TY  - JOUR
A1  - Thomas, Marius Levin
A1  - Ďurán, Ivan Bašták
A1  - Schmidli, Jürg
T1  - Toward parametrization of precipitating shallow cumulus cloud organization via moisture variance
T2  - JGR : Atmospheres
N2  - The influence of the initial vertical moisture profile on precipitating shallow cumulus cloud organization in terms of the column-averaged moisture variance is investigated using large-eddy simulations. Five idealized simulations based on the Rain in Cumulus over the Ocean field experiment with different initial moisture profiles are investigated. All cases simulate precipitating shallow cumulus convection in a marine sub-tropical region under large-scale subsidence. The results show that the moisture variance is mainly generated through the interaction of the moisture flux and the moisture gradient in the gradient production term at the top of the boundary layer. The development is characterized by three regimes: initial, transition, and quasi-steady regime. During the initial regime, the moisture gradient is built up by moisture accumulation until precipitating convection starts. Within the transition regime, precipitation enables mesoscale cloud organization with enhanced convective activity and moisture fluxes. The moisture variance increases from the moist to the dry initial moisture profiles. In a following quasi-steady regime, the moisture variance is approximately preserved. Thereby, the initial moisture gradient between the average sub-cloud layer and the free atmosphere is found to be an important factor for the generation of the quasi-steady column-averaged moisture variance. The result suggests that a resolved-scale variable like the moisture gradient can be used to estimate the quasi-steady state conditions resulting from cloud organization. This finding may serve as a starting point for the parametrization of the subgrid scale cloud organization caused by precipitating shallow convection.
KW  - large-eddy simulation
KW  - shallow cumulus convection
KW  - atmospheric boundary layer
KW  - cloud organization
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/63935
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-639357
SN  - 2169-8996
N1  - This research was funded by Hans Ertel Centre for Weather Research of DWD (3rd phase, The Atmospheric Boundary Layer in Numerical Weather Prediction) grant number 4818DWDP4. This work used resources of the Deutsches Klimarechenzentrum (DKRZ) granted by its Scientific Steering Committee (WLA) under project ID bb1096. Open access funding enabled and organized by Projekt DEAL.
VL  - 126
IS  - 15, art. e2021JD034939
SP  - 1
EP  - 14
PB  - Wiley
CY  - Hoboken, NJ
ER  -