TY - JOUR

T1 - Numerical simulation of the development of the convective boundary layer during a cold air outbreak

AU - Raasch, S.

N1 - Funding Information: Thanks are due to Mrs. Rosemarie Lorenz for typing the manuscript and drafting the figures. The model runs were performed on the CYBER 180-995 of the Regionales Rechenzentrum fiir Niedersachsen in Hannover and on a CRAY-XMP of the Konrad-Zuse-Zentrum fiir Informationstechnik Berlin.

PY - 1990/9

Y1 - 1990/9

N2 - During cold air outbreaks, cold and stably stratified air masses are advected from land or ice surfaces over a warmer sea surface. Due to the heating from below, a convective boundary layer develops. For small fetches, convection is organized in the form of horizontal roll vortices, which at greater distances join in a zone with open or closed cells. The formation of the convective boundary layer, and the associated roll vortices, is simulated with a numerical model and results are compared with observations obtained during the MASEX experiment off the east coast of the United States. To validate the model, a comparison with a one-dimensional mixed-layer model is also made, with special attention given to the exact representation of the observed initial and boundary conditions. Comparisons between model results and observations show good qualitative and quantitative correspondence in mean temperature and heat flux profiles respectively at different distances from the coast. Maximum values of vertical velocity are well reproduced. Turbulent kinetic energy is found to be concentrated in the small updraft regions of the rolls, which is in accordance with observations from the MASEX-experiment.

AB - During cold air outbreaks, cold and stably stratified air masses are advected from land or ice surfaces over a warmer sea surface. Due to the heating from below, a convective boundary layer develops. For small fetches, convection is organized in the form of horizontal roll vortices, which at greater distances join in a zone with open or closed cells. The formation of the convective boundary layer, and the associated roll vortices, is simulated with a numerical model and results are compared with observations obtained during the MASEX experiment off the east coast of the United States. To validate the model, a comparison with a one-dimensional mixed-layer model is also made, with special attention given to the exact representation of the observed initial and boundary conditions. Comparisons between model results and observations show good qualitative and quantitative correspondence in mean temperature and heat flux profiles respectively at different distances from the coast. Maximum values of vertical velocity are well reproduced. Turbulent kinetic energy is found to be concentrated in the small updraft regions of the rolls, which is in accordance with observations from the MASEX-experiment.

UR - http://www.scopus.com/inward/record.url?scp=0025014090&partnerID=8YFLogxK

U2 - 10.1007/BF00119429

DO - 10.1007/BF00119429

M3 - Article

AN - SCOPUS:0025014090

VL - 52

SP - 349

EP - 375

JO - Boundary-Layer Meteorology

JF - Boundary-Layer Meteorology

SN - 0006-8314

IS - 4

ER -