Important observed characteristics of the pre-storm atmospheric environment are often related and sometimes forced by surface features. Gibson and vonder Haar [1990] use visible and infrared (hourly) imagery from geostationary satellites to discern the diurnal cycle in precipitation. For their study region, maximum cloud cover over land occurs at 1400 hours local time but the maximum convection is delayed by an hour. The convective activity is shown to possess strong relation to small terrain features. Steep terrain coincide with cloudiness maxima and mountain (valley) breeze is evident in the diurnal dynamics of this phenomenon.
Betts and Ball [1994] analyze the diurnal growth of the atmospheric boundary layer and link some of its key features to the land surface coupling. They show that strong local interaction on the diurnal time scale and regional coupling on the seasonal time scale are possible. Betts and Ball [1994] show that the diurnal cycles of the atmospheric boundary layer potential and equivalent potential temperatures (potential temperature is conserved under adiabatic displacement of air; equivalent potential temperature is defined such that it is additionally conserved under saturated-adiabatic processes) as well as the specific humidity depend on both soil moisture and potential temperature entrainment at boundary layer height. The latter is in turn partly determined by the magnitude of turbulence generated by the thermals rising from the heated surface. For example, wet soil conditions force higher maximum equivalent potential temperatures, reduced dry air entrainment and eventually greater cloudiness and precipitation potential. Blyth et al. [1994] consider additional effects of surface conditions on the formation precipitation. At a field experiment in southwest France (the HAPEX-MOBILHY, [ André, 1986]), they show that the surface roughness due to the presence of tall forest trees is an important mechanical forcing. Furthermore the negative sensible heat flux at the surface due to the formation of a stable atmospheric profile over the moist forested site provides additional energy for an enhanced latent heat flux during low radiative forcing conditions. Generally Blyth et al. [1994] find 30% more precipitation over the forested surface when compared to bare soil.
The communication of surface influence (albedo, heat capacity, soil capillary and vegetation control) on surface heat flux and their partitioning into sensible and latent heat is through the atmospheric boundary layer. The turbulence in this part of the near surface atmosphere both responds to the surface conditions as well as modifies them. For this reason Garratt [1993], in his review of the treatment of the land surface boundary in climate models, places special emphasis on the coupling of soil hydrology and atmospheric model climate through the boundary layer formulations. Similarly Jacobs and de Bruin [1992] show that the feedback mechanisms imbedded in the dynamics of the boundary layer significantly enhance the sensitivity of surface evapotranspiration to parameters such as albedo and factors such as available energy.