Internal Wave and Turbulence Observations with Very High-Resolution Temperature Sensors along the Cabauw Mast

Knowledge about the characteristics of the atmospheric boundary layer is vital for the understanding of
redistribution of air and suspended contents that are particularly driven by turbulent motions. Despite many modeling
studies, detailed observations are still demanded of the development of turbulent exchange under stable and unstable conditions.
In this paper, we present an attempt to observationally describe atmospheric internal waves and their associated
turbulent eddies in detail, under varying stable conditions. Therefore, we mounted 198 high-resolution temperature (T)
sensors with 1-m spacing on a 200-m-long cable. The instrumented cable was attached along the 213-m-tall meteorological
mast of Cabauw, Netherlands, during late summer 2017. The mast has standard meteorological equipment at extendable
booms at six levels in height. A sonic anemometer is at 60 m above ground. The T sensors have a time constant in air of
ta ≈ 3 s and an apparent drift about 0.18C month21. Also due to radiation effects, short-term measurement instability is
0.058C h21 during nighttime and 0.58C h21 during daytime. These T-sensor characteristics hamper quantitative atmospheric
turbulence research, due to a relatively narrow inertial subrange of maximum one order of magnitude. Nevertheless,
height–time images from two contrasting nights show internal waves up to the buoyancy period of about 300 s, and shear
and convective deformation of the stratification over the entire 197-m range of observations, supported by nocturnal
marginally stable stratification. Moderate winds lead to 20-m-tall convection across weaker stratification, weak winds
to episodic ,10-m-tall shear instability across larger stratification.