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Chuva Online

Mapping the rain in São Paulo

Image of a rainy afternoon: the color spectrum shows rainfall intensity, ranging from blue (light) to red (heavy)

Image of a rainy afternoon: the color spectrum shows rainfall intensity, ranging from blue (light) to red (heavy)

The colored dots on the screen herald the rain so anxiously awaited by the denizens of São Paulo in recent months. The image, which is publicly available at, is the result of a joint effort by the University of São Paulo (USP) and the meteorology company Climatempo. With the help of two meteorological mini-radars installed on diametrically opposing sides of the city (one in the Cidade Universitária campus and one at USP Leste), viewers can see where the rain is falling – updated every 5 minutes – across much of the São Paulo Metropolitan Region.  The image has a resolution of 90 meters, the highest available in Brazil. “At the level of detail indicated by this resolution, if it’s raining hard at one point along a given street, we can distinguish that from the amount of rainfall 90 meters further along that same street,” says Professor Carlos Morales from the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) at USP, coordinator of the Chuva Online (“rain online”) project. Morales says that the radar equipment was purchased from an Italian company, each costing R$300,000 (one paid for by USP and the other by Climatempo). He explains that USP developed the software used for data analysis, particularly for weather events, when it measures levels of rainfall and hail. This data can be cross-referenced with reported flooding incidents across the city. The two radar devices are already connected to the city’s civil monitoring and defense systems and will also be important for use by professors in teaching meteorology and for very short-notice weather forecasts.  A third device is in the pipeline for installation at Água Funda Park, where IAG maintains a weather station, across from the São Paulo Zoo.