Energy, Momentum and Mass Transfers Above Vegetative Surfaces

摘要

During the summer and fall of 1966 three comprehensive studies of energy, momentum, and mass transfers above a grass field were conducted at the Davis field site. Of the three studies, one was designed specifically to examine horizontal divergence under fairly strong advection, while the other two were made under essentially non-advection conditions. Chapter I provides information describing the conditions under which the studies were conducted. Included are general weather condition and plots of the energy balance components and leaf temperatures as well as air temperature and wind at 2 meters. A detailed analysis of flux-gradient relationships could not be started in time for inclusion in this report due to problems in programming outlined in Chapter V. Magnetic tapes were produced containing point-by-point data, 1/2-hour means and standard deviations in engineering units for all parameters measured. Chapter II provides a list of instrumentation used and includes detailed descriptions of the new instrumentation for sensing dry-bulb temperature and wet-bulb depression as well as soil temperature. Modification of an air sampling system for determination of 15-minute means of absolute humidity at eight levels is also discussed. An evaluation of wind instrumentation is discussed in detail. The remainder of the report is concerned with modifications in the data recording system, including a conversion from a punch card to an incremental magnetic tape output. Data management and data processing are also discussed. (Author)