The Respones of Daily and Sub-Daily Extreme Precipitations to Changes in Surface and Dew-Point Temperatures

Extreme precipitation events are expected to increase in frequency and intensity in the future climate, but the magnitude of these changes remains uncertain. The relationship between extreme precipitation and the surface temperature has been investigated to more robustly assess projected increases in extreme precipitation considering that projected temperature is more adequately simulated. Relationships between extreme precipitation (daily and sub-daily) and surface air temperature (SAT) or surface dew-point temperature (SDPT) are analyzed in this study using the 50-members ensemble from the fifth version of the Canadian Regional Climate Model covering the Northeastern North America region over the period 1956-2099. Temperature-precipitation scaling rates (TPSRs) were estimated using local SAT and SDPT seasonal anomalies as covariate over both periods for 2-100-year extreme precipitation events and durations ranging from 1 to 24 h. Contrasting responses were obtained when using SAT or SDPT, especially in the southern part of the domain. Median scaling rates over the entire domain for SDPT were close to the Clausius-Clapeyron scaling (approximate to 7% 1 degrees C) while they were much smaller for SAT and even negative in southern regions, showing that moisture availability is a key factor for these regions. TPSR based on SDPT is also more robustly constrained and can be used to estimate changes in short-duration extreme precipitation in a future period from TPSR in the historical period over a large part of the domain. Plain Language Summary Extreme precipitation events are expected to be more intense and frequent in the future. The magnitude of these changes remains, however, uncertain. It is also possible to relate extreme precipitation changes to changes in surface temperature. The basic idea is that a warmer atmosphere can hold more moisture and therefore trigger more intense precipitation. Such a relationship can estimate future changes in extreme precipitation since simulated temperature from climate models is more reliable than precipitation. The response of extreme precipitation events to changes in surface air temperature and the surface dew-point temperature was analyzed over the Northeastern North America region using a large ensemble of 50 climate simulations covering the period 1956-2099. It was shown that more robust estimates of the temperature-precipitation relationship are obtained when using the surface dew-point temperature, confirming that available moisture can be a limiting factor in increasing extreme precipitation for some regions. Those estimates were consistent between the historical and future climate over a large part of the study region for the more extreme events and confirm that future extreme precipitation changes can be estimated from changes in dew-point temperature.

Automated summary

Extreme precipitation events are expected to increase in the future climate, and the relationship between extreme precipitation and surface temperature or dew-point temperature has been analyzed. The results show that dew-point temperature can provide more robust estimates of future extreme precipitation changes than surface air temperature.