subdaily precipitation-temperature sensitivities (apparent scaling) aim to provide evidence and improved understanding of how extreme precipitation will respond to a warming climate. However, interpretation of apparent scaling results is hindered by large variations in derived scaling rates and divergence from theoretical and modelled projections of systematic increases in extreme precipitation intensities (climate scaling). In warmer climatic regions, rainfall intensity has been reported to increase with temperature to a maximum before decreasing, creating a second order discontinuity or “hook” like structure. Here we investigate spatial and temporal discrepancies in apparent scaling results by isolating rainfall events and conditioning event precipitation on duration. We find that previously reported negative apparent scaling at higher temperatures which creates the hook structure, is the result of a decrease in the duration of the precipitation event, and not to the decrease in precipitation rate. We introduce standardized pooling using long records of Australian station data across climate zones, to show average precipitation intensities and 1-h peak precipitation intensities increase with temperature across all event durations and locations investigated. For shorter duration events (< 6-h), average precipitation intensity scaling is in line with the expected Clausius- Clapeyron (CC) relation at ~7 %/°C, and this decreases with increasing duration, down to 2 %/°C at 24-h duration. Consistent with climate scaling derived from model projections, 1-h peak precipitation intensities are found to increase with temperature at elevated rates compared to average precipitation intensities, with super-CC scaling (10 – 14 %/°C) found for short-duration events in tropical climates.


Author(s):  
V.V. Ilinich ◽  
◽  
A.A. Naumova

the presented research is dedicate to confirming the hypothesis about increase in extreme precipitation of recent decades, affecting the degree of soil erosion in crop rotations.


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