The flux Richardson number R, (also known as the mixing efficiency) for the stably stratified atmospheric boundary layer is investigated as a function of the gradient Richardson number Ri(g), using data taken during two field studies: the Vertical Transport and Mixing Experiment (VTMX) in Salt Lake City, Utah (October 2000), and a long-term rural field data set from Technical Area 6 (TA-6) at Los Alamos National Laboratory, New Mexico. The results show the existence of a maximum R(f) (0.4-0.5) at a gradient Richardson number of approximately unity. These large-Reynolds-number results agree well with recent laboratory stratified shear layer measurements, but are at odds with some commonly used R(f) parameterizations, particularly under high-Ri(g) conditions. The observed variations in buoyancy flux and turbulent kinetic energy production are consistent with the concept of global intermittency of the atmospheric stable boundary layer.
Flux Richardson number measurements in stable atmospheric shear flows / E. R., Pardyjak; Monti, Paolo; H. J. S., Fernando. - In: JOURNAL OF FLUID MECHANICS. - ISSN 0022-1120. - STAMPA. - 459:(2002), pp. 307-316. [10.1017/s0022112002008406]
Flux Richardson number measurements in stable atmospheric shear flows
MONTI, Paolo;
2002
Abstract
The flux Richardson number R, (also known as the mixing efficiency) for the stably stratified atmospheric boundary layer is investigated as a function of the gradient Richardson number Ri(g), using data taken during two field studies: the Vertical Transport and Mixing Experiment (VTMX) in Salt Lake City, Utah (October 2000), and a long-term rural field data set from Technical Area 6 (TA-6) at Los Alamos National Laboratory, New Mexico. The results show the existence of a maximum R(f) (0.4-0.5) at a gradient Richardson number of approximately unity. These large-Reynolds-number results agree well with recent laboratory stratified shear layer measurements, but are at odds with some commonly used R(f) parameterizations, particularly under high-Ri(g) conditions. The observed variations in buoyancy flux and turbulent kinetic energy production are consistent with the concept of global intermittency of the atmospheric stable boundary layer.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
