Spectral behaviour of a coupled land-surface and boundary-layer system

The temporal spectral response of a coupled land-atmosphere system to daily forcing of net radiation at the land surface is investigated using the analytic approach. The original definition of the problem dates back to an early study by Lettau. The present study builds on the problem and introduces some important additions, with a focus on the propagation of heat flux and temperature waves in both the soil and the atmospheric boundary layer. The study highlights the dependence of the complex amplitude of surface temperature and heat fluxes on the different land-surface parameters, such as friction velocity, evaporative fraction, aerodynamic resistance and vegetation height. Finally, the dependency of surface state variables to the frequency of the forcing is analyzed.