1. Drivers of precipitation change: an energetic understanding
Tom Richardson and PDRMIP authors* Chris Smith
*submitted to Journal of Climate

2. Rapid adjustment is precipitation response to forcing in fixed-SST run
Introduction
Split precipitation response into rapid adjustment and hydrological sensitivity
Rapid adjustment is precipitation response to forcing in fixed-SST run
Hydrological sensitivity
𝑃 𝑡𝑜𝑡 − 𝑃 𝑎𝑑𝑗 𝑇 𝑡𝑜𝑡 − 𝑇 𝑎𝑑𝑗
Longwave atmospheric cooling
Latent heat of
condensation
Sensible heat
𝐿 𝑐 ∆𝑃=∆𝐿𝑊𝐶−∆𝑆𝑊𝐴−∆𝑆𝐻+∆𝐻
Shortwave atmospheric absorption
Change in
precipitation
Horizontal transports

3. Global adjustment & HS
2.9 – 3.2% K-1

4. Land/sea split

5. Conclusions
Global hydrological sensitivity is consistent between forcings, driven mainly by increased longwave atmospheric cooling
CO2 and BC produce largest negative precipitation adjustments per unit radiative forcing, due to enhanced atmospheric absorption
SO4 and solar forcing drive strongest adjustments over land due to changes in horizontal energy transport, due to horizontal transport