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Diurnal equilibrium convection and land surface–atmosphere interactions in an idealized cloud‐resolving model
Author(s) -
Schlemmer Linda,
Hohenegger Cathy,
Schmidli Juerg,
Schär Christoph
Publication year - 2012
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.1892
Subject(s) - parametrization (atmospheric modeling) , convection , atmospheric sciences , environmental science , atmosphere (unit) , water content , precipitation , latent heat , moisture , planetary boundary layer , boundary layer , soil water , climatology , meteorology , geology , soil science , mechanics , physics , geotechnical engineering , quantum mechanics , radiative transfer
Abstract The influence of soil moisture and atmospheric stability on mid‐latitude diurnal convection and land–atmosphere exchange is investigated in an idealized cloud‐resolving modelling framework using a full set of parametrization schemes. In each member of a series of month‐long experiments, the model attains a state where deep, precipitating convection is triggered every day. This state is referred to as equilibrium diurnal convection. The triggering occurs via different mechanisms depending on the atmosphere–soil setting. In our framework latent heat fluxes comprise the primary control over the precipitation amounts. We find that evaporation is regulated by the availability of energy on the one hand and the availability of soil moisture and the near‐surface saturation deficit of the atmosphere on the other. Increased cloud cover over wet soils reduces net short‐wave radiation but increases net long‐wave radiation, leading to a near‐compensation of the two effects on available energy. Increased boundary layer moisture is removed by deep convection, thus increasing the near‐surface saturation deficit and preventing a negative feedback of boundary layer moisture content on the latent heat fluxes. We also find that there is a spatial correlation between soil moisture and precipitation anomalies, suggesting that the soil moisture precipitation feedback acts on a scale of 10–50 km. Copyright © 2012 Royal Meteorological Society