Abstract

To understand the expected changes of extreme rainfalls due to climate change, the sensitivity of rainfall to surface temperature is often calculated. However, as surface temperatures may not be a good indicator of atmospheric moisture, an alternative is to use atmospheric temperatures, but the use of atmospheric temperatures lacks precedent. Using radiosonde atmospheric temperature data at a range of geopotential heights from 34 weather stations across Australia and its territories, we examine whether atmospheric temperature can improve our understanding of rainfall-temperature sensitivities. There is considerable variability in the calculated sensitivity when using atmospheric air temperature, while atmospheric dew point temperature showed robust positive sensitivities, similar to when surface dew point temperature measurements were used. We conclude atmospheric dew point temperature may be a promising candidate for future investigations of empirically calculated sensitivities of rainfall to temperature but does not appear superior to the use of surface dew point temperature measurements.

Highlights

  • Climate change represents one of the most pressing issues facing society due to its effect on meteorological and hydrological events

  • Scaling using atmospheric temperatures for geopotential interval 0–2.5 km We begin by presenting results for the scaling of rainfall with atmospheric air temperature for Sydney Airport (−33.946, 151.1731) located in the temperate south-east of Australia and Darwin Airport (−12.4239, 130.8925) in the tropical north for the lowest geopotential interval (0–2.5 km)

  • The overall results using quantile regression were very similar to equal-width binning, with positive atmospheric dew point temperature scaling observed through all geopotential height intervals

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Summary

Introduction

Climate change represents one of the most pressing issues facing society due to its effect on meteorological and hydrological events. Understanding the relationship between temperature and extreme rainfall is a key step towards understanding the effects of climate change on rainfall. If the saturation vapour pressure increases at this rate it is plausible to suggest the maximum rainfall intensity should increase at a similar rate (Trenberth 2011, Westra et al 2014). This scaling relationship is based on two core assumptions; that relative humidity will remain approximately constant in the future (Soden and Held 2006), and that extreme rainfall events precipitate all available moisture (Lenderink and van Meijgaard 2010). The possible violation of these assumptions, alongside artefacts introduced due to the use of surface temperatures in the calculations results in deviations from the C–C relationship being observed

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