Joint Seminar: Physical and observational constraints on the anvil cloud feedback
Changes in anvil cloud area with warming are one of the largest sources of uncertainty in Earth's climate sensitivity (Sherwood et al 2020). Here, we develop a simple theory of cloud radiative effects and derive an equation for the tropical anvil cloud area feedback. Our theory shows that the feedback is given by the product of the present day (and thus measurable) cloud radiative effect and the fractional change in anvil area with warming. Satellite observations suggest a cloud radiative effect ≈ −1 Wm −2 and a sensitivity of anvil clouds to surface temperature ≈ −11% K −1 at the interrannual time scale (Saint-Lu et al, 2020), leading to a tropical anvil cloud area feedback of 0.08 ± 0.05 Wm −2 K −1. This feedback is thus weaker and better constrained than previously thought. We then use our theory to derive an equation for the proportionally higher anvil temperature feedback, which depends on the change in anvil temperature with warming. Satellite observations suggest this change is ≈ 0.44 K K −1. Combining the resultant temperature feedback with the area feedback leads to a total anvil cloud feedback of −0.01 ± 0.09 Wm −2 K −1. Changes in anvil clouds with warming appear to have little effect on climate sensitivity.
Datum
16.05.2023
Uhrzeit
15:15 Uhr
Ort
- Bundesstr. 53, room 022/023
- Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg