Methodology
public data from official agencies, explained simply. This page covers what applies to the whole site; each section has its own rules in a block at the bottom.
First of all
Where the data comes from
Every figure shows where it came from. These are the sources and the license or terms of use of each.
| Source | What we use | Terms |
|---|---|---|
| INPE · Fire Program | Heat spots every 10 minutes and official statistics since 1998 | INPE open data |
| NASA FIRMS | Fire intensity (radiative power) | NASA data, with registration and credit |
| INMET and Civil Defense (IDAP) | Official severe-weather and risk warnings | Open data, CAP protocol |
| CEMADEN | Rain measured by rain gauges | Access by registration |
| ANA | River levels (telemetry) and the Drought Monitor | River levels: access by registration (HidroWebService). Drought Monitor: open data |
| SGB · SACE | Official attention, alert and flood reference levels for rivers | SGB public data |
| ONS | Energy stored in reservoirs | CC BY (open data) |
| NOAA · CPC | RONI, ONI, Niño regions and the monthly El Niño bulletin | US public data |
| Open-Meteo | Forecast (daily and hour by hour), air quality (CAMS) and rain (ERA5) | CC BY 4.0, non-commercial use |
| OpenAQ | Air quality monitoring stations | Open data, credit to the networks |
| Agência Brasil (EBC) | Title, summary, image and link of news stories | CC BY 4.0 |
| IBGE | Municipalities, states and the 2022 Census | IBGE open data |
| OpenStreetMap, via OpenFreeMap | Place and street names on the map | ODbL, © OpenStreetMap contributors |
| EOX · Sentinel-2 cloudless | Satellite imagery for the map (contains modified Copernicus Sentinel data) | CC BY-NC-SA 4.0, non-commercial use |
| Natural Earth | Country borders and river lines on the map | Public domain |
How each page calculates
Each page ends with the block “Where the numbers come from and what they do not say”, with the details. Here is a summary of each one.
The hotspot count is INPE's official one, only with hotspots in Brazilian municipalities. A “likely” hotspot was seen by 2 or more satellite passes about 2 km apart within 36 hours, or has high confidence or an intensity of 20 MW or more (NASA FIRMS). A heat spot is not a confirmed fire.
The map is the Drought Monitor's (ANA), monthly, with categories D0 to D4; the percentage is always over the monitored municipalities. Days without rain and rain against normal use the 1991–2020 ERA5 average.
The index is Brazil's official IQAr, calculated on the CAMS model (Open-Meteo) for the 100 largest cities and, where they exist, on real measurements from OpenAQ stations. A model is not a measurement.
Warnings are INMET's and Civil Defense's, as published. Measured rain comes from CEMADEN rain gauges and the 7-day and hour-by-hour (3-day) forecast from Open-Meteo. Heavy rain is 50 mm or more a day; extreme, 100 mm or more.
Each station is compared with itself at this time of year since 1990: drought is a level in the lowest 10%, high water in the highest 10% and alert in the highest 2%. When the SGB publishes official attention, alert and flood levels, they apply. The range for the coming days is statistical, not an official forecast.
The main index is NOAA's RONI (the traditional ONI appears alongside). An El Niño event is 5 or more consecutive seasons at +0.5 ºC or more, as NOAA defines it.
Only Agência Brasil, with title, summary, image and link. Each story gets topics by keyword; highlights cross a topic that is high in the data with a story from the last 3 days.
A city page puts together what exists for the municipality: official warnings that mention it, Drought Monitor status, likely hotspots and rain gauges within 50 and 30 km, the nearest rivers and, for weather and air, the nearest tracked city (up to 100 km). The week highlights are the extremes of the 7-day forecast; recent rain, the month's normal and the 1991–2020 extremes come from the ERA5 reanalysis (a model on a grid of about 25 km), so they are neither measurements nor official station records.
Updates and history
Limits