for the estimates at regional levels. This could predict the estimates one month before the end of the harvest.

Resumo -O objetivo deste trabalho foi elaborar e testar modelos para a estimativa de rendimento de arroz irrigado, no Estado do Rio Grande do Sul. O estudo foi realizado com dados meteorológicos de temperatura mínima do ar, radiação solar global e dados de estatísticas agrícolas de rendimento de arroz irrigado, das seis regiões orizícolas do Rio Grande do Sul, referentes às safras 1982/1983 até 2005/2006. Foram feitas análises de tendência tecnológica dos rendimentos, e foram estabelecidos os indicadores agrometeorológicos para o ajuste de modelos de estimativa de rendimento de arroz irrigado, para o Rio Grande do Sul. Existe tendência tecnológica de aumento nos rendimentos de arroz irrigado no Estado. As variáveis meteorológicas avaliadas -dias com temperatura mínima do ar inferior a 15°C e radiação solar global -podem ser usadas como indicadores do rendimento de arroz irrigado. Os modelos agrometeorológicos elaborados para as seis regiões orizícolas e para o Estado do Rio Grande do Sul apresentam características de precisão, fácil implementação e baixo custo e podem, portanto, ser introduzidos ao programa nacional de previsão de safras.Termos para indexação: Oryza sativa, previsão de safras, radiação solar, temperatura mínima. Agrometeorological modelling of irrigated rice yield in Rio Grande do Sul, BrazilAbstract -The objective of this work was to elaborate and test models to estimate the irrigated rice yield, in Rio Grande do Sul State, Brazil. The study was carried out using meteorological data of minimum air temperature, global solar radiation and data of agricultural statistics about the irrigated rice yield, involving six rice production regions of Rio Grande do Sul, relative to crop years from 1982/1983 to 2005/2006. Analyses of yield technological tendencies were performed, and agrometeorological indicators for model adjustments of irrigated rice yields were established. There is a technological tendency of increasing the irrigated rice yield in the State. The analyzed meteorological variables -global solar radiation and days with minimum air temperature below or equal to 15°C -can be used as indicators of the irrigated rice yield. The adjusted agrometeorological models, elaborated for the six rice production regions and for the Rio Grande do Sul State, show characteristics of accuracy, easy implementation and low cost, which make them able to be introduced in the national program of crop forecast.

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O presente artigo descreve uma experiência de iniciação científica e desenvolvimento tecnológico: a construção de estações meteorológicas baseadas em hardware e software livres com vistasà formação de uma rede de ciência cidadã para monitoramento meteorológico e ambiental. O projeto de pesquisa e desenvolvimento conta com a participação de estudantes de diferentes níveis de ensino eáreas do conhecimento. Os resultados estão relacionadosà obtenção de medidas com o primeiro protótipo a partir da plataforma Arduino. Palavras-chave: ciência cidadã; instrumentação meteorológica. This paper reports an experience of scientific research and technological development: the construction of weather stations based on free hardware and software aimed at the formation of a citizen science network for meteorological and environmental monitoring. Students from different grade levels and subject areas are participating in this research and development project. The results are related to measurements with the first prototype from the Arduino platform.

Cyanobacterial blooms in marine and freshwater environments may be favored by shifts in physical water column parameters due to warming under climate change. The Patos Lagoon (PL), a subtropical coastal environment in southern Brazil, is known for recurrent blooms of Microcystis aeruginosa complex (MAC). Here, we analyze the variability of these blooms and their relation to changes in wind direction and speed, rainfall and freshwater run-off from 2000 to 2017. Also, we discuss both longer time-series of air temperature and rainfall and a review of local studies with microcystins produced by these noxious species. Since the 1980s, MAC blooms were associated to negative anomalies in annual precipitation that occur during La Niña periods and, in the last years (2001–2014), accompanied by a trend in low river discharge. MAC blooms were conspicuous from December to March, i.e., austral summer, with massive patches seen in satellite images as for 2017. We suggest that low rainfall and run-off years under NE wind-driven hydrodynamics might accumulate MAC biomass in the west margin of the PL system. In contrast, a positive, long-term trend in precipitation (from 1950 to 2016; slope = 3.9868 mm/yr, p < 0.05) should imply in high river discharge and, consequently, advection of this biomass to the adjacent coastal region. Due to the proximity to urban areas, the blooms can represent recreational and economic hazards to the region.