Avaliação de modelos físico-matemáticos para estimativa da umidade relativa do ar e déficit de pressão de vapor a partir de dados de temperatura do ar

• Autor(a) principal: Delgado, Rafael Coll
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5289
• topic: Umidade relativa do ar; Déficit de pressão de vapor; Temperatura do ar; Air relative humidity; Vapor pressure deficit; Air temperature; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::AGROMETEOROLOGIA

Relative humidity (RH) air and vapor pressure deficit (VPD) have important role in agriculture, particularly in the sense of adapting a calendar of short-term agricultural activities such as pesticide application, daily evapotranspiration estimates for irrigation management, fire forecast, determination of leaf wetness duration etc. Minimum and maximum air temperatures of 18 conventional and 22 automatic weather stations were used to develop a predictive model of air relative humidity and vapor pressure deficit for the State of Minas Gerais. The objectives of this work were: a) to evaluate the applicability of physico-mathematical models to calculate (RH) and (VPD) from air temperature data in different Minas Gerais locations; and b) to analyze the spatialization of RH and VPD estimated by different methodologies, on hourly and daily basis. The Willmott s index of agreement, root mean square error, mean absolute error, seatter diagram and Pearson s correlation coefficient obtained from the moment-product method and linear regression analysis were used to evaluate how well the models fit the observed data. The models stood out for their effectiveness, mainly VPD and RH estimates, in comparison with data provided by the INMET automatic stations. The results of the models for vapor pressure deficit and relative humidity from conventional stations data were not very precise and there was strong indication of imperfect instrument calibration or even parallaxes errors and errors in values of daily relative humidity by inadequate reading and operation of the wet-bulb psychrometer ventilation system. Problems in conventional stations were also reported by other researchers using only minimum air temperature data in The United States. It was found an increase in the dependence of the variables air relative humidity and vapor pressure deficit on the altitude of the locations, for both conventional and automatic stations. The VPD3 and RH3 models showed, on average, better (r2) for all the conventional stations. The RH2, VPD1 and VPD4 models, in this order, showed better (r2) for all the automatic stations in Minas Gerais. However, the application of the studied models for estimating air relative humidity and vapor pressure deficit was proven to be also an important tools for the prediction of extreme situations of these variables. In addition, it was demonstrated that these methods for estimation of these meteorological elements can be used in locations where only maximum and minimum daily temperature data are available or even in sites with imperfect routine observations, considering the possible use of the models in estimating missing data of climatological series in the state of Minas Gerais.