Rodolfo A. de Guzman
The development and structure of the axisymmetric tropical cyclone is investigated using theoretical and numerical approaches. The relationship of the distribution of the diabatic heating to the growth of the system is a focal concern of this study. Firstly, an axisymmetric model of the free atmospheric circulation of a tropical cyclone in steady state is developed. The sensitivity of the transverse circulation and heating distribution to the specification of the spatial distribution of the prescribed vortex flow and the vertical velocity at the top of the boundary layer is discussed. Using a momentum integral boundary layer treatment, the model response to specified tangential wind distributions is evaluated as well. Also, the scale selection role of the amplitude and vertical partitioning of the diabatic heating within a CISK framework is demonstrated. In particular, the development of a disturbance with typhoon-like characteristics is shown analytically and numerically to be possible when the heating profile has a low-level maximum. In the numerical model, this development occurs without using a balanced vortex as initial condition. The effects of the differences between the treatments using an analytical Ekman-CISK model and a primitive equation numerical model is elaborated upon. Comparison with pertinent observational studies reveals some of the realistic features of our model results.
Rodito D. Buan
An attempt was made to understand how the amount/intensity and distribution pattern of the weather parameters at different stages of growth affect the sugarcane yield. The mathematical model and system used appear to be sufficiently for practical purposes, giving an objective information which is far better than subjective guesses made in the past about the effects of weather on sugarcane yield. The second degree multiple regression equation was employed in an attempt to quantify the relationship between sugarcane yield and meteorological parameters. The results showed that sugarcane reacts differently to climatic parameters during different stages of development. The resultant response is manifested in the final yield. Above average weekly total rainfall had a favorable effect on yield during emergence, but a markedly reduced effect during tillering to maturity. Above average maximum temperature depressed yield during the emergence and in the last part of the ripening stage to harvest; however, a markedly favorable effect during the three-fourths to full canopy or during the later part of tillering through elongation stages. Above average minimum temperature had a favorable effect of the growth stages of sugarcane except, during the later part of ripening to harvest. Above average weekly total sunshine duration had varying degrees of favorable effects on the growth of sugarcane from emergence to maturity. Beneficial effects of a low magnitude was observed during early emergence and late maturity, while maximum favorable effect was observed during the elongation period. This is because the elongation period coincides with the peak monsoon period whereby cloudiness reduces sunlight-an element very much needed by the crop at this stage; while low magnitude effect of sunshine during early emergence and late maturity might be due to too high sunshine intensities during this period. Above average weekly total solar radiation depressed yield during emergence period while favorable effect was observed for the subsequent stage. The peak beneficial effect was observed during the elongation stage which coincides with the effect of sunshine duration. Generally, sugarcane was observed to be more sensitive to climatic variables used in this study during emergence, elongation and ripening stages. The use of the "Selected Development Stages" method to predict sugarcane yield gave relatively better results as compared to the second degree multiple regression equation model. The reason for this may attributed to the consideration given to the effects of the interaction among variables. Nevertheless, the multiple correlation coefficients cannot be considered significant owing to the limited period of data utilized. Its performance is, however, better than the first model in predicting the final yield of sugarcane. The "selected development stages" method will be very useful in predicting yield of sugarcane, with a lead time of about two to three months before harvest. The results of this study show that a reliable scheme for forecasting sugarcane yield well in advance of harvest is feasible, using selected weather parameters as predictors.
Teresita S. Laudet
This study aimed to determine the growth and development response of winged bean and its microclimate; as monoculture and as intercropped with corn and with ampalaya. The methodology involved planting of winged bean under simulated conditions of short (11 hours), normal (12 hours) and long (13 hours) day length and as monocrop and intercrop with corn and with ampalaya. As intercrop, the microclimate of winged bean is modified. The statistical analysis made use of strip-plot in randomized complete block design. Comparison of treatment means was made during the least significant differences (LSD) test.