A new international law has opened 41 million previously unavailable readings from weather stations in eight countries, revealing a little-used sensor channel that could sharpen forecasts of heat and frost. The Open Instrument Accord took effect on Sunday in France, Kenya, Chile, Portugal, Ghana, Japan, Uruguay and New Zealand, requiring public agencies to release data from publicly funded environmental equipment.
The first archive, published at midnight, covers six years of measurements from 3,200 stations. Researchers say a hidden infrared channel in many units recorded the temperature of the surface below and the open sky above. Early comparisons suggest some city and farming districts stay warm at night 2.1°C (3.8°F) longer than conventional forecasts indicate.
The sensor behind the surprise
The readings were not secret in the sense of being deliberately concealed, said Camila Carvalho, a climate analyst at the fictional Lumen Earth Lab. The sensors were built into instruments used for frost alerts, but their secondary measurements were filed as diagnostics and rarely passed on to research teams. “We had a second pair of eyes on the night sky and left them pointed at the floor,” Carvalho said.
Researchers compared the infrared records with standard air-temperature readings and cloud observations. In a sample of 620 agricultural and urban sites, the ground stayed warmer than the air for an extra two hours on 28% of clear nights. That gap matters: forecasts based on air temperature alone can miss when crops remain vulnerable to frost, or when built-up areas keep releasing heat after sunset.
Philippe Leconte, an atmospheric physicist advising the accord’s data panel, said the pattern is worrying because warmer nights can stress crops and raise demand for cooling. “If a forecast says the danger has passed while the ground is still holding heat, farmers and city planners are making decisions with half the picture,” he said. He cautioned that the early analysis does not yet show how much the effect is changing over time.
From archive to useful forecasts
The accord’s rules require public agencies to share measurements collected with public money, but do not force private operators to reveal commercial data. Eight governments agreed to common file formats and a 30-day release window, a practical choice intended to let research teams compare readings across borders without replacing their existing monitoring systems.
Sandra Farina, a crop-weather specialist who helped test the archive, said the extra channel could improve frost warnings for small farms that cannot afford their own instruments. The readings could also help city councils identify neighbourhoods where night-time heat persists. Her team plans to publish a larger comparison in February, after checking the raw records against sensors calibrated independently.
The gap in coverage remains substantial: the first release includes only publicly supported stations, and older instruments may never have recorded the additional readings at all. But the new law gives researchers a way to spot missing data rather than mistake silence for a cool night. For Carvalho, that is a useful start: “The surprise is that the measurements were there. Now we can put them to work.”
