Thermodynamically inconsistent extreme precipitation sensitivities across continents driven by cloud-radiative...

Area of Science:

• Climate Science
• Atmospheric Physics
• Hydrology

Background:

• Global warming is projected to increase the intensity of extreme precipitation events.
• Observation-based estimates of extreme precipitation-temperature (EP-T) sensitivities exhibit significant spatial and temporal variability.
• Negative EP-T sensitivities are often observed in warmer regions, contradicting theoretical expectations.

Purpose of the Study:

• To investigate the reasons behind the observed variability in EP-T sensitivities.
• To identify and remove confounding factors affecting EP-T sensitivity estimates.
• To provide a more accurate assessment of how extreme precipitation intensifies with temperature.

Main Methods:

• Utilized a thermodynamically constrained surface-energy balance model.
• Quantified and removed confounding cloud radiative effects from observational data.
• Analyzed EP-T sensitivities across different latitudinal bands (tropics, mid-latitudes).

Main Results:

• Cloud radiative effects were identified as a significant confounder, introducing artificial covariation between rainfall and temperature.
• After removing cloud effects, positive EP-T sensitivities were found across continental regions.
• Median EP-T sensitivities shifted from negative to positive values, particularly in the tropics (from -4.9%/°C to 6.1%/°C).
• Regional variability in estimated sensitivities decreased substantially (over 40% in tropics, 30% in mid-latitudes).

Conclusions:

• The projected intensification of extreme rainfall with increasing global temperatures is consistent with observational data when confounding cloud radiative effects are accounted for.
• The study reconciles observational estimates with theoretical predictions of EP-T relationships.
• Accurate assessment of EP-T sensitivity is crucial for understanding and projecting future flood risks and ecosystem impacts.