Uso da temperatura para cálculo do índice de seca de regiões produtoras de uva

Abstract

RESUMO-O Sistema de Classificação Climática Multicritérios Geovitícola (CCM), empregado na caracterização climática de regiões produtoras de uvas, é composto pelos índices Heliotérmico (IH), de Frio Noturno (IF) e de Seca (IS) sendo que este se baseia no balanço hídrico potencial do solo. Para se calcular os valores de IS, são necessários dados da precipitação pluvial e da evapotranspiração potencial (ETP), estimados pelo método-padrão de Penman-Monteith. Nem todas as regiões vitícolas, no entanto, apresentam as variáveis meteorológicas necessárias para o uso desse método. Daí a importância de métodos que permitem estimar a ETP com base apenas em dados da temperatura do ar, como o de Hargreaves. No presente trabalho, foram comparados os Índices de Seca calculados com base nos valores de ETP estimados, empregando-se os métodos de Penman-Monteith e Hargreaves, para diferentes regiões vitícolas do mundo. Foram utilizados dados climáticos de 83 estações meteorológicas, representativas de regiões vitícolas localizadas em 18 países. A equação de Hargreaves obteve um desempenho classificado como muito bom, podendo ser adotada no sistema CCM, quando não se dispõe de dados para o uso do método de Penman-Monteith. Termos para indexação: viticultura, videira, zoneamento climático. USING TEMPERATURE TO CALCULATE THE DRYNESS INDEX OF GRAPE PRODUCTION REGIONSABSTRACT -The Geoviticulture Multicriteria Climatic Classification System (CCM), used to characterize the climate in grape production regions, is composed by the Heliothermal Index (HI), the Cool Night Index (CI) and the Dryness Index (DI), which is based on the potential soil water balance. The calculation of DI values requires precipitation and evapotranspiration potential (ETP) data, estimated using the standard Penman-Monteith method. However, not all grape regions have the climatic variables required to use this ETP method. Therefore, it is important to use other methods to estimate ETP based only on air temperature available data, such as the Hargreaves ETP method. The present study compared the Drought Index values calculated using the Penman-Monteith and the Hargreaves methods for different grape growing regions of the world. Climate data from 83 meteorological stations were used, representing grapevine regions located in 18 countries. The Hargreaves equation achieved a very good performance and can be used in the CCM system in places where there are insufficient data for the Penman-Monteith method.

Estimating MCC System Dryness Index using the Vineyard Water Indicator

“…Climate data of 80 winegrowing regions in 18 countries were used [9]. The Dryness Index (DI) was calculated using the following expression [5]:…”

“…where "ETP" is the potential evapotranspiration (mm) calculated by the standard Penman-Monteith method [9]; k is the coefficient of radiation absorption by vine plant (k = 0.1 for the first month, 0.3 for the second month and 0.5 for the other months). "Es" was calculated using the expression:…”

Climatic water indices for viticulture

“…Climate data were obtained from the Geoviticulture Multicriteria Climatic Classification System (Geoviticulture MCC System) global database (Embrapa Uva e Vinho, 2018), from historical series of 30 years , corresponding to 82 wine-growing regions located in 18 countries: Argentina, South Africa, Australia, Brazil, Canada, Chile, Slovakia, Slovenia, Israel, Spain, France, New Zealand, Peru, Portugal, Switzerland, Tunisia, Turkey, and Uruguay. According to the Geoviticulture MCC System, these regions have climatic classes ranging from humid to very dry conditions (Conceição et al, 2012), making it possible to obtain a high variability of water indices.…”

“…Mi Wo + Pm -Tv -Es in which: Σ is the mathematical summation symbol; Wo is the initial soil-water storage, in mm; Pm is the monthly rainfall, in mm; Tv is the monthly potential vineyard transpiration, in mm; Es is the monthly soil evaporation, in mm; and Mi and Mf are the initial and final months of the grapevine cycle, corresponding respectively to the months of April and September in the Northern Hemisphere, and to October and March in the Southern Hemisphere. Tv was calculated using the expression Tv = ETPm × k, in which: ETPm is the potential monthly evapotranspiration (mm), estimated by the standard Penman-Monteith method (Conceição et al, 2012); and k is the coefficient of radiation absorption by the vines. The Es was estimated by the expression Es = (ETPm/Nm) × (1-k) × JPm, in which: Nm is the number of days of the month; and JPm is the number of days per month of actual soil evaporation.…”