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An emulator approach to stratocumulus susceptibility
- Source :
- Atmospheric Chemistry and Physics, Vol 19, Pp 10191-10203 (2019), Atmospheric Chemistry and Physics 19 (2019) 15, Atmospheric Chemistry and Physics, 19(15), 10191-10203
- Publication Year :
- 2019
- Publisher :
- Copernicus Publications, 2019.
-
Abstract
- The climatic relevance of aerosol–cloud interactions depends on the sensitivity of the radiative effect of clouds to cloud droplet number N, and liquid water path LWP. We derive the dependence of cloud fraction CF, cloud albedo AC, and the relative cloud radiative effect rCRE=CF⋅AC on N and LWP from 159 large-eddy simulations of nocturnal stratocumulus. These simulations vary in their initial conditions for temperature, moisture, boundary-layer height, and aerosol concentration but share boundary conditions for surface fluxes and subsidence. Our approach is based on Gaussian-process emulation, a statistical technique related to machine learning. We succeed in building emulators that accurately predict simulated values of CF, AC, and rCRE for given values of N and LWP. Emulator-derived susceptibilities ∂lnrCRE/∂lnN and ∂lnrCRE/∂lnLWP cover the nondrizzling, fully overcast regime as well as the drizzling regime with broken cloud cover. Theoretical results, which are limited to the nondrizzling regime, are reproduced. The susceptibility ∂lnrCRE/∂lnN captures the strong sensitivity of the cloud radiative effect to cloud fraction, while the susceptibility ∂lnrCRE/∂lnLWP describes the influence of cloud amount on cloud albedo irrespective of cloud fraction. Our emulation-based approach provides a powerful tool for summarizing complex data in a simple framework that captures the sensitivities of cloud-field properties over a wide range of states.
- Subjects :
- Physics
Meteorologie en Luchtkwaliteit
Atmospheric Science
WIMEK
010504 meteorology & atmospheric sciences
Meteorology and Air Quality
Cloud cover
Cloud fraction
Subsidence (atmosphere)
010502 geochemistry & geophysics
Atmospheric sciences
01 natural sciences
lcsh:QC1-999
Aerosol
lcsh:Chemistry
Overcast
lcsh:QD1-999
Cloud albedo
Life Science
Liquid water path
Boundary value problem
lcsh:Physics
Astrophysics::Galaxy Astrophysics
0105 earth and related environmental sciences
Subjects
Details
- Language :
- English
- ISSN :
- 16807316 and 16807324
- Database :
- OpenAIRE
- Journal :
- Atmospheric Chemistry and Physics, Vol 19, Pp 10191-10203 (2019), Atmospheric Chemistry and Physics 19 (2019) 15, Atmospheric Chemistry and Physics, 19(15), 10191-10203
- Accession number :
- edsair.doi.dedup.....3de16df7ef620b5ba3243b196ce1483b