Time Series Analysis Of Transport Processes And Estimation Of Transfer Resistance Within And Above A Crop Canopy

The changes in speed of agriculture, meteorological and ecological processes arethe results of the interactions between vegetation and atmosphere. Photosynthesisand transpiration are processes in which heat, water vapor and mass are beingtransported between vegetation and atmosphere. The processes are driven or affectedby meteorological and environmental factors like solar radiation and wind, the ratesof transport of heat, water vapor and CO2 absorbed by plant change the regional orglobal climatic mode. Since the resistance to transport is highly variable, and isaffected by physiological and water conditions in different ways in different parts,the quantitative estimation of it is needed in predicting the rates of photosynthesisand transpiration, and the ratio between them, the water use efficiency. Land surfacefluxes are non-linear and non-stationary stochastic variables. The analysis of thespectral properties of time series of land surface fluxes and the estimation of transferresistance are the main content of this thesis.1. Continuous wavelet transform and discrete multi-resolution analysis of surface fluxes and atmosphericstabilityVariations of land surface fluxes of sensible heat (H), latent heat (LE), and CO2(F-CO2) obtained from the eddy-covariance measurements above a winter wheatfield from March 30 to April 24, 2001 were studied at scales ranging from 10 minutesto days. Atmospheric stability ? (? = z/L) and three non-dimentional coefficients(T/T*, q/q* and c/c*) were also calculated from the eddy covariance measurements.Wavelet transform was used in the analysis of land surface fluxes and atmosphericstability, to reveal the changes in land surface fluxes at hours to days scales. Themain results are: (1) Concise and compact information about the fluxes, net radiation(Rn), temperature (T) and ? in the scale-time domain were extracted from the data bycontinuous wavelet analysis, and 1d, 0.5d and short-period (less than 0.5d)components were revealed. Continuous wavelet coefficients were used tocharacterize periodic components of changes in fluxes and ? . (2) Discrete-timemulti-resolution analysis was used to concentrate total energy variance of time seriesof the measurements to a small number of coefficients, plotting the relative energydistribution to get several meaningful characteristics of the data. (3) Under neutralatmospheric conditions, the relative energy distributions of the Haar multi-resolutionanalysis of the three non-dimensional coefficients (T/T*, q/q* and c/c*) displayedclear similarities.2. The use of infrared thermometry in the estimations ofleaf surface effective wind speed and boundary layerresistance within a maize canopy Infrared thermometric observations of leaf surfaces and measurements ofmicroclimatic variables were made at three heights within a maize canopy every 2hin daytime in summer. Infrared photographs of leaves at different heights in a maizecanopy were taken from which surface temperature distributions over the leaveswere obtained. By reversing the relation between wind speed, boundary layerresistance over leaf surface, and partition of radiation energy into sensible and latentheat obtained in wind tunnel experiments under laminar flow, the vertical...