The evapotranspiration in climate classification. In: Evapotranspiration/Book 2. ISBN 978-953-307-512-9

• Grant number: 11/07042-5
• Support Opportunities: Regular Research Grants - Publications - Books published abroad
• Start date: September 01, 2011
• End date: August 31, 2012
• Field of knowledge: Agronomical Sciences - Agronomy - Agricultural Meteorology
• Principal Investigator: Antonio Ribeiro da Cunha
• Grantee: Antonio Ribeiro da Cunha
• Host Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The evapotranspiration in climate classification. Authors: Antonio Ribeiro da Cunha e Edgar Ricardo Schöffel. Climate is the average atmospheric condition of a particular place or region, ranging from months to millions of years, being 30 years the classical period defined by the World Meteorological Organization. Second Köppen (1936) climate is "the sum of the atmospheric conditions that make a place the earth's surface more or less habitable for humans, animals and plants", while Thornthwaite (1948), "the interaction of meteorological factors that contribute to give the place its character and individuality". The World Meteorological Organization defines normal as "period averages computed for a relatively long period of at least three consecutive decades", i.e. "mean climatological data computed for the following consecutive periods of 30 years: 1 January 1901 to December 31 , 1930, 1 January 1931 to December 31, 1960, etc." (WMO, 1984). The climate classifications are intended the organize large amount of information to facilitate the rapid retrieval and communication, grouping items according to their similarities to provide an estimate of the climatic resources of a particular place or region, serving for various purposes. They simplify the climatic data of a place or region, provides a concise description of climate factors in terms of real assets (the which creates the local climate), provides a means by which the climatic regions can be accurately identified and can be used in global, local or micro scale, being the starting point for analyzing the causes of climate variations. The Köppen climate classification is relatively simple and very popular. It associates vegetation types with climate prevailing in the regions, taking into account the temperature and precipitation. Already the Thornthwaite classification is based on two major climate indices, moisture content and the annual potential evapotranspiration. The main difficulty in climate classification is related to the inadequacy of climatic data available, both in terms of surface coverage as in terms of duration and reliability. The climatic elements most frequently used to characterize the climate are the mean values of temperature and precipitation. It was made a review comparing the classification of Köppen and Thornthwaite. Through application examples was presented some differences between the classifications of Köppen and Thornthwaite. The locations was selected according to:: a) effect of altitude: Campos do Jordão (SP) and Santos (SP), b) effect of latitude: Boa Vista (RR) and Santa Maria (RS), c) effect of longitude: João Pessoa (PB) and Porto Velho (RO) and d) effect of ocean currents: Angra dos Reis (RJ) e Cabo Frio (RJ). The methodology describes how one should proceed to both classifications. The Köppen classification is still the most widely used despite its limitations, since it only depends on temperature and precipitation. The Thornthwaite classification seems more appropriate in the scope of its subdivisions and other climatic types according to temperature, precipitation and evapotranspiration (moisture factor), featuring more detail for a place or region, even using the estimated potential evapotranspiration according to the annual temperature variation and photoperiod, is still a more complete and comprehensive. Through the classification of Thornthwaite, when analyzing the deficiency or excess moisture, the concentration of thermal efficiency or potential evapotranspiration during the summer, allows climatic information more detailed from location - climate subtype, showing that Thornthwaite (1948) improved the climate classification system when introduced the water factor as a function of evapotranspiration and water balance. (AU)