Momentum and mass transfers in the surface boundary layer

Turbulent fluctuations in COz concentrations over a paddy field are measured by a fastresponse device with an open sensing path. This IR device coupled with a sonic anemometer constitutes an eddy correlation instrument to measure CO1 fluxes. Three experiments were conducted in the surface layer over paddy 90 cm high. The stability (z -d)/L ranged from -0.14 to 0.20, where L denotes the Monin-Obukhov length.COz power spectra show the range of applicability of the -2/3 power law to be between f = 0.2 and f = 2, where f is the frequency normalized by wind speed and height. The cospectral estimate between CO2 and vertical component of wind speed ranging from f = 0.005 to f = 2 shows a peak at about f = 0.15 under near-neutral stratification.Hourly means of CO* flux measured by the eddy correlation method increase with intensity of net radiation. The maximum value of downward flux of CO* rises to 0.6 mg cm-* hr-' over the paddy field at the stage of ear emergence.Some turbulence statistics relating to the CO2 transport are evaluated: the correlation coefficient between CO2 and vertical velocity is about -0.3, and that between CO* and humidity attains -0.7 --0.8 under unstable stratification; nondimensional gradients 4, for CO* and ~5, for wind speed are 0.89 and 0.99, respectively.

Section: Turbulence Statisticsmentioning

confidence: 99%

“…Some turbulence statistics relating to CO* transport are discussed. The nondimensional gradients += for CO2 and & for u are calculated and the ratio &,/4c is compared with the ratio &,/4w given by Pruitt et al (1973), where &,, is the nondimensional gradient of specific humidity.…”

Section: Introductionmentioning

confidence: 99%

Turbulent transport of carbon dioxide over a paddy field

Ohtaki

1980

“…Therefore, generalization about flux-gradient relations under near neutral conditions is well established, although some uncertainties still remain. Under stable conditions, flux-profile relationships are reported by McVehil (1964), Webb (1970), Businger et al (1971), Pruitt et al (1973) and Hicks (1976). For unstable conditions, the flux-profile forms are outlined in the papers by Ellison (1957), Yamamoto (1959Yamamoto ( , 1975 Panofsky et al (1960), Swinbank (1964Swinbank ( , 1968 Sellers (1962), Dyer and Hicks (1970), Businger et al (197 l), Hicks (1976) and Lettau (1979).…”

Section: Introductionmentioning

confidence: 99%

Examination of the empirical flux-profile models in the atmospheric surface boundary layer

Viswanadham

1982

“…In Figures 1 and 2, the behaviour of the velocity and temperature profiles in the constant flux region are compared with data collected by Pruitt et al (1973). The velocity and temperature gradients are universal functions of the Monin-Obukhov length scale L and can be described by the dimensionless parameters: …”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…Relationships for $M (Equation(26)) collected byPruitt et al (1973) and calculations by presentmodel. Data: (A) Webb (t965), Panofsky (1963); (A)Swinbank (1968); (V)Businger etai.…”

mentioning

confidence: 99%

A turbulent energy model for geophysical flows

Hassid

Galperin

1983

A simple turbulent flow model for geophysical flows is presented, which is based on the transport equation for turbulent energy and on algebraic expressions relating the Reynolds stress and turbulent heat flux to the velocity and temperature gradients. The model, which is similar to the 2.5 level closure model of Mellor and Yamada, includes constraints based on the realizability conditions as well as expressions for the length scale which account for the influence of stratification and the Coriolis acceleration. The model is shown to reproduce satisfactorily the main features ofexisting laboratory measurements of stress-induced and convective turbulent entrainment in stratified flows.