Database INMET's for 54 conventional stations in Brazil

Wind speed data are collected from INMET's network of conventional stations and made available by the project “Meteorological Database for Teaching and Research (BDMEP)” ( https://bdmep.inmet.gov.br/ ). Originally, data were collected at 3 synoptic times (0000, 1200, and 1800 UTC) and then averages of these three times across the database were calculated. Therefore, the temporal sampling of the analyzed series is daily, and the period of analysis was 60 years, starting on January 1, 1961, and ending on December 31, 2020.
Among the existing multiple imputation techniques, the bootstrap expectation maximization (EM) algorithm was chosen, which imputes the missing observations by estimates generated by the EM algorithms implemented in several bootstrap samples of the data. To assess the quality of the imputed data, the data set from each station was divided into 3 groups according to the percentage of missing data: Group 1 (0-10%); Group 2 (11-20%); Group 3 (21-30%). The evaluation of the imputation method was carried out through descriptive analysis, using the boxplot graph and measures such as minimum, maximum, first and third quartile, median, mean and standard deviation.
To verify equality between the means and medians of the imputed faulty data, Student's t tests and Wilcoxon were used, respectively. When the p-value associated with each test was greater than the significance level, the equality hypothesis was rejected. Both tests were performed at a 5% significance level. For the analysis of a comparison between the two climatologies, only the data referring to the meteorological stations in which the statistical tests detected equality of means and medians between the imputed and faulty data were used.
We applied a filter to exclude time series with a number of failures greater than 30%, leaving, therefore, 54 weather stations. The states of Acre (AC), Rondônia (RO), Amapá (AP), Mato Grosso do Sul (MS), Alagoas (AL), Espírito Santo (ES), Piaui (PI), Pernambuco (PE), Alagoas (AL) and Santa Catarina (SC) do not have meteorological stations that passed the criteria established in the study.