TRANSPORT OF HEAT, WATER VAPOR AND CARBON DOXIDE BY LONG PERIOD EDDIES IN THE STABLE BOUNDARY LAYER

Conference · Mon Jul 26 04:00:00 EDT 2010

OSTI ID:986349

Kurzeja, R

The vertical transport of heat and trace chemicals for a night in April has been studied with a wavelet analysis and conventional one-hour averages. It was found that for the night of April 20, 2009, turbulent kinetic energy, heat and trace chemicals were transported directed downward from the jet core. The most significant periods for this transport were less than 5 minutes and greater than one hour with intermittent transport taking place in the 5 min to 1 hour time frame. The nocturnal boundary layer is characterized by turbulent intermittency, long period oscillations, and a slow approach to equilibrium, (Mahrt, 1999). Although turbulence is usually maintained by surface friction, downward transport from low-level jets can also play an important role in turbulence maintenance and in the transport of scalars, Mahrt (1999), Banta et al. (2006). The eddy covariance flux measurement technique assumes continuous turbulence which is unusual in the stable boundary because significant flux transport occurs via turbulent eddies whose periods are long compared with the averaging time (Goulden et al., 1996). Systematic error in eddy flux measurements is attributed mainly to the neglect of long period eddies. Banta et al. (2006) noted that observations of turbulence below the low level jet suggested that while upward transport of turbulence kinetic energy (TKE) is common, downward transport from the jet can also occur. They found that in the CASES 99 experiments that turbulence scaled well with the strength of the low-level jet, and that surface cooling was more important than surface roughness. Because nocturnal turbulence is intermittent and non-stationary, the appropriate averaging time for calculation of TKE and EC fluxes is not obvious. Wavelet analysis is, thus, a more suitable analysis tool than conventional Fourier analysis.

• Research Organization: SRS
• Sponsoring Organization: DOE
• DOE Contract Number: AC09-08SR22470
• OSTI ID: 986349
• Report Number(s): SRNS-STI-2010-00459
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ATMOSPHERIC CIRCULATION
BOUNDARY LAYERS
CARBON DIOXIDE
HEAT TRANSFER
KINETIC ENERGY
MASS TRANSFER
METEOROLOGY
OSCILLATIONS
TURBULENCE
WATER VAPOR