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Diurnal evolution of non-precipitating marine stratocumuli in an LES ensemble.
- Source :
- EGUsphere; 4/11/2024, p1-42, 42p
- Publication Year :
- 2024
-
Abstract
- We explore the impacts of the diurnal cycle, free-tropospheric (FT) humidity values, and interactive surface fluxes on the cloud system evolution of non-precipitating marine stratocumuli based on a large ensemble of large-eddy simulations. Cases are separated into three categories based on their degree of decoupling and cloud liquid water path (LWP<subscript>c</subscript>). A new budget analysis method is proposed to analyze the evolution of LWP<subscript>c</subscript> under both coupled and decoupled conditions. More coupled clouds start with relatively low LWP<subscript>c</subscript> and cloud fraction (f <subscript>c</subscript>) but experience the least decrease in LWP<subscript>c</subscript> and f <subscript>c</subscript> during the daytime. More decoupled clouds undergo greater daytime reduction in LWP<subscript>c</subscript> and f <subscript>c</subscript>, especially those with higher LWP<subscript>c</subscript> at sunrise because they suffer from faster weakening of a net radiative cooling. During the nighttime, a positive correlation between FT humidity and LWP<subscript>c</subscript> emerges, consistent with higher FT humidity reducing both radiative cooling and the humidity jump, both of which reduce entrainment and increase LWP<subscript>c</subscript>. The time rate of change in the LWP<subscript>c</subscript> is more likely to be negative for higher LWP<subscript>c</subscript> and greater inversion base height (z <subscript>i</subscript>), conditions under which entrainment dominates as turbulence develops. In the morning, the rate of the LWP<subscript>c</subscript> reduction depends on the LWP<subscript>c</subscript> at sunrise, z <subscript>i</subscript>, and the degree of decoupling, with distinct contributions from subsidence and radiation. Under well-mixed conditions, it takes about 10 h for the surface fluxes to offset 15 % of the changes in entrainment warming and drying, assuming no changes in transfer coefficients or surface wind speed. [ABSTRACT FROM AUTHOR]
- Subjects :
- LARGE eddy simulation models
WIND speed
BUDGET
SUNRISE & sunset
HUMIDITY
COOLING
Subjects
Details
- Language :
- English
- Database :
- Complementary Index
- Journal :
- EGUsphere
- Publication Type :
- Academic Journal
- Accession number :
- 176565760
- Full Text :
- https://doi.org/10.5194/egusphere-2024-1033