Analysis of turbulent exchange and coherent structures in the stable atmospheric boundary layer based on tower observations

• We examined stable boundary layer data to extract intermittent turbulent episodes.
• We analyzed the coherent structures related to intermittent turbulent events.
• Wavelet method permits to separate the different scales presents in the atmosphere.
• Wavelet method highlights the role of the different scales in the scalar transfer.

Using data collected at the Spanish low troposphere research centre CIBA (Centro de Investigación de la Baja Atmósfera) and at the Cabauw Experimental Site for Atmospheric Research (CESAR) in the Netherlands, we analyzed the most significant features of different coherent structures occurring in the stable atmospheric boundary layer. In particular, we used both the Reynolds and wavelet methods to analyze a solitary wave, a gravity wave, a density current and a low-level jet. For each of these structures, we found that wavelet analysis had the capacity to distinguish the different scales involved in these events due to the different timing and heights of the thermal instabilities and downdrafts associated with the disturbances. In addition, the wavelet method highlights the different roles of turbulence and coherent structures in the transfer of heat, moisture and CO2 in the nocturnal boundary layer.