Frequência de observação de variáveis micrometeorológicas em doséis de canola

Abstract

The purpose of this work was to characterize the micrometeorological variables measured in canola tests and identify the minimum frequency of observation of them. The experiments were conducted at UFSM, with cv. Diamante in the years 2018 and 2019, under the experimental design of randomized blocks, in a 2x4 bifactorial, with the treatments consisting of the interaction of two surface soil drainages (with and without) with four spacings between the sowing lines (0.17; 0.34, 0.51 and 0.68 m), with four repetitions. Photosynthetically active radiation (PAR), PAR interception efficiency, radiation balance, air temperature, relative air humidity and wind speed were measured and stored at reading intervals every 30 seconds. The databases were composed only of days that presented 2,880 daily observations. Named Database 1, created by days with and without rain and named Database 2, composed only of days without rain. From the measurement, 27 dissimilar frequencies of observations were simulated for each micrometeorological variable, descriptive analyzes were carried out, the model assumptions were tested and the minimum observation frequency was identified using the Hierarchical Agglomerative Method of the furthest neighbor, for the two databases. Statistical analyzes were carried out using the R software, adopting an error probability level of 5%. It was found that the simulated frequencies follow the pattern of frequency 1, in which checks are every 30 seconds, with the exception of frequencies 24 (punctual observations once a day, at 0 o'clock) and 26 (punctual observations once a day, at 12pm). In both databases, the partial pressure of water vapor is higher in the upper stratum of the canola canopy, as is the air temperature. The intercepted RFA has the same profile regardless of the factors used and the RFA interception efficiency is greater at intermediate spacings (0.34m and 0.51m). The highest radiation balance was found in database 2, where days with recorded precipitation and highest wind speeds in the upper stratum of the canopy were removed, and in database 1, which took into account all days of comments. For both databases, with the formation of 14 clusters, the minimum frequency identified is occasional observations every 8 hours, starting at midnight. The partial pressure of water vapor is greater in the upper stratum of the canola canopy, as are the air temperature and wind speed. The intercepted RFA has the same profile regardless of the factors used and the RFA interception efficiency is greater at intermediate spacings (0.34m and 0.51m). The highest radiation balance was found in database 2, from which days with recorded precipitation were removed. For both databases, with the formation of 14 clusters, the minimum frequency represented is exact observations every 8 hours, at 0 hours.