Relationship of extreme precipitation, dry-bulb temperature, and dew point temperature across Australia

Conrad Wasko,William Tang Lu,Rajeshwar Mehrotra

doi:10.1088/1748-9326/aad135

Conrad Wasko, William Tang Lu + Show 1 more

Open Access

https://doi.org/10.1088/1748-9326/aad135

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Abstract

Precipitation extremes are expected to intensify due to an increased moisture holding capacity in the atmosphere with higher temperatures; according to the Clausius–Clapeyron (CC) relation this increase is approximately 7% for every degree increase in temperature. Contrary to expectation, the relationship between precipitation extremes and surface temperature often differs from 7%/°C. Here, we explore this relationship further by estimating the sensitivity of precipitation with both dry-bulb temperature and dew point temperature across Australia.A much better correspondence to the CC relation is obtained when surface dew point temperature is used for the calculation of precipitation-temperature sensitivities instead of surface dry-bulb temperature with most sites exhibiting sensitivities close to, or in excess of, the CC relation. The sensitivity obtained using dew point temperature is more consistent across climatic region, precipitation duration, and precipitation percentile. We conclude that dew point temperature is a better measure of precipitation changes due to increases in atmospheric moisture than dry-bulb temperature.

Highlights

It is generally accepted that climate change will result in warming in most regions around the world (Collins et al 2013, Meehl et al 2012) increasing the capacity of the atmosphere to hold moisture leading to increased precipitation extremes (Trenberth et al 2003, O’Gorman 2015)
The precipitation sensitivity with dew-point temperature is similar to 7%/◦C for both the 50th and 99th percentiles for Sydney, while for Alice Springs increases of 9.1% and 12.8% are observed for the 99th and 50th percentiles respectively
These results reveal that dew point temperature can overcome the limitation of moisture availability as it is a more direct measure of moisture availability in the atmosphere than temperature alone (Lenderink and van Meijgaard 2010)

Summary

Introduction

It is generally accepted that climate change will result in warming in most regions around the world (Collins et al 2013, Meehl et al 2012) increasing the capacity of the atmosphere to hold moisture leading to increased precipitation extremes (Trenberth et al 2003, O’Gorman 2015). Predicted increases in extreme precipitation are generally based on the Clausius– Clapeyron (CC) relation which states that the moisture holding capacity of the atmosphere should increase by approximately 7% per degree increase in temperature, increasing extreme precipitation by a similar rate (Trenberth et al 2003, Westra et al 2014). Super CC sensitivities have been observed in some model studies, large uncertainties remain (Bao et al 2017, Zhang et al 2017). Many authors focus on understanding how historical precipitation extremes respond to temperature to exploit the higher confidence modelled temperature predictions (Lenderink and Attema 2015, Wasko and Sharma 2017, Westra et al 2014)

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