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- Author or Editor: James Harrington x
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Abstract
Long dry spells (sequence of dry days) are rare events, but they are important because they correlate significantly with the area burned during bad wildfire years. Previous attempts to model the frequency of dry spells have been successful for spells of short duration, but have failed for prolonged dry spells.
In the current study, an empirical method has been developed that yields a realistic estimate of the probability of a spell of any duration. The theoretical framework proposes that the data can be explained partly by the dichotomy of weather into blocked and nonblocked westerly flows. A bimodal distribution of dry consecutive days is a consequence of this dichotomy.
The transitional probability of a dry day following k dry days generally pub at k = 1, declines to a shoulder for small k values, and then rises slowly to an asymptotic value that must be estimated from sparse and highly irregular data.
Abstract
Long dry spells (sequence of dry days) are rare events, but they are important because they correlate significantly with the area burned during bad wildfire years. Previous attempts to model the frequency of dry spells have been successful for spells of short duration, but have failed for prolonged dry spells.
In the current study, an empirical method has been developed that yields a realistic estimate of the probability of a spell of any duration. The theoretical framework proposes that the data can be explained partly by the dichotomy of weather into blocked and nonblocked westerly flows. A bimodal distribution of dry consecutive days is a consequence of this dichotomy.
The transitional probability of a dry day following k dry days generally pub at k = 1, declines to a shoulder for small k values, and then rises slowly to an asymptotic value that must be estimated from sparse and highly irregular data.
Abstract
Power spectra of mesoscale eddies with periods ranging from 10 min to 8 hr were computed for the months of January and July from three years of surface wind data obtained at Columbia, Mo. To educe the degree of determinism in the spectra, their variability with time of year, time of day, wind speed and direction, and with the presence or absence of thunderstorms was measured.
Diurnal spectra for January and July were found to be similar. A comparison of semidiurnal daytime and nighttime spectra showed that the former contained considerably more energy than the latter and that the difference was greater in July than in January. The eddy energy was shown to increase by a factor of approximately 7 at night in the presence of thunderstorms. No effect of wind direction could be found.
Over a large portion of the lower mesoscale range the diurnal power spectra followed a −1 law, similar to that for “wall turbulence” in the layer of strong shear in the boundary layer over a flat plate.
Abstract
Power spectra of mesoscale eddies with periods ranging from 10 min to 8 hr were computed for the months of January and July from three years of surface wind data obtained at Columbia, Mo. To educe the degree of determinism in the spectra, their variability with time of year, time of day, wind speed and direction, and with the presence or absence of thunderstorms was measured.
Diurnal spectra for January and July were found to be similar. A comparison of semidiurnal daytime and nighttime spectra showed that the former contained considerably more energy than the latter and that the difference was greater in July than in January. The eddy energy was shown to increase by a factor of approximately 7 at night in the presence of thunderstorms. No effect of wind direction could be found.
Over a large portion of the lower mesoscale range the diurnal power spectra followed a −1 law, similar to that for “wall turbulence” in the layer of strong shear in the boundary layer over a flat plate.
Abstract
A mathematical model is developed to predict the microclimatic modification of air near the ground by the evaporation of an ultrafine water mist. The model equations with realistic parameters and boundary values are solved using the Patankar and Spalding control volume integral technique. The reported field experiment provides reasonable preliminary confirmation of the model. The maximum predicted cooling under the conditions tested is −14.6°C.
Abstract
A mathematical model is developed to predict the microclimatic modification of air near the ground by the evaporation of an ultrafine water mist. The model equations with realistic parameters and boundary values are solved using the Patankar and Spalding control volume integral technique. The reported field experiment provides reasonable preliminary confirmation of the model. The maximum predicted cooling under the conditions tested is −14.6°C.
