Using data from the CASES-97 experiment, we discuss the factors influencing the late-morning evolution of temperature and water vapor for two cloudless fair weather days, one with partially- dried out ground, and one with a very wet surface. The heat and moisture budgets are based on 8-10 eddy-correlation surface flux stations placed according to land use as well as geographically (surface fluxes and surface conditions), 915 MHz wind profilers (winds and boundary-layer depth), radiosondes (horizontal advection), and aircraft (vertical flux divergence, horizontal advection, time evolution). Because the boundary layer evolves rapidly with time, we try two techniques to calculate the vertical flux divergence. Data from the nearby S-Pol radar and the synoptic network will be used to check some of the budget terms.
For the water vapor budget, the time trend seems to be roughly balanced by vertical flux divergence and horizontal advection by late morning. For the heat budget, however, the budget does not balance and additional sources of warming are needed. We will estimate the contributions of radiation and vertical subsidence, the most likely candidates for the imbalance.