H199-0011
How to estimate potential rainfall load: thermodynamic entropy perspective
How to estimate potential rainfall load: thermodynamic entropy perspective
Wednesday, 16 December 2020
Poster
Abstract:
For a sustainable urban drainage system, it is essential to understand the city's potential rainfall load.
Urban boundary layer (UBL) interaction affects this potential rainfall load.
This study examined the effect in terms of thermodynamic entropy.
We computed entropy using thermodynamic forces induced from the land surface(thermal, vapor, momentum) and surface energy fluxes (sensible heat, latent heat, turbulent shear).
From the extreme rainfall events recorded in downtown Chicago, we included the time before and after the events. We examined the correlation between the entropy value and the observed rainfall.
Extreme rainfall occurred when the total entropy value was close to zero.
Based on this finding, we focused on two factors: turbulent shear and thermal buoyance. Turbulent shear keeps increasing the entropy of the UBL, and thermal buoyance pulls the entropy out of the UBL resulting in reducing the entropy in the system. We found out that the urban boundary layer maintains a nonequilibrium static state through the land-atmosphere feedback process. In the future study, we will explore this conceptual model to see how the entropy emitted from the UBL system interacts with arbitrary potential rainfall.
Urban boundary layer (UBL) interaction affects this potential rainfall load.
This study examined the effect in terms of thermodynamic entropy.
We computed entropy using thermodynamic forces induced from the land surface(thermal, vapor, momentum) and surface energy fluxes (sensible heat, latent heat, turbulent shear).
From the extreme rainfall events recorded in downtown Chicago, we included the time before and after the events. We examined the correlation between the entropy value and the observed rainfall.
Extreme rainfall occurred when the total entropy value was close to zero.
Based on this finding, we focused on two factors: turbulent shear and thermal buoyance. Turbulent shear keeps increasing the entropy of the UBL, and thermal buoyance pulls the entropy out of the UBL resulting in reducing the entropy in the system. We found out that the urban boundary layer maintains a nonequilibrium static state through the land-atmosphere feedback process. In the future study, we will explore this conceptual model to see how the entropy emitted from the UBL system interacts with arbitrary potential rainfall.