The local dependency of precipitation on historical changes in temperature

Abstract

Globally, mean and extreme precipitation will increase with climate change. This is largely controlled by moisture and energy availability which is linked to temperature. Therefore, changes in precipitation are regularly presented proportional to a change in mean global temperature, and temperature is often proposed as a covariate for projecting precipitation with climatic change. However, studies which investigate the association between precipitation and temperature largely focus on the day-to-day association between precipitation and temperature fluctuations at a gauged location, which is not necessarily equivalent to changes in precipitation at climatic spatial and time scales. To assess whether temperature changes may help inform changes in precipitation with climatic change, we evaluate the historical relationship between precipitation and annual temperature fluctuations. We find positive correlations between precipitation and mean annual dew point temperature. These associations are strongest for annual average precipitation and weakest for the shortest, most extreme precipitation. We find that the strength of this correlation is more strongly linked to the number of rain days, rather than the precipitation depth itself. When dry-bulb temperatures are used in place of dew point temperature, the association between precipitation and temperature is either negative or zero. As a strong association between wet day dry-bulb and dew point temperatures exists, changes in temperature may aid in understanding the changes to precipitation as global temperatures increase. However, as the precipitation-dew point correlation is not necessarily physically related to the precipitation depth but rather to precipitation occurrence; precipitation-temperature sensitivities need to be interpreted with caution.