Transport of heat, water vapor, and carbon dioxide by long-period eddies in the stable boundary layer

The transport of heat, water vapor and carbon dioxide in the stable boundary layer between 30 and 60 meters is examined with data from a tall tower in a complex landscape. Three stable nights characterized by a low-level jet with core between 300-500 meters above ground level were studied with a wavelet analysis of the wind speeds, temperature and mixing ratios.

All relevant quantities exhibited significant energy with periods of 30 min to 2 hours. Net transport was evaluated by comparing the flux in the planar fit coordinate system for an averaging period of >4 hours with one-hour averages, and with a wavelet analysis of the time rate of change of the layer-mean quantities.

It was found that net transport was significantly less than suggested by the covariances, but that eddies of 30-120 min periods were nevertheless significant contributors to the net transport. Transport at 30m was found to alternate between the behavior seen at 60m (long period, episodic)and continuous turbulence.